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	summary
	description	Referring initially to FIG. 2, an imaging system in accordance with the present invention is shown and generally designated 10. As shown in FIG. 2, the system 10 includes an X-ray source 12 configured to produce a spectrum of X-ray radiation 14. An optional collimator 16 may be provided to collimate the radiation 14 emitted from the X-ray source 12 into one or more beams 18a-c. As such, each beam 18 emanates from the X-ray source 12 in a slightly different direction, and consequently, along a separate path 20a-c. It is to be appreciated that the use of three beams 18 is merely exemplary and that as many beams 18 as desired may be used in accordance with the present invention. In detail, as shown in FIG. 2, beam 18a initially travels substantially along path 20a, beam 18b initially travels substantially along path 20b and beam 18c initially travels substantially along path 20c. Referring still to FIG. 2, a detector array 22 is shown positioned to receive the beams 18 from the source 12. Specifically, the detector array 22 is shown having three detectors 24a-c, with detector 24 a positioned to receive beam 18a, detector 24b positioned to receive beam 18b and detector 24c positioned to receive beam 18c. For the present invention, an object 26 can be interposed between the X-ray source 12 and the detector array 22 to thereby allow the beams 18 to be modified by passing through the object 26 before reaching the detectors 24. In accordance with the present invention, the detectors 24 can be any type of detector known in the pertinent art capable of receiving radiation and producing an electrical signal that is proportional to the intensity of the radiation received. For example, the detectors 24 can be solid state detectors (separate or having a charge couple detector structure), gas-filled detectors or scintillators with photo-multipliers. Preferably, each detector 24 is a small-area X-ray detector. For the present invention, the output of each detector 24 is electrically wired to a computer (not shown) to allow the signals generated by the detectors 24 to be processed. Also shown in FIG. 2, the X-ray source 12 can be slideably mounted on a circular track 28 that extends around the object 26. Additionally, as shown, each detector 24 or the entire detector array 22 can be slideably mounted on the track 28. As such, the X-ray source 12 and detectors 24 can be moved either continuously or incrementally around the track 28 and relative to the object 26. The dashed lines in FIG. 2 show an exemplary second position for the X-ray source 12 and detectors 24. By moving the X-ray source 12, each radiation beam 18 emanating from the X-ray source 12 can be caused to successively travel on different paths 20 through the object 26. For example, as shown in FIG. 2, when X-ray source 12 is in the initial position represented by the solid lines, beam 18 a travels substantially along path 20a, and when X-ray source 12 is moved to a second position represented by dashed lines, beam 18a travels substantially along path 20d. Similarly, beam 18b travels substantially along path 20e and beam 18c travels substantially along path 20f when the X-ray source 12 is in the position indicated by dashed lines. Accordingly, the detector array 22 can be moved in conjunction with the X-ray source 12 to allow each detector 24 to track a single X-ray beam 18, as that X-ray beam 18 travels on successive paths 20 through the object 26. An important aspect of the present invention is that the X-ray radiation 14 is filtered between the X-ray source 12 and the detectors 24. By cross-referencing FIGS. 2 and 3, it can be seen that a wheel 30 having two attached filters 32, 34 can be used to successively filter each X-ray beam 18a-c on each path 20. As further shown, a motor 40 having a shaft 42 can be used to rotate the wheel 30 and filters 32, 34 to successively filter each beam 18 twice while the beam 18 travels substantially along a single path 20. Thus, for a path 20, the beam 18 is first filtered with filter 32 and then filtered with filter 34. Additionally, each time a beam 18 is moved to a new path 20, the wheel 30 is rotated through one complete revolution to once again successively filter the beam 18 with each filter 32, 34. Alternatively, the wheel 30 can be located between the X-ray source 12 and the collimator 16 (this configuration not shown). As shown, a bracket 44 can be used to attach the motor 40 to the X-ray source 12 to allow the wheel 30, the filters 32, 34, the motor 40 and the shaft 42 to travel with the X-ray source 12 as the source 12 moves along the track 28 relative to the object 26. Each time a beam 18 is successively filtered by filter 32 and filter 34, two different electrical signals are produced by a detector 24 (i.e. one electrical signal for filtration with filter 32 and one electrical signal for filtration with filter 34). For the present invention, a computer processor (not shown) can be configured to manipulate the two electrical signals created for each path 20 to produce an image signal for the path 20. For example, each path 20 can be used to produce an image signal that represents a single pixel in the final image. Or stated another way, a computer processor can be configured to subtract, pixel by pixel, the digital images created by each filter 32, 34 to produce the contrast enhancement image. Once an image signal is established for each desired path 20, conventional tomography techniques known in the pertinent art can be used to combine all the image signals (one image signal for each path 20) into a composite image that shows the internal features of the object 26. Referring now to FIG. 3, a filter pair having two different filters 32, 34 is mounted on the wheel 30 to allow each beam 18 on each path 20 to be successively filtered twice It is to be appreciated that a plurality of identical filter pairs, with each pair having two different filters 32, 34, can be mounted on the wheel 30 (multiple filter pair not shown). For example, when two identical filter pairs are used, the wheel 30 is rotated through 180 degrees for each path 18. As further detailed below, a unique filter pair is designed for use with a specific contrast agent that is prescribed for introduction into the object 26. Specifically, the chemical constituents and thickness of each filter 32, 34 is determined with reference to the specific contrast agent that is being used. FIG. 4 shows an exemplary filter 32 having layers 46, 48, 50 and 52. Specifically, the filter 32 can include an optional transparent layer 46, a filtering layer 48, an optional additional balance layer 50 and an optional protective layer 52. It is to be appreciated that each filter 32, 34 will have different layers 46, 48, 50, 52, the layers 46, 48, 50, 52 differing in both chemical makeup and thickness. For the present invention, the optional transparent layer 46 can be included to support as well as protect the other layers 48, 50, 52. The optional protective layer 52 can be included to protect the other layers 48, 50 from corrosion or other environmental factors. The function of the filtering layer 48 and the additional balance layer 50 are discussed below. As seen by cross-referencing FIGS. 3 and 4, a metal ring 54 can be used to hold the layers 46, 48, 50, 52 together and attach them to the wheel 30. When used in conjunction with a contrast agent containing a chemical element having a KEDGE CONTRAST AGENT, a filter pair is constructed in accordance with the present invention having a filter 32 with a filtering layer 48 that contains a chemical element having a KEDGE that is greater than KEDGE, CONTRAST AGENT, and a filter 34 with a filtering layer 48 that contains a chemical element having a KEDGE that is less than KEDGE CONTRAST AGENT. The invention includes specific chemical elements and thickness"" sufficient to create filter pairs for various contrast agents as shown in Table 1. Referring back to FIG. 2, in the operation of the present invention, a contrast agent is first introduced into the object 26. Once introduced, the contrast agent will be selectively absorbed or localized in specific regions to thereby establish portions of the object 26 having differing concentrations of contrast agent. Table 1, below, lists a number of suitable contrast agents that are either in current use for imaging portions of the human body or are contemplated for future use. It is to be appreciated that conventional methods of administering the contrast agent that are known in the pertinent art can be employed. Further, it is anticipated that the present invention is applicable to the imaging of a non-human object 26, such as a structural component for a machine or device (not shown). In this case, a material in the structural component can be used as a contrast agent and a suitable filter pair constructed accordingly. Once a contrast agent has been introduced, the object 26 can be placed between the X-ray source 12 and the detector array 22 as shown in FIG. 2. Next, the X-ray source 12 is located at a first position and activated to produce one or more beams 18a-c travelling through the object 26 on a first set of paths 20a-c. Next, the wheel 30 containing the filters 32, 34, is rotated to successively interpose each of the two filters 32, 34, between the X-ray source 12 and the object 26 to filter each of the beams 18 with each of the two filters 32, 34. This results in the production of two intensity-proportional signals by a detector 24 for each beam 18. It is to be appreciated that the two signals will be temporally spaced from each other, the spacing corresponding to the time the beam 18 strikes the wheel 30 between adjacent filters 32, 34. Referring now to FIG. 5A, a typical emission spectrum for a conventional X-ray source 12 that has passed through a portion of the body having no contrast agent is shown by curve 56. When the spectrum represented by curve 56 reaches a detector 24, an electronic signal that is approximately proportional to the area under curve 56 (the intensity of the emission) is produced. Curve 60 in FIG. 5A represents the spectrum that results after radiation produced by a typical X-ray source 12 is passed through a portion of the body having exemplary contrast agent, Gd, in the absence of filters. Referring now to FIG. 5B, curve 58 represents the spectrum that results after radiation producing curve 56 in FIG. 5A is now passed through filter 34 and a portion of the body having no contrast agent. In this case, filter 34 has a filtering layer 48 having a chemical element with a KEDGE of approximately 49 keV. Accordingly, the electronic signal (hereinafter referred to as the filter 34 signal) produced by a detector 24 when filter 34 is interposed between the X-ray source 12 and the detector 24 will be approximately proportional to the area under curve 58. Similarly, a curve representing the spectrum that results after radiation producing curve 65 in FIG. 5A is now passed through filter 32 and a portion of the body having no contrast agent is shown in FIG. 5C and designated curve 65. Accordingly, the electronic signal (hereinafter referred to as the filter 32 signal) produced by a detector 24 when filter 32 is interposed between the X-ray source 12 and the detector 24 will be approximately proportional to the area under curve 58. The processor subtracts the filter 34 signal produced by the detector 24 with the filter 34 interposed along the path 20 from the filter 32 signal produced by the detector 24 with the filter 32 interposed along the path 20 to produce an image signal for the path 20. It is to be appreciated that the image signal simulates an image signal that would be obtained if a quasi-monochromatic beam having an average energy approximately equal to KEDGE CONTRAST AGENT were to be passed through the object 26. More specifically, the image signal produced for paths 20 having no contrast agent simulates the exemplary quasi-monochromatic spectrum shown in FIG. 6A and designated 66. Similarly, the image signal produced for paths 20 having contrast agent simulates the exemplary quasi-monochromatic spectrum shown in FIG. 6B and designated 68. These image signals constitute the data processed for tomography or angiography. The image signal strongly varies with concentration and thickness of the contrast element due to the variation of absorption. This results in an enhanced contrast image between the region with the contrast agent and the region without. Referring now to FIG. 7, the effect of additional balance layers 50 in a filter pair is shown. Specifically, FIG. 7 compares the quasi-monochromatic signal that is simulated without additional balance layers 50 (curve 70) and the quasi-monochromatic signal that is simulated with additional balance layers 50 (curve 72). The curve 72 was generated for a filter pair having a filter 32 with a filtering layer 48 that includes 140.0 xcexcm of 65Tb and an additional balance layer 50 of 200.0 xcexcm of 65Tb and a filter 34 with a filtering layer 48 that includes 236.0 xcexcm of 63Eu and an additional balance layer 50 of 200.0 xcexcm of 65Tb. With cross reference to Table 1 and FIG. 7, these two filters 32, 34 can be used in a filter pair in conjunction with the contrast agent Gd to generate the image signal. As shown in FIG. 7, the use of additional balance layers 50 reduces the non-zero difference of the filter transmission outside the energy pass band. Of course, this effect is obtained by paying the price of reducing the radiation intensity within the pass band (by a factor of about two, in this case). In practice, the additional balance layer 50 is designed to provide a compromise between the enhancement of the quality of monochromatization (i.e. a thicker additional balance layer 50 providing better balance) and the intensity level within the energy pass band (i.e. a larger number of photons to provide a better Signal-To-Noise ratio). Referring back to FIG. 2, once image signals are obtained for the first set of paths 20a-c, the X-ray source 12 and collimator 16 can be moved to a second position (shown by dashed lines) to cause the beams 18a-c emanating from the collimator 16 to travel along a new set of paths 20d-f. While the X-ray source 12 and collimator 16 are at the second position, the wheel 30 is again rotated to successively interpose each of the filters 32, 34 between the X-ray source 12 and the object 26 to again filter each of the beams 18a-c with each of the two filters 32, 34. Again, two intensity-proportional signals are produced by a detector 24 for each beam 18. For the present invention, these two signals can be manipulated by a processor (not shown) to produce image signals for each new path 20d-f. This process of moving the X-ray source 12 and producing two image signals for each new path 20 can be repeated as desired. Further, it is to be appreciated that the X-ray source 12 can be moved continuously around the object 26. When this technique is used, the wheel 30 containing filter 32 and filter 34 can be rotated continuously as the X-ray source 12 moves. By rotating the wheel 30 very rapidly, each beam 18 can be filtered by each filter 32, 34 before significant movement of the beam 18 occurs. Thus, in effect, each beam 18 remains on a single path 20 while the successive filtration takes place. It is to be appreciated that the image signals described above may also be obtained by first acquiring electrical signals for all paths 18 with the filter 32 interposed along the paths 18, followed by the acquisition of electrical signals for all paths 18 with filter 34 interposed along the paths 18. Once an image signal is produced for all paths 20 of interest, conventional tomography techniques can be used to combine all the image signals (one image signal for each path 20) into a composite image that shows the internal features of the object 26. Referring now to FIGS. 8A-8C, another embodiment of an imaging system in accordance with the present invention is shown and generally designated 10xe2x80x2. As shown in FIG. 8A, the system 10xe2x80x2 includes an X-ray source 12xe2x80x2 configured to produce a spectrum of X-ray radiation 14xe2x80x2. As further shown, a detector array 22xe2x80x2 is shown positioned to receive the radiation 14xe2x80x2 from the source 12xe2x80x2. For the present invention, an object 26xe2x80x2 is interposed between the X-ray source 12xe2x80x2 and the detector array 22xe2x80x2 to thereby allow the radiation 14xe2x80x2 to be modified by passing through the object 26xe2x80x2 before reaching the detector array 22xe2x80x2. For the present embodiment, the object 26xe2x80x2 can be a human body, suitcase, machine component or any other object that requires internal imaging. As further shown, a filter set 74 is provided to filter the radiation 14xe2x80x2 before the radiation 14xe2x80x2 reaches the detector array 22xe2x80x2. Preferably, in this embodiment, the filter set 74 and detector array 22xe2x80x2 are stationary during the imaging procedure. With cross reference now to FIGS. 8A, 8B and 8C, it can be seen the filter set 74 includes a plurality of filters 32 and a plurality of filters 34. It is to be appreciated that the filters 32a-p and 34a-p (see FIG. 8B) as well as the filters 32q-r and 34q-r (see FIG. 8C) are only exemplary. As best seen in FIG. 8B, the filters 32, 34 are preferably arranged in a planar, two dimensional array. For an object 26xe2x80x2 having a contrast agent containing a chemical element having a KEDGE CONTRAST AGENT, each filter 32 contains a chemical element having a KEDGE that is greater than KEDGE, CONTRAST AGENT, and each filter 34 contains a chemical element having a KEDGE that is less than KEDGE CONTRAST AGENT. It is to be further appreciated that the specific chemical elements and thickness"" shown in Table 1 can be used to prepare the filters 32, 34 in the filter set 74. As best seen in FIG. 8B, within the planar, two dimensional array, the filters 32, 34 are preferably arranged in an alternating, checker board pattern. With this pattern, a plurality of filter pairs is established, with each pair containing one filter 32 and an adjacent filter 34. For example, filter 32a and 34a constitute a filter pair for the present invention. Similarly, filter 32b and 34b constitute a filter pair for the present invention and so on. As best seen with cross reference to FIGS. 8A and 8C, the detector array 22xe2x80x2 includes a planar array of detectors 76, of which detectors 76a-d are exemplary, with one detector 76 for each filter 32, 34. In accordance with the present invention, the detector array 22xe2x80x2 is preferably an amorphous silicon array of digital detectors 76, with each detector 76 producing an electrical signal that is proportional to the intensity of the radiation received. Furthermore, a pair of detectors 76, such as detector 76a and detector 76b, is provided for each filter pair (32, 34). As shown, the detector pair 76a, 76b is positioned to receive filtered radiation from the filter pair (32q, 34q). For the present invention, the output of each detector 76 is electrically wired (via wires 78, of which wires 78a-d are exemplary) to a computer (not shown) to allow the signals generated by the detectors 76 to be processed. It is to be appreciated that for each filter pair (32, 34), a corresponding pair of detectors 76 produces two different electrical signals (i.e. one electrical signal for filtration with filter 32 and one electrical signal for filtration with filter 34). For the present invention, a computer processor (not shown) can be configured to manipulate the two electrical signals created for each filter pair to produce an image signal for the filter pair (32, 34). More specifically, the processor subtracts the electrical signal corresponding to filtration with filter 34 from the electrical signal corresponding to filtration with filter 32 to produce an image signal for the filter pair (32, 34). It is to be appreciated that each filter pair (32, 34) can be used to produce an image signal that represents a single pixel in the final image. Once an image signal is established for each filter pair (32, 34), the processor can be used to combine all the image signals (one image signal for each filter pair (32, 34) into a composite image that shows the internal features of the object 26xe2x80x2. In another embodiment of the present invention, the detector array 22xe2x80x2 and filter set 74 as shown in FIG. 8a are formed as linear arrays. It is to be appreciated that a single filter pair 32, 34 can be used in this embodiment. Preferably, for this embodiment, the X-ray source 12xe2x80x2, linear detector array 22xe2x80x2 and filter set 74 are mounted on a track (such as the track 28 shown in FIG. 2) for movement relative to the object 26xe2x80x2. During imaging, the X-ray source 12xe2x80x2 is moved along the track 28 to successive positions, and an image signal is generated (as described above) from the filter pair (32, 34) for each position of the X-ray source 12xe2x80x2. Once an image signal is produced for each desired position of the X-ray source 12xe2x80x2, conventional tomography techniques can be used to combine all the image signals into a composite image that shows the internal features of the object 26xe2x80x2. While the particular imaging systems and methods as herein shown and disclosed in detail are fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that they are merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.
	claims	1. A calibration device for confirming or calibrating a biopolymeric array optical scanner, said device comprising: a polymer layer comprising at least one fluorescent agent, wherein said device has minimal local and global nonuniformities and is dimensioned for placement in an optical scanner. 2. The device according to claim 1 , wherein said at least one fluorescent agent is distributed substantially uniformly throughout said polymer. claim 1 3. The calibration device according to claim 1 , wherein said polymer is selected from the group consisting of acrylates, epoxides, urethanes, polycarbonates, polyolefins, polyetherketones, polyesters, polystyrenes, polyethylstyrene, polysiloxanes, and copolymers thereof. claim 1 4. The calibration device according to claim 1 , wherein said polymer is polymethyl-methacrylate. claim 1 5. The calibration device according to claim 1 , wherein the thickness of said polymer layer ranges from about 0.25 micron to about 10 microns. claim 1 6. The calibration device according to claim 1 , wherein the thickness of said polymer layer ranges from about 0.4 micron to about 1 micron. claim 1 7. The calibration device according to claim 1 , wherein said device comprises a single polymer layer. claim 1 8. The calibration device according to claim 1 , wherein said device comprises a plurality of polymer layers. claim 1 9. The calibration device according to claim 1 , wherein said at least one fluorescent agent is present in said polymer in a final concentration ranging from about 1 ppm to about 5000 ppm. claim 1 10. The calibration device according to claim 1 , wherein said at least one fluorescent agent absorbs and emits light in the portion of the electromagnetic spectrum to which a photomultiplier tube of said optical scanner is sensitive. claim 1 11. The calibration device according to claim 1 , wherein said at least one fluorescent agent absorbs and emits light in the wavelength range selected from the group consisting of ultraviolet, visible and infrared. claim 1 12. The calibration device according to claim 1 , wherein said global nonuniformity of said calibration device is less than about 5%. claim 1 13. The calibration device according to claim 1 , wherein said local nonuniformity of said calibration device is less than about 5%. claim 1 14. The calibration device according to claim 1 , wherein said polymer layer comprises at least two fluorescent agents. claim 1 15. The calibration device according to claim 1 , wherein said polymer layer is selected from the group consisting of a spin-coated polymer layer, a draw coated polymer layer, a roller coated polymer layer, an electrodeposited polymer layer and a sprayed polymer layer. claim 1 16. A method for calibrating a biopolymeric array optical scanning system, said method comprising: (a) illuminating a surface of a calibration device with at least one light source, wherein said calibration device is a calibration device according to claim 1 ; claim 1 (b) obtaining fluorescence data from said surface of said calibration device; and (c) calibrating said optical scanning system based upon said fluorescence data. 17. The method according to claim 16 , wherein said step of illuminating comprises illuminating said surface of said calibration device in the portion of the electromagnetic spectrum to which a photomultiplier tube of said optical scanner is sensitive. claim 16 18. The method according to claim 16 , wherein said step of illuminating comprises illuminating said surface of said calibration device in the wavelength range selected from the group consisting of ultraviolet, visible and infrared. claim 16 19. The method according to claim 16 , wherein said step of obtaining fluorescence data comprises detecting a signal related to the intensity of emitted light from said fluorescent agent. claim 16 20. The method according to claim 16 , wherein said step of calibrating comprises calibrating the scale factor of said system. claim 16 21. The method of claim 20 , wherein said scale factor calibration comprises adjusting the sensitivity of an optical detector of said system. claim 20 22. The method according to claim 16 , wherein said step of calibrating comprises calibrating the focus position of said system. claim 16 23. The method according to claim 22 , wherein said focus position calibration comprises adjusting the distance between a scanning stage and a lens of said system. claim 22 24. The method according to claim 16 , wherein said step of calibrating comprises calibrating the dynamic focus of said system. claim 16 25. The method according to claim 24 , wherein said dynamic focus calibration comprises adjusting the rate of speed at which an optical stage of said system travels. claim 24 26. The method according to claim 16 , wherein said step of calibrating comprises determining the amount of oscillation in an intensity image and adjusting the rate of speed of said optical stage according to said oscillation data. claim 16 27. The method according to claim 16 , wherein said step of calibrating comprises calibrating at least one scanner mirror of said system. claim 16 28. The method according to claim 27 , wherein said at least one scanner mirror calibration comprises adjusting said at least one scanner mirror to synchronize the light beams of said system. claim 27 29. The method according to claim 16 , further comprising the steps of subtracting a background signal from said obtained fluorescent data to obtain a background corrected value. claim 16 30. The method according to claim 16 , wherein said fluorescent agent(s) is distributed substantially uniformly throughout said surface. claim 16 31. The method according to claim 16 , further comprising the step of verifying the jitter of said optical scanning system. claim 16 32. A method for performing a hybridization assay, said method comprising: (a) calibrating an optical scanner with a calibration device, wherein said calibration device is calibration device according to claim 1 , claim 1 (b) performing a hybridization assay with at least one array, and (c) scanning said array with said calibrated optical scanner. 33. A method comprising forwarding data representing a result of a scan obtained by the method of claim 32 . claim 32 34. The method according to claim 33 , wherein said data is transmitted to a remote location. claim 33 35. A method comprising receiving data representing a result of an interrogation obtained by the method of claim 33 . claim 33 36. A method for manufacturing a calibration device, said method comprising spin-coating a composition onto a substrate to produce a calibration device according to claim 1 . claim 1 37. The method according to claim 33 , further comprising photobleaching at least one region of said device. claim 33 38. A kit for calibrating a biopolymeric array optical scanner, said kit comprising: (a) at least one device according to claim 1 ; and claim 1 (b) a substrate comprising instruction for using said device to calibrate a biopolymeric array optical scanner. 39. A kit for calibrating a biopolymeric array optical scanner, said kit comprising: (a) at least one device according to claim 1 ; and claim 1 (b) an array. 40. The device according to claim 1 , wherein said polymer layer is present on a substrate having a length ranging from about 4 mm to 200 mm. claim 1 41. The device according to claim 40 , wherein said substrate has a length ranging from about 4 mm to 150 mm. claim 40 42. The device according to claim 41 , wherein said substrate has a length ranging from about 4 mm to 125 mm. claim 41 43. The device according to claim 1 , wherein said polymer layer is present on a substrate having a width ranging from about 4 mm to 200 mm. claim 1 44. The device according to claim 43 , wherein said substrate has a width ranging from about 4 mm to 120 mm. claim 43 45. The device according to claim 44 , wherein said substrate has a width ranging from about 4 mm to 80 mm. claim 44 46. The device according to claim 1 , wherein said polymer layer is present on a substrate having a thickness ranging from about 0.01 mm to 5.0 mm. claim 1 47. The device according to claim 46 , wherein said substrate has a thickness ranging from about 0.1 mm to 2 mm. claim 46 48. The device according to claim 46 , wherein said subsrate has a thickness ranging from about 0.2 mm to 1 mm. claim 46 49. A calibration device for confirming or calibrating a biopolymeric array optical scanner, said device comprising: a polymer layer comprising at least one fluorescent agent, wherein said device has minimal local and global nonuniformities; and a transparent substrate; wherein said device is dimensioned for placement in an optical scanner. 50. The calibration device according to claim 49 , wherein said transparent substrate is glass. claim 49 51. The calibration device according to claim 50 , wherein said at least one fluorescent agent is distributed substantially uniformly throughout said polymer. claim 50 52. The calibration device according to claim 49 , wherein the thickness of said polymer layer ranges from about 0.25 micron to about 10 microns. claim 49 53. The calibration device according to claim 49 , wherein said global nonuniformity of said calibration device is less than about 5%. claim 49 54. The calibration device according to claim 49 , wherein said local nonuniformity of said calibration device is less than about 5%. claim 49 55. A calibration device for confirming or calibrating a biopolymeric array optical scanner, said device comprising: a polymer layer comprising at least one fluorescent agent, wherein said device has minimal local and global nonuniformities; and a substrate having a length ranging from about 4 mm to 200 mm, a width ranging from about 4 mm to 200 mm and a thickness ranging from about 0.01 mm to 5.0 mm; wherein said device is dimensioned for placement in an optical scanner. 56. The calibration device according to claim 55 , wherein said substrate is transparent. claim 55 57. The calibration device according to claim 55 , wherein said at least one fluorescent agent is distributed substantially uniformly throughout said polymer. claim 55 58. The calibration device according to claim 55 , wherein the thickness of said polymer layer ranges from about 0.25 micron to about 10 microns. claim 55 59. The calibration device according to claim 55 , wherein said global nonuniformity of said calibration device is less than about 5%. claim 55 60. The calibration device according to claim 55 , wherein said local nonuniformity of said calibration device is less than about 5%. claim 55 61. An optical scanner comprising a calibration device according to claim 1 . claim 1
	abstract	The invention concerns an illumination system for wavelengths (193 nm, particularly for EUV lithography with at least one light source, which has an illumination A in one surface;
	abstract	Direct synthesis methods are generally provided that include reacting Na2(WO4)·2H2O (and/or Na2(GeO4)·2H2O) with NaF in an inert atmosphere at a reaction tion temperature of about 950° C. to about 1400° C., along with the resulting structures and compositions.
	summary
	claims	1. An apparatus directing x-rays along a predetermined axis, said apparatus comprising:an x-ray optic having one or more nested x-ray reflector rings positioned relative to a source generating broad spectrum x-rays so that generated x-rays moving away from the predetermined axis are collected by said reflector incident at or close to a Bragg angle to thereby reflect the collected x-rays into a conically parallel beam;a first diffractor positioned relative to said x-ray optic to receive incident thereon the conically parallel beam, said first diffractor selected from a truncated cone and a cylinder and diffracting the conically parallel beam toward the predetermined axis; anda second diffractor positioned relative to said first diffractor and having a geometry effective to receive incident thereon and redirect the conically parallel beam along the predetermined axis as a collimated beam of substantially parallel x-rays. 2. The apparatus of claim 1, wherein a target lies along the predetermined axis so as to thereon receive the collimated beam of substantially parallel x-rays. 3. The apparatus of claim 1, further comprising a beam block positioned to prevent x-rays from the source other than the diffracted conically parallel beam of x-rays from reaching said second diffractor. 4. The apparatus of claim 1, wherein said x-ray optic has an x-ray grazing incidence reflecting surface along a full figure of revolution geometry effective for collecting a solid angle of x-rays diverging from said source and the solid angle is defined by the formula 2π(cos(Θ1)−cos(Θ2)) so as to collimate the collected x-rays into a conically parallel beam of x-rays. 5. The apparatus of claim 1, wherein said first diffractor comprises a truncated cone having an x-ray diffracting surface along an interior of the cone, the truncated cone optionally having a slit along a full lengthwise dimension. 6. The apparatus of claim 1, wherein said second diffractor comprises a truncated cone having an x-ray diffractive surface along an exterior surface of said truncated cone.
062529390	abstract	The X-ray examination apparatus includes an X-ray source, an X-ray detector and an X-ray filter which is located between the X-ray source and the X-ray detector. The X-ray filter includes elements, notably capillary tubes, and the X-ray absorptivity of separate filter elements is adjustable by adjustment of a quantity of X-ray absorbing liquid in the respective filter elements. The quantity of X-ray absorbing liquid in the individual filter elements is adjusted by way of electric voltages applied to the individual filter elements. A control system is provided to apply the electric voltages selectively to the individual filter elements. The control system includes voltage lines and switching elements which electrically couple the filter elements to an electric voltage source. The filter elements are formed by spaces between corrugated plates or parallel plates provided with separating members, such as protrusions which extend transversely of the plates. The voltage lines are disposed on the plates. Preferably, the plates are formed from a stack of extendable wall foils and separating foils are provided partially between the wall foils so as to adapt the spacing of the voltage lines to the spacing of the switching elements.
047028823	description	DETAILED DESCRIPTION OF THE INVENTION Reference will not be made in detail to the presently preferred embodiment of the invention, examples of which are illustrated in the accompanying drawings. In the following description, like reference characters designate like or corresponding parts throughout the several views. Also, in the following description, it is to be understood that such terms as "forward", "rearward", "left", "right", "upwardly", "downwardly", and the like, are words of convenience and are not to be construed as limiting terms. Referring now to the drawings, and particularly to FIG. 1, there is shown a partially sectioned elevational view with parts broken away for clarity of a fuel assembly constructed in accordance with well known practices, generally indicated by the numeral 10, which incorporates a preferred embodiment of the invention. The fuel assembly 10 basically comprises a lower end structure or bottom nozzle 12 for supporting the assembly on the lower core plate (not shown) in the core region of a reactor (not shown). A number of longitudinally extending control rod guide thimbles 14 project upwardly from the bottom nozzle 12. A plurality of transversely extending fuel rods spacer grids 16 are axially spaced along the guide thimbles 14. An organized array of elongated fuel rods 18 are transversely spaced and supported by the spacer grids 16. An instrumentation tube 20 is located in the center of the assembly. An upper end structure top nozzle, generally designated by the numeral 22, is attached to the upper ends of the guide thimbles 14 in a manner more fully described below to form an integral assembly capable of being conventionally handled without damaging the assembly components. The top nozzle 22 includes a transversely extending adapter plate 24 having upstanding sidewalls 26 secured to the peripheral edges thereof and defining an enclosure or housing. An annular flange 28 is secured to the top of the sidewalls 26. Suitably clamped to the annular flange 28 are holddown springs 30 (only one of which is illustrated in FIG. 1 for clarity) which cooperate with the upper core plate (not shown) in a conventional manner to prevent hydraulic lifting of the fuel assembly caused by upward flow of coolant through the assembly while also allowing for changes in the fuel assembly length due to core-induced thermal expansion and the like. Disposed within the opening defined by the annular flange 28 is a conventional rod cluster control assembly 32 having radially extending flukes 34 connected to the upper end of the control rods 36 for vertically moving the control rods in the control rod guide thimbles 14 in a well known manner. With the exception of the top spacer grid 38, each of the spacer grids 16 may be of any suitable, conventional design for laterally spacing and supporting the fuel rods 18. The fuel assembly 10 depicted in the drawings is of the type having a square array of fuel rods 18 with the control rod guide thimbles strategically arranged within the fuel rod array. Further, the bottom nozzle 12 and likewise the top nozzle 22 are generally square in cross section. The specific fuel assembly represented in the drawings is for illustration only; it is to be understood that neither the shape of the nozzles nor the number and configuration of the fuel rods and guide thimbles are to be limiting and that the invention is equally applicable to shapes, configurations, and arrangements other than the ones specifically illustrated. To form the fuel assembly 10, the transverse spacer grids 16 are attached to the longitudinally extending guide thimbles 14 at predetermined axially spaced locations. The fuel rods 18 are inserted through the spacer grids 16 in order to form the fuel rod array. The lower nozzle 12 is suitably attached to the lower ends of the guide thimbles 14 and the top nozzle 22 is attached to the upper ends of the guide thimbles 14 in the manner described below in accordance with the improved attaching structure of the present invention. Referring now to FIGS. 2, 2a and 3, a first preferred embodiment of the improved attaching structure for removably mounting the top nozzle 22 on the upper end of the guide thimbles 14 and the top spacer grids 38 will be discussed. Although each of the guide thimbles 14 compressively supports the top nozzle 22, the description that follows is directed to the support arrangement for only one of the guide thimbles, the other guide thimbles supporting the top nozzle in the same manner. Similarly, although each side of the top fuel rod spacer grid 38 has an skirt extension 40 for tensively supporting the top nozzle 22, the description which follows is directed to the arrangement between the top nozzle 22 and only one of the spacer grid skirt extensions 40. It should however be understood that each of the four available skirt extensions 40 are preferably used. The improved structure for removably supporting and attaching the top nozzle 22 includes thimble collars 44 which are welded or otherwise secured to the guide thimbles 14 and which are radially dimensioned to support the top nozzle 22 by bearing against the adapter plate 24 under compressive loading, and skirt extensions 40 formed in the top spacer grid 38 which removably attach, preferably without any loose attachment parts, to the sidewall 26 of the top nozzle 22 in order to support the fuel assembly under tensile loading. Details of these elements and connections as well as another preferred embodiment of a quick disconnect top nozzle fuel assembly will now be described. According to a preferred embodiment of the present invention, compressive loads from the top nozzle 22, such as loads imposed by the holddown springs 30, are transmitted via the load collars 44 on the guide thimbles 14, while tensive loads, such as lifting loads, are transferred through the top nozzle 22 onto upwardly extending skirt extensions 40 of the top spacer grid 38. The top spacer grid assembly 38 may be fastened in any conventional manner, for example, by bulging techniques, to the guide thimbles 14. Thus, any tensive loads on the grid skirt extensions 40 are transferred through the spacer grids 38 to the guide thimbles 14 eliminating many of the costly, complex and loose components previously used to connect the guide thimbles to the top nozzle. As alluded to above, the guide thimbles 14 are clearance fitted into apertures 46 in the adapter plate 24. The amount of radial clearance is preferably small, on the order of about two mils. Preferably, at least the portion of the guide thimble 14 in the vicinity of the top nozzle 22 is formed of stainless steel and the load collar 44 is formed from a coaxial stainless steel sleeve brazed, welded, or otherwise attached on to the guide thimble in the vicinity of its top end. The load collar 44 is radially dimensioned to be larger than the aperture 46, thereby any compressive load on the top nozzle 22 will be borne by the guide thimble 14 via the load collar 44. However, the clearance fit between the guide thimble 14 and the apertures 46 permits the top nozzle to be removed from the guide thimbles in the manner described below and require no unlocking, unscrewing, or other detachment operations between the guide thimble 14 and the top nozzle 22. The grid skirt extension 40 may be of any desired geometry for providing mechanical support to the fuel assembly while permitting adequate coolant flow through the fuel assembly. The skirt extention 40 extends along the sidewall 26 of the top nozzle 22. It should be understood that the sheet metal skirt extensions 40, while strong under tensive stresses, will buckle relatively easy under compressive loading and are therefore not primarily relied upon to provide compressive strength. Each of the grid skirt extensions 40 includes means for securing the top spacer grid assembly 38 to the top nozzle 22 in a manner whereby it can support tensive loads. Such means may include aperture 42 in the grid skirt extension which aligns with apertures 48 in the sidewalls 26. Each sidewall 26 has a spring steel tang 50 extending generally parallel to the sidewall 26 to form therebetween a space for the skirt extension 40. A number of generally orthgonally locking pins 52, corresponding to the number of aligned apertures 42 and 48, are provided in the grid skirt extensions 40. The tangs 50 may be welded, integrally formed with, or otherwise secured to the sidewall 26 or to the annular flange 28. As best seen in FIG. 2a, the tang 50 preferably includes a notched end 54 which may be easily gripped by the end 56 of a pull-back tool 58. As best seen in FIG. 3, the end 56 of the pull back tool is complementary shaped with respect to the notched end 54 of the tang 50. In use, the top nozzle 22 may be removed by pulling back the tang 50, i.e. to the left as viewed in FIG. 2a, until the locking pin 52 clears the aperture 42 whereupon the top nozzle may be simply lifted off of the clearance fitted guide thimbles 14. For reassembly, the tang 50 need only be pulled back with respect to the sidewall 26 enough to provide sufficient clearance between the sidewall and the locking pin 52 for passage of the grid skirt extension 40. Thereupon, the apertures 46 in the adapter plate 24 can be aligned with the guide thimbles 14 and the apertures 42 aligned with the apertures 48 and the locking pin 52. Upon release of the tang 50, the locking pins 52 will lock the sidewall 26 to the grid skirt extensions 40. Turning now to FIGS. 4, 5a, and 5b, a second embodiment of the invention will be described. In the embodiment of FIG. 4, the spacer grid skirt extensions 40 terminate in a tang 58 which is designed to engage the complementary slot 60 formed in the sidewall 26 of the top nozzle 22. Each tang 58 preferably has an upstanding flange portion 62 designed to be engaged by a combination lift and release tool 64 as described below. The sidewall 26 of the top nozzle is preferably provided with a hole 68 through which a skirt extention deflecting portion 66 of the lift release tool 64 is designed to protrude. The protruding portion 66 of the tool 64 may simply comprise a small cylindrical member sized to clearance fit through the hole 68 and protrude far enough to deflect the tang 58 out of engagement with the slot 60. This is best seen in FIG. 5a. In this position, the top spacer grid 38 is unlatched from the top nozzle 22. The tool 64 further comprises a tang capture portion 70 having a notched end 72 designed to capture a flange 62 on the tang 58 and hold the tang in a position deflected away from the sidewall 26 and out of mating engagement with the slot 60 so that when the protruding portion 66 of the tool 64 is withdrawn from contact with the tange 58, i.e. moved to the right as viewed in FIG. 5b, the tang capture portion 70 of the tool 64 can be lowered to engage the the flange 62 allowing the top nozzle to be lifted. During lifting, the portion of the tool 64 which bears against the annular flange 28 may be used to support the top nozzle. Thus, by modifying the top spacer grid assembly to support tensive loads on the fuel assembly and by providing load collars on the guide thimbles to support compressive loads, a fuel assembly according to the present invention can be quickly and simply constituted and reconstituted and individual fuel rods in a fuel assembly can be handled on a routine basis at the end of each fuel cycle merely by removing the top nozzle in the manner described above. In addition to the other advantage described above, the quick disconnect top nozzle permits the enrichment of fuel rods within each fuel assembly to be more precisely tailored to more closely approximate the optimum hydrogen to uranium ratio for a given burnup. Further, the quick disconnect top nozzle permits rapid access to the fuel rods while eliminating the many costly, intricate, and loose attaching components of prior art attachment designs. The foregoing description of a preferred embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. Other quick disconnect latching schemes between the top grid assembly and the top nozzle can be used and other compressive load supporting devices than simple load collars can be employed. The embodiments presented were choosen 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 comtemplated. It is intended that the scope of the invention be defined by the claims appended hereto.
	claims	1. A sensor for measuring electrochemical corrosion potential in a nuclear reactor comprising: a tubular ceramic probe having a closed tip at one end packed with a metal and metal oxide powder; a metal support tube having one end receiving an opposite end of said probe, and joined thereto by a braze joint therewith; an electrical conductor extending through said support tube and probe, and having an end buried in said powder for electrical contact therewith; and a plasma sprayed ceramic band locally coating said probe and tube at said braze joint for sealing thereof, wherein said plasma sprayed ceramic band has a coefficient of thermal expansion that is compatible with that of said tubular ceramic probe and wherein said plasma sprayed ceramic band spaced from said probe tip. 2. A sensor according to claim 1 wherein both said probe and band comprise zirconia. claim 1 3. A sensor according to claim 2 wherein said probe comprises magnesia-stabilized-zirconia, and said band comprises yttria-stabilized-zirconia. claim 2 4. A sensor according to claim 3 wherein said powder comprises iron and iron oxide. claim 3
039649644	description	The present invention will be described as it would be applied to the EBR-II reactor and details of this reactor not found in the present drawing can be found in the ANL reports cited above. It is, of course, apparent that a failed element detection and location system according to the present invention could be incorporated in any fast reactor, although modifications to the reactor might be necessary. Referring now to FIG. 1 of the drawing, the EBR-II is a sodium-cooled, pool-type fast reactor comprising a core 10 including a plurality of vertically disposed fuel assemblies 11 enclosed within a reactor vessel 12 having a movable cover 13, the cover being shown in raised position for fuel handling operations. Each fuel assembly 11 incorporates a bundle of fuel pins consisting of a nuclear fuel enclosed within gastight cladding. Reactor vessel 12 is submerged within a pool 14 of sodium contained within a primary tank (not shown) provided with a cover 15 having a rotating plug 16 therein through which extend control rods 17, reactor vessel cover 13 elevating column 18, and a gripper mechanism 19. Gripper mechanism 19 is capable of raising a fuel assembly 11 completely out of the reactor core 10 whereupon a transfer arm 20 is capable of transferring the assembly 11 to a storage rack (not shown) and ultimately to a transfer port (not shown) where the assembly can be removed from the reactor. Loading involves a reverse series of operations. As shown in FIG. 2 and in more detail in FIGS. 3 and 4, a gas trap consisting of an inverted funnel 21, a normally closed valve 22 at the apex of the funnel and an actuating rod 23 attached to the valve 22 and extending axially upwardly through the upper plenum 24 of the fuel assembly. As in the EBR-II reactor, an upper adapter 25 provided with a locating slot 26 is attached to the top of the fuel assembly. The gas trap is supported in the upper portion of a fuel assembly several feet above the core region by a bracket 27. The diameter of the funnel 21 at its greatest is substantially less than that of the subassembly. A preferred size would be about 1.1 inches since an EBR-II subassembly is .about.2.3 inches in diameter. The diameter could vary between about 0.7 inch and 1.2 inches, this being about 1/3 or 1/2 that of the subassembly. Actuating rod 23 extends upwardly through the adapter 25 and a short distance into locating slot 26 when valve 22 is closed. Spring 28 maintains the valve 22 in normally closed position. Also shown in FIG. 4, mostly in phantom, is the lower end of gripper mechanism 19. This includes gripper jaws 29 and an orientation blade 30, which elements are present in the EBR-II gripper mechanism. Identification of failed fuel elements according to the present invention is apparent from FIGS. 3 and 4. To interrogate a fuel assembly, gripper mechanism 19 is lowered onto adapter 25 as in a normal fuel handling operation, whereupon orientation blade 30 pushes downwardly on actuating rod 23. A downward motion of approximately 1/16 to 1/8 inch of the actuating rod 23 ensues. Any fission gases released in the fuel assembly will rise in the assembly and some will be trapped in the funnel 21, the remainder rising to the reactor cover gas to annunciate the fission product release. When a fission product release has been indicated, the gripper mechanism is lowered onto the adapter 25 of each of the fuel subassemblies in turn as described above. The downward motion of the actuating rod is sufficient to open the valve and release a bubble of fission product gas in every assembly in which a gas release has occurred. Conventional monitoring equipment can be used to detect the increase in reactivity in the cover gas caused by release of the bubble. To estimate the sensitivity of the detection procedure according to the present invention, the change in cover gas signal-to-noise ratio was evaluated for a release yielding an original S/N ratio of 250 (.sup.133 Xe) from a 10 atom percent burnup element. A bubble occupying 1.1 cc at shutdown conditions in the trap would increase the signal 25% 2 days after the original release. The definition of signal-to-noise ratio is: For a given index isotope, .sup.133 Xe, for example, the signal-to-noise ratio is the increase in .sup.133 Xe content in the reactor cover gas divided by the background .sup.133 Xe component in the cover gas from the unavoidable tramp uranium present in the reactor system. PA1 1. The information storage mechanism is almost completely passive and with considered design should present no safety problems. PA1 2. Retrieving the information stored in the gas trap can be accomplished with existing equipment, or at least existing reactor access facilities in an operating LMFBR. PA1 3. any or all subassemblies (with the exception of instrumented subassemblies) can be interrogated without perturbation or removal from the core, thereby eliminating extensive fuel handling operations associated with search and removal efforts. PA1 4. Analysis of the information contained in the gas bubble can be accomplished with existing instruments. PA1 5. The technique lends itself readily to moderate discrete steps in improvement; i.e. minor design changes in the gas trap, improvements in the method and delivery of the bubble to the cover gas, etc., can be performed independently as time and funds permit (for an operating reactor). PA1 6. The technique does not depend on any method, whatever it may be, for inducing a secondary release from the leaking element. The invention described above has the following apparent advantages:
059178795	description	DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT A preferred embodiment of this invention is described below. FIG. 1 illustrates an application example of the reflective reduction imaging optical system for X-ray lithography of this invention. FIG. 2 is a diagram illustrating its main portion. As can be seen from these figures, from the side of mask M to the side of wafer W, in order, the following mirrors are placed coaxially: first concave mirror G.sub.4, plane mirror G.sub.3, convex mirror G.sub.2, and second concave mirror G.sub.1. The concave mirrors G.sub.4 and G.sub.1, and the convex mirror G.sub.2 are formed in aspherical shapes. The convex mirror G.sub.2 is placed at the pupil plane, and the side of wafer W becomes telecentric. The parameters of this application example are shown in Table I, which follows. In the "overall parameters", NA represents the numerical aperture and RF represents the ring field. In the "parameters of the mirrors", the first column represents the identification of the reflective surface from the side of wafer W, the second column r represents the apex radius of curvature of the various reflective surfaces, the third column d represents the distance between apexes of the various reflective surfaces, the fourth column .kappa. represents the conical coefficient of each reflective surface, and the fifth column .PHI. represents the aperture. The conical coefficient .kappa. is defined by the following formula. Aspherical coefficient C.sub.n is set at 0 for each reflective surface. In this application example, the aspherical shapes are the so-called secondary aspherical surfaces. In particular, first concave mirror G.sub.4 is formed as an ellipsoidal surface. ##EQU1## wherein y is the height in the direction perpendicular to the optical axis; S(y) is the displacement in the direction of the optical axis at height y; PA1 r is the apex radius of curvature; PA1 .kappa. is the conical coefficient; and PA1 C.sub.n is the nth aspherical coefficient. Aperture .PHI. refers to the aperture, including the portion actually cut off for guaranteeing the optical path. TABLE I ______________________________________ "Overall parameters" Magnification: 1/4 Wafer-side NA: 0.06 (mask-side NA: 0.015) Wafer-side RF inner radius: 29.8 (mask-side RF inner radius: 119.2) Wafer-side RF outer radius: 30.0 (mask-side RF inner radius: ______________________________________ 120) "Parameters of mirrors" r d .kappa. .phi. ______________________________________ W -- 289.9966 G.sub.1 -353.8219 -176.50426 1.19513 73.8 G.sub.2 -266.80893 200 1.38210 21.3 G.sub.3 0 -271.76014 -- 107.2 G.sub.4 1069.69783 2008.57114 0.41521 221.2 M -- ______________________________________ FIG. 3 is a diagram illustrating the lateral aberration on the meridional plane in this application example. This diagram shows the aberration on the mask M surface when an X-ray of 13 nm is incident from the side of wafer W. Consequently, height Y.sub.0 of the object is the height on wafer W. It can be seen from this figure that good imaging performance is obtained in this application example. As explained above, in this application example, by scanning with mask M and wafer W in synchronization with each other in the ring field, an exposure apparatus having a wide field is obtained. In the ring field, an image with a high resolution and a small skew aberration can be obtained. Also, as the reduction side, that is, the wafer side, becomes the telecentric ring field, or the aperture stop position is on convex mirror G.sub.2, it is possible to obtain the same exposure condition everywhere in the ring field. As the optical path is reflected back by plane mirror G.sub.3, there is no mechanical interference by the wafer in the optical path from the mask. Also, since the incident angles (the angle from the normal to the reflective surface) of the light beam on reflective surfaces G.sub.1 -G.sub.4 are nearly 0.degree., it is possible to suppress the wavefront aberration caused by the phase shift by the various reflective surfaces. In particular, in this application example, since a plane mirror and ellipsoidal mirrors are used, when these mirrors are manufactured, it is easy to obtain surfaces with a high precision. This is an advantage. In this application example, among the secondary aspherical surfaces, ellipsoidal and oblate spheroidal surfaces are used. However, it is also possible to use parabolic or hyperbolic surfaces for the secondary aspherical surfaces. As described above, it is possible to obtain a reflective reduction imaging optical system for X-ray lithography with a good imaging performance and with a simple construction. While the invention has been described above with respect to certain embodiments thereof, it will be appreciated by a person skilled in the art that variations and modifications may be made without departing from the spirit and scope of the invention.
	claims	1. A treatment planning system for creating treatment plan information for particle therapy, comprising:an input device;an arithmetic device for performing arithmetic processing based on a result of input to the input device and creating treatment plan information; anda display device for displaying the treatment plan information;wherein the arithmetic device calculates a scanning path by setting a pre-specified direction as a main direction for scanning irradiation positions with an ion beam using scanning magnets, the pre-specified direction being along a direction of movement of a target of treatment. 2. The treatment planning system according to claim 1,wherein the arithmetic device calculates a position of a specific region based on a plurality of tomography images of a plurality of states of a target region; extracts a direction of movement of the position of the specific region; and applies the direction extracted and projected on an ion beam scanning surface as the pre-specified direction. 3. The treatment planning system according to claim 1,wherein the arithmetic device sets a plurality of straight lines parallel with the pre-specified direction and arranges irradiation positions to be irradiated with an ion beam on the straight lines. 4. The treatment planning system according to claim 1,wherein the arithmetic device calculates, without changing pre-specified irradiation positions, a scanning path such that a main scanning direction coincides with the pre-specified direction. 5. The treatment planning system according to claim 2,wherein the arithmetic device calculates an amount of the target movement in a direction perpendicular to the ion beam scanning surface and calculates the scanning path when the ion beam is irradiated from the direction of an amount of the target movement is smaller than a predetermined amount. 6. A particle therapy system for irradiating an affected area of a patient with an ion beam, comprising:an input device;a central control unit calculates a scanning path based on a result of input to the input device as a main direction for scanning irradiation positions with the ion beam using scanning magnets;an irradiation control system controls to change the calculated scanning path of the ion beam by controlling the scanning magnets based on the direction of movement of a target of treatment, but still scans the same irradiation positions calculated by the central control unit. 7. A device for calculating a scanning path for particle irradiation comprising:an input device for inputting data relating to a target area movement;an arithmetic device for performing arithmetic processing based on a result of data input of the input device and creating scanning path information for the target area; anda display device for displaying the scanning path information;wherein the arithmetic device calculates a scanning path by setting a pre-specified direction as a main direction for scanning irradiation positions with an ion beam using scanning magnets, the pre-specified direction being along a direction of the target area movement. 8. The device according to claim 7,wherein the arithmetic device calculates a position of a specific region based on a plurality of tomography images of a plurality of states of a target region; extracts a direction of movement of the position of the specific region; and applies the direction extracted and projected on an ion beam scanning surface as the pre-specified direction. 9. The device according to claim 7,wherein the arithmetic device sets a plurality of straight lines parallel with the pre-specified direction and arranges irradiation positions to be irradiated with an ion beam on the straight lines. 10. The device according to claim 7,wherein the arithmetic device calculates, without changing pre-specified irradiation positions, a scanning path such that a main scanning direction coincides with the pre-specified direction. 11. The device according to claim 8,wherein the arithmetic device calculates an amount of the target movement in a direction perpendicular to the ion beam scanning surface and calculates the scanning path when the ion beam is irradiated from the direction of an amount of the target movement is smaller than a predetermined amount. 12. A particle therapy system including the device according to claim 7 for irradiating an affected area of a patient with an ion beam, comprising:an irradiation control system control a scanning path of the ion beam by controlling the scanning magnets based on the calculated scanning path. 13. The particle therapy system according to claim 6,wherein the central control unit calculates the scanning path before the irradiation positions are scanned. 14. The particle therapy system according to claim 6,wherein the irradiation control system controls to change the calculated scanning path before scanning the irradiation positions. 15. The particle therapy system according to claim 6,wherein the irradiation control system controls to discretely scan the irradiation positions by controlling to irradiate the ion beam at the irradiation positions and controlling to suspend irradiation of the ion beam when moving from one irradiation position to another irradiation position.
	description	The United States Government has rights in this invention pursuant to Contract No. DE-AC02-05CH11231, between the U.S. Department of Energy (DOE) and University of California, Berkeley, representing the Lawrence Berkeley National Laboratory. One or more embodiments of the present invention relates to a method of remediating uranium from a contaminated environment and, more specifically, to a method for precipitating uranium from an aqueous and/or sediment. Uranium contamination in soil and water is of global concern and has been identified at a number of sites worldwide. Contamination may occur as a result of a variety of different activities, both natural and anthropogenic, including military testing, radiation accidents, nuclear fuel cycle activities (uranium mining, ore processing, fuel fabrication and reprocessing), electricity generation, mining and processing of other natural resources, and application of radionuclides in other industries. In oxygen-containing groundwater, uranium is generally found in the hexavalent oxidation state. In waste, uranium is present primarily as soluble salts of the uranyl ion (UO22+). The oxidized or hexavalent (VI) state of uranium is highly soluble and mobile, while the reduced or tetravalent (IV) state is relatively insoluble and, thus, immobile. As U(VI) is transported through groundwater, it can bond to minerals or carbonate and calcium species commonly found in groundwater. The latter scenario is problematic because the U(VI) remains highly mobile. When reduced from the oxidation state, U(VI), to a lower oxidation state, such as U(IV), the solubility of uranium decreases and it becomes immobilized. In contrast to U(VI), U(IV) does not form soluble solids even in the presence of calcium and carbonate. As U(VI) is transported through groundwater, it can bond to surfaces of minerals, a process which may retard its transport. It has recently been shown, however, that U(VI) also bonds strongly to the common groundwater species carbonate and calcium to form stable dissolved ternary complexes, which can effectively compete with mineral surfaces as “reservoirs” for U(VI). As a consequence, significant amounts of U(VI) remain in groundwater, thus maintaining relatively high mobility for U(VI), a highly undesirable scenario. Conversely, the tetravalent oxidation state, U(IV), forms sparingly soluble solids, even in the presence of dissolved carbonate and calcium, and thus tends to be relatively immobile. Various strategies for remediation of uranium from groundwater and soil have been proposed in order to reduce the detrimental effects of uranium contamination on ecosystems and local communities. These methods are sometimes able to reduce uranium concentrations below regulatory limits [the U.S. EPA Maximum Contaminant Level (MCL) for U is 0.13 μM]. These strategies include physical, chemical and biological technologies. For example, iron barriers, soluble reductive agents, microbial stabilization via reduction and precipitation, and emplacement of solid phosphate barriers have been pursued as potential technologies to remediate uranium from a contaminated environment. Currently, one of the most researched methods of uranium remediation is microbial mediated reduction of soluble uranyl species. This technique typically relies on injection of organic carbon into the contaminated environment to stimulate microbial U(VI) reduction to U(IV) solids. Under reducing conditions, microbial bioreduction produces elevated concentrations of bicarbonate and organic ligands from microbial utilization of organic carbon which promotes higher aqueous U(VI) concentrations. Consequently, organic carbon concentrations must be kept at concentrations high enough to maintain reducing conditions, but low enough to limit the formation of aqueous U(VI) carbonates. In addition, reducing conditions in the contaminated environment must be maintained due to the fact that U dissolves upon a return to the original oxidizing conditions of the subsurface environment. Another proposed remediation method is precipitation of uranium with phosphate in contaminated sediments. Phosphate reacts with U(VI) to form aqueous and ternary surface U(VI) complexes, poorly soluble uranyl phosphate precipitates, and U(VI) adsorbing phosphate minerals. Generally, one or more embodiments of the present invention relates to a method of precipitating uranium from an aqueous solution and/or sediment in the form of a precipitate. The embodiments are particularly useful for remediating uranium from contaminated aqueous environments found at a number of Department of Energy and other sites throughout the world. One or more embodiments of the present invention may be generally described as precipitating uranium in the form of a low solubility precipitate comprising uranium. In one or more embodiments, the precipitate is a uranyl vanadate. More specifically, the precipitate may comprise compounds elementally similar to carnotite or tyuyamunite. The precipitation stabilizes uranium as a solid in oxidizing conditions and, thus, eliminates the need for constant observation and maintenance of specific biogeochemical conditions in a remediated area in order to maintain conditions in which uranium remains as a solid. Because this approach does not rely on maintaining reducing conditions, the need for an indefinite supply of electron donor is circumvented. Consequently, uranium availability will remain controlled even after biogeochemical conditions return to that of the regional environment. As described above, one or more embodiments of the present invention relate to precipitation of uranium from an aqueous solution and/or sediment through precipitation of uranium. In one embodiment, the uranium precipitate comprises a uranyl vanadate. A uranyl vanadate is a compound comprising a uranium ion in its +6 oxidation state, e.g., (UO2)2+, and an oxoanion of vanadium generally in its highest oxidation state of +5. Precipitation of a low solubility uranyl vanadate is effective for controlling aqueous U concentrations in contaminated water and sediments due to the very low solubility observed in carnotite [K2(UO2)2V2O8] and tyuyamunite [Ca(UO2)2V2O8] in some oxidized U ore deposits. Vanadium is present in groundwater and sediments at varying levels primarily as the V(V) species, but also occurs in the III and IV oxidation states. Typical soils and sediments contain V at concentrations ranging from about 3 to 300 mg/kg. In groundwater, V is reported to be present at median and maximum concentrations of 1.4 μg/L (0.03 μM) and 190 μg/L (3.7 μM), respectively. While no MCL has been established for V, it is on the EPA Contaminant Candidate List. Subsurface transport of V(V) is controlled by sorption onto Fe oxides, thereby also moderating aqueous V(V) concentrations in the subsurface environment. Vanadate is typically present in groundwater as the oxyanion H2VO4− over the pH range between about 3.8 and 8.0. Remediation of uranium contaminated subsurface environments through precipitation of uranyl vanadate with K+ or Ca2+ under conditions representative of near-surface groundwater has not been attempted. One or more embodiments of the present invention relate to a method of precipitating uranium from an aqueous solution, comprising the step of: mixing a solution comprising a monovalent or divalent cation with an aqueous solution comprising uranium and vanadium creating a mixed solution, wherein a precipitate is formed in the mixed solution. In one or more embodiments, the precipitate comprises a uranyl vanadate. Another embodiment comprises the further step of removing the precipitate from the mixed solution. One or more embodiments further include the step of adjusting the pH of the mixed solution to a pH between about 4.5 and 8.5, preferably between about 5.5 and 6.5. In another embodiment of the present invention, the aqueous solution comprising uranium and vanadium is mixed with a solution comprising a monovalent cation selected from the group consisting of potassium, lithium, rubidium and cesium. In yet another embodiment, the pH of the mixed solution comprising a monovalent cation is adjusted to a pH between about 4.5 and 8.5, preferably between about 5.5 and 6.5. In one or more preferred embodiments the aqueous solution is mixed with a solution comprising potassium, and preferably potassium vanadate. In another embodiment of the present invention, the aqueous solution containing uranium and vanadium is mixed with a solution comprising a divalent cation selected from the group consisting of calcium, strontium and barium. In yet another embodiment, the pH of the mixed solution comprising a divalent cation adjusted to a pH between about 4.5 and 8.5, preferably between about 5.5 and 6.5. In one or more preferred embodiments, the aqueous solution is mixed with a solution comprising the divalent cation calcium. In one preferred embodiment, the solution comprising calcium is a calcium sulfate, specifically calcium sulfate dehydrate. Yet another embodiment further comprises the step of mixing a second solution comprising vanadium with the aqueous solution comprising uranium prior to precipitation wherein the ratio of the concentration of vanadium to uranium in the aqueous solution is less than or equal to about 1:1. In one or more embodiments, the solution comprises a monovalent cation selected from the group consisting of potassium, lithium, rubidium and cesium. In additional embodiments, the solution comprises a divalent cation selected from the group consisting of calcium, strontium and barium. In one or more embodiments of the present invention, the method can be performed in situ or ex situ with respect to a subsurface environment. In situ precipitation of uranium from an aqueous solution or sediment involves the treatment in the contaminated environment, e.g., a subsurface environment having groundwater and sediment contaminated with uranium. On the other hand, ex situ treatment of an aqueous solution or sediment containing uranium is carried out above-ground or outside the original environment by physically extracting the impacted medium, e.g., aqueous solution or sediment. The medium can then be treated on-site and returned to the original environment or transported for treatment and disposal. In one or more embodiments of ex situ precipitation, the precipitate can be removed from the aqueous solution. Additionally, one or more embodiments of the present invention can be used in conjunction with an in situ leaching (ISL) process. ISL works through a closed loop system in which oxygen and carbon dioxide, for example, are circulated in groundwater through wells in order to dissolve uranium from existing ore. The water containing the dissolved uranium is then transported to a treatment site where the uranium is extracted from the water. The one or more embodiments of the present invention could be useful in extracting uranium and other constituents of the ore than may be dissolved, such as vanadium, from the circulated water. One or more embodiments also relate to a method of treating a sediment comprising uranium and vanadium, comprising: (a) providing a sediment comprising uranium and vanadium; and, (b) mixing said sediment with a solution comprising a monovalent or divalent cation, wherein a precipitate comprising uranium and vanadium is formed. In another embodiment, the method further comprises adjusting the pH of the sediment to between about pH 4.5 and 8.5, preferably between about 5.5 and 6.5. Additional embodiments include mixing the sediment with a solution comprising vanadium, wherein the ration of the concentration of vanadium to uranium in the sediment is less than or equal to about 1:1. In one or more embodiments, the monovalent cation is selected from the group consisting of lithium, potassium, rubidium and cesium. Yet another embodiment is directed to mixing a solution comprising potassium, as the monovalent cation, with the sediment. In multiple other embodiments, a solution comprising a divalent cation may be mixed with the sediment to precipitate a uranyl vanadate precipitate containing a divalent cation. In one or more embodiments, the divalent cation is selected from the group consisting of calcium, strontium and barium. One or more embodiments of the present invention are directed to a method of extracting uranium and/or vanadium from an aqueous solution, comprising: (a) providing an aqueous solution comprising uranium and/or vanadium; (b) adjusting the pH of the aqueous solution to between about 4.5 and 8.5; (c) mixing the aqueous solution comprising uranium with a solution comprising vanadium; and, (d) mixing a solution comprising a monovalent or divalent cation with the aqueous solution and the solution comprising vanadium, wherein a precipitate comprising uranium is formed. In a preferred embodiment, the pH of the solution is between about 5.5 and 6.5. Another embodiment includes the further step of removing the precipitate from the solution. In one or more embodiments, the monovalent cation is selected from the group consisting of lithium, potassium, rubidium and cesium. Yet another embodiment is directed to mixing a solution comprising potassium, as the monovalent cation, with the solution comprising uranium. In multiple other embodiments, a solution comprising a divalent cation may be mixed with the aqueous solution comprising uranium to precipitate a uranyl vanadate precipitate containing a divalent cation. In one or more embodiments, the divalent cation is selected from the group consisting of calcium, strontium and barium. In a preferred embodiment, the divalent cation is calcium. In yet another embodiment, a method of precipitating uranium is presented comprising the steps of: (a) measuring the uranium and vanadium concentration of an aqueous solution comprising uranium and/or vanadium; (b) mixing a solution comprising a monovalent or divalent cation with the aqueous solution comprising uranium and/or vanadium, wherein the ratio of the concentration of monovalent or divalent cation to uranium is greater than or equal to about 1:1; (c) mixing a solution comprising vanadium with the aqueous solution comprising uranium if no vanadium is detected in the aqueous solution in step (a) or if the amount of vanadium detected in the aqueous solution is less than the amount of uranium detected, wherein the ratio of the concentration of vanadium to uranium is greater than or equal to about 1:1; and, (d) adjusting the pH of the mixed solutions to between about pH 4.5 and 8.5, wherein a precipitate comprising uranium is formed. In another embodiment, the cation solution comprises the monovalent cation potassium, the ratio of the concentration of monovalent or divalent cation to uranium is greater than or equal to about 10:1, and the ratio of the concentration of vanadium to uranium is greater than or equal to about 10:1. In yet another embodiment, the cation solution comprises the monovalent cation potassium, the pH of the mixed solution is between about 5.0 and 6.0, the ratio of the concentration of potassium to uranium is greater than or equal to about 25:1, and the ratio of the concentration of vanadium to uranium is greater than or equal to about 5:1. In one preferred embodiment, the cation solution comprises the monovalent cation potassium, the pH of the mixed solution is between about 7.8 and 8.1, the ratio of the concentration of potassium to uranium is greater than or equal to about 100:1, and the ratio of the concentration of vanadium to uranium is greater than or equal to about 10:1. In another preferred embodiment, the cation solution comprises the divalent cation calcium, the pH of the mixed solution is between about 6.0 and 6.5, the ratio of the concentration of calcium to uranium is greater than or equal to about 10:1, and the ratio of the concentration of vanadium to uranium is greater than or equal to about 1:1. Mixing Aqueous Solution Comprising U with Solution Comprising a Monovalent or Divalent Cation Generally, an aqueous solution comprising uranium and vanadium is mixed with a solution comprising a monovalent or divalent cation. The presence or absence and concentration of uranium and/or vanadium in an aqueous solution can be confirmed through testing methods known to one of skill in the art, including but not limited to chromatographic, spectroscopic and electrochemical methods that may be performed in situ or ex situ. More specifically, concentrations of uranium and/or vanadium may be determined using inductively coupled plasma mass spectrometry (ICP-MS) or atomic (optical) emission spectroscopy (ICP-AES or ICP-OES), in addition to kinetic phosphorescence analysis (KPA). In one or more embodiments, the aqueous solution comprising uranium and vanadium is groundwater. In one or more embodiments, the solution comprising a monovalent or divalent cation can be a monovalent cation selected from the group consisting of potassium, rubidium, lithium and cesium. In one or more embodiments, the solution comprising a monovalent cation is a vanadate or chloride or sulfate salt of the monovalent cation. In one or more preferred embodiments, the monovalent cation is potassium. In one or more preferred embodiments, the solution comprising potassium is potassium vanadate, potassium chloride or a sulfate salt of potassium. While many solutions containing a monovalent cation are compatible, the preferred solution has a neutral to slightly acidic pH. In one or more additional embodiments, the solution comprising a monovalent or divalent cation can be a divalent cation selected from the group consisting of calcium, strontium and barium. In one or more embodiments, the solution comprising a divalent cation is a vanadate or chloride or sulfate salt of the monovalent cation. In one or more preferred embodiments, the divalent cation is calcium. In yet another preferred embodiment, the solution comprising calcium is calcium chloride or a sulfate salt of calcium, such as calcium sulfate dihydrate. While many solutions containing a monovalent cation are compatible, the preferred solution has a neutral to slightly acidic pH. In one or more embodiments of the present invention, the aqueous solution comprising uranium and vanadium may reside in a subsurface environment. The mixing of the aqueous solution and solution comprising a monovalent or divalent cation may occur in the subsurface environment, i.e., in situ. Methods of delivering solutions to a subsurface environment, i.e., in situ remediation, are known to one of skill in the art, including but not limited to the use of trenches, filter galleries, wells and injection ports to introduce the solutions into the subsurface. In one or more embodiments, the aqueous solution comprising uranium and vanadium may be mixed with the solution comprising a monovalent or divalent cation outside the environment in which the aqueous solution typically resides, e.g., ex situ. In one such embodiment, an aqueous solution comprising uranium and vanadium is pumped out of a subsurface environment and mixed with a monovalent or divalent cation solution in order to form a uranyl vanadate precipitate. The precipitate can then be removed from the aqueous solution by filtration or other separation methods known to one of skill in the art, and as more fully described below. The uranium and vanadium-free aqueous solution may be subsequently pumped back into its original subsurface environment. Various methods used to carry out mixing in accordance with the present invention are known to one of skill in the art. Exemplary ex situ methods include but are not limited to excavation of uranium containing sediment or removal of uranium-containing aqueous solution and subsequent mixing performed via in-drum, in-plant or area mixing processes, which may be performed in mobile or fixed treatment plants, and in conjunction with in situ leaching processes. Mixing Sediment Comprising U with Solution Comprising a Monovalent or Divalent Cation In one or more embodiments, the method relates to removing uranium and vanadium from sediment. The presence or absence and concentration of uranium and/or vanadium in an aqueous solution can be confirmed through testing methods known to one of skill in the art, including but not limited to ICP-MS, ICP-AES or KPA. The sediment can be any type of solid that contains uranium and/or vanadium. In one or more preferred embodiments, the sediment is from a subsurface environment. In one or more embodiments, the solution comprising a monovalent or divalent cation are similar to those described above. Also, as described above, one or more embodiments of the method can be carried out in a subsurface environment that includes sediment and/or groundwater comprising uranium and vanadium, i.e., in situ. Alternatively, one or more embodiments of the present invention can be performed outside the original sediment environment, i.e., ex situ. For example, in one or more embodiments, sediment can be removed from a subsurface environment through methods known to one of skill in the art, e.g., excavation. The sediment comprising uranium and/or vanadium is then mixed with a solution comprising a monovalent or divalent cation ex situ in order to precipitate the uranium and vanadium. Subsequently, the uranium and vanadium precipitate may removed from the solution containing the sediment through filtration or other separation method. The uranium and vanadium-free sediment may be subsequently returned to its original environment. Precipitation of Uranium In one or more embodiments of the present invention, uranium and/or vanadium are precipitated out of a solution and/or sediment in order to remove the uranium and/or vanadium from the solution and/or sediment. In one or more preferred embodiments, the precipitate is a uranyl vanadate. A uranyl vanadate is a compound comprising a uranium ion in its +6 oxidation state, e.g., (UO2)2+, and an oxoanion of vanadium generally in its highest oxidation state of +5. Precipitation of a uranyl vanadate may be accomplished through mixing an aqueous solution and/or sediment comprising uranium and/or vanadium with a solution comprising a monovalent and/or divalent cation at an appropriate pH level, as further described herein. Alternatively, an aqueous solution comprising uranium and/or vanadium may be mixed with a solution comprising vanadium and a solution comprising a monovalent or divalent cation where there is no vanadium present in the initial solution comprising uranium or where the amount of vanadium in the initial solution is not sufficient to precipitate enough uranium to lower it below the MCL. In the case of a monovalent cation, one or more preferred embodiments use a solution comprising a cation selected from the group consisting of lithium, potassium, rubidium and cesium. The resulting precipitate is the corresponding lithium uranyl vanadate [Li2(UO2)2V2O8], potassium uranyl vanadate [K2(UO2)2V2O8], rubidium uranyl vanadate [Rb2(UO2)2V2O8], or cesium uranyl vanadate [Cs2(UO2)2V2O8], or substantially similar compounds. For example, a solution comprising uranium and vanadium may be mixed with a solution of potassium vanadate, potassium chloride, or any potassium solution having a slightly acidic to neutral pH, to form a precipitate, which may have a chemical formula substantially similar to K2(UO2)2V2O8. In the case of a divalent cation, one or more preferred embodiments use a solution comprising a cation selected from the group consisting of calcium, strontium and barium. The resulting precipitate is the corresponding calcium uranyl vanadate [Ca(UO2)2V2O8], strontium uranyl vanadate [Sr(UO2)2V2O8], or barium uranyl vanadate [Ba(UO2)2V2O8], or substantially similar compounds. For example, a solution comprising uranium and vanadium may be mixed a solution of calcium chloride, or any calcium solution having a slightly acidic to neutral pH, to form a precipitate, which may have a chemical formula substantially similar to Ca(UO2)2V2O8. Adjusting the pH of the Mixed Solution In one or more embodiments of the method, the pH of a mixed solution comprising an aqueous solution and/or sediment comprising uranium and vanadium and a solution comprising a monovalent or divalent cation is adjusted to be more acidic or more basic. In one or more embodiments, the pH of the mixed solution is between about 4.5 and 8.5, preferably between about 5.5 and 6.5. Generally speaking, in order to adjust to pH of the solution higher, i.e., more basic, a basic solution is added to the solution comprising an aqueous solution and/or sediment comprising uranium and vanadium. The amount of acidic or basic solution to be added to the mixed solution is dependent on the starting pH, the desired pH and the concentration and pH of the solution to be added, which can be determined through trial titration experiments, among other methods. Examples of compatible basic solutions that can be used to obtain this result are potassium hydroxide, calcium hydroxide or sodium bicarbonate. Conversely, the pH can be lowered through the addition of an appropriate amount of acidic solution. Examples of a compatible acidic solution that can be used to obtain this result are hydrochloric acid, nitric acid, HEPES buffer or MES buffer, although any number of acidic solutions may be used. In one or more preferred embodiments, the pH may be maintained between about 4.5 and 8.5, as described by the above methods, and preferably between about 5.5 and 6.5. Addition of acidic or basic solutions in situ can be performed in the same manner as the addition of the monovalent or divalent cation containing solution discussed above. The amount of acidic or basic solution to be used in an in situ process will be determined on a case-by-case basis according to methods known to one of skill in the art depending on a number of factors, including the starting pH and geochemical characteristics of the environment. For an ex situ method, the acidic or basic solution can be added in any manner that will facilitate substantially uniform mixing of the acidic or basic solution with the uranium and/or vanadium containing solution and/or sediment, which will be determined by the manner and place in which ex situ treatment occurs. Extracting/Mining U from an Aqueous Solution In one or more embodiments of the method, uranium is removed from an aqueous solution by mixing a solution comprising vanadium and a second solution comprising a monovalent or divalent cation with the solution comprising uranium, wherein a precipitate is formed. Subsequently, or concurrently, the pH of the mixed solutions may be adjusted to between about 4.5 and 8.5, preferably between about 5.5 and 6.5, which may be accomplished through one of the above methods or by any method known to one of skill in the art. In a preferred embodiment, the solution comprising vanadium can be potassium metavanadate. Monovalent and divalent cations for use with one or more embodiments of the present invention are the same as those described above. In one or more embodiments, the aqueous solution comprising uranium may be removed from a subsurface environment according to method known to one of skill in the art, including but not limited to the use of wells, pump systems and other extraction methods. After removal from the subsurface environment, the aqueous solution can be treated as described above. The precipitate can then be removed from the aqueous solution by filtration sedimentation, or other separation methods known to one of skill in the art. Equilibrium Calculations Uranium concentrations in equilibrium with carnotite and tyuyamunite were calculated using PHREEQC 2.12, a computer program designed to perform a wide variety of low-temperature aqueous geochemical calculations. Solutions were modeled with a range of K, Ca and V concentrations, in equilibrium with the atmosphere (pCO2=3.5) and with a moderately elevated pCO2=2.5 representative of slightly reducing pore waters. The majority of calculations were performed with representative groundwater concentrations of Ca2+=1 mM and K+=0.1 mM. Thermodynamic data was taken from the Nuclear Energy Agency compilation and other sources. Calculations were performed for U concentrations with 1 μM vanadate in equilibrium with carnotite and tyuyamunite. Carnotite and tyuyamunite were able to control U concentrations below the MCL over a broad range of pH. Enhanced U solubility through formation of carbonate complexes is again evident from a comparison of the pCO2 3.5 and 2.5 curves in FIG. 1. FIGS. 1A and 1B also demonstrate the effects of varying levels of Ca2+ on dissolved U concentrations for equilibrium with carnotite and tyuyamunite. For example, FIGS. 1A and 1B show that increased Ca2+ concentrations stabilize U at higher concentrations in the higher pH range through formation of strong Ca-U-carbonate complexes. Further, Ca2+ drives U concentrations lower in tyuyamunite in high to intermediate pH ranges as Ca is a component of tyuyamunite. These effects on U(VI) complexation are predicted to maintain U concentrations above the MCL at pH>7.5, even in the presence of 1 μM V. Consequently, in alkaline systems, pH neutralization is a prerequisite for controlling U(VI) concentrations through precipitation of carnotite or tyuyamunite. An important long-term condition to consider involving uranyl vanadate solid phases are those in which V concentration is not fixed at a single value, but instead is supplied by the dissolution of its uranyl minerals, carnotite and tyuyamunite. Such conditions might be present where carnotite or tyuyamunite naturally occur or are present as a result of remediation treatment, and subsequently begin to dissolve in groundwater with low V and U concentrations. The case for equilibrium U concentrations resulting from dissolution of carnotite in the reference groundwater (0.1 mM K+, 1 mM Ca2+, pCO2 3.5 and 2.5) as the sole source of V and U are shown in FIG. 2. This demonstrates that the U-MCL will be approached, but U concentrations will exceed the MCL in the reference groundwater when U and V are supplied only by carnotite dissolution. However, within the 5<pH<7 range, expected U concentrations exceed the MCL by less than 1 μM. It is also important to test the effect of K+ concentrations under conditions of equal U and V concentrations because, as a component of carnotite, elevated K+ concentrations will suppress U concentrations. The influence of varying K+ levels is presented in FIGS. 3A and 3B for the cases of pH=6.0 and 7.0, Ca2+=1 mM, at pCO2=3.5 and 2.5. As predicted, FIGS. 3A and 3B illustrate that the influence of carbonate and Ca2+ are minor at pH=6.0 and major at pH=7.0. Thus, at sub-mM concentrations of K+, carnotite can control U slightly below its MCL at a moderate pCO2 of 2.5, but that significantly higher K+ would be required at pH 7.0 and elevated CO2. Batch Experiments Based on thermodynamic calculations, experiments involving the precipitation of carnotite were conducted at pH of 6.0 and 7.8. These two pH values were predicted to be near-optimal (lowest U concentration) and marginal (negligible U concentration change). Batch experiments were performed to determine the extent of homogenous U(VI) precipitation from solutions in response to additions of K+ and V(V), in order to form K2(UO2)2V2O8 or an elementally similar precipitate. Uranyl nitrate (Spectrum Chemical) was used to prepare stock U(VI) solutions. Among commonly available vanadate compounds, potassium metavanadate, KVO3 (Aldrich), was selected because it required little pH adjustment for the tested range, and it includes K. Upon dissolution in water at dilute concentrations, dissociated VO3− converts to H2VO4−. Samples were prepared in duplicate 40 mL batches in screw cap Teflon vials, to contain ˜1 μM U, with K+ concentrations of 0.1, 0.19, 1.0, and 10 mM, V(V) concentrations from 0 to 500 μM, and NaNO3 added to set the ionic strength equal to 100 mM. Inclusion of nitrate also ensured that solutions remained oxidizing. The pH values of 6.0 and 7.8 were established using 1 mM 2-(N-morpholino)ethanesulfonic acid (MES) buffer and 1 mM NaHCO3, respectively. Subsequent measurements indicated that the solutions remained within ±0.1 pH units throughout the experiments. Capped vials were continuously agitated on a reciprocating shaker (˜1 cycle s−1) maintained at room temperature (20±1° C.), and sampled at prescribed times from 1 day up to 50 days. At sampling times, vials were temporarily opened to withdraw 1 mL samples, which were then centrifuged (14000 relative centrifugal force for 60 min). Supernatant solutions were withdrawn after centrifugation for U analysis by kinetic phosphorescence analysis (KPA, Chemchek), and K and V analysis by ICP-OES. In all of these batch experiments, the KPA detection limit was 0.2 nM. The one or more embodiments of the present invention may be performed in situ or ex situ, depending on a number of considerations, including cost, efficiency, and the composition of the subsurface environment, among other considerations. Examples of in situ and ex situ remediation techniques compatible with the one or more embodiments of the present invention are generally described above. Homogenous precipitation of U(VI) in aqueous solutions was measured and exhibited complex dependence in various K+ and V(V) concentrations. Time trends for the influence of K+ concentrations on U(VI) precipitation at pH 6.0 and pCO2 ˜3.5 are shown for V concentrations of 5 and 50 μM in FIGS. 4A and 4B, respectively. For experiments conducted at pH 6.0, U concentrations decreased from 0.78 μM to 0.89 μM to below the MCL (0.13 μM) almost immediately in most cases. However, experiments with 50 μM V were not able to reduce U concentrations below the MCL with the addition of 0.1 or 1.0 mM K+, as depicted in FIG. 4B. Also, of note is that the test of 10 mM K+ with 5 μM V lowered U concentrations below the detection limit within 21 days. At the lower levels of 0.1 and 1.0 mM K+, rates of U removal were similar and controlled U concentrations below the MCL for the 50 day time period tested, as shown in FIG. 4A. Based on this data, at a pH of about 6.0, a solution containing the monovalent cation potassium will effectively precipitate uranium from an aqueous solution when the ratio of the concentration of vanadium to uranium is about 5:1, the ratio of the concentration of potassium to uranium is greater than or equal to about 100:1 and the ratio of the concentration of potassium to vanadium is greater than or equal to about 20:1. Also, precipitation of uranium occurs where the ratio concentration of vanadium to uranium is greater than or equal to about 50:1 and the ratio of the concentration of potassium to uranium is greater than or equal to about 10000:1 and the ratio of the concentration of potassium to vanadium is greater than or equal to about 200:1. Time trends for the influence of K+ concentrations on U(VI) precipitation at pH 7.8 and pCO2 ˜3.5 are shown for V concentrations of 5 and 50 μM in FIGS. 5A and 5B, respectively. At pH 7.8, 5 μM V(V) was insufficient to lower U concentrations below the MCL regardless of K+ concentration, despite that equilibrium calculations predicted substantial carnotite precipitation. As depicted in FIG. 5B, U removal was effective with 50 μM V(V) with no variation in effectiveness in changes of K+ concentration over 0.1 mM K. Based on this data, at a pH of about 7.8, a solution containing the monovalent cation potassium will effectively precipitate uranium from an aqueous solution when the ratio of the concentration of vanadium to uranium is about 50:1, the ratio of the concentration of potassium to uranium is greater than or equal to about 100:1 and the ratio of the concentration of potassium to vanadium is greater than or equal to about 2:1. However, where the ratio of the concentration of vanadium to uranium was about 5:1, precipitation did not occur. Due to the rapid and similar removal of U at pH 6.0 with V(V)=5 μM at K+ concentrations equal to 0.1 mM and 1.0 mM shown in FIG. 5A, additional measurements were performed with further variation of V around the lower concentration. These experiments yielded similarly rapid removal of U with the lowest final U concentrations being obtained using initial V(V) concentrations between 2 to 10 μM. Comparisons of the experiments conducted in Examples 1-3 with thermodynamic predictions are shown in FIG. 6. As shown, the extent of U removal after 50 days with higher initial V(V) concentration was less effective in tests conducted at pH 6.0. In addition, at pH 7.8, experiments with 5 μM V showed little variation with increased K+, even with higher levels of K+ where predictions from carnotite solubilities are expected to drive U concentrations below the MCL. For the pH 7.8 experiments conducted with 50 μM V, U concentrations dropped below the MCL with both 0.1 mM and 1.0 mM K. The composition of the U-containing solid phase was examined in a separate, 2 L batch solution. The precipitated solid was collected on 0.2 μm filters and analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray diffraction (XRD). The ICP-OES analysis of the acid-digested precipitate yielded a K:U:V ratio of 1.24:1.00:1.09, compared to an ideal ratio of 1:1:1 for carnotite. The solid phase was determined to be amorphous in the XRD measurement. Despite the lack of crystallinity in the precipitate, the similar K:U:V elemental ratios and the approximate agreement of measured aqueous U concentrations with thermodynamic predictions support precipitation of a carnotite-like phase. Batch experiments were also performed on U-contaminated sediments from Oak Ridge (pH 8.1) and Savannah River (pH 5.2). The sediments were spiked with U(VI)-nitrate to a final U concentration of 100 mg/kg, then treated in suspensions with V concentration ranging from 0.05 to 1.5 mM, and K+ from 0.1 to 5 mM. The Oak Ridge sediment had an initial aqueous U concentration of approximately 1.9 μM and was treated with 300 μM V and 1 mM K+ and uranium levels were reduced to less than the MCL within one day. The Savannah River sample had an initial aqueous U concentration of approximately 2.1 μM and exhibited similar reduction of U(VI) concentrations within 1 day upon treatment with 50 μM V and 0.1 mM K. U(VI) concentrations were further reduced over the extended time period of the tests. Control suspensions (U-contaminated to 100 mg/kg, but not V addition) had aqueous phase U concentrations in the range of 1.0 to 4.5 μM. The results of these experiments are summarized in FIG. 7. The effect of V concentration on U(VI) removal was also examined at two K+ concentrations for both the Oak Ridge and Savannah River sediments. Two separate Savannah River sample sediments (pH 5.2) were treated with 0.1 mM K+ and 0.5 mM K+, respectively, and V concentrations ranging from approximately 20 μM to 125 μM. Similarly, two separate Oak Ridge (pH 8.1) sample sediments were treated with 1 mM K+ and 5 mM K+, respectively, and V concentrations ranging from approximately 120 μM to 1 mM. The experiments with both sediments demonstrate that U(VI) removal is proportional to V concentration. The results of these experiments are summarized in FIG. 8. Based on this data, at a pH of about 5.2, a solution containing the monovalent cation potassium will effectively precipitate uranium from sediment when the ratio of the concentration of vanadium to uranium is greater than or equal to about 10:1, the ratio of the concentration of potassium to uranium is greater than or equal to about 25:1 and the ratio of the concentration of potassium to vanadium is greater than or equal to about 1:2.5. In addition, at a pH of about 8.1, a solution containing the monovalent cation potassium will effectively precipitate uranium from sediment when the ratio of the concentration of vanadium to uranium is greater than or equal to about 100:1, the ratio of the concentration of potassium to uranium is greater than or equal to about 500:1 and the ratio of the concentration of potassium to vanadium is greater than or equal to about 1:1. Laboratory experiments were conducted in order to test the effectiveness of precipitation of a calcium uranyl vanadate solid from aqueous solutions initially containing high levels of U. An initial stock solution was prepared containing components of the target precipitate at concentrations of 8 μM U(VI), 20 μM V(V), and 3 mM Ca2+. Uranyl nitrate, sodium metavanadate, and calcium sulfate dihydrate were used as starting reagents. Other ions in solution were Mg2+ (3 mM), Na+ (5 mM), SO42− (6 mM), Cl− (1 mM), NO3− (1 mM), initial HCO3+ (3 mM), and initial pH of 8.0. This stock solution was split into smaller Teflon vials, which were adjusted to different pH values (6.0, 6.5, 7.0, 7.5, and the unadjusted ≈8.0). The pH-adjusted vials were placed on a shaker for continuous agitation, with periodic sampling for analysis of the aqueous phase chemical composition. Nitric acid, HEPES buffer (1 mM), and MES buffer (1 mM) were used for pH adjustments. The presence of nitrate (1 mM) and periodic opening of the vials for pH adjustment ensured that all solutions remained oxidizing. Prior to chemical analyses, solutions were centrifuged to remove potentially suspended particles. Concentrations of U, V, and Ca were measured on days 1, 2, 3, 4, 8, and 15 by ICP-MS. Time trends of U concentrations at various pH values are depicted in FIG. 9. Based on this data, between the pH of about 6.0 to 6.5, the divalent cation calcium will effectively remove uranium from an aqueous solution when the ratio of the concentration of calcium to uranium is greater than or equal to about 10:1 and the ratio of the concentration of vanadium to uranium is greater than or equal to about 1:1. A number of the examples described above are also described in Tokunaga, T., et al., Environ. Sci. Technol., 2009, 43, 5467-5471, which is incorporated by reference herein. It is to be understood that the above-described examples are only illustrative of the application of the principles of the present invention and it is not intended to be exhaustive or limit the invention to the precise form disclosed. Numerous modifications and alternative arrangements will be apparent to those skilled in the art in light of the above teachings without departing from the spirit and scope of the present invention. It is intended that the scope of the invention be defined by the claims appended hereto. In addition, the previously described versions of the present invention have many advantages, including but not limited to those described above. However, the invention does not require that all advantages and aspects be incorporated into every embodiment of the present invention. All publications and patent documents cited in this application are incorporated by reference in their entirety for all purposes to the same extent as if each individual publication or patent document were so individually denoted.
	summary
051606976	description	DETAILED DESCRIPTION FIG. 1 shows a lower 1 of a fuel assembly for a pressurized-water nuclear reactor consisting of an adapter plate 2 of square shape resting on supporting feet 3 welded to the lower face of the adapter plate 2. The adapter plate 2 consists having a metal plate of a thickness of the order of 20 mm, chamfered on its outer upper edge and traversed by water passage orifices placed in a regular arrangement, to be described hereinbelow. In general terms, the water passage orifices and fuel rods of the assembly are placed in such relative positions that a fuel rod of the assembly is never completely in vertical alignment with a water passage orifice. Thus, the rods are always held within the assembly by a part of the connector ensuring their retention. The supporting feet 3 are arranged at the four corners of the adapter plate 2. Two of the supporting feet, 3a and 3b, which are placed along a diagonal 5 of the adapter plate 2, comprise cylindrical holes 4 intended for engaging onto pins fixed to the lower core plate, on which the lower connector 1 comes to rest during the installation of the assembly. The two supporting feet located on the second diagonal 5' of the adapter plate 2 do not have any holes similar to the holes 4 of the supporting feet 3a and 3b. FIG. 1 also shows the two medians 6 and 6' of the adapter plate which constitute, with the diagonals 5 and 5', axes of symmetry in relation to which the water passage orifices extending through the adapter plate 2 are arranged completely symmetrically, as will be described below. To describe the arrangement of the orifices extending through the adapter plate 2, the eight sectors 7a, 7b, 7c, 7d, 7e, 7f, 7g and 7h of the surface of this plate which are delimited by the diagonals 5 and 5' and by the medians 6 and 6' will be considered. These eight sectors are constituted by identical right-angled triangles having a common vertex consisting of the center of the plate 2. The shape, dimensions and arrangement of the orifices extending through the adapter plate are identical in each of the triangular sectors 7a to 7h. Consequently, each of the orifices extending through the adapter plate 2 is symmetrical with an identical orifice both in relation to a median and in relation to a diagonal of the adapter plate. The set of orifices is therefore arranged completely symmetrically in relation to both the diagonals and the medians of the adapter plate. Moreover, some of the water passage orifices, 8, extending through the adapter plate in the region of each of the triangular sectors 7a to 7h have a cross-section of oblong shape more or less elongate along the longitudinal axis of the cross-section. In the preferred embodiment illustrated in FIG. 1, twelve water passage orifices of oblong shape extend through the adapter plate 2 in each of the triangular sectors 7a to 7h. Since the arrangement, shape and dimension of the orifices are identical in each of the triangular sectors delimited by the diagonals and by the medians of the plate 2, only the arrangement of the orifices within the sector 7a will be described below. Within the sector 7a, the adapter plate 2 has extending through it ten oblong orifices having axes parallel to the median 6 of the adapter plate 2 which forms one of the sides of the triangular sector 7a. These ten oblong orifices are arranged as follows: three orifices 8a of small length are aligned along the outer edge of the plate delimiting the sector 7a; three oblong orifices 8b, slightly greater in length than orifices 8a, are aligned in a second row parallel to the row of orifices 8a and arranged towards the inside of the adapter plate 2, i.e., nearer its center than the row of orifices 8a; one orifice 8c of greater length is interposed between two orifices 8a and two orifices 8b and extends in the space separating the row of orifices 8a from the row of orifices 8b; one orifice 8d, the length of which is intermediate between in both instances of an orifice 8b and in both instances of an orifice 8c, is placed at the outer end of the row of orifices 8a and extends in the space separating the rows of orifices 8a and 8b; one orifice 8e, smaller in length than orifice 8d, is arranged after this orifice towards the outside of the row of orifices 8a and 8d in the direction of the corner of the plate 2; finally, one orifice 8f of a length substantially equal to that of orifices 8a is placed in proximity to the center of the plate 2. The set of oblong orifices 8 arranged in the triangular sector 7a also comprises two orifices 8g, substantially identical in length to orifices 8a and 8f. The two orifices 8g have longitudinal axes parallel to the median 6' of the adapter plate 2 and to the outer side of the adapter plate 2 delimiting the sector 7a. The orifices 8g are interposed between the row of orifices 8b and the orifice 8f. In addition to the twelve orifices of oblong shape, the adapter plate comprises, in each of the triangular sectors 7a, nine cylindrical orifices of circular cross-section. These orifices are arranged as follows: five orifices are centered on the diagonal 5; two orifices are centered on the median 6; and two orifices are located entirely within the triangular sector 7a. Of these nine circular orifices, the two circular orifices located in proximity to the corner of the plate 2 above the foot 3a, and one on the diagonal 5 and the other within the sector 7a, have a smaller diameter than the other seven circular orifices. Of these other orifices of larger diameter, the three orifices 9a, of which one is located on the diagonal 5, another on the median 6 and the third within the triangular sector 7a, serve for the engagement and fastening of the end of guide tubes of the assembly. Two orifices 9b, of which one is located on the diagonal 5 and the other on the median 6, are used for fastening the filtration plate to the adapter plate by means of rivets. The other orifices of circular shape constitute water passages, like oblong water passages 8. FIG. 2 shows the adapter plate 2 of FIG. 1, to the upper face of which a filtration plate 11 of small thickness has been attached and fastened in an abutting arrangement. As regards a connector of an assembly for a pressurized-water nuclear reactor, of which the adapter plate has a side about 20 cm in length and a thickness of the order of 20 mm, a filtration plate of a thickness of about 2 mm is used. The filtration plate 11 is fastened to the adapter plate 2 by means of eight rivets 12, each introduced into an orifice 9b extending through the adapter plate 2. The sixteen guide tubes 13 of the assembly are each fastened in an orifice 9a of the adapter plate and extend through a corresponding orifice of the filtration plate. In the central part of the connector 1, an instrumentation tube 14 is fastened within an orifice of circular cross-section extending through the adapter plate and a corresponding orifice of the filtration plate. The filtration plate 11 comprises sets 15 of orifices of small dimensions in the form of square-mesh networks, and, when the plate 11 is laid against the adapter plate 2, these come into alignment with the oblong water passage orifices 8 of the adapter plate and with the circular orifices 9, with the exception of the orifices 9a and 9b used for fastening the guide tubes 13 and rivets 12. Each of the filtration sets 15 is in the form of a square-mesh sieve arranged in a rectangular or square orifice extending through the filtration plate 11. The sieves of the sets 15 consist of thin wires or bars 16, intersecting and fastened to one another. The sieves could also be produced by punching of the plate 11, so as to delimit the cells of the sieves by means of ligaments consisting of the metal of the plate 11. The square meshes of the sieves 15 are of a dimension of the order of 3 mm. The filtration sets or sieves 15 arranged in alignment with the orifices of largest dimensions of the adaptor plate, such as the orifices 8c, 8d and 8e, may comprise one or more reinforcing struts 16' of larger cross-section than the wires or ligaments 16 constituting the sieve 15. In fact, the cross-sections of the wires or ligaments constituting the sieves 15 have the smallest possible dimensions, in order to reduce the head loss during the passage of the cooling water and to increase the cooling flow for the fuel assembly. The sieves 15 are therefore liable to experience deformation when debris of large mass is retained, where sieves superposed on the orifices of largest cross-section are concerned, with the result that struts 16' may be necessary to obtain sufficient rigidity and strength of the sieves 15. FIG. 3 illustrates a second embodiment of the adaptor plate of a connector according to the invention. The adaptor plate 22 of the connector 21 comprises orifices which are arranged completely symmetrically in relation to the diagonals 25 and 25' and to the medians 26 and 26' of the adaptor plate, as in the embodiment of FIGS. 1 and 2. As before, the diagonals and medians define eight triangular sectors 27a, 27b, 27c, 27d, 27e, 27f, 27g and 27h, in which the orifices of the adaptor plate have identical shapes, dimensions and arrangements. The orifices extending through the sector 27a of the plate 22 will be described. Within the sector 27a, a set of oblong orifices 28 and orifices of circular cross-section 29 extend through the plate. The set of oblong orifices comprises: two orifices 28a of great length arranged in a first row along the edge of the adaptor plate parallel to the median 26', two oblong orifices 28b, of smaller length than the orifices 28a, arranged in a row parallel to the median 26' and placed towards the inside of the adaptor plate in relation to the row of orifices 28a, one orifice 28c of substantially the same length as orifices 28b and aligned with a circular orifice 29 in a third row parallel to the median 26', one orifice 28d, and one orifice 28'd shorter than orifice 28d, both arranged in a fourth row, one orifice 28e and one orifice 28f parallel to the median 26' and located in sequence in the direction of the center of the plate 22. In addition to the oblong orifices 28 and the circular orifice 29 plate 22 comprises a water passage orifice 30 in the form of a triangle with rounded corners placed in proximity to the center of the plate 22. As in the embodiment of FIGS. 1 and 2, the circular orifices 29a are intended for receiving guide tubes of the assembly and the circular orifices 29b for receiving fastening rivets of a filtration plate which is laid against the adaptor plate 22 and which comprises orifices of small dimension which come into alignment with the water passage orifices 28 and 29. In sector 27a of the embodiment of FIG. 3, the oblong orifices all extend in the same direction parallel to one of the medians of the adapter plate within a triangular sector. However, for the adapter plate 22 as a whole, the oblong orifices arranged symmetrically are oriented in the directions of both medians 26 and 26'. FIG. 4 illustrates a third embodiment of an adapter plate of a connector according to the invention. The corresponding elements in FIGS. 3 and 4 bear the same references. The two versions differ in that the oblong orifice 28'd of small length is replaced by a triangular orifice 31' with rounded corners in the second version, and in that the adaptor plate comprises twenty-four orifices 29a allowing the fastening of guide tubes, instead of sixteen orifices as in the embodiments of FIGS. 1, 2 and 3. In this third embodiment, eight additional holes, 29b, allow the fastening of a filtration plate by means of rivets. The lower connector according to the invention permits the passage of a high flow of water in the fuel assembly, while at the same time ensuring efficient filtration of this fluid. The arrangement of the apertures, in two different directions and symmetrically, allows the adapter plate to have good mechanical strength in these two directions and thus prevents a preferred orientation of the deformations along one of the axes. The rigidity of the adapter plate is identical in both directions of the adaptor plate, in contrast to the situation when the orifices are arranged in only one direction. Furthermore, the machining of the adaptor plate becomes easier and the adaptor plate experiences only slight deformations during the welding thereof for the purpose of making the connector. The number and distribution of the oblong water passage orifices of the adaptor plate, may be varied from those indicated or described above. The adaptor plate of a connector according to the invention may comprise solely water passage orifices, of oblong cross-section, or both oblong water passage orifices and cylindrical water passage orifices of circular cross-section. Finally, the invention can be used not only in fuel assemblies for a pressurized-water nuclear reactor, but also in fuel assemblies for any water-cooled nuclear reactor.
	claims	1. A gamma-ray imaging device, comprising:a scintillator which converts gamma rays into localized flashes of light;an image intensifier that collects a substantial fraction of the light from each flash produced by a single gamma-ray photon and produces an amplified flash of light;an optical system including a video camera to image each amplified flash onto an imaging detector that operates at a frame rate fast enough to allow spatial separation of most of the clusters of pixels that receive light from different gamma-ray interactions in the scintillator; anda processing unit programmed with instructions, the instructions when executed identify the clusters of pixels on the video camera associated with respective amplified flashes of individual gamma-ray photons and use the data from said cluster of pixels to perform a statistical estimation of a position where the corresponding gamma-ray photon interacted with the scintillator and the energy deposited in the interaction. 2. The gamma-ray detection device according to claim 1, wherein optical radiation of each amplified flash has a wavelength in a range from 100 nm to 1000 nm. 3. The gamma-ray detection device according to claim 1, wherein the scintillator comprises at least one of a columnar scintillator, a scintillation screen, or a monolithic scintillator. 4. The gamma-ray detection device according to claim 1, wherein the optical intensifier comprises:a photocathode made of at least one of Bialkali Antimonide, Multialkali Antimonide, Gallium-Arsenic-Phosphorus (GaAsP), or Gallium Arsenic (GaAs). 5. The gamma-ray detection device according to claim 4, wherein the optical intensifier further comprises a microchannel plate. 6. The gamma-ray detection device according to claim 1, wherein said processing unit is configured to:subtract a background image from the interaction image associated with the light from the different gamma-ray interactions;identify pixels of the interaction image that are above a certain threshold intensity value within a region-of-interest to define a cluster;calculate a centroid of the cluster; andgenerate a mean value of all the pixel that are located within the region-of-interest. 7. The gamma-ray detection device according to claim 1, wherein said processing unit is configured to:use a maximum-likelihood algorithm to estimate a vertical position, a horizontal position, said energy, and a depth of interaction of the gamma-rays in the scintillator. 8. The gamma-ray detection device according to claim 1, wherein a rear surface of the scintillator and a faceplate of the image intensifier are in direct contact with each other. 9. A system for capturing tomographic imaging data comprising:a plurality of aperture plates arranged around an inspection area, the plates having at least one pinhole; anda plurality of gamma-ray detection devices according to claim 1 arranged around the inspection area so that a plurality of respective optical axes of the plurality of gamma-ray detection devices intersect with the inspection area, the plurality of aperture plates arranged between the detection devices and the inspection area,wherein each of the plurality of gamma-ray detection devices are arranged at a different angle of orientation towards the inspection area. 10. The system for capturing tomographic imaging data according to claim 9, whereina distance from a front surface of the gamma-ray detection devices and the corresponding aperture plates is a range of 2 mm to 200 mm. 11. The gamma-ray detection device according to claim 1, wherein the intensifier comprises:a first image intensifier configured to intensify optical radiation from a first portion of a rear surface of the scintillator to generate first intensified optical radiation;a second image intensifier configured to intensify optical radiation from a second portion of the rear surface of the scintillator to generate second intensified optical radiation;a first and second optical coupling system configured to guide the first and second intensified optical radiation, respectively; anda first and second detector configured to detect the first and second intensified optical radiation and to generate first and second images, respectively, representing respective gamma-ray interactions in the scintillator. 12. The gamma-ray detection apparatus according to claim 11,wherein the first portion and the second portion of the rear surface of the scintillator are overlapping. 13. The gamma-ray detection apparatus according to claim 11, further comprising:a lens unit configured to split the optical radiation from the rear surface of the scintillator into optical radiation from a first portion and a second portion of the rear surface of the scintillator, respectively. 14. A method for gamma-ray imaging, comprising:in a scintillator, converting gamma rays into localized flashes of light;collecting a substantial fraction of the light from each flash produced by a single gamma-ray photon and producing an amplified flash of light with an image intensifier;imaging each amplified flash onto an imaging detector that operates at a frame rate fast enough to allow spatial separation of most of the clusters of pixels that receive light from different gamma-ray interactions in the scintillator; andidentifying the clusters of pixels on the video camera associated with respective amplified flashes of individual gamma-ray photons and using the data from said cluster of pixels to perform a statistical estimation of a position where the corresponding gamma-ray photon interacted with the scintillator and the energy deposited in the interaction. 15. The method according to claim 10, wherein said identifying further comprises:filtering digital data of the imaged amplified flashes to remove noise by a median filter; andidentifying the cluster of pixels by using a thresholding algorithm that is applied to the filtered digital image. 16. The method according to claim 14, wherein said identifying further comprises:storing calibration data representing reference clusters generated from a plurality of interaction depths and gamma-ray energies; andcomparing the cluster of pixels of the digital data image with the reference clusters by using a maximum-likelihood algorithm to estimate a horizontal position, a vertical position, a depth, and the energy of the interaction of the gamma-ray in the scintillator. 17. The method according to claim 14, wherein said method further comprises:calculating a kurtosis value for the cluster of pixels, whereinsaid step of processing the digital data image subjects the kurtosis value to the maximum-likelihood estimation. 18. The method according to claim 14, wherein in said step of processing the digital data image by the maximum-likelihood estimation, the maximum-likelihood estimation uses calibration data based on an eccentricity of the cluster.
044779216	claims	1. In an X-ray lithography source tube of the type comprising an electron beam source and a target for generating X-rays, wherein the electron beam source is a ring-shaped shielded cathode and the target is a water-cooled inverted cone: the improvement in which said target is in the form of a composite target cone comprising at least an X-ray generating layer and a water-interface layer; wherein said water-interface layer includes a layer of high thermal conductivity material covered at said water-interface layer by a layer of high corrosion resistance material; and wherein said layer of high thermal conductivity material is formed of copper and said layer of high corrosion resistance material is formed of palladium. 2. The X-ray lithograph source tube of claim 1 wherein said X-ray generating layer is formed of a member of the class consisting of platinum, silver, palladium, rhodium, molybdenum, tungsten, silicon, aluminum and copper. 3. The X-ray lithography source tube of claim 1 being characterized by having a high radiant intensity and by being a soft tube, wherein said high radiant intensity is at least one hundred milliwatts per steradian at 10 kw input power. 4. In an X-ray lithography source tube of the type comprising an electron beam source and a target for generating X-rays, wherein the electron beam source is a ring-shaped shielded cathode and the target is a water-cooled inverted cone: the improvement in which said target is in the form of a composite target cone comprising at least an X-ray generating layer and a water-interface layer, wherein said water-interface layer includes a layer of high thermal conductivity material covered at said water-interface layer by a layer of high corrosion resistance material, and wherein said water-interface layer further includes a layer of high-melting-point material covering said layer of high thermal conductivity material and facing said X-ray generating layer. 5. The X-ray lithography source tube of claim 4 wherein said layer of high-melting point material is formed of tantalum. 6. The X-ray lithograph source tube of claim 5 wherein said X-ray generating layer is about five micrometer thick, said layer of high thermal conductivity mate-ial is about fourteen mil thick, said layer of high corrosion resistance material is about one micrometer thick, and said layer of high-melting point material is about 0.2 micrometer thick. 7. An X-ray lithography apparatus comprising: (a) an X-ray lithography source tube including an electron beam source and a target for generating X-rays, said tube maintained under pressure by a source of vacuum; (b) a processing chamber mounted in operative association with said X-ray lithography source tube and including a mask and a work support, said chamber also maintained under pressure by said source of vacuum; (c) said target being a composite target cone including an X-ray generating layer and a water-interface layer; (d) said X-ray generating layer being formed of a member of the class consisting of platinum, silver, palladium, rhodium, molybdenum, tungsten, silicon, aluminum and copper; (e) wherein said water-interface layer includes a layer of high thermal conductivity material covered at said water-interface layer by a layer of high corrosion resistance material, and wherein said water-interface layer further includes a layer of high thermal conductivity material and facing said X-ray generating layer. 8. The X-ray lithography apparatus of claim 7 wherein said layer of high thermal conductivity material is formed of copper and said layer of high corrosion resistance material is formed of palladium, and wherein said layer of high-melting point material is formed of tantalum. 9. The X-ray lithography apparatus of claim 8 wherein said X-ray generating layer is about five micrometer thick, said layer of high thermal conductivity material is about fourteen mil thick, said layer of high corrosion resistance material is about one micrometer thick, and said layer of high-melting point material is about 0.2 micrometer thick.
	summary
	claims	1. An extreme ultra violet light source device of a laser produced plasma type comprising:a target supply unit configured to supply a target material;a chamber in which plasma is generated by irradiating the target material with a laser beam;collector optics configured to collect extreme ultra violet light radiated from the plasma; anda magnetic field forming unit including (1) plural coils configured to form, when applied with electric currents, magnetic fields having different intensity from each other at both sides of a position where the target material is irradiated with the laser beam and (2) a shielding unit configured to shield a part of the magnetic fields formed by said plural coils. 2. The extreme ultra violet light source device according to claim 1, wherein said magnetic field forming unit includes plural magnetic cores having different shapes from each other and/or different sizes from each other and inserted into central openings of said plural coils, respectively. 3. The extreme ultra violet light source device according to claim 1, wherein said plural coils includes superconducting coils. 4. The extreme ultra violet light source device according to claim 1, wherein said magnetic field forming unit is configured to apply electric currents having different magnitudes from each other to said plural coils, respectively. 5. The extreme ultra violet light source device according to claim 1, wherein said magnetic field forming unit is configured to apply electric currents in different directions from each other to said plural coils, respectively. 6. The extreme ultra violet light source device according to claim 1, wherein numbers of turns and/or diameters of turns of winding wires in said plural coils are different from each other. 7. The extreme ultra violet light source device according to claim 1, wherein said magnetic field forming unit is configured to form asymmetric magnetic fields in which a central axis of lines of magnetic flux is not a straight line. 8. The extreme ultra violet light source device according to claim 7, wherein said plural coils are provided to face each other at a predetermined angle. 9. The extreme ultra violet light source device according to claim 1, wherein said magnetic field forming unit is configured to form asymmetric magnetic fields with respect to a surface perpendicular to a central axis of lines of magnetic flux. 10. The extreme ultra violet light source device according to claim 9, wherein said magnetic field forming unit is configured to form asymmetric magnetic fields having a higher magnetic flux density at one side of a central axis of lines of magnetic flux and a lower magnetic flux density at the other side thereof. 11. The extreme ultra violet light source device according to claim 1, further comprising:an ion ejection port provided in a direction from a higher magnetic flux density to a lower magnetic flux density of the magnetic fields formed by said magnetic field forming unit. 12. The extreme ultra violet light source device according to claim 1, further comprising:an electric field forming unit configured to form an electric field in the magnetic fields formed by said magnetic field forming unit. 13. The extreme ultra violet light source device according to claim 1, wherein a central axis of said target supply unit is oriented in a direction perpendicular to a central axis of lines of magnetic flux of the magnetic fields formed by said magnetic field forming unit. 14. The extreme ultra violet light source device according to claim 1, wherein said shielding unit contains one of iron, cobalt, nickel and ferrite. 15. An extreme ultra violet light source device of a laser produced plasma type comprising:a target supply unit configured to supply a target material;a chamber in which plasma is generated by irradiating the target material with a laser beam;collector optics configured to collect extreme ultra violet light radiated from the plasma; anda magnetic field forming unit including (1) plural permanent magnets configured to form magnetic fields having different intensity from each other at both sides of a position where the target material is irradiated with the laser beam and (2) a shielding unit configured to shield a part of the magnetic fields formed by said plural permanent magnets. 16. The extreme ultra violet light source device according to claim 15, wherein said shielding unit contains one of iron, cobalt, nickel and ferrite. 17. The extreme ultra violet light source device according to claim 15, wherein said magnetic field forming unit is configured to form asymmetric magnetic fields in which a central axis of lines of magnetic flux is not a straight line. 18. The extreme ultra violet light source device according to claim 17, wherein said plural permanent magnets are provided to face each other at a predetermined angle.
047028807	abstract	A process for improving resistance of control rod guide tube split pins in nuclear reactors to stress corrosion cracking comprising heating the split pin to a critical elevated temperature level, cooling at least the surface portions of the split subject to stress corrosion cracking and then permitting the split pin to come to ambient temperature.
	abstract	A nuclear power plant and method of operation for augmenting a second reactor thermal power output in a second operation cycle to a level larger than a first reactor thermal power output in the previous operation cycle. The plant is equipped, for example, with a reactor; a steam loop comprising high and low pressure turbines; a condenser for condensing steam discharged therefrom the low pressure turbine; a feedwater heater for heating feedwater supplied from the condenser; and a feedwater loop for leading feedwater discharged from the feedwater heater to the reactor. The operation method includes decreasing a ratio of extraction steam which is led to the feedwater heater from a steam loop in the second operation cycle.
	description	Thermoelectric devices and materials can be utilized to convert heat energy to electric power. Thermoelectric devices are further known to be implemented within a nuclear fission reactor system, so as to convert nuclear fission reactor generated heat to electric power during reactor operation. In one aspect, a method includes but is not limited to, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy and supplying the electrical energy to at least one mechanical pump of the nuclear reactor system. In addition to the foregoing, other method aspects are described in the claims, drawings, and text forming a part of the present disclosure. In one or more various aspects, related systems include but are not limited to circuitry and/or programming for effecting the herein-referenced method aspects; the circuitry and/or programming can be virtually any combination of hardware, software, and/or firmware configured to effect the herein-referenced method aspects depending upon the design choices of the system designer. In one aspect, a system includes but is not limited to a means for, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy and a means for supplying the electrical energy to at least one mechanical pump of the nuclear reactor system. In addition to the foregoing, other system aspects are described in the claims, drawings, and text forming a part of the present disclosure. In one aspect, a system includes but is not limited to at least one thermoelectric device for converting nuclear reactor generated heat to electrical energy upon a nuclear reactor system shutdown event and at least one electrical output of the at least one thermoelectric device electrically coupled to at least one mechanical pump of the nuclear reactor system for supplying the electrical energy to the at least one mechanical pump of the nuclear reactor system. In addition to the foregoing, other system aspects are described in the claims, drawings, and text forming a part of the present disclosure. In addition to the foregoing, various other method and/or system and/or program product aspects are set forth and described in the teachings such as text (e.g., claims and/or detailed description) and/or drawings of the present disclosure. The foregoing is a summary and thus may contain simplifications, generalizations, inclusions, and/or omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is NOT intended to be in any way limiting. Other aspects, features, and advantages of the devices and/or processes and/or other subject matter described herein will become apparent in the teachings set forth herein. In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. Referring generally to FIGS. 1A through 1G, a system 100 for the thermoelectric conversion of nuclear reactor generated heat upon a nuclear reactor shutdown event 110 is described in accordance with the present disclosure. Upon a shutdown event 110 (e.g., routine shutdown or emergency shutdown) of a nuclear reactor system 100, a thermoelectric device 104 (e.g., a junction of two materials with different Seebeck coefficients) may convert heat (e.g., operational heat, decay heat, or residual heat) produced by the nuclear reactor 102 of the nuclear reactor system 100 to electrical energy. Then, the electrical output 108 of the thermoelectric device 104 may supply electrical energy to a mechanical pump 106 of the nuclear reactor system 100. In embodiments, the nuclear reactor 102 of the nuclear reactor system 100 may include, but is not limited to, a thermal spectrum nuclear reactor 141, a fast spectrum nuclear reactor 142, a multi-spectrum nuclear reactor 143, a breeder reactor 144, or a traveling wave reactor 145. For example, the heat produced from a thermal spectrum nuclear reactor 141 may be thermoelectrically converted to electrical energy via one or more than one thermoelectric device 104. Then, the electrical output 108 of the thermoelectric device may be used to supply electrical energy to a mechanical pump 106 of the nuclear reactor system 100. By way of further example, the heat produced from a traveling wave nuclear reactor 145 may be thermoelectrically converted to electrical energy via one or more than one thermoelectric device 104. Then, the electrical output 108 of the thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of the nuclear reactor system 100. In another embodiment, the nuclear reactor shutdown event 110 may be established by a signal from an operator 111. For example, the nuclear reactor shutdown event may be established by a remote signal, such as a wireline signal (e.g., copper wire signal or fiber optic cable signal) or a wireless signal (e.g., radio frequency signal) from an operator (e.g., human user). Then, upon establishing the nuclear reactor shutdown event 110 via a signal from an operator, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. In another embodiment, the nuclear reactor shutdown event 110 may be established by a reactor control system 112 (e.g., a system of microprocessors or computers programmed to monitor and respond to specified reactor conditions, such as temperature). For instance, the nuclear reactor shutdown event may be established by a wireline signal (e.g., digital signal from microprocessor) sent from a reactor control system 112. In a further embodiment, the reactor control system 112 may be responsive to one or more signals from a safety system 113 (e.g., thermal monitoring system, radiation monitoring system, pressure monitoring system, or security system). For instance, at a critical temperature a safety system may send a digital signal to the reactor control system 112. In turn, the nuclear reactor shutdown event may be established via a signal from the reactor control system 112. In a further embodiment, the safety system of the nuclear reactor system may be responsive to a sensed condition 114 of the nuclear reactor system 100. For example, the safety system of the nuclear reactor system 100 may be responsive to one or more external conditions 115 (e.g., loss of heat sink, security breach, or loss of external power supply to support systems) or one or more internal conditions 116 (e.g., reactor temperature or core radiation levels). By way of further example, the safety system, upon sensing a loss of heat sink, may send a signal to the reactor control system 112. In turn, the reactor control system 112 may establish the nuclear reactor shutdown event 110. Then, upon establishing the nuclear reactor shutdown event 110 via a signal from a reactor control system 112, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. In an embodiment, upon a nuclear reactor shutdown event 110, nuclear reactor generated heat may be converted to electrical energy via a thermoelectric device 104 placed in thermal communication (e.g., placed in thermal communication ex-situ or in-situ) with a portion of the nuclear reactor system 100. For example, the thermoelectric device 104 may be placed in thermal communication with a portion of the nuclear reactor system 100 during the construction of the nuclear reactor system 100. By way of further example, the nuclear reactor system 100 may be retrofitted such that a thermoelectric device 104 may be placed in thermal communication with a portion of the nuclear reactor system 100. Further, the thermoelectric device 104 may be placed in thermal communication with a portion of the nuclear reactor system 100 during operation of the nuclear reactor system 100 via a means of actuation (e.g., thermal expansion, electromechanical actuation, piezoelectric actuation, mechanical actuation). Then, a thermoelectric device 104 in thermal communication with a portion of the nuclear reactor system 100 may convert nuclear reactor generated heat to electrical energy. In another embodiment, upon a nuclear reactor shutdown event 110, nuclear reactor generated heat may be converted to electrical energy via a thermoelectric device 104 having a first portion 124 in thermal communication with a first portion 125 of the nuclear reactor system 100 and a second portion 126 in thermal communication with a second portion 127 of the nuclear reactor system 100. For example, the first portion 124 of the thermoelectric device 104 may be in thermal communication with a heat source 128 of the nuclear reactor system. By way of further example, the heat source 128 may include, but is not limited to, a nuclear reactor core 129, a pressure vessel 130, a containment vessel 131, a coolant loop 132, a coolant pipe 133, a heat exchanger 134, or a coolant 135 of the coolant system 154 of the nuclear reactor system 100. In another embodiment, the second portion 127 of the nuclear reactor system may be at a temperature lower than the first portion 125 of the nuclear reactor system 100. For example, the first portion 125 of the nuclear reactor system 100 may comprise a portion of the primary coolant system (e.g., at a temperature above 300° C.) of the nuclear reactor system 100 and the second portion 127 of the nuclear reactor system 100 may comprise a portion of a condensing loop (e.g., at a temperature below 75° C.) of the nuclear reactor system 100. By way of further example, the second portion 127 of the nuclear reactor system 100 may include, but is not limited to, a coolant loop 136, a coolant pipe 137, a heat exchanger 138, a coolant 139 of a coolant system 154, or an environmental reservoir 140 (e.g., a lake, a river, or a subterranean structure). For instance, a first portion 124 of a thermoelectric device 104 may be in thermal communication with a heat exchanger 134 of the nuclear reactor system 100 and the second portion 126 of the thermoelectric device 104 may be in thermal communication with an environmental reservoir 140, such as a lake. In another embodiment, the thermoelectric device 104 and a portion of the nuclear reactor system 100 may both be in thermal communication with a means for optimizing thermal conduction 162 (e.g., thermal paste, thermal glue, thermal cement, or other highly thermally conductive materials) between the thermoelectric device 104 and the portion of the nuclear reactor system 100. For example, the first portion 124 of the thermoelectric device 104 may be contacted to the first portion 125 of the nuclear reactor system 100 using thermal cement. In an embodiment, the thermoelectric device 104 used to convert nuclear reactor generated heat to electrical energy may comprise at least one thermoelectric junction 117 (e.g., a thermocouple or other device formed from a junction of more than one material each with different Seebeck coefficients). For example, the thermoelectric junction 117 may include, but is not limited to, a semiconductor-semiconductor junction 118 (e.g., p-type/p-type junction or n-type/n-type junction) or a metal-metal junction 120 (e.g., copper-constantan). By further example, the semiconductor-semiconductor junction may include a p-type/n-type semiconductor junction (e.g., p-doped bismuth telluride/n-doped bismuth telluride junction, p-doped lead telluride/n-doped lead telluride junction, or p-doped silicon germanium/n-doped silicon germanium junction). In another embodiment, the thermoelectric device 104 used to convert nuclear reactor generated heat to electrical energy may comprise at least one nanofabricated thermoelectric device 121 (i.e., a device wherein the thermoelectric effect is enhanced due to nanoscale manipulation of its constituent materials). For example, the nanofabricated device may include, but is not limited to, a device constructed in part from a quantum dot material (e.g., PbSeTe), a nanowire material (e.g., Si), or a superlattice material (e.g., Bi2Te3/Sb2Te3). In another embodiment, the thermoelectric device 104 used to convert nuclear reactor generated heat to electrical energy may comprise a thermoelectric device optimized for a specified range of operating characteristics 122. For example, the thermoelectric device optimized for a specified range of operating characteristics 122 may include, but is not limited to, a thermoelectric device having an output efficiency optimized for a specified range of temperature. For instance, the thermoelectric device 104 may include a thermoelectric device with a maximum efficiency between approximately 200° C. and 500° C., such as a thermoelectric device comprised of thallium doped lead telluride. It will be appreciated in light of the description provided herein, that a nuclear reactor system 100 incorporating a thermoelectric device 104 may incorporate a thermoelectric device having a maximum output efficiency within the operating temperature range of the nuclear reactor system 100. In another embodiment, the heat generated by the nuclear reactor 102 may be converted to electrical energy using a first thermoelectric device optimized for a first range of operating characteristics and a second thermoelectric device optimized for a second range of operating characteristics 123. For example, the output efficiency of a first thermoelectric device may be optimized for a first range in temperature and the output efficiency of a second thermoelectric device may be optimized for a second range in temperature. For instance, the nuclear reactor generated heat may be converted to electrical energy using a first thermoelectric device having a maximum efficiency between approximately 500° and 600° C. and a second thermoelectric device having a maximum efficiency between approximately 400° and 500° C. In a further embodiment, the heat generated by the nuclear reactor 102 may be converted to electrical energy using a first thermoelectric device optimized for a first range of operating characteristics, a second thermoelectric device optimized for a second range of operating characteristics, and up to and including a Nth device optimized for a Nth range of operating characteristics. For instance, the nuclear reactor generated heat may be converted to electrical energy using a first thermoelectric device with a maximum efficiency between approximately 200° and 300° C., a second thermoelectric device with a maximum efficiency between approximately 400° and 500° C., and a third thermoelectric device with a maximum efficiency between approximately 500° and 600° C. In another embodiment, the heat generated by the nuclear reactor 102 may be converted to electrical energy using two or more series coupled thermoelectric devices 104. For example, the heat generated by the nuclear reactor 102 may be converted to electrical energy using a first thermoelectric device S1 and a second thermoelectric device S2, where the first thermoelectric device S1 and the second thermoelectric device S2 are electrically coupled in series. By way of further example, the heat generated by the nuclear reactor 102 may be converted to electrical energy using a first thermoelectric device S1, a second thermoelectric device S2, a third thermoelectric device S3, and up to and including an Nth thermoelectric device SN, where the first thermoelectric device S1, the second thermoelectric device S2, the third thermoelectric device S3, and the Nth thermoelectric device SN are electrically coupled in series. In another embodiment, the heat generated by the nuclear reactor 102 may be converted to electrical energy using two or more parallel coupled thermoelectric devices 104. For example, the heat generated by the nuclear reactor 102 may be converted to electrical energy using a first thermoelectric device P1 and a second thermoelectric device P2, where the first thermoelectric device P1 and the second thermoelectric device P2 are electrically coupled in parallel. By way of further example, the heat generated by the nuclear reactor 102 may be converted to electrical energy using a first thermoelectric device P1, a second thermoelectric device P2, a third thermoelectric device P3, and up to and including an Nth thermoelectric device PN, where the first thermoelectric device P1, the second thermoelectric device P2, the third thermoelectric device P3, and the Nth thermoelectric device PN are electrically coupled in parallel. In another embodiment, the heat generated by the nuclear reactor 102 may be converted to electrical energy using one or more than one thermoelectric module 148. For example, a thermoelectric module in thermal communication with the nuclear reactor system 100 (e.g., first portion of a thermoelectric module in thermal communication with a heat source 128 and the second portion of a thermoelectric module in thermal communication with an environmental reservoir 140) may convert nuclear reactor generated heat to electrical energy. For example, the thermoelectric module 148 may comprise a prefabricated network of parallel coupled thermoelectric devices, series coupled thermoelectric devices, and combinations of parallel coupled and series coupled thermoelectric devices. By way of further example, a thermoelectric module 148 may include a first set of parallel coupled thermoelectric devices, a second set of parallel coupled thermoelectric devices, and up to and including a Mth set of parallel coupled thermoelectric devices, where the first set of devices, the second set of devices, and the Mth set of devices are electrically coupled in series. By way of further example, a thermoelectric module 148 may include a first set of series coupled thermoelectric devices, a second set of series coupled thermoelectric devices, and up to and including a Mth set of series coupled thermoelectric devices, where the first set of devices, the second set of devices, and the Mth set of devices are electrically coupled in parallel. In an embodiment, the heat generated by the nuclear reactor 102 may be converted to electrical energy using one or more than one thermoelectric device sized to meet a selected operational requirement 150 of the nuclear reactor system 100. For example, the thermoelectric device may be sized to partially match the heat rejection 151 of the thermoelectric device with a portion of the heat produced by the nuclear reactor system 100. For instance, the thermoelectric device may be sized by adding or subtracting the number of thermoelectric junctions 117 used in the thermoelectric device 104. By way of further example, the thermoelectric device may be sized to match the power requirements 152 of a selected operating system (e.g., control system, safety system, or coolant system). For instance, the thermoelectric device may be sized to match the mechanical pump power requirements 153 of a coolant system 154 of the nuclear reactor system 100. In certain embodiments, the thermoelectric device 104 used to convert heat produced by the nuclear reactor system 100 to electrical energy may be protected via regulation circuitry 170, such as voltage regulation circuitry (e.g., voltage regulator), current limiting circuitry (e.g., blocking diode or fuse), or bypass circuitry 172 (e.g., bypass diode or active bypass circuitry). For example, the regulation circuitry used to protect the thermoelectric device 104 may include a fuse, wherein the fuse is used to limit current from passing through a short-circuited portion of a set of two or more thermoelectric devices 104. In a further embodiment, bypass circuitry configured to actively electrically bypass 174 one or more than one thermoelectric device 104 may be used to protect one or more than one thermoelectric device 104. For example, the bypass circuitry configured to actively electrically bypass 174 a thermoelectric device 104 may include, but is not limited to, an electromagnetic relay system 176, a solid state relay system 178, a transistor 180, or a microprocessor controlled relay system 182. By way of further example, the microprocessor controlled relay system 182 used to electrically bypass a thermoelectric device 104 may be responsive to an external parameter (e.g., signal from an operator) or an internal parameter (e.g., current flowing through a specified thermoelectric device). In another embodiment, one or more than one thermoelectric device 104 used to convert heat produced by the nuclear reactor system 100 to electrical energy may be augmented by one or more than one reserve thermoelectric device 188 (e.g., a thermoelectric junction or a thermoelectric module) and reserve actuation circuitry 189. For example, the electrical output 108 of one or more than one thermoelectric device 104 may be augmented using the output of a reserve thermoelectric device 188, where the one or more than one reserve thermoelectric device may be selectively coupled to one or more than one thermoelectric device 104 using reserve actuation circuitry 189. For example, in the event a first thermoelectric device 104 of a set of thermoelectric devices fails, a reserve thermoelectric device may be coupled to the set of thermoelectric devices in order to augment the output of the set of thermoelectric devices. By way of further example, the reserve actuation circuitry 189 used to selectively couple the one or more reserve thermoelectric devices 188 with the one or more thermoelectric devices 104 may include, but is not limited to, a relay system 190, an electromagnetic relay system 191, a solid state relay system 192, a transistor 193, a microprocessor controlled relay system, a microprocessor controlled relay system programmed to respond to an external parameter (e.g., required electrical power output of nuclear reactor system 100 or availability of external electric grid power), or a microprocessor controlled relay system programmed to respond to an internal parameter (e.g., output of one or more than one thermoelectric device 104). In another embodiment, the electrical output 108 of one or more than one thermoelectric device 104 used to convert heat produced by the nuclear reactor system 100 to electrical energy may be modified using power management circuitry. For example, the power management circuitry 197 used to modify the electrical output 108 of a thermoelectric device 104 may include, but is not limited to, a power converter, voltage converter (e.g., a DC-DC converter or a DC-AC inverter), or voltage regulation circuitry 198. By way of further example, the voltage regulation circuitry 198 used to modify the electrical output 108 of a thermoelectric device 104 may include, but is not limited to, a Zener diode, a series voltage regulator, a shunt regulator, a fixed voltage regulator or an adjustable voltage regulator. In an embodiment, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy during initiation of a nuclear reactor shutdown. For example, during initiation of a routine nuclear reactor shutdown (e.g., scheduled shutdown) or an emergency nuclear reactor shutdown (e.g., SCRAM), the thermoelectric device 104 may convert heat produced by the nuclear reactor system to electrical energy. In another embodiment, preceding initiation of a nuclear reactor shutdown, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. For example, preceding initiation of a routine nuclear reactor shutdown or emergency nuclear reactor shutdown, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. In an additional embodiment, following initiation of a nuclear reactor shutdown, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. For example, following initiation of a routine nuclear reactor shutdown or emergency nuclear reactor shutdown, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. In another embodiment, upon a nuclear reactor shutdown event 110, nuclear reactor generated decay heat may be thermoelectrically converted to electrical energy. For example, after the shutdown of a nuclear reactor system 100, a thermoelectric device 104 may convert the persisting radioactive decay heat to electrical energy. Then, the electrical output 108 of the thermoelectric device may be used to power the mechanical pump 106. In an additional embodiment, upon a nuclear reactor shutdown event 110, nuclear reactor generated residual heat may be thermoelectrically converted to electrical energy. For example, after the shutdown of a nuclear reactor system 100, a thermoelectric device 104 may convert the residual heat of the nuclear reactor to electrical energy. Then, the electrical output 108 of the thermoelectric device may be used to power the mechanical pump 106. In an embodiment, the electrical output 108 of a thermoelectric device 104 may supply electrical energy to a mechanical pump 106 circulating coolant through a portion of the reactor core or a heat exchanger 162 of the nuclear reactor system 100. For example, the electrical output 108 of a thermoelectric device 104 may supply electrical energy to a mechanical pump 106 circulating coolant through the heat exchanger between the primary coolant loop and an intermediate coolant system of a nuclear reactor system 100. In another embodiment, the electrical output 108 of a thermoelectric device 104 may supply electrical energy to a mechanical pump 106 circulating a pressurized gas coolant (e.g., helium, nitrogen, supercritical CO2, or steam) of a coolant system 154 of a nuclear reactor system 100. For example, the electrical output 108 of a thermoelectric device 104 may supply electrical energy to a mechanical pump 106 circulating pressurized helium through the primary coolant system of a nuclear reactor system 100. In another embodiment, the electrical output 108 of a thermoelectric device 104 may supply electrical energy to a mechanical pump 106 circulating a liquid coolant of a coolant system 154 of the nuclear reactor system 100. For example, the liquid coolant circulated by the mechanical pump 106 may include, but is not limited to, a liquid metal coolant (e.g., liquid sodium, liquid lead, or liquid lead bismuth), a liquid salt coolant (e.g., lithium fluoride or other fluoride salts), or a liquid water coolant. Further, the mechanical pump 106 may circulate a liquid coolant through a coolant pool of a pool-type nuclear reactor system 100. For instance, the mechanical pump 106 may circulate liquid sodium in a pool-type breeder nuclear reactor system 100. In another embodiment, the electrical output 108 of a thermoelectric device 104 may supply electrical energy to a mechanical pump 106 circulating a mixed phase coolant of a coolant system 154 of the nuclear reactor system 100. For example, the mechanical pump 106 may circulate a gas-liquid (e.g., steam-liquid water) mixed phase coolant of a coolant system 154 of a nuclear reactor system 100. In another embodiment, the electrical output 108 of a thermoelectric device 104 may be used to partially drive a mechanical pump 106 of the nuclear reactor system 100. For example, the electrical output 108 of a thermoelectric device 104 may partially drive a mechanical pump 106 coupled to a coolant system 154 (e.g., primary coolant system or secondary coolant system) of the nuclear reactor system 100. In an embodiment, the electrical output 108 of a thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 of a nuclear reactor system 100 and coupled in series 155 with an additional mechanical pump. For example, a first mechanical pump 106 may be driven by the electrical output 108 of a thermoelectric device and may, in combination with a series connected additional mechanical pump 155, circulate a coolant through a coolant system 154 of the nuclear reactor system 100. In another embodiment, the electrical output 108 of a thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 of a nuclear reactor system 100 and coupled in parallel 156 with an additional mechanical pump. For example, a first mechanical pump 106 may be driven by the electrical output 108 of a thermoelectric device and may, in combination with a parallel connected additional mechanical pump 156, circulate a coolant through a coolant system of the nuclear reactor system 100. In another embodiment, the electrical output 108 of a thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 in order to provide supplemental pumping power 157 to the coolant system 154. For example, the mechanical pump 106 driven by the electrical output 108 of the thermoelectric device 104 may be used to supplement the pumping power of another mechanical pump. For instance, during partial loss of external electric power, in which external grid power to a first mechanical pump partially fails, the electrical output 108 of one or more than one thermoelectric device 104 may be used to drive a second mechanical pump 106 in order to supplement the pumping power 157 of the first mechanical pump. By way of further example, the supplemental pumping power 157 provided by a mechanical pump 106 driven by the electrical output 108 of a thermoelectric device 104 may be used to enhance the mass flow rate 158 of coolant in a coolant system 154. In another embodiment, the electrical output 108 of a thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 in order to provide auxiliary pumping power 159 to the coolant system 154. For example, during malfunction of a first mechanical pump, in which the first mechanical pump totally fails, the electrical output 108 of one or more than one thermoelectric device 104 may be used to drive a second mechanical pump 106 in order to provide auxiliary pumping power 159 to the coolant system 154 of the nuclear reactor system 100. By way of further example, the auxiliary pumping power 159 provided by a mechanical pump 106 driven by the electrical output 108 of a thermoelectric device 104 may be used to establish a mass flow rate 160 of coolant in a coolant system 154. By way of further example, a mass flow rate 160 may be established by a mechanical pump 106 driven by the electrical output 108 of the thermoelectric device 104, where the mass flow rate is established in order to maintain coolant circulation in a coolant system 154 of the nuclear reactor system 100. For instance, the established coolant mass flow rate may maintain coolant circulation in a portion of the nuclear reactor system 100, including, but not limited to, a reactor coolant pool, a reactor coolant pressure vessel, a reactor heat exchange loop, or an ambient coolant reservoir. By way of further example, a mechanical pump 106 driven by the electrical output 108 of a thermoelectric device 104 may be used to establish a mass flow rate 160 in a liquid sodium coolant of a primary coolant loop of a nuclear reactor system 100 in order to maintain circulation of the liquid sodium coolant. Following are a series of flowcharts depicting implementations. For ease of understanding, the flowcharts are organized such that the initial flowcharts present implementations via an example implementation and thereafter the following flowcharts present alternate implementations and/or expansions of the initial flowchart(s) as either sub-component operations or additional component operations building on one or more earlier-presented flowcharts. Those having skill in the art will appreciate that the style of presentation utilized herein (e.g., beginning with a presentation of a flowchart(s) presenting an example implementation and thereafter providing additions to and/or further details in subsequent flowcharts) generally allows for a rapid and easy understanding of the various process implementations. In addition, those skilled in the art will further appreciate that the style of presentation used herein also lends itself well to modular and/or object-oriented program design paradigms. FIG. 2 illustrates an operational flow 200 representing example operations related to the thermoelectric conversion of nuclear reactor generated heat to electrical energy upon a nuclear reactor system shutdown event. In FIG. 2 and in following figures that include various examples of operational flows, discussion and explanation may be provided with respect to the above-described examples of FIG. 1, and/or with respect to other examples and contexts. However, it should be understood that the operational flows may be executed in a number of other environments and contexts, and/or in modified versions of FIG. 1. Also, although the various operational flows are presented in the sequence(s) illustrated, it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently. After a start operation, the operational flow 200 moves to a converting operation 210. Operation 210 depicts, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy. For example, as shown in FIG. 1, upon a shutdown event 110 of a nuclear reactor system 100, a thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. Then, supplying operation 220 depicts supplying the electrical energy to at least one mechanical pump of the nuclear reactor system. For example, as shown in FIG. 1, the electrical output 108 of a thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of the nuclear reactor system 100. FIG. 3 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 3 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 302, an operation 304, and/or an operation 306. At operation 302, nuclear reactor generated heat may be thermoelectrically converted to electrical energy during initiation of a nuclear reactor shutdown. For example, as shown in FIG. 1, during initiation of a nuclear reactor shutdown 102, a thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. At operation 304, nuclear reactor generated heat may be thermoelectrically converted to electrical energy preceding initiation of a nuclear reactor shutdown. For example, as shown in FIG. 1, preceding initiation of a nuclear reactor shutdown 102, a thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. At operation 306, nuclear reactor generated heat may be thermoelectrically converted to electrical energy following initiation of a nuclear reactor shutdown. For example, as shown in FIG. 1, following initiation of a nuclear reactor shutdown 102, a thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 4 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 4 illustrates example embodiments where the converting operation 210 may include at least one additional operation. Additional operations may include an operation 402, an operation 404, and/or an operation 406. At operation 402, upon a nuclear reactor system shutdown event, nuclear reactor generated decay heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 may convert radioactive decay heat produced by the nuclear reactor system 100 to electrical energy. At operation 404, upon a nuclear reactor system shutdown event, residual nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 may convert residual heat produced by the nuclear reactor system 100 to electrical energy. At operation 406, upon a nuclear reactor system shutdown event established by at least one signal from an operator, nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, a nuclear reactor system shutdown event 110 may be established by at least one signal from an operator 111 (e.g., a human user). Upon establishing the nuclear shutdown event, a thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 5 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 5 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 502, an operation 504, an operation 506, and/or an operation 508. At operation 502, upon a nuclear reactor system shutdown event established by at least one reactor control system, nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, a nuclear reactor system shutdown event 110 may be established by a reactor control system 112. Upon establishing the nuclear shutdown event, a thermoelectric device 104 may then convert heat produced by the nuclear reactor system 100 to electrical energy. Further, at operation 504, upon a nuclear reactor system shutdown event established by a reactor control system responsive to a signal from a safety system, nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, a nuclear reactor system shutdown event 110 may be established by a reactor control system responsive to a signal (e.g., wireline signal or wireless signal) from a safety system 113 (e.g., security system or temperature monitoring system). Upon establishing the nuclear reactor shutdown event, a thermoelectric device 104 may then convert heat produced by the nuclear reactor system 100 to electrical energy. Further, at operation 506, upon a nuclear reactor system shutdown event established by a reactor control system responsive to a signal from a safety system, where the safety system is responsive to a sensed nuclear reactor system condition, nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, a nuclear reactor system shutdown event 110 may be established by a reactor control system responsive to a signal from a safety system 113, where the safety system is responsive to a sensed condition 114 of the nuclear reactor system 100. Upon establishing the nuclear reactor system shutdown event, a thermoelectric device 104 may then convert heat produced by the nuclear reactor system 100 to electric energy. Further, at operation 508, upon a nuclear reactor system shutdown event established by a reactor control system responsive to a signal from a safety system, where the safety system is responsive to a sensed external condition of the nuclear reactor system, nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, a nuclear reactor system shutdown event 110 may be established by a reactor control system responsive to a signal from a safety system 113, where the safety system is responsive to a sensed external condition 115 (e.g., security breach or access to external power supply) of the nuclear reactor system 100. Upon establishing the nuclear reactor system shutdown event, a thermoelectric device 104 may then convert heat produced by the nuclear reactor system 100 to electric energy. FIG. 6 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 6 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 602. Further, at operation 602, upon a nuclear reactor system shutdown event established by a reactor control system responsive to a signal from a safety system, where the safety system is responsive to a sensed internal condition of the nuclear reactor system, nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, a nuclear reactor system shutdown event 110 may be established by a reactor control system responsive to a signal from a safety system 113, where the safety system is responsive to a sensed internal condition 116 (e.g., temperature or radiation levels of reactor) of the nuclear reactor system 100. Upon establishing the nuclear reactor system shutdown event, a thermoelectric device 104 may then convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 7 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 7 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 702, an operation 704, an operation 706, and/or an operation 708. At operation 702, upon a nuclear reactor system shutdown event, nuclear reactor generated heat may be converted to electrical energy using at least one thermoelectric device. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 placed in thermal communication with the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. At operation 704, upon a nuclear reactor system shutdown event, nuclear reactor generated heat may be converted to electrical energy using at least one thermoelectric junction. For instance, upon a nuclear reactor system shutdown event 110, a thermoelectric junction 117 (e.g., thermocouple) placed in thermal communication with the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. Further, at operation 706, upon a nuclear reactor system shutdown event, nuclear reactor generated heat may be converted to electrical energy using at least one semiconductor-semiconductor junction. For example, as shown in FIG. 1, the thermoelectric device 104 may comprise a semiconductor-semiconductor thermoelectric junction 118 (e.g., p-type/p-type junction of different semiconductor materials). For instance, upon a nuclear reactor system shutdown event 110, a semiconductor-semiconductor junction 118 placed in thermal communication with the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. Further, at operation 708, upon a nuclear reactor system shutdown event, nuclear reactor generated heat may be converted to electrical energy using at least one p-type/n-type semiconductor junction (e.g., p-doped lead telluride/n-doped lead telluride junction). For example, as shown in FIG. 1, the thermoelectric device may comprise a p-type/n-type semiconductor junction 119. For instance, upon a nuclear reactor system shutdown event 110, a p-type/n-type semiconductor junction placed in thermal communication with the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 8 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 8 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 802. Further, at operation 802, upon a nuclear reactor system shutdown event, nuclear reactor generated heat may be converted to electrical energy using at least one metal-metal thermoelectric junction. For example, as shown in FIG. 1, the thermoelectric device 104 may comprise a metal-metal thermoelectric junction 120 (e.g., copper-constantan junction). For instance, upon a nuclear reactor system shutdown event 110, a metal-metal thermoelectric junction 120 placed in thermal communication with the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 9 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 9 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 902, an operation 904, and/or an operation 906. The operation 902 illustrates upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device, the thermoelectric device having at least a first portion in thermal communication with a first portion of the nuclear reactor system and at least a second portion in thermal communication with a second portion of the nuclear reactor system. For example, as shown in FIG. 1, a first portion 124 of a thermoelectric device 104 may be in thermal communication with a first portion 125 of a nuclear reactor system 100, while a second portion 126 of the thermoelectric device 104 may be in thermal communication with a second portion 127 of the nuclear reactor system. Then, upon a nuclear reactor system shutdown event 110, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. Further, the operation 904 illustrates upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device, the thermoelectric device having at least a first portion in thermal communication with at least one heat source of the nuclear reactor system. For example, as shown in FIG. 1, the first portion 125 of the nuclear reactor system may comprise a heat source 128 of the nuclear reactor system 100. Therefore, a first portion of a thermoelectric device 124 may be in thermal communication with a heat source 128 of the nuclear reactor system 100. Then, upon a nuclear reactor system shutdown event 110, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. Further, the operation 906 illustrates upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device, the thermoelectric device having at least a first portion in thermal communication with at least a portion of a nuclear reactor core, at least a portion of at least one pressure vessel, at least a portion of at least one containment vessel, at least a portion of at least one coolant loop, at least a portion of at least one coolant pipe, at least a portion of at least one heat exchanger, or at least a portion of the coolant of the nuclear reactor system. For example, as shown in FIG. 1, the first portion 125 of the nuclear reactor system 100 may include, but is not limited to, a nuclear reactor core 129, a pressure vessel 130 of the nuclear reactor system 100, a containment vessel 131 of the nuclear reactor system 100, a coolant loop 132 of the nuclear reactor system 100, a coolant pipe 133 of the nuclear reactor system, a heat exchanger 134 of the nuclear reactor system 100 or the coolant 135 of the nuclear reactor system 100. By way of further example, a first portion of a thermoelectric device 124 may be in thermal communication with a coolant loop 132 of the nuclear reactor system 100. Then, upon a nuclear reactor system shutdown event 110, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 10 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 10 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 1002, and/or an operation 1004. Further, the operation 1002 illustrates upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device, the thermoelectric device having at least a second portion in thermal communication with a second portion of the nuclear reactor system, the second portion of the nuclear reactor system at a lower temperature than the first portion of the nuclear reactor system. For example, as shown in FIG. 1, a second portion 126 of a thermoelectric device 104 may be in thermal communication with a second portion 127 of a nuclear reactor system 100, where the second portion 127 of the nuclear reactor system 100 is at a lower temperature than the first portion 124 of the nuclear reactor system 100. Then, upon a nuclear reactor system shutdown event 110, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. Further, the operation 1004 illustrates upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device, the thermoelectric device having at least a second portion in thermal communication with at least a portion of at least one coolant loop, at least a portion of at least one coolant pipe, at least a portion of at least one heat exchanger, at least a portion of the coolant of the nuclear reactor system, or at least a portion of at least one environmental reservoir. For example, as shown in FIG. 1, the second portion 127 of the nuclear reactor system 100, which is at a temperature lower than the first portion 124 of the nuclear reactor system, may include, but is not limited to, a coolant loop 136 of the nuclear reactor system 100, a coolant loop 137 of the nuclear reactor system 100, a heat exchanger 138 of the nuclear reactor system 100, coolant 139 of the nuclear reactor system 100, or an environmental reservoir 140, such as a body of water. By way of further example, the second portion 126 of a thermoelectric device 104 may be in thermal communication with a coolant pipe 137 of the nuclear reactor system 100, where the coolant pipe 137 is at a temperature lower than the first portion of the nuclear reactor system 124. Then, upon a nuclear reactor system shutdown event 110, the thermoelectric device 104 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 11 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 11 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 1102, an operation 1104, an operation 1106, and/or an operation 1108. At operation 1102, upon a nuclear reactor system shutdown event, thermal spectrum nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 may convert heat generated by a thermal spectrum nuclear reactor 141 of a nuclear reactor system 100 to electrical energy. At operation 1104, upon a nuclear reactor system shutdown event, fast spectrum nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 may convert heat generated by a fast spectrum nuclear reactor 142 of a nuclear reactor system 100 to electrical energy. At operation 1106, upon a nuclear reactor system shutdown event, multi-spectrum nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 may convert heat generated by a multi-spectrum nuclear reactor 143 of a nuclear reactor system 100 to electrical energy. At operation 1108, upon a nuclear reactor system shutdown event, breeder nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 may convert heat generated by a breeder nuclear reactor 144 of a nuclear reactor system 100 to electrical energy. FIG. 12 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 12 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 1202, an operation 1204, an operation 1206, and/or an operation 1208. At operation 1202, upon a nuclear reactor system shutdown event, traveling wave nuclear reactor generated heat may be thermoelectrically converted to electrical energy. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 may convert heat generated by a traveling wave nuclear reactor 145 of a nuclear reactor system 100 to electrical energy. At operation 1204, upon a nuclear reactor system shutdown event, nuclear reactor generated heat may be converted to electrical energy using at least two series coupled thermoelectric devices. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a first thermoelectric device S1 electrically coupled in series to a second thermoelectric device S2 may convert heat produced by the nuclear reactor system 100 to electrical energy. Further, a first thermoelectric device S1, a second thermoelectric device S2, a third thermoelectric device S3, and up to and including a Nth thermoelectric device SN may be used to convert nuclear reactor generated heat to electric energy, where the first thermoelectric device S1, the second thermoelectric device S2, the third thermoelectric device S3, and up to and including the Nth thermoelectric device SN are series coupled. At operation 1206, upon a nuclear reactor system shutdown event, nuclear reactor generated heat may be converted to electrical energy using at least two parallel coupled thermoelectric devices. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a first thermoelectric device P1 electrically coupled in parallel to a second thermoelectric device P2 may convert heat produced by the nuclear reactor system 100 to electrical energy. Further, a first thermoelectric device P1, a second thermoelectric device P2, a third thermoelectric device P3, and up to and including a Nth thermoelectric device PN may be used to convert nuclear reactor generated heat to electric energy, where the first thermoelectric device P1, the second thermoelectric device P2, the third thermoelectric device P3, and up to and including the Nth thermoelectric device PN are parallel coupled. At operation 1208, upon a nuclear reactor system shutdown event, nuclear reactor generated heat may be converted to electrical energy using at least one thermoelectric module. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric module 148 placed in thermal communication with the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. For example, a thermoelectric module may comprise a prefabricated network of a number of series coupled thermoelectric devices, a number of parallel coupled thermoelectric devices, or combinations of parallel coupled thermoelectric devices and series coupled thermoelectric devices. FIG. 13 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 13 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 1302, and/or an operation 1304. The operation 1302 illustrates, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device sized to meet at least one selected operational requirement of the nuclear reactor system. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 sized to meet an operational requirement 150 (e.g., electric power demand) of the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. The operation 1304 illustrates, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device sized to at least partially match the heat rejection of the at least one thermoelectric device with at least a portion of the heat produced by the nuclear reactor. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 sized to match the heat rejection 151 of the thermoelectric device with the heat produced by the nuclear reactor 102 of the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 14 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 14 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 1402, and/or an operation 1404. Further, the operation 1402 illustrates, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device sized to at least partially match the power requirements of at least one selected operation system. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 sized to match the power requirements of a selected operation system 152 (e.g., coolant system, control system, or security system) of the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. Further, the operation 1404 illustrates, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device sized to match the power requirements of at least one mechanical pump. For example, as shown in FIG. 1, upon a nuclear reactor system shutdown event 110, a thermoelectric device 104 sized to match the power requirements of a mechanical pump 153 (e.g., mechanical pump used to circulate coolant in the primary coolant system) of the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 15 illustrates an operational flow 1500 representing example operations related to the thermoelectric conversion of nuclear reactor generated heat to electrical energy upon a nuclear reactor system shutdown event. FIG. 15 illustrates an example embodiment where the example operational flow 200 of FIG. 2 may include at least one additional operation. Additional operations may include an operation 1510, an operation 1512, and/or an operation 1514. After a start operation, a converting operation 210, and a supplying operation 220, the operational flow 1500 moves to a driving operation 1510. Operation 1510 illustrates at least partially driving at least one mechanical pump. For example, as shown in FIG. 1, the electrical output 108 of the thermoelectric device 104 may be used to partially drive a mechanical pump 106 of the nuclear reactor system 100. The operation 1512 illustrates at least partially driving at least one mechanical pump coupled to at least one coolant system of the nuclear reactor system. For example, as shown in FIG. 1, the electrical output 108 of the thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 of the nuclear reactor system 100. Further, the operation 1514 illustrates at least partially driving at least one mechanical pump coupled to at least one coolant system of the nuclear reactor system, the at least one mechanical pump in series with at least one additional mechanical pump. For example, as shown in FIG. 1, the electrical output 108 of the thermoelectric device 104 may be used to partially drive a first mechanical pump 106 coupled to a coolant system 154 of the nuclear reactor system 100, where the first mechanical pump 106 is coupled in series 155 with a second mechanical pump. FIG. 16 illustrates alternative embodiments of the example operational flow 1500 of FIG. 15. FIG. 16 illustrates example embodiments where the operation 1510 may include at least one additional operation. Additional operations may include an operation 1602. Further, the operation 1602 illustrates at least partially driving at least one mechanical pump coupled to at least one coolant system of the nuclear reactor system, the at least one mechanical pump in parallel with at least one additional mechanical pump. For example, as shown in FIG. 1, the electrical output 108 of the thermoelectric device 104 may be used to partially drive a first mechanical pump 106 coupled to a coolant system 154 of the nuclear reactor system 100, where the first mechanical pump 106 is coupled in parallel 156 with a second mechanical pump. FIG. 17 illustrates alternative embodiments of the example operational flow 1500 of FIG. 15. FIG. 17 illustrates example embodiments where the operation 1510 may include at least one additional operation. Additional operations may include an operation 1702, and/or an operation 1704. Further, the operation 1702 illustrates at least partially driving at least one mechanical pump coupled to at least one coolant system of the nuclear reactor system, the at least one mechanical pump supplying supplemental pumping power to the at least one coolant system. For example, as shown in FIG. 1, the electrical output 108 of the thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 of the nuclear reactor system 100, where the mechanical pump 106 provides supplemental pumping power 157 to the coolant system 154. Further, the operation 1704 illustrates at least partially driving at least one mechanical pump coupled to at least one coolant system of the nuclear reactor system, the at least one mechanical pump supplying supplemental pumping power to the at least one coolant system, the supplemental pumping power enhancing a pumping mass flow rate. For example, as shown in FIG. 1, the electrical output 108 of the thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 of the nuclear reactor system 100, where the mechanical pump 106 provides supplemental pumping power 157 to the coolant system 154 in order to enhance the pumping mass flow rate 158 of the coolant. FIG. 18 illustrates alternative embodiments of the example operational flow 1500 of FIG. 15. FIG. 18 illustrates example embodiments where the operation 1510 may include at least one additional operation. Additional operations may include an operation 1802, an operation 1804, and/or an operation 1806. Further, the operation 1802 illustrates at least partially driving at least one mechanical pump coupled to at least one coolant system of the nuclear reactor system, the at least one mechanical pump supplying auxiliary pumping power to the at least one coolant system. For example, as shown in FIG. 1, the electrical output 108 of the thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 of the nuclear reactor system 100, where the mechanical pump 106 provides auxiliary pumping power 159 to the coolant system 154. Further, the operation 1804 illustrates at least partially driving at least one mechanical pump coupled to at least one coolant system of the nuclear reactor system, the at least one mechanical pump supplying auxiliary pumping power to the at least one coolant system, the auxiliary pumping power establishing a coolant mass flow rate. For example, as shown in FIG. 1, the electrical output 108 of the thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 of the nuclear reactor system 100, where the mechanical pump 106 provides auxiliary pumping power 159 to the coolant system 154 in order to establish a mass flow rate 160 of the coolant. Further, the operation 1806 illustrates at least partially driving at least one mechanical pump coupled to at least one coolant system of the nuclear reactor system, the at least one mechanical pump supplying auxiliary pumping power to the at least one coolant system, the auxiliary pumping power establishing a coolant mass flow rate, the coolant mass flow rate maintaining circulation in at least one reactor coolant pool, at least one reactor coolant pressure vessel, at least one reactor heat exchanger, or at least one ambient coolant. For example, as shown in FIG. 1, the electrical output 108 of the thermoelectric device 104 may be used to partially drive a mechanical pump 106 coupled to a coolant system 154 of the nuclear reactor system 100, where the mechanical pump 106 provides auxiliary pumping power 159 to the coolant system 154 in order to establish a coolant mass flow rate 160 for maintaining circulation 161 in a reactor coolant pool, a reactor coolant pressure vessel, a reactor heat exchange loop, or an ambient coolant. FIG. 19 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 19 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 1902. Further, the operation 1902 illustrates, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one nanofabricated thermoelectric device. For example, as shown in FIG. 1, the thermoelectric device 104 may comprise a nanofabricated thermoelectric device 121 (e.g., device constructed using a quantum well material, a nanowire material, or superlattice material). For instance, upon a nuclear reactor system shutdown event 110, a nanofabricated thermoelectric device 121 in thermal communication with the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 20 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 20 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 2002. Further, the operation 2002 illustrates, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device optimized for a specified range of operating characteristics. For example, as shown in FIG. 1, the thermoelectric device 104 may comprise a thermoelectric device optimized for a specified range of operating characteristics 122 (e.g., temperature or pressure). For instance, upon a nuclear reactor system shutdown event 110, a thermoelectric device optimized for a specified range of operating characteristics 122 in thermal communication with the nuclear reactor system 100 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 21 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 21 illustrates example embodiments where the operation 210 may include at least one additional operation. Additional operations may include an operation 2102. Further, the operation 2102 illustrates, upon a nuclear reactor system shutdown event, thermoelectrically converting nuclear reactor generated heat to electrical energy using at least one thermoelectric device optimized for a first range of operating characteristics and at least one additional thermoelectric device optimized for a second range of operating characteristics, the second range of operating characteristics different from the first range of operating characteristics. For example, as shown in FIG. 1, a first thermoelectric device optimized for a first range of operating characteristics and a second thermoelectric device optimized for a second range of operating characteristics 123, wherein the first range of operating characteristics is different from the second range of operating characteristics, may be placed in thermal communication with the nuclear reactor system 100. For instance, upon a nuclear reactor system shutdown event 110, the first thermoelectric device and the second thermoelectric device 123 may convert heat produced by the nuclear reactor system 100 to electrical energy. FIG. 22 illustrates an operational flow 2200 representing example operations related to the thermoelectric conversion of nuclear reactor generated heat to electrical energy upon a nuclear reactor system shutdown event. FIG. 22 illustrates an example embodiment where the example operational flow 200 of FIG. 2 may include at least one additional operation. Additional operations may include an operation 2210. After a start operation, a converting operation 210, and a supplying operation 220, the operational flow 2200 moves to an optimizing operation 2210. Operation 2210 illustrates substantially optimizing the thermal conduction between a portion of at least one nuclear reactor system and a portion of at least one thermoelectric device. For example, as shown in FIG. 1, at the position of thermal communication between the thermoelectric device 104 and the nuclear reactor system 100, the thermal conduction between the thermoelectric device 104 and the nuclear reactor system 100 may be optimized. For example, the thermal conduction optimization 162 may include, but is not limited to, placing thermal paste, thermal glue, or a highly thermal conductive material between the thermoelectric device 104 and the nuclear reactor system 100. FIG. 23 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 23 illustrates example embodiments where the operation 220 may include at least one additional operation. Additional operations may include an operation 2302, an operation 2304, and/or an operation 2306. The operation 2302 illustrates supplying the electrical energy to at least one mechanical pump of the nuclear reactor system, the at least one mechanical pump circulating coolant through a portion of at least one nuclear reactor core or a portion of at least one heat exchanger. For example, as shown in FIG. 1, the electrical output 108 of a thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of a nuclear reactor system 100, wherein the mechanical pump 106 circulates coolant through a nuclear reactor core or a heat exchanger 162. The operation 2304 illustrates supplying the electrical energy to at least one mechanical pump of the nuclear reactor system, the at least one mechanical pump circulating at least one pressurized gas coolant. For example, as shown in FIG. 1, the electrical output 108 of a thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of a nuclear reactor system 100, wherein the mechanical pump 106 circulates a pressurized gas coolant 163 (e.g., helium) through a portion of the nuclear reactor system 100. The operation 2306 illustrates supplying the electrical energy to at least one mechanical pump of the nuclear reactor system, the at least one mechanical pump circulating a mixed phase coolant. For example, as shown in FIG. 1, the electrical output 108 of a thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of a nuclear reactor system 100, wherein the mechanical pump 106 circulates a mixed phase coolant 164 (e.g., mixture of gas and liquid coolant) through a portion of the nuclear reactor system 100. FIG. 24 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 24 illustrates example embodiments where the operation 220 may include at least one additional operation. Additional operations may include an operation 2402, and/or an operation 2404. The operation 2402 illustrates supplying the electrical energy to at least one mechanical pump of the nuclear reactor system, the at least one mechanical pump circulating at least one liquid coolant. For example, as shown in FIG. 1, the electrical output 108 of a thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of a nuclear reactor system 100, wherein the mechanical pump 106 circulates a liquid coolant 165 (e.g., liquid water) through a portion of the nuclear reactor system 100. Further, the operation 2404 illustrates supplying the electrical energy to at least one mechanical pump of the nuclear reactor system, the at least one mechanical pump circulating at least one liquid metal coolant. For example, as shown in FIG. 1, the electrical output 108 of a thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of a nuclear reactor system 100, wherein the mechanical pump 106 circulates a liquid metal coolant 166 (e.g., liquid sodium) through a portion of the nuclear reactor system 100. FIG. 25 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 25 illustrates example embodiments where the operation 220 may include at least one additional operation. Additional operations may include an operation 2502. Further, the operation 2502 illustrates supplying the electrical energy to at least one mechanical pump of the nuclear reactor system, the at least one mechanical pump circulating at least one liquid salt coolant. For example, as shown in FIG. 1, the electrical output 108 of a thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of a nuclear reactor system 100, wherein the mechanical pump 106 circulates a liquid salt coolant 167 (e.g., fluoride salts) through a portion of the nuclear reactor system 100. FIG. 26 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 26 illustrates example embodiments where the operation 220 may include at least one additional operation. Additional operations may include an operation 2602. Further, the operation 2602 illustrates supplying the electrical energy to at least one mechanical pump of the nuclear reactor system, the at least one mechanical pump circulating liquid water. For example, as shown in FIG. 1, the electrical output 108 of a thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of a nuclear reactor system 100, wherein the mechanical pump 106 circulates a liquid water coolant 168 through a portion of the nuclear reactor system 100. FIG. 27 illustrates alternative embodiments of the example operational flow 200 of FIG. 2. FIG. 27 illustrates example embodiments where the operation 220 may include at least one additional operation. Additional operations may include an operation 2702. Further, the operation 2702 illustrates supplying the electrical energy to at least one mechanical pump of a pool type nuclear reactor system. For example, as shown in FIG. 1, the electrical output 108 of a thermoelectric device 104 may be used to supply electrical energy to a mechanical pump 106 of a pool cooled 169 nuclear reactor system 100. FIG. 28 illustrates an operational flow 2800 representing example operations related to the thermoelectric conversion of nuclear reactor generated heat to electrical energy upon a nuclear reactor system shutdown event. FIG. 28 illustrates an example embodiment where the example operational flow 200 of FIG. 2 may include at least one additional operation. Additional operations may include an operation 2810, an operation 2812, an operation 2814, and/or an operation 2816. After a start operation, a converting operation 210, and a supplying operation 220, the operational flow 2800 moves to a protecting operation 2810. Operation 2810 illustrates protecting at least one thermoelectric device with regulation circuitry. For example, as shown in FIG. 1, one or more than one thermoelectric device 104 may be protected using regulation circuitry 170, such as voltage regulation circuitry (e.g., voltage regulator) or current limiting circuitry (e.g., blocking diode or fuse). The protecting operation 2812 illustrates protecting at least one thermoelectric device with bypass circuitry. For example, as shown in FIG. 1, one or more than one thermoelectric device 104 may be protected using bypass circuitry 172, such as a bypass diode. Further, the operation 2814 illustrates protecting at least one thermoelectric device with bypass circuitry configured to electrically bypass the at least one thermoelectric device. For example, as shown in FIG. 1, one or more than one thermoelectric device 104 may be protected using bypass circuitry configured to electrically bypass 174 one or more than one thermoelectric device 104. Further, the operation 2816 illustrates electrically bypassing the at least one thermoelectric device using at least one electromagnetic relay system, at least one solid state relay system, at least one transistor, at least one microprocessor controlled relay system, at least one microprocessor controlled relay system programmed to respond to at least one external parameter, or at least one microprocessor controlled relay system programmed to respond to at least one internal parameter. For example, as shown in FIG. 1, one or more than one thermoelectric device 104 may be electrically bypassed using an electromagnetic relay system 176, a solid state relay system 178, a transistor 180, a microprocessor controlled relay system 182, a microprocessor controlled relay system programmed to respond to one or more than one external parameters 184, or a microprocessor controlled relay system programmed to respond to one or more than one internal parameters 186. FIG. 29 illustrates an operational flow 2900 representing example operations related to the thermoelectric conversion of nuclear reactor generated heat to electrical energy upon a nuclear reactor system shutdown event. FIG. 29 illustrates an example embodiment where the example operational flow 200 of FIG. 2 may include at least one additional operation. Additional operations may include an operation 2910, and/or an operation 2912. After a start operation, a converting operation 210, and a supplying operation 220, the operational flow 2900 moves to an augmenting operation 2910. Operation 2910 illustrates selectively augmenting at least one thermoelectric device using at least one reserve thermoelectric device and reserve actuation circuitry configured to selectively couple the at least one reserve thermoelectric device to the at least one thermoelectric device. For example, as shown in FIG. 1, the electrical output from one or more than one thermoelectric device 104 may be augmented using one or more than one reserve thermoelectric device 188, where the one or more than one reserve thermoelectric device 188 may be selectively coupled to the thermoelectric device 104 using reserve actuation circuitry 189. The augmenting operation 2912 illustrates selectively coupling at least one reserve thermoelectric device to the at least one thermoelectric device using at least one relay system, at least one electromagnetic relay system, at least one solid state relay system, at least one transistor, at least one microprocessor controlled relay system, at least one microprocessor controlled relay system programmed to respond to at least one external parameter, or at least one microprocessor controlled relay system to respond to at least one internal parameter to the at least one thermoelectric device. For example, as shown in FIG. 1, the electrical output from one or more than one thermoelectric device 104 may be augmented using one or more than one reserve thermoelectric device 188, where the one or more than one reserve thermoelectric device 188 may be selectively coupled to the thermoelectric device 104 using a relay system 190, an electromagnetic relay system 191, a solid state relay system 192, a transistor 193, a microprocessor controlled relay system 194, a microprocessor controlled relay system programmed to respond to at least one external parameter 195, or a microprocessor controlled relay system programmed to respond to at least one internal parameter 196. FIG. 30 illustrates an operational flow 3000 representing example operations related to the thermoelectric conversion of nuclear reactor generated heat to electrical energy upon a nuclear reactor system shutdown event. FIG. 30 illustrates an example embodiment where the example operational flow 200 of FIG. 2 may include at least one additional operation. Additional operations may include an operation 3010, and/or an operation 3012. After a start operation, a converting operation 210, and a supplying operation 220, the operational flow 3000 moves to an output modifying operation 3010. Operation 3010 illustrates modifying the at least one thermoelectric device output using power management circuitry. For example, as shown in FIG. 1, the electrical output of a thermoelectric device 104 may be modified using power management circuitry, such as a voltage converter (e.g., DC-DC converter or DC-AC inverter). The operation 3012 illustrates modifying the at least one thermoelectric device output using voltage regulation circuitry. For example, as shown in FIG. 1, the electrical output of a thermoelectric device 104 may be modified using voltage regulation circuitry, such as a voltage regulator (e.g., Zener diode, an adjustable voltage regulator or a fixed voltage regulator). Those having skill in the art will recognize that the state of the art has progressed to the point where there is little distinction left between hardware, software, and/or firmware implementations of aspects of systems; the use of hardware, software, and/or firmware is generally (but not always, in that in certain contexts the choice between hardware and software can become significant) a design choice representing cost vs. efficiency tradeoffs. Those having skill in the art will appreciate that there are various vehicles by which processes and/or systems and/or other technologies described herein can be effected (e.g., hardware, software, and/or firmware), and that the preferred vehicle will vary with the context in which the processes and/or systems and/or other technologies are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may opt for a mainly hardware and/or firmware vehicle; alternatively, if flexibility is paramount, the implementer may opt for a mainly software implementation; or, yet again alternatively, the implementer may opt for some combination of hardware, software, and/or firmware. Hence, there are several possible vehicles by which the processes and/or devices and/or other technologies described herein may be effected, none of which is inherently superior to the other in that any vehicle to be utilized is a choice dependent upon the context in which the vehicle will be deployed and the specific concerns (e.g., speed, flexibility, or predictability) of the implementer, any of which may vary. Those skilled in the art will recognize that optical aspects of implementations will typically employ optically-oriented hardware, software, and or firmware. In some implementations described herein, logic and similar implementations may include software or other control structures. Electronic circuitry, for example, may have one or more paths of electrical current constructed and arranged to implement various functions as described herein. In some implementations, one or more media may be configured to bear a device-detectable implementation when such media hold or transmit device-detectable instructions operable to perform as described herein. In some variants, for example, implementations may include an update or modification of existing software or firmware, or of gate arrays or programmable hardware, such as by performing a reception of or a transmission of one or more instructions in relation to one or more operations described herein. Alternatively or additionally, in some variants, an implementation may include special-purpose hardware, software, firmware components, and/or general-purpose components executing or otherwise invoking special-purpose components. Specifications or other implementations may be transmitted by one or more instances of tangible transmission media as described herein, optionally by packet transmission or otherwise by passing through distributed media at various times. Alternatively or additionally, implementations may include executing a special-purpose instruction sequence or invoking circuitry for enabling, triggering, coordinating, requesting, or otherwise causing one or more occurrences of virtually any functional operations described herein. In some variants, operational or other logical descriptions herein may be expressed as source code and compiled or otherwise invoked as an executable instruction sequence. In some contexts, for example, implementations may be provided, in whole or in part, by source code, such as C++, or other code sequences. In other implementations, source or other code implementation, using commercially available and/or techniques in the art, may be compiled/implemented/translated/converted into a high-level descriptor language (e.g., initially implementing described technologies in C or C++ programming language and thereafter converting the programming language implementation into a logic-synthesizable language implementation, a hardware description language implementation, a hardware design simulation implementation, and/or other such similar mode(s) of expression). For example, some or all of a logical expression (e.g., computer programming language implementation) may be manifested as a Verilog-type hardware description (e.g., via Hardware Description Language (HDL) and/or Very High Speed Integrated Circuit Hardware Descriptor Language (VHDL)) or other circuitry model which may then be used to create a physical implementation having hardware (e.g., an Application Specific Integrated Circuit). Those skilled in the art will recognize how to obtain, configure, and optimize suitable transmission or computational elements, material supplies, actuators, or other structures in light of these teachings. The foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Insofar as such block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those within the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one embodiment, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception logic, etc.), etc.). In a general sense, those skilled in the art will recognize that the various embodiments described herein can be implemented, individually and/or collectively, by various types of electromechanical systems having a wide range of electrical components such as hardware, software, firmware, and/or virtually any combination thereof; and a wide range of components that may impart mechanical force or motion such as rigid bodies, spring or torsional bodies, hydraulics, electro-magnetically actuated devices, and/or virtually any combination thereof. Consequently, as used herein “electromechanical system” includes, but is not limited to, electrical circuitry operably coupled with a transducer (e.g., an actuator, a motor, a piezoelectric crystal, a Micro Electro Mechanical System (MEMS), etc.), electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of memory (e.g., random access, flash, read only, etc.)), electrical circuitry forming a communications device (e.g., a modem, communications switch, optical-electrical equipment, etc.), and/or any non-electrical analog thereto, such as optical or other analogs. Those skilled in the art will also appreciate that examples of electromechanical systems include but are not limited to a variety of consumer electronics systems, medical devices, as well as other systems such as motorized transport systems, factory automation systems, security systems, and/or communication/computing systems. Those skilled in the art will recognize that electromechanical as used herein is not necessarily limited to a system that has both electrical and mechanical actuation except as context may dictate otherwise. In a general sense, those skilled in the art will recognize that the various aspects described herein which can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, and/or any combination thereof can be viewed as being composed of various types of “electrical circuitry.” Consequently, as used herein “electrical circuitry” includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of memory (e.g., random access, flash, read only, etc.)), and/or electrical circuitry forming a communications device (e.g., a modem, communications switch, optical-electrical equipment, etc.). Those having skill in the art will recognize that the subject matter described herein may be implemented in an analog or digital fashion or some combination thereof. Those skilled in the art will recognize that at least a portion of the devices and/or processes described herein can be integrated into a data processing system. Those having skill in the art will recognize that a data processing system generally includes one or more of a system unit housing, a video display device, memory such as volatile or non-volatile memory, processors such as microprocessors or digital signal processors, computational entities such as operating systems, drivers, graphical user interfaces, and applications programs, one or more interaction devices (e.g., a touch pad, a touch screen, an antenna, etc.), and/or control systems including feedback loops and control motors (e.g., feedback for sensing position and/or velocity; control motors for moving and/or adjusting components and/or quantities). A data processing system may be implemented utilizing suitable commercially available components, such as those typically found in data computing/communication and/or network computing/communication systems. One skilled in the art will recognize that the herein described components (e.g., operations), devices, objects, and the discussion accompanying them are used as examples for the sake of conceptual clarity and that various configuration modifications are contemplated. Consequently, as used herein, the specific exemplars set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar is intended to be representative of its class, and the non-inclusion of specific components (e.g., operations), devices, and objects should not be taken limiting. Although a user is shown/described herein as a single illustrated figure, those skilled in the art will appreciate that the user may be representative of a human user, a robotic user (e.g., computational entity), and/or substantially any combination thereof (e.g., a user may be assisted by one or more robotic agents) unless context dictates otherwise. Those skilled in the art will appreciate that, in general, the same may be said of “sender” and/or other entity-oriented terms as such terms are used herein unless context dictates otherwise. With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations are not expressly set forth herein for sake of clarity. The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures may be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable,” to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components, and/or wirelessly interactable, and/or wirelessly interacting components, and/or logically interacting, and/or logically interactable components. In some instances, one or more components may be referred to herein as “configured to,” “configurable to,” “operable/operative to,” “adapted/adaptable,” “able to,” “conformable/conformed to,” etc. Those skilled in the art will recognize that such terms (e.g., “configured to”) can generally encompass active-state components and/or inactive-state components and/or standby-state components, unless context requires otherwise. While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that typically a disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms unless context dictates otherwise. For example, the phrase “A or B” will be typically understood to include the possibilities of “A” or “B” or “A and B. With respect to the appended claims, those skilled in the art will appreciate that recited operations therein may generally be performed in any order. Also, although various operational flows are presented in a sequence(s), it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently. Examples of such alternate orderings may include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. Furthermore, terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise.
	abstract	An apparatus is described for catching and cooling a melt, in particular a core melt in a containment of a nuclear power plant. A porous body with which the melt comes into contact is provided. A pre-pressurized coolant is fed to the porous body so that the cavities in the porous body are filled with the coolant. After contact between the melt and the porous body, the pre-pressurized coolant penetrates into the melt and as a result leads to fragmentation, solidification and long-term cooling.
041464230	abstract	The invention relates to a nuclear reactor having a pressure vessel of pre-stressed concrete. The reactor contains a containment vessel spaced from the pressure vessel by means of an insulation gap. The containment vessel consists of two parts having no mechanical joint between them. It is described how the insulation fluid in the insulation gap is prevented from penetrating into the interior of the reactor.
	description	This application is a divisional of U.S. application Ser. No. 13/303,723 filed Nov. 23, 2011, which is a divisional of U.S. application Ser. No. 12/441,919 filed Mar. 19, 2009, which is a National Stage Entry of PCT/US2007/021344 filed Oct. 3, 2007, which claims priority from U.S. Provisional Application No. 60/849,869, filed Oct. 6, 2006, all of which are incorporated herein by reference. The invention relates generally to radioisotope elution systems and, more specifically, to self-aligning components for use in such systems. This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. Nuclear medicine uses radioactive material for diagnostic and therapeutic purposes by injecting a patient with a dose of the radioactive material, which concentrates in certain organs or biological regions of the patient. Radioactive materials typically used for nuclear medicine include Technetium-99m, Indium-111, and Thallium-201 among others. Some chemical forms of radioactive materials naturally concentrate in a particular tissue, for example, iodide (I-131) concentrates in the thyroid. Radioactive materials are often combined with a tagging or organ-seeking agent, which targets the radioactive material for the desired organ or biologic region of the patient. These radioactive materials alone or in combination with a tagging agent are typically referred to as radiopharmaceuticals in the field of nuclear medicine. At relatively low doses of the radiopharmaceutical, a radiation imaging system (e.g., a gamma camera) may be utilized to provide an image of the organ or biological region that collects the radiopharmaceutical. Irregularities in the image are often indicative of a pathology, such as cancer. Higher doses of the radiopharmaceutical may be used to deliver a therapeutic dose of radiation directly to the pathologic tissue, such as cancer cells. A variety of systems are used to generate, enclose, transport, dispense, and administer radiopharmaceuticals. Using these systems often involves manual alignment of components, such as male and female connectors of containers. Unfortunately, the male connectors can be damaged due to misalignment with the corresponding female connectors. For example, hollow needles can be bent, crushed, or broken due to misalignment with female connectors. As a result, the systems operate less effectively or become completely useless. If the systems contain radiopharmaceuticals, then the damaged connectors can result in monetary losses or delays with respect to nuclear medicine procedures. Certain exemplary aspects of the invention are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below. In some embodiments of the present invention, a radioisotope elution system includes self-aligning components that protect needles from being damaged. In one embodiment, a radioisotope generator includes an alignment structure that is keyed to a complementary alignment structure on a lid of an auxiliary radiation shield. The complementary alignment structure may be inserted into the alignment structure, and the position of the lid relative to the radioisotope generator may be generally fixed. Once these components are aligned, apertures in the lid may be used to guide various components onto the needles of the generator in a controlled manner, thereby reducing the likelihood of a misaligned component damaging the needles. A first aspect of the present invention is directed to a radioisotope elution system that includes a radioisotope generator having an alignment structure configured to interface with a complementary alignment structure on a radiation shield. A second aspect of the invention is directed to a radiation shield for shielding a radioisotope generator. The radiation shield has a shield lid that includes an alignment structure configured to align the shield lid to a radioisotope generator. A third aspect of the invention is directed to radioisotope elution system that includes an auxiliary shield having a top plane, a shield lid that includes a handle, and a radioisotope generator disposed in the auxiliary shield and biased by the weight of the shield lid. The shield lid may be disposed in the auxiliary shield, and the handle may cross the top plane. A fourth aspect of the invention is directed to a method of operating a radioisotope elution system. The method includes aligning a radiation shield lid to a radioisotope generator via a first alignment structure on the radiation shield lid and a second alignment structure on the radioisotope generator. Various refinements exist of the features noted above in relation to the various aspects of the present invention. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present invention alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of the present invention without limitation to the claimed subject matter. One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. When introducing elements of various embodiments of the present invention, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, the use of “top”, “bottom”, “above”, “below” and variations of these terms is made for convenience, but does not require any particular orientation of the components. As used herein, the term “coupled” refers to the condition of being directly or indirectly connected or in contact. FIG. 1 shows an exemplary radioisotope elution system 10 that includes an auxiliary shield assembly 12, an elution tool 14, and an eluant assembly 16. As discussed below, a variety of alignment structures, alignment mechanisms, and/or alignment indicators may be incorporated into the radioisotope elution system 10 to facilitate proper alignment of the various containers, hollow needles, radioisotope generator, and other components residing inside the auxiliary shield assembly 12. The illustrated auxiliary shield assembly 12 includes an auxiliary shield lid 18 and an auxiliary shield 20. For brevity, the auxiliary shield lid 18 is referred to as a “lid.” The auxiliary shield 20 may include a top ring 22, a base 24, and a plurality of step-shaped or generally tiered modular rings 26, which are disposed one over the other between the base 24 and the top ring 22 (see FIGS. 1 and 7). Substantially all or part of the illustrated auxiliary shield assembly 12 may be made of one or more suitable radiation shielding materials, such as depleted uranium, tungsten, tungsten impregnated plastic, or lead. One or more of the components of the auxiliary shield assembly 12 may be lined with, powder coated on, and/or embedded in other materials, such as an appropriate polymer material. For instance, in some embodiments, at least a portion (e.g., a majority, or a substantial entirety) of the lid 18 of the assembly 12 may be over-molded with polycarbonate resin (or other appropriate polymer). Embedding or over-molding the shielding materials may promote safety, enhance durability, and/or facilitate formation of components with smaller dimensional tolerances than components made entirely out of shielding materials. Moreover, the modular aspect of the rings 24 may tend to enhance adjustment of the height of the auxiliary shield 12, and the step-shaped configuration may tend to contain some radiation that might otherwise escape through an interface between the modular rings 26. While FIG. 1 depicts one example of an auxiliary shield assembly 12, it should be noted that other auxiliary shield assemblies may be employed. FIGS. 2, 3 are exploded views of the radioisotope elution system 10 from different perspectives. The auxiliary shield assembly 12 is designed to house a radioisotope generator 28 within the auxiliary shield 20 and under the lid 18. The radioisotope generator 28 may include a generator body 30, a needle assembly 32, and a cap 34. The illustrated generator body 30 includes an elution column configured to generate and output a desired radioisotope. Except for the needle assembly 32, the various components of the elution column of the radioisotope generator 28 are not shown in detail. However, elution columns are well known to those of ordinary skill in the art (see U.S. Pat. No. 5,109,160 and US Patent Application Publication No. 2005/0253085, for example). As such, one of ordinary skill in the art could easily employ various aspects of the invention with radioisotope generators having a wide range of elution column designs. Certain medically useful radioisotopes have relatively short half-lives (e.g., technetium-99m (Tc99m) has a half-life of approximately 6 hours). To potentially expand the useful life of the radioisotope generator 28, the elution column may include a more stable radioisotope that decays into the desired radioisotope (e.g., molybdenum-99 (Mo99) has a half-life of approximately 66 hours and decays into Tc99m). As the desired radioisotope is needed, it may be separated from the more stable radioisotope with an elution process, as explained below. The generator body 30 may also include shielding configured to diminish radiation, and tubing to conduct fluids into and out of the elution column. Externally, the illustrated generator body 30 includes a lifting strap 36, two strap supports 38, 40, and outer rings 42, 44. The two strap supports 38, 40 extend upward from the generator body 30 and pivotably interconnect (e.g., connect in a manner that enables pivoting or pivot-like motion (e.g., flexing, elastic deformation, etc.)) to opposing ends of the lifting strap 36. The outer rings 42, 44 are near the top and bottom of the generator body 30, respectively. As depicted in FIG. 7, the outer rings 42, 44 extend radially from the generator body and limit the range of non-axial movement (e.g., movement other than up or down translation) of the generator body 30 within the auxiliary shield 20. The needle assembly 32 may include an input needle 46, an output needle 48, and a vent needle 50. The tubing in the generator body 30 may fluidly interconnect (e.g., connect either directly or indirectly in a manner that enables fluid to flow there between) to needles 46, 48, and/or 50. Specifically, the input needle 46 may fluidly interconnect with an input to the elution column, and the output needle 48 may fluidly interconnect with an output from the elution column. The vent needle 40 may vent to atmosphere to equalize pressure during an elution, as explained below. The needles 46, 48, 50 are hollow to facilitate fluid flow therein. The cap 34 may include needle apertures 52, 54, support channels 56, 58, tabs 60, 62, 64, 66, a top surface 67, and an alignment structure 68. Here, the term “alignment structure” refers to a member or surface that reduces the range of relative motion between two components as those components are interconnected, coupled, or brought into proximity. In other words, an alignment structure reduces the number of degrees of freedom between components as the components are interfaced (e.g., brought into contact with each other or an intermediary component such that mechanical forces may be transmitted from one alignment structure to another). The needle apertures 52, 54 are disposed within the alignment structure 68. In other embodiments, the needle apertures 52, 54 may be positioned elsewhere relative to the alignment structure 68, e.g., not within it or on a separate component. The support channels 56, 58 are shaped to complement the strap supports 38, 40 and orient the cap 34 relative to the generator body 30. That is, the support channels 56, 58 cooperate with the strap supports 38, 40 to align the cap 34 to the generator body 30 in one of a finite number of discrete orientations and positions, such as a single orientation and position. The illustrated alignment structure 68 generally defines a cylinder with an oval base 70 and walls 72 that are generally perpendicular to the base 70. As used herein, the term “cylinder” refers to a surface or solid bounded by two parallel planes and generated by a straight line (i.e., a generatrix) moving parallel to the given planes and tracing a curve (including but not limited to a circle) bounded by the planes and lying in a plane perpendicular or oblique to be given planes. The base 70 is generally parallel to the base 24 of the auxiliary shield 20, and the cylinder defined by the alignment structure 68 has a single plane of symmetry that is generally perpendicular to the base 70. The illustrated alignment structure 68 is recessed in word into the cap 34 and maybe generally characterized as a female alignment structure. In other embodiments, the alignment structure 68 may have a variety of different shapes and configurations. For example, the alignment structure 68 may be generally asymmetric, or the alignment structure 68 may extend outward from the cap 34. As described below, the alignment structure 68 may align the lid 18 to the radioisotope generator 28. FIG. 4 depicts the radioisotope generator 28 in an assembled state. The needle assembly 32 is disposed between the cap 34 and the generator body 32. The needles 46, 48, 50 extend through the apertures 52, 54, and the tabs 60, 62, 64, 66 are inserted into the generator body 32. Additionally, the strap supports 38, 40 are aligned with and inserted in the support channels 56, 58, respectively, thereby generally fixing the position and orientation of the cap 34 relative to the generator body 30. With reference to FIGS. 2, 3, and 5, the lid 18 will now be described. In the present embodiment, the lid 18 includes a bottom surface 74, a complementary alignment structure 76, a sidewall 78, handles 80, 82, an elution tool aperture 84, and an eluant aperture 86. The lid 18 may be made of appropriate radiation shielding materials, such as those discussed above. The handles maybe generally U-shaped. The illustrated complementary alignment structure 76, which may be generally characterized as a male alignment structure, extends downward from the bottom surface 74 and includes a mating surface 88 that is generally perpendicular to the bottom surface 74. The complementary alignment structure 76 generally defines a right cylinder (e.g., a cylinder with sidewalls that are perpendicular to the base) with an oval base that is complementary (e.g., keyed) to the alignment structure 68. In other words, the complementary alignment structure 76 is configured to mate with the alignment structure 68 on the radioisotope generator 30. When the alignment structures 76, 68 are mated, the sidewall 72 may be in contact with or proximate to the mating surface 88 on the lid 18, and contact between the surfaces may reduce the number of degrees of relative freedom between these components. In short, the alignment structures 76, 78 may cooperate to align the lid 18 with the radioisotope generator 30. The elution tool aperture 84 and eluant aperture 86 extend through the illustrated lid 18. These apertures 84, 86 may have a generally circular horizontal cross-section that is generally constant through at least a portion of the vertical thickness of the lid 18. The apertures 84, 86 may be disposed within and extend through the complementary alignment structure 76. In other embodiments, these features 84, 86, 76 may be disposed else elsewhere with respect to one another. The eluant aperture 86 may include a flared portion 90 (see FIGS. 3 and 6) for positioning subsequently discussed components. Referring general to FIGS. 2 and 3, the elution tool 14 may have a generally cylindrical shape and include an outer shield 92 and an eluate receptacle 94. The outer shield 92 is made of radiation shielding material, such as those discussed above, and is shaped to be inserted through the elution tool aperture 84 on the lid 18. During insertion, contact between the outer shield 92 and the elution tool aperture 84 may generally confine the elution tool 14 to translating up and down and substantially prevent the elution tool 14 from translating horizontally or rotating about a horizontal axis (e.g., rotating end-over-end). In other words, the elution tool aperture 84 may cooperate with the outer shield 92 to position the elution tool 14 over the input needle 48 and guide the elution tool 14 along a path that is generally parallel (e.g., coaxially) with the input needle 48, thereby generally preventing the elution tool 14 from potentially damaging the input needle 48. The eluate receptacle 94 may be generally enveloped by the outer shield 92 with the exception of an aperture 96 in the bottom of the outer shield 92. The eluate receptacle 94 may include an evacuated vial, a conduit, or some other container configured to receive fluid from the output needle 48 on the radioisotope generator 28. The eluant assembly 16 may include an eluant shield 98 and an eluant source 100. The illustrated eluant shield 98 has a handle 102, guide members 104, 106, and a recessed portion 108. The eluant shield 98 may be made of radiation shielding material, such as those materials discussed above. The guide members 104, 106 are shaped to fit within the flared portion 90 of the lid 18 and guide the eluant shield 98 into a resting position on the lid 18 (see FIG. 1). The recessed portion 108 generally corresponds to the shape of the top of the eluant source 100, which may be a vial of saline or other appropriate fluid. The eluant source 100 has a generally cylindrical shape and is sized such that it may pass through the eluant aperture 86 in the lid 18. When the eluant source 100 is inserted through the eluant aperture 86, contact with the walls of the eluant aperture 86 many generally constrain movement of the eluant source to up-and-down translation and rotation about a vertical axis. In other words, this contact may tend to prevent the eluant source 100 from translating horizontally or rotating about a horizontal axis during insertion. That is, the position and orientation of the eluant aperture 86 generally determines the position and orientation of the eluant source 100 when the eluant source 100 is positioned therein. FIGS. 6, 7 depict top and cross-section views, respectively, of the assembled radioisotope elution system 10. The radioisotope generator 28 is positioned within a cylindrical receptacle 108 in the auxiliary shield 20, and the top surface 67 of the cap 34 recessed below a top plane 110 of the auxiliary shield 20. Contact between the outer rings 42, 44 and the walls of the cylindrical receptacle 108 may tend to reduce horizontal translation of the radioisotope generator 28 and rotation of the radioisotope generator 28 about horizontal axes (e.g., rotating end-over-end). The lid 18 also fits into the cylindrical receptacle 108, and the shape of the outer walls 78 generally corresponding to the shape of the side walls of the cylindrical receptacle 108. Contact between the sidewalls 78 and the sidewalls of the cylindrical receptacle 108 may tend to reduce horizontal translation of the lid 18 and rotation of the lid 18 about horizontal axes. The lid 18 may be generally free to slide vertically within the cylindrical receptacle 108 until the bottom surface 74 of the lid 18 makes contact with the top surface 67 of the cap 34. In other words, the lid 18 may rest on the radioisotope generator 28 with the radioisotope generator 28 carrying the weight of the lid 18. A variety of components may interface with the lid 18. As discussed above, the eluant source 100 may slide through the eluant aperture 86 in the lid 18, and contact between these components 86, 100 may tend to reduce horizontal translation of the eluant source 100 and rotation of the eluant source 100 about horizontal axes. Similarly, the elution tool 14 may slide through the elution tool aperture 84, and contact between these components 14, 84 may tend to reduce horizontal translation of the elution tool 14 and rotation of the elution tool 14 about horizontal axes. In other words, the lid 18 may tend to constrain movement of the elution tool 14 and eluant source 100 to an up-and-down motion that is parallel (e.g., coaxial) with the needles 46, 48, 50 as these components 14, 100 are brought in contact with the needles 46, 48, 50. Aligning the elution tool 14 and eluant source 100 with the needles 46, 48, 50 before they make contact may reduce the chances of the needles 46, 48, 50 being damaged. The eluant shield 98 may rest on the lid 18 and cover a portion of the eluant source 100 that extends above a top of the lid 18. In the assembled state depicted by FIGS. 6, 7, the lid 18 is aligned to the radioisotope generator 28. The complementary alignment structure 76 on the lid 18 is inserted into the alignment structure 68 on the cap 34. Contact between the sidewalls 88 of the complementary alignment structure 76 and the sidewalls 72 of the alignment structure 68 may tend to reduce rotation of the lid 18 about vertical axes and reduce horizontal translation of the lid 18. In other words, when assembled, the lid 18 and radioisotope generator 28 generally have a single degree of freedom, i.e., vertical translation of the lid 18 in the cylindrical receptacle 108 away from the radioisotope generator 28. Other embodiments may include a latch or locking device for the lid 18 and reduce the number of degrees of freedom to zero. In operation, an eluant inside the eluant source 100 is circulated through the inlet needle 46, through the radioisotope generator 28 (including the elution column), and out through the outlet needle 48 into the eluate receptacle 94. This circulation of the eluant washes out or generally extracts a radioactive material, e.g., a radioisotope, from the radioisotope generator 28 into the eluate receptacle 94. For example, one embodiment of the radioisotope generator 28 includes an internal radiation shield (e.g., lead shell) that encloses a radioactive parent, such as molybdenum-99, affixed to the surface of beads of alumina or a resin exchange column. Inside the radioisotope generator 28, the parent molybdenum-99 transforms, with a half-life of about 66 hours, into metastable technetium-99m. The daughter radioisotope, e.g., technetium-99m, is generally held less tightly than the parent radioisotope, e.g., molybdenum-99, within the radioisotope generator 28. Accordingly, the daughter radioisotope, e.g., technetium-99m, can be extracted or washed out with a suitable eluant, such as an oxidant-free physiologic saline solution. Upon collecting a desired amount (e.g., desired number of doses) of the daughter radioisotope, e.g., technetium-99m, within the eluate receptacle 94, the elution tool 14 can be removed from the radioisotope elution system 10. As discussed in further detail below, the extracted daughter radioisotope can then, if desired, be combined with a tagging agent to facilitate diagnosis or treatment of a patient (e.g., in a nuclear medicine facility). The illustrated radioisotope elution system 10 is a dry elution system. Prior to an elution, the eluant receptacle 94 is substantially evacuated, and the eluant source 100 is filled with a volume of saline that generally corresponds to the desired volume of radioisotope solution. During an elution, the vacuum in the eluant receptacle 94 draws saline from the eluant source 100, through the radioisotope generator 28, and into the eluant receptacle 94. After substantially all of the saline has been drawn from the eluant source 100, a remaining vacuum in the eluant receptacle 94 draws air through the radioisotope generator 28, thereby removing fluid that might otherwise remain in the radioisotope generator 28. Air or other appropriate fluids may flow into the eluant source 100 through the vent needle 50 and into the radioisotope generator 28 through the input needle 46. The volume and pressure of the eluant receptacle 94 may be selected such that substantially all of the eluant fluid is drawn out of the radioisotope generator 28 by the end of an elution operation. In view of the operation of the elution system 10, proper alignment of the various components may be particularly important to the life of the needles 46, 48, 50 and, thus, proper circulation of the eluant from the eluant source 100 through the radioisotope generator 28 and into the eluant receptacle 94. For example, when the eluant source 100 is coupled to the needles 46, 50, it may bend the needles 46, 50 if not properly aligned. Similarly, pressing the elution tool 14 down onto the needle 48 may bend the needle 48 if the elution tool 14 is not properly aligned. Certain embodiments of a subsequently described elution process may align the eluant source 100 with the needles 46, 50 before the eluant source 100 contacts the needles 46, 50 and, also, may align the elution tool 14 with the needle 48 before the elution tool 14 contacts the needle 48. Moreover, certain embodiments may guide the elution tool 14 and the eluant source 100 through an up or down movement that is parallel with the needles 46, 48, 50 when the elution tool 14 and eluant source 100 are positioned over the needles 46, 48, 50 and properly oriented. An elution process 112 will now be described with reference to FIG. 8. Initially, a radiation shield, such as the lid 18, is aligned to a generator, as depicted by block 114. In the embodiment of FIGS. 1-7, aligning a radiation shield includes interfacing the alignment structure 68 on the cap 34 with the complementary alignment structure 76 on the lid 18. The lid 18 is inserted into the cylindrical receptacle 108 in the auxiliary shield 20 and lowered until the lid 18 makes contact with the top surface 67 of the cap 34. Then the lid 18 is rotated about a vertical axis within the cylindrical receptacle 108 until the complementary alignment structure 76 slides into the alignment structure 68. The complementary alignment structure 76 is inserted into the alignment structure 68 until the bottom surface 74 of the lid 18 makes contact with the top surface 67 of the cap 34. At this point, the position and orientation of the lid 18 is generally determined by the position and orientation of the radioisotope generator 28. In other words, the lid 18 is referenced to the radioisotope generator 28. Once aligned, in some embodiments, lid 18 and radioisotope generator 28 may have a single degree of relative freedom: for example, the lid 18 may translate vertically within the cylindrical receptacle 108, but the lid 18 may be generally obstructed from rotating about horizontal or vertical axes or translating horizontally. Because the lid 18 can translate vertically within the cylindrical receptacle 108, the radioisotope elution system 10 may accommodate radioisotope generators 28 of a variety of sizes. In other words, the lid 18 is able to self-adjust the height to match the generator 28. For example, the lid 18 may translate further into the cylindrical receptacle 108 to accommodate a smaller radioisotope generator 28 or less distance to accommodate a larger radioisotope generator 28. After aligning the radiation shield to the generator, a source of eluant may be aligned to the radiation shield, as depicted by block 116. For example, the eluant source 100 may be aligned to the lid 18. Aligning the eluant source 100 may include vertically orienting eluant source 100 over the eluant aperture 86 and inserting the eluant source 100 through the eluant aperture 86 until the needles 46, 50 have substantially penetrated the eluant source 100. Because the lid 18 is aligned (or referenced) to the radioisotope generator 28 and the eluant source 100 is aligned (or referenced) to the lid 18, the eluant source 100 may be aligned (or referenced) to the radioisotope generator 28. Moreover, the path traveled by the eluant source 100 as it interfaces or makes contact with the needles 46, 50 may be controlled by the eluant aperture 86. That is, the eluant aperture 86 may guide the eluant source 100 onto the needles 46, 50 in a path that is substantially parallel to the needles 46, 50. Next an elution tool is aligned to the radiation shield, as depicted by block 118. In the embodiment of FIGS. 1-7, the elution tool 14 may be aligned with the elution aperture 84 on the lid 18. Aligning the elution tool 14 may include positioning the elution tool 14 over the elution aperture 84 and vertically orienting the elution tool 14 so that it may be inserted into the elution aperture 84. As the elution tool 14 is inserted, the elution receptacle 94 may vertically translate in a direction that is parallel with the needle 48. That is the eluant aperture 84 may guide the elution tool 14 onto the needle 48 in a path and orientation that are referenced to the needle 48. During insertion, movement of the elution tool 14 relative to the needle 48 and radioisotope generator 28 may be generally limited to vertical translation and rotation about a vertical axis. FIG. 9 depicts another radioisotope elution system 120. The embodiment of FIG. 9 includes a T-shaped handle 122 that extends upward from the lid 18 and through the top plane 110 of the auxiliary shield 20. The present embodiment includes a pair of T-shaped handles 122 symmetrically dispose on the lid 18. Other embodiments may include handles with different shapes and/or handles that do not extend above the top plane 110. FIG. 10 depicts a radioisotope elution system 124 that is configured to indirectly align the lid 18 with the radioisotope generator 28. In the present embodiment, the lid 18 includes alignment structures 126, 128, and the radioisotope generator 28 includes alignment structure 130, 132. The auxiliary shield 20 includes complementary alignment structures 134, 136, 138, 140, which mate with (or are keyed to) the alignment structures 128, 126, 130, 132. Specifically, the triangle-shaped alignment structures 128, 126 on the lid 18 interface with the complementary alignment structures 136, 140 to align the lid 18 to the auxiliary shield 22. Similarly, the square-shaped alignment structures 130, 132 interface with the complementary alignment structures 134, 138 to align the radioisotope generator 28 to the auxiliary shield 22. That is, both the radioisotope generator 28 and the lid 18 are aligned to the auxiliary shield 22, thereby aligning these components 18, 28 with each other. In other words, the lid 18 is indirectly aligned with the radioisotope generator 28 through the auxiliary shield 22. Other embodiments may include alignment structures with different shapes, different positions, and/or other intermediary components. FIG. 11 is a flowchart illustrating an exemplary nuclear medicine process that uses the radioactive isotope produced by the previously discussed radioisotope elution systems 10, 110, 124. As illustrated, the process 162 begins by providing a radioactive isotope for nuclear medicine at block 164. For example, block 164 may include eluting technetium-99m from the radioisotope generator 22 illustrated and described in detail above. At block 166, the process 162 proceeds by providing a tagging agent (e.g., an epitope or other appropriate biological directing moiety) adapted to target the radioisotope for a specific portion, e.g., an organ, of a patient. At block 168, the process 162 then proceeds by combining the radioactive isotope with the tagging agent to provide a radiopharmaceutical for nuclear medicine. In certain embodiments, the radioactive isotope may have natural tendencies to concentrate toward a particular organ or tissue and, thus, the radioactive isotope may be characterized as a radiopharmaceutical without adding any supplemental tagging agent. At block 170, the process 162 then may proceed by extracting one or more doses of the radiopharmaceutical into a syringe or another container, such as a container suitable for administering the radiopharmaceutical to a patient in a nuclear medicine facility or hospital. At block 172, the process 162 proceeds by injecting or generally administering a dose of the radiopharmaceutical into a patient. After a pre-selected time, the process 162 proceeds by detecting/imaging the radiopharmaceutical tagged to the patient's organ or tissue (block 174). For example, block 174 may include using a gamma camera or other radiographic imaging device to detect the radiopharmaceutical disposed on or in or bound to tissue of a brain, a heart, a liver, a tumor, a cancerous tissue, or various other organs or diseased tissue. FIG. 12 is a block diagram of an exemplary system 176 for providing a syringe having a radiopharmaceutical disposed therein for use in a nuclear medicine application. As illustrated, the system 176 includes the radioisotope elution systems 10, 110, 124. The system 176 also includes a radiopharmaceutical production system 178, which functions to combine a radioisotope 180 (e.g., technetium-99m solution acquired through use of the radioisotope elution system 10) with a tagging agent 182. In some embodiment, this radiopharmaceutical production system 178 may refer to or include what are known in the art as “kits” (e.g., Technescan® kit for preparation of a diagnostic radiopharmaceutical). Again, the tagging agent may include a variety of substances that are attracted to or targeted for a particular portion (e.g., organ, tissue, tumor, cancer, etc.) of the patient. As a result, the radiopharmaceutical production system 178 produces or may be utilized to produce a radiopharmaceutical including the radioisotope 180 and the tagging agent 182, as indicated by block 184. The illustrated system 176 may also include a radiopharmaceutical dispensing system 186, which facilitates extraction of the radiopharmaceutical into a vial or syringe 188. In certain embodiments, the various components and functions of the system 176 are disposed within a radiopharmacy, which prepares the syringe 188 of the radiopharmaceutical for use in a nuclear medicine application. For example, the syringe 188 may be prepared and delivered to a medical facility for use in diagnosis or treatment of a patient. FIG. 13 is a block diagram of an exemplary nuclear medicine imaging system 190 utilizing the syringe 188 of radiopharmaceutical provided using the system 176 of FIG. 12. As illustrated, the nuclear medicine imagining system 190 includes a radiation detector 192 having a scintillator 194 and a photo detector 196. In response to radiation 198 emitted from a tagged organ within a patient 200, the scintillator 194 emits light that is sensed and converted to electronic signals by the photo detector 196. Although not illustrated, the imaging system 190 also can include a collimator to collimate the radiation 198 directed toward the radiation detector 192. The illustrated imaging system 190 also includes detector acquisition circuitry 202 and image processing circuitry 204. The detector acquisition circuitry 202 generally controls the acquisition of electronic signals from the radiation detector 192. The image processing circuitry 204 may be employed to process the electronic signals, execute examination protocols, and so forth. The illustrated imaging system 190 also includes a user interface 206 to facilitate user interaction with the image processing circuitry 204 and other components of the imaging system 190. As a result, the imaging system 190 produces an image 208 of the tagged organ within the patient 200. Again, the foregoing procedures and resulting image 208 directly benefit from the radiopharmaceutical produced by the elution systems 10, 110, 124. While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cap all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
	claims	1. A modular portable cask transfer facility for transferring a canister containing spent nuclear fuel materials from or to a transportation cask respectively to or from a storage overpack by using a transfer cask, the facility comprising:a plurality of parallel elongated telescoping leg assemblies, each leg assembly having an elongated telescoping leg mounted on a movable dolly, each telescoping leg having a longitudinal body extending from a top end to a bottom end that is mounted to the movable telescoping leg dolly, the tops ends being movable vertically in relation to the bottom ends, each longitudinal body of each telescoping leg comprising an elongated movable outer part around and guided by a stationary inner part;a plurality of elongated seismic restraint rods, each restraint rod connecting either a top end or a bottom end of one movable outer part of one telescoping leg to a bottom end or a top end, respectively, of another adjacent movable outer part of an adjacent leg;a plurality of parallel elongated lift beams, each of the lift beams having a longitudinal body extending from a first end to a second end, each of the lift beams supported at the top ends of the telescoping legs and oriented in a direction that is perpendicular to the telescoping legs;a trolley beam assembly comprising a movable elongated trolley beam, the trolley beam having a longitudinal body extending between a first end and a second end, the trolley beam oriented in a direction that is perpendicular to the lift beams, the trolley beam supported by first and second movable dollies, the first and second movable dollies supported by the longitudinal bodies of the lift beams;a means for connecting the transfer cask to the trolley beam so that the transfer cask can be moved vertically as the top ends of the telescoping legs are moved vertically; anda hoist associated with the trolley beam, the hoist for connecting to the canister, the hoist for moving the canister vertically, the hoist for moving the canister from and into the storage overpack, respectively, into and from the transfer cask;whereby, based upon the separate telescoping legs and the hoist, the transfer cask and the canister can be moved vertically independently of each other. 2. The facility of claim 1, further comprising a transfer cask having a plurality of lift plates on its sides and wherein the means for connecting comprises a plurality of lift links mounted to the trolley beam and a plurality of elongated connectors connecting the lift links to the lift plates. 3. The facility of claim 2, wherein the elongated connectors are slings. 4. The facility of claim 2, wherein the elongated connectors are fixed links. 5. The facility of claim 2, wherein the transfer cask comprises a canister that contains the spent nuclear fuel materials. 6. The facility of claim 1, wherein the movable telescoping leg dollies and the movable trolley beam dollies are self-propelled dollies. 7. The facility of claim 1, further comprising a hydraulic system designed to move the top ends of the telescoping legs vertically in relation to the bottom ends. 8. The facility of claim 1, wherein the telescoping leg assemblies comprise four and wherein the lift beams comprise two. 9. The facility of claim 1, wherein the hoist is an air operated chain hoist. 10. A method, comprising:assembling and using the modular portable cask transfer facility of claim 1 at a first nuclear power plant;after using the assembled facility, disassembling the facility into separate modular parts wherein the separate modular parts include at least the following: each of the telescoping leg assemblies, each of the lift beams, the trolley beam with mounted lift links, each of the slings, and the hoist;transporting the separate modular parts to a second nuclear power plant that is different than the first nuclear power plant; andreassembling the facility from the separate modular parts at the second nuclear power plant and using the reassembled facility at the second nuclear power plant. 11. A modular portable cask transfer facility for transferring a canister containing spent nuclear fuel materials from or to a transportation cask respectively to or from a storage overpack, the facility comprisinga plurality of parallel elongated telescoping leg assemblies, each leg assembly having an elongated telescoping leg mounted on a movable dolly, each telescoping leg having a longitudinal body extending from a top end to a bottom end that is mounted to the movable telescoping leg dolly, the tops ends being movable upwardly and downwardly in relation to the bottom ends, each longitudinal body of each telescoping leg comprising an elongated movable outer part around and guided by a stationary inner part;a plurality of elongated seismic restraint rods, each restraint rod connecting either a top end or a bottom end of one movable outer part of one telescoping leg to a bottom end or a top end, respectively, of another adjacent movable outer part of an adjacent leg;a plurality of parallel elongated lift beams, each of the lift beams having a longitudinal body extending from a first end to a second end, each of the lift beams supported at the top ends of the telescoping legs and oriented in a direction that is perpendicular to the telescoping legs;a trolley beam assembly comprising a movable elongated trolley beam mounted on first and second trolley beam dollies, the trolley beam oriented in a direction that is perpendicular to the lift beams, the trolley beam having a longitudinal body extending between a first end and a second end, the trolley beam supported by the first and second trolley beam dollies residing upon the longitudinal bodies of the lift beams;a plurality of lift links mounted to the trolley beam;a transfer cask containing the canister, the transfer cask can be moved vertically as the top ends of the telescoping legs are moved vertically;a plurality of lift plates mounted to the transfer cask;a plurality of elongated connectors connecting lift links to the lift plates; anda hoist connected to a canister lift adaptor that is mounted to the canister and designed to move the canister vertically independently of the transfer cask into and out of the storage overpack. 12. The facility of claim 11, wherein the movable telescoping leg dollies and the movable trolley beam dollies are self-propelled dollies. 13. The facility of claim 11, further comprising a hydraulic system designed to move the top ends of the telescoping legs vertically in relation to the bottom ends. 14. The facility of claim 11, wherein the telescoping leg assemblies comprise four and wherein the lift beams comprise two. 15. The facility of claim 11, wherein the hoist is an air operated chain hoist. 16. The facility of claim 11, wherein the elongated connectors are slings. 17. The facility of claim 11, wherein the elongated connectors are fixed links. 18. A method, comprising:assembling and using the modular portable cask transfer facility of claim 11 at a first nuclear power plant;after using the assembled facility, disassembling the facility into separate modular parts wherein the separate modular parts include at least the following: each of the telescoping leg assemblies, each of the lift beams, the trolley beam with mounted lift links, each of the slings, and the hoist;transporting the separate modular parts to a second nuclear power plant that is different than the first nuclear power plant; andreassembling the facility from the separate modular parts at the second nuclear power plant and using the reassembled facility at the second nuclear power plant.
	summary
	abstract	Various embodiments of a nuclear fuel for use in various types of nuclear reactors and/or waste disposal systems are disclosed. One exemplary embodiment of a nuclear fuel may include a fuel element having a plurality of tristructural-isotropic fuel particles embedded in a silicon carbide matrix. An exemplary method of manufacturing a nuclear fuel is also disclosed. The method may include providing a plurality of tristructural-isotropic fuel particles, mixing the plurality of tristructural-isotropic fuel particles with silicon carbide powder to form a precursor mixture, and compacting the precursor mixture at a predetermined pressure and temperature.
056365128	description	DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in detail, wherein like numerals indicate like elements, a nuclear rocket engine 2 is illustrated according to the principles of the present invention. Nuclear rocket engine 2 generally includes a primary feed system 4 connected to a nuclear reactor 6 for heating rocket propellant and a nozzle 8 for accelerating the rocket propellant to provide thrust for the rocket. Referring to FIG. 1, primary feed system 4 is a "topping power cycle" in which excess reactor 6 heat is used to run feed system 4. The rocket propellant, liquid hydrogen, is stored in a main tank 10 located within the rocket upstream of feed system 4. A turbopump 12 coupled to main tank 10 functions to draw the hydrogen from main tank 10, pressurize it and then pump the high pressure hydrogen through feed system 4. To help start pump 12, an electric pump 14 is positioned along an alternative flow path 16 between main tank 10 and pump 12. A pump inlet valve 18 is coupled to main tank 10 to allow the liquid hydrogen to enter electric pump 14 and control the flow of hydrogen into the system. Electric pump 14 initially draws hydrogen from main tank 10 to start the flow of hydrogen through pump 12. Once pump 12 begins running, electric pump 14 is turned off and valve 18 is opened. In addition, electric pump 14 functions to pump hydrogen through feed system 4 when the system is operating in the low and zero thrust modes and pump 12 is shut down (discussed in greater detail below). Pump 12 is coupled to a recuperator 20 by a primary feed line 24 and to nozzle coolant passages 7 by a secondary feed line 26. A control valve 28 is positioned along primary feed line 24 to control the amount of hydrogen that flows though primary and secondary feed lines 24, 26. Preferably, a small portion of the hydrogen flows through secondary feed line 26 into nozzle coolant passages 7 to cool nozzle 8. Most of the hydrogen will be directed through primary feed line 24 into recuperator 20. Recuperator 20 serves to transfer heat to the liquid hydrogen from heated, gaseous hydrogen within nuclear reactor 6. Recuperator 20 is preferably a large, high surface area heat exchanger that performs a variety of functions discussed below. A turbine 30 is coupled to pump 12 by a rotating shaft 32 and primary feed line 24. Turbine 20 rotates shaft 26 and drives pump 12 when the heated hydrogen from recuperator 20 enters turbine 30. The hydrogen then flows through reactor pressure vessel coolant passages 34 to cool the pressure vessel. A bypass valve 36 is positioned along a turbine bypass line 38 to allow the hydrogen to flow around turbine 30. Bypass line 38 provides an additional flow passage for the hydrogen when turbine 30 is shut down in the low and zero thrust modes. In addition, valve 36 controls the power output by turbine 30. It should be noted that the invention is not limited to the configuration discussed above. For example, a plurality of turbopumps and turbines can be coupled in parallel to run feed system 4. In addition, other conventional power systems may be utilized to pump rocket propellant through reactor 6. As shown in FIG. 1, the hydrogen flowing along primary and secondary feed lines 24, 26 combine after passing through and receiving excess reactor heat from nozzle coolant passages 7 and pressure vessel 34. The hydrogen then flows into nuclear reactor 6 to cool the various components of the reactor 6 (fuel assembly casings 42, moderator rods 44 and a reflector assembly 46). Fuel assembly casings 42 house fuel assemblies 48, which produce a nuclear fission reaction to heat the hydrogen to extremely high temperatures, typically in excess of 4000.degree. F. Reflector assembly 46 controls the fission reaction by reflecting and absorbing neutrons. Preferably, a neutron shield 50 is disposed between fuel assemblies 48 and the rest of the rocket forward of the fuel assemblies 48 to slow and deflect the neutrons away from the rocket and into space. The hydrogen flows through passages in neutron shield 50 to cool neutron shield 50. Reflector assembly 46, moderator rods 44 and fuel assembly casings 42 transfer excess reactor heat (created as a byproduct of fuel fissions) to the hydrogen. Although the hydrogen has been heated in recuperator 20, it has cooled somewhat in turbine 30, and its temperature remains low enough to receive the excess reactor heat and thereby cool the components of reactor 6. In the low and zero thrust modes (FIGS. 2 and 3), pre-heating the liquid hydrogen facilitates the cooling of reactor 6 because it increases the Reynolds number of the hydrogen flowing through the reactor components. A low Reynolds number would cause the hydrogen to flow through locally cool areas in reactor 6 and bypass hotter areas. These hotter areas would receive very little coolant possibly causing reactor 6 to melt. The heated hydrogen flows from reactor 6 into recuperator 20 where it cools to a low temperature and transfers most of its heat to the liquid hydrogen coming from pump 12. A recuperator bypass valve 52 is connected between the outlet of reactor 6 and recuperator 20. Closing recuperator bypass valve 52 causes the hydrogen exiting reactor 6 to bypass recuperator 20 and enter directly into fuel assemblies 48. Opening recuperator bypass valve 52 allows the hydrogen to flow through recuperator 20 as described above. Recuperator bypass valve 52 will generally be closed when nuclear engine 2 is throttling down in the low and zero thrust modes so that the heated hydrogen can run the auxiliary feed system described below. After losing most of its heat in recuperator 20, the hydrogen then enters fuel assemblies 48, where it is heated to the full outlet temperature and propelled through nozzle 8. Nozzle 8 is preferably a convergent-divergent expansion nozzle that accelerates the hydrogen to mach 1.0 at the throat. The hydrogen is then expanded and accelerated beyond mach 1.0 into space to provide thrust for the rocket. It should be noted that the components of reactor 6 are shown schematically in FIG. 1 to illustrate the hydrogen flow path. As will be apparent to one of ordinary skill in the art, the invention can be utilized with a variety of conventional nuclear reactors and nozzles. An auxiliary feed system 60 is coupled to a recycling port along primary feed line 24 between pump 12 and turbine 30, as shown to the right side of FIG. 1. Preferably, auxiliary feed system 60 is a Brayton power cycle. However, variations of this cycle and a variety of other conventional power cycles with appropriate heat exchangers could be used in conjunction with the present invention. Auxiliary feed system 60 includes a turbine 62 and a compressor 64 coupled by a rotating shaft 66. Turbine 62 has an inlet connected to primary feed line 24 by a bleed line 70 and an outlet connected to the inlet of a space radiator 84 by a recuperator bypass line 72. Radiator 84 withdraws heat from the hydrogen passing through and then radiates this heat into space. Radiator 84 has a longer flow path than indicated in FIG. 1 and is positioned throughout the rocket. Preferably, radiator 84 is constructed to radiate a megawatt or more of heat at about 1000.degree. F. A motor generator 74 integrated along rotating shaft 66 receives mechanical energy from turbine 62 and converts this energy into electricity. Alternatively, motor generator 74 can receive electricity from a storage source (not shown) and cause shaft 66 to rotate to start auxiliary feed system 60. A bleed valve 80 is positioned along bleed line 70 to draw some of the heated hydrogen leaving recuperator 20 into the inlet of turbine 62. The hydrogen provides turbine 62 with power to rotate shaft 66 and drive motor generator 74. A variable control valve 82 is disposed between space radiator 84 and the outlet of turbine 62. Variable control valve 82 functions to vary the amount of hydrogen that flows along a recuperator line 86 into recuperator 20 (see FIG. 2 and 3) and the amount of hydrogen that flows along recuperator bypass line 72 directly into radiator 84. The hydrogen that flows through recuperator 20 will transfer some of the reactor waste heat to the liquid hydrogen from main tank 10, thereby retaining the heat in the system. A flow diverter valve 88 is positioned between recuperator 20 and fuel assemblies 48 to direct this hydrogen towards radiator 84 (see FIG. 2). The hydrogen that bypasses recuperator 20 and flows directly into radiator 84 will discharge the waste heat into space to decrease the overall heat within the system. As discussed below, this allows the operator to vary the amount of heat that is retained in rocket engine 2 in the zero thrust mode (FIG. 3). The gaseous hydrogen exiting radiator 84 is directed through a gas line 89 into main tank 10 when a three-position valve 94 is closed. Pumping hydrogen gas back into main tank 10 serves to maintain a positive pressure within main tank 10 so that hydrogen will flow into primary feed system 4. A pressure regulator 90 meters the rate of flow along gas line 89 and the pressure in tank 10. In the low and zero thrust modes, some of the hydrogen exiting radiator 84 will flow through compressor 64. Compressor 64 pressurizes the hydrogen and pumps hydrogen gas along a closed-loop line 92 back to primary feed line 24 or into reactor 6 upstream of fuel assemblies 48. Three-position valve 94 is disposed along closed loop line 92 between compressor 64 and primary feed line 24. Three-position valve 94 controls flow so that the hydrogen is either directed into fuel assemblies 48 to be ejected from rocket engine 2 or pumped back into primary feed line 24 along closed loop line 92. Valve 94 may also be closed to direct all of the hydrogen along line 89, as discussed above (e.g. high thrust mode). A closed-loop bypass valve 96 is connected between fuel assemblies 48 and nozzle 8. Opening closed-loop valve 96 allows the fully heated hydrogen to exit nozzle 8 and provide thrust for the rocket. Closing closed-loop valve 96 causes the hydrogen to flow into auxiliary feed system 60 through a recycling port between the fuel assemblies 48 and nozzle 8 through bypass line 98 (see FIG. 3). Preferably, valve 96 will not be closed when reactor 6 is at or near full power. At this power level, the hydrogen exiting fuel assemblies 84 is at maximum temperature and could damage the components of auxiliary feed system 60, such as turbine 62. A turbine bypass valve 100 is positioned on a turbine bypass line 102 upstream of turbine 62 and a vent 104 is positioned downstream of turbine 62. Vent 104 is connected to auxiliary feed system 60 by a release valve 106. Closing turbine bypass valve 100 allows turbine 62 to generate full power. Opening release valve 106 causes some of the hydrogen to bleed into space, thereby lowering the pressure at the turbine outlet. This creates a suction at the turbine outlet and facilitates starting turbine 62 when the Brayton Cycle commences operation. Vent 104 may also consist of a number of smaller attitude control nozzles (ACS, not shown) disposed at the rear end of the rocket. Each ACS nozzle is connected to auxiliary power system 60 by a release valve. The release valves can each be individually opened to vent some of the heated hydrogen gas circulating through auxiliary feed system 60 out of the ACS nozzles and into space. Venting warm hydrogen gas out of the ACS nozzles allows the operator to control the attitude of the rocket without a separate chemical propulsion system. In use, auxiliary feed system 60 can be operated in three different modes, a high thrust mode (FIG. 1), a low thrust mode (FIG. 2) and a zero thrust mode (FIG. 3). In the high thrust mode, nuclear reactor 6 is operating at or near full power (thrust) and auxiliary feed system 60 mainly operates to convert reactor waste heat into electricity. In this mode, pump inlet valve 18 is open and turbine bypass valve 36 is generally closed so that hydrogen from main tank 10 flows through pump 12, which pumps most of the hydrogen through recuperator 20 and turbine 30. The hydrogen drives turbine 30, cools pressure vessel 34, then combines with hydrogen from nozzle coolant passages 7 and cools the reactor components (moderator rods 44, fuel assembly casings 42 and reflector assembly 46). After cooling reactor 6, the heated hydrogen passes through recuperator 20 to transfer heat to the liquid hydrogen from pump 12 and then flows through fuel assemblies 48 and nozzle 8 as described above. Bleed valve 80 is configured so that a small portion of the heated hydrogen from pump 12 flows along bleed line 70 into turbine 62 of auxiliary feed system 60. Turbine 62 then spins rotatable shaft 66 to generate electricity with motorgenerator 74 for all of the rocket's electrical needs. Hydrogen is also available for attitude control thrust through vent 104, as described above. The hydrogen then flows along recuperator bypass line 72 into radiator 84, where it radiates heat into space. The hydrogen gas is then metered through pressure regulator 90 to main tank 10 to maintain the pressure level in tank 10. The high thrust mode is the main operating mode of auxiliary feed system 60 when reactor 6 is operating at full power. Once the rocket has reached cruise velocity, thrust is terminated to conserve propellant and nuclear fuel. Because of delay neutrons and daughter products inherent with nuclear fission reactions, it takes a long time for the reactor to completely shut down. Generally, reactor power decays exponentially so that reactor 6 will drop from about 1000 megawatts (full power) to about 300 megawatts in the first second and to about 100 megawatts in the next 30-60 seconds. Nuclear engine 2 will preferably remain in the high thrust mode during this initial 30-60 seconds to maintain a high flow rate and to release the energy generated from the remaining reactor power out of rocket engine 2. Once the power level reaches about 50-100 megawatts or about 5-10% of full power, nuclear engine 2 will preferably be shifted into the low thrust mode, as shown in FIG. 2. The low thrust mode is used to slowly throttle hydrogen flow through feed system 4 as reactor 6 approaches the 1% power level. Nuclear engine will preferably remain in the low thrust mode for about 30-60 minutes, but this may vary depending on the half-life of the fission reaction products. In this mode, pump 12 and turbine 30 of primary feed system 4 are shut down so that pump 12 does not surge from the greatly decreased flow rate. However, liquid hydrogen must still be pumped from main tank 10 through nozzle 8 because the power level is too high to discharge all of the energy through space radiator 84. To continue pumping hydrogen into primary feed system 4, bypass valve 18 is closed and electric pump 14 is started with excess electricity created by motorgenerator 74. Electric pump 14 pumps liquid hydrogen through recuperator 20 and bypass valve 36 is opened so that the hydrogen can bypass the non-functioning turbine 30. Bleed valve 80 is configured so that bleed line 70 is closed off and all of the hydrogen flows through the reactor components. Recuperator bypass valve 52 is closed so that the hydrogen exiting reactor 6 bypasses recuperator 20 and enters fuel assemblies 48. The hydrogen is heated to about 30-50% of the full outlet temperature (depending on the power level of reactor 6) and discharged through nozzle 8 to provide low thrust for the rocket. A portion of the hydrogen exiting fuel assemblies 48 (preferably about 50%) is bled along closed-loop line 98 into turbine 62. The hydrogen entering turbine 62 is much hotter in the low thrust mode than in the high thrust mode because it is coming directly from the outlet of fuel assemblies 48. Turbine 62 can therefore spin motorgenerator 74 to create electricity to run pump 14 and drive compressor 64 to pump the hydrogen through the system. Variable control valve 82 directs all of the hydrogen through recuperator 20 to transfer heat to the liquid hydrogen from pump 12. The hydrogen then enters radiator 84 and releases the majority of its remaining heat into space. A portion of the cooled gaseous hydrogen is directed along tank line 89 into main tank 10 to maintain a positive pressure in tank 10. The rest of the hydrogen enters compressor 64, where it is compressed and directed back into fuel assemblies 48 by three-position valve 94. The cold hydrogen entering fuel assemblies 48 mixes with the hot hydrogen from reactor 6 to reduce the overall outlet temperature of fuel assemblies 48. This reduces the power/flow ratio to throttle the flow through nuclear engine 2. In addition, the low outlet temperature prevents internal parts within the fuel assemblies from breaking because these parts generally cannot withstand high temperatures when propellant flow through reactor 6 is low. Once reactor 6 has been brought down to about 1% of full power, nuclear engine 2 can be shifted into the zero thrust mode. Nuclear engine 2 can remain in this mode for the remainder of the mission unless thrust is needed (e.g. to overcome atmospheric friction or gravitational pulls in space). As shown in FIG. 3, the zero thrust mode is a closed loop in which hydrogen is conserved in the system rather than discharged through nozzle 8. In this mode, pressure regulator 90 is closed so that hydrogen gas does not create positive pressure within main tank 10. Therefore, liquid hydrogen will not be released from main tank 10 into primary feed system 4 through closed valve 18, except as required to adjust fluid pressure within the system. The hydrogen that is already in primary feed system 4 flows through recuperator 20, around turbine 30 along turbine bypass line 38 and into reactor 6. The heated hydrogen bypasses recuperator 20 and enters fuel assemblies 48, where it is further heated by the decaying power in fuel assemblies 48. Closed-loop valve 96 is closed so that all of the hydrogen bypasses nozzle 8 and flows into turbine 62 of auxiliary feed system 60. Turbine 62 drives compressor 64 and motorgenerator 74 to pump the flow through the system and create electricity for all spaceship systems including power to electric pump 14. Control valve 82 can be varied in this mode to direct a first portion of the hydrogen through recuperator 20 and a second portion of the hydrogen directly into radiator 84. The first portion of hydrogen transfers the heat picked up from cooling reactor 6 to the cooler hydrogen in primary feed line 24 to retain heat within the system. The second portion of hydrogen discharges most of its heat into space. At higher thermal power levels (i.e. reactor 6 is still close to 1% of full power), the majority of the hydrogen will preferably bypass recuperator 20 to discharge the heat into space. At this point, reactor 6 power levels are still too high and this energy should be radiated out of the system. During operation at lower thermal power levels, however, reactor power is preferably conserved to produce electricity, refrigerate main tank 10 and provide thrust through ACS nozzles. Therefore, the majority or all of the hydrogen will be directed through recuperator 20 to retain the heat within nuclear engine 2. Another problem caused by shutting down nuclear rocket engines is that the engine may have to be started up again during the mission (start-up). Start-up consists of starting reactor 6 and allowing primary feed system 4 to pump hydrogen from a main tank 10 into reactor 6. This operation requires balancing the cooling needs of the fission reactor 6 with the pressure and flow limitations of turbopumps 12. If the pressure and flow limitations of turbopumps 12 are not met, the pumps 12 could stall during start-up. This causes too little flow into reactor 6 and possible overheating. It also delays start-up which wastes hydrogen propellant. If too much flow is introduced into reactor 6, a reactor power spike can result because the fission efficiency in reactor 6 (a key factor determining the power generated by the reactor) improves with an increased amount of hydrogen. These problems are solved by starting from the zero thrust mode, transitioning to the low thrust mode as reactor 6 power increases and then shifting into the high thrust mode to reach full reactor power (thrust). To cold start rocket engine 2, hydrogen is circulated through primary feed system 4, reactor 6 and auxiliary feed system 60 in the same manner as in the zero thrust mode. Motor generator 74 spins compressor 64 to circulate hydrogen. If there is an electric power failure, vent 104 is opened to cause flow through turbine 62 to bleed into space. Instead of radiating all of the heat into space or transferring all of the heat through recuperator 20, however, heat from the recuperator 20 is used to drive turbine 62 at a higher speed. Turbine 62 then drives compressor 64 which, in turn, pressurizes the hydrogen. When the circulating hydrogen reaches the appropriate pressure and temperature conditions, reactor 6 is started. Pump 14 starts, valve 96 is opened and the system is reconfigured into the low thrust mode. With this configuration, the operator can start the engine to achieve a desired amount of thrust almost immediately because the low thrust mode chills the main pump 12 with pump 14 effluent and primary feed system 4 is pre-heated and pre-pressurized to the appropriate temperature and pressure by circulating hydrogen through auxiliary feed system 60, as discussed above. At the moment the desired high thrust is needed, the operator opens valves 80 and 90 to provide positive pressure in main tank 10 and primary feed system 4 will immediately start at the appropriate temperature and pressure conditions for the desired thrust. This scheme avoids the previous problems of cold starting the engine with cold, low pressure hydrogen from main tank 10. The above is a detailed description of a particular embodiment of the invention. It is recognized that departures from the disclosed embodiment may be made within the scope of the invention and that obvious modifications will occur to a person skilled in the art. The full scope of the invention is set out in the claims that follow and their equivalents. Accordingly, the claims and specification should not be construed to unduly narrow the full scope of protection to which the invention is entitled.
055219500	claims	1. An unlatching tool for pulling a control rod release handle carried by a control rod for decoupling the control rod from a control rod drive in a boiling water reactor without first removing the associated fuel support, comprising: an elongated housing having an end cap at a distal end and a hoist cable attachment on its proximal end; no more than one unlatching finger pivotally mounted to the elongated housing near the distal end of the elongated housing; a positioning projection for contacting the fuel support to position the unlatching tool such that the unlatching finger is at a predetermined elevation relative to the control rod release handle; and a mechanism for actuating the unlatching finger, the actuating mechanism comprising an actuating rod slidably mounted in the elongated housing for movement in a longitudinal direction parallel to the length of the elongated housing and a linkage that couples the fidger to the actuating rod, wherein the actuating mechanism is adapted to move the finger between a retracted position wherein the finger is substantially parallel with the elongated housing and an extended position wherein the finger extends substantially perpendicular to the elongated housing such that the finger can readily engage the control rod release handle when the unlatching tool is lifted, and said linkage has a cutout which is L-shaped. an elongated housing having an end cap at a distal end and a hoist cable attachment on its proximal end; no more than one unlatching finger pivotally mounted to the elongated housing near said distal end of said elongated housing; and a mechanism for actuating said unlatching finger, said actuating mechanism comprising an actuating rod slidably mounted in the said elongated housing for movement in a longitudinal direction parallel to the length of said elongated housing and a linkage that couples said unlatching finger to said actuating rod, wherein said actuating mechanism is adapted to move said unlatching finger between a retracted position wherein said unlatching finger is substantially parallel with said elongated housing and an extended position wherein said unlatching finger extends substantially perpendicular to said elongated housing such that said unlatching finger can readily engage the control rod release handle when the unlatching tool is lifted, and said linkage has a cutout which is L-shaped. 2. An unlatching tool for pulling a control rod release handle carried by a control rod for decoupling the control rod from a control rod drive in a boiling water reactor without first removing the associated fuel support, comprising:
050193244	claims	1. In a nuclear facility having a lock, a container, and a centering arrangement for aligning a lock opening in the lock with a loading opening in the base wall of the container for holding radioactive materials passed through the two openings when the container is docked at the lock, the centering arrangement comprising: a guided vehicle movable in a horizontal direction; a carrier pivotally mounted on said vehicle for pivotal movement between a vertical position and a horizontal position; said lock having a fixed point thereon; said carrier having a carrier longitudinal axis and disposed on said vehicle so as to cause said axis to be in alignment with said fixed point when said carrier is in said horizontal position; said carrier having an upper region defining an opening through which the container is lowered when loaded into said carrier while said carrier is in said vertical position; said carrier and said container conjointly defining first, second and third contact engaging interfaces as said container is lowered into said carrier; first centering means at said first interface for adjusting the rotational position of the container about the longitudinal axis thereof to precenter the loading opening with respect to the lock opening; second centering means at said second interface for positioning the container so as to cause the longitudinal axis thereof to be centered on said carrier longitudinal axis with a first degree of accuracy; third centering means at said third interface for further positioning the container so as to cause the longitudinal axis thereof to be centered to said carrier longitudinal axis with a second degree of accuracy greater than said first degree of accuracy thereby providing a precise alignment of said loading opening with said lock opening when the container is docked at said lock; and, holding means for securing said container in said carrier after the container is completely lowered and centered in said carrier. 2. The centering arrangement of claim 1, the container having an upper end opposite said base wall thereof; said carrier having a bottom opposite said upper region thereof and a lower region next to said bottom; said first interface being at said upper region of said carrier and said upper end of said container; and, said second interface being disposed at the lower region of said carrier. 3. The centering arrangement of claim 2, said second centering means comprising an annular member mounted in said carrier at said lower region of said carrier and having an annular conical surface for contact engaging the outer surface of the container as it is lowered into the carrier thereby centering said longitudinal axes with respect to each other to said first degree of accuracy. 4. The centering arrangement of claim 3, said loading opening and said container having respective cross sections defining respective center points; said first centering means comprising a first guide part disposed on said upper end of said container and a second guide part formed on said carrier at said upper region thereof for engaging said first guide part to define said first interface as said container is lowered into said carrier for adjusting the rotational position of the container about the longitudinal axis thereof; and, said guide parts being positioned on said container and said carrier, respectively, so as to intersect a line (y) passing through said center points at said first interface. 5. The centering arrangement of claim 4, said line (y) being a vertical line after the container is completely centered and at rest in said carrier. 6. The centering arrangement of claim 4, said second guide part being a plate defining a slot having a V-shaped opening at its outer end for guiding said first guide part as the container is lowered into the carrier. 7. The centering arrangement of claim 4, said container having holding means detachably mounted on said upper end of the container; and, said first guide part being mounted on said holding means. 8. The centering arrangement of claim 4, said third centering means comprising two center pins mounted on said bottom of said carrier and two centering holes formed in said base wall of the container for receiving respective ones of said centering pins therein.
	summary
	description	The present invention relates to a multiple layer multileaf collimator with improved resolution. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein. FIG. 1 illustrates a radiation treatment device 2 which utilizes a multiple layer multileaf collimator 4 in accordance with the present invention along with a treatment processing unit 100. The radiation treatment device 2 comprises a gantry 6 which can be swiveled around a horizontal axis of rotation 8 in the course of therapeutic treatment. Collimator 4 is fastened to a projection of gantry 6. To generate the high-powered radiation required for the therapy, a linear accelerator is located in gantry 6. The axis of the radiation bundle emitted from the linear accelerator and gantry 6 is designated 10. Electron, photon, or any other detectable radiation can be used for the therapy. During the treatment, the radiation beam is trained on a zone 12 of an object 13, for example, a patient who is to be treated, and who lies at the isocenter of the gantry rotation. The rotational axis 8 of the gantry 6, the rotational axis 14 of a treatment table 16, and the beam axis 10 all preferably intersect in the isocenter. The multiple layer multileaf collimator 4 in accordance with the present invention suitably comprises two pairs of opposing elongated radiation blocking leaves, the pairs in separate planes and offset at a desired angle relative to one another. As mentioned above, a prior art approach to multiple multileaf collimator design is described in U.S. Pat. No. 5,591,983 (hereinafter Yao). FIG. 2a illustrates a side view of a prior art multiple layer collimator 4xe2x80x2 as presented in Yao. Two identical layers, an upper layer 20 and a lower layer 22, of pairs of opposed leaves are shown. The top layer 20 comprises a middle section having a plurality of relatively narrow leaves 24 positioned in a side-by-side relationship, which is flanked on its left side by a relatively wide trimmer leaf 26 and on its right side by a relatively wide end leaf 28. The construction of bottom layer 22 is a mirror image of layer 20 and therefor common reference numbers are used for leaves 26 and 28. However, since in the middle section of layers 20 and 22, the narrow leaves are physically overlapping, the narrow leaves of layer 22 are referred by reference 30. It should also be noted that although wide and narrow leaves are shown in this embodiment, the leaves can all be of substantially the same widths or can be different widths and they could still be utilized within the spirit and scope of the present invention. As shown in a top view of collimator 4xe2x80x2 in FIG. 2b, top layer 20 being shown in solid lines and bottom layer 22 being shown in dashed lines, frame 32 supports each of the leaves 24 and 28 of the top layer 20 and each of leaves 30 and 28 of lower layer 22 in a paired opposed relationship, so that they are independently movable in their longitudinal dimension into and out of beam axis 10 (the Y direction shown in FIG. 2b). In general, the maximum size field is a rectangle of dimension Wxc3x97L. For the illustration of FIG. 2b, the leaves 24 and 30 are shown in various positions to create shape 34. The operation of the leaves of layer 20 and layer 22 for creating a treatment field is as is conventional in prior art single layer multileaf collimator arrangements, which are well understood by those skilled in the art. FIG. 3 illustrates a portion of the top view of FIG. 2b in greater detail. As functionally shown therein, frame 32 includes a plurality of motors 40 mounted thereon which are used in a conventional manner to individually position the leaves, e.g, 24, and 30, of the collimator 4xe2x80x2 into and out of the radiation beam for controllably defining the treatment field. One example of drive means (not shown) suitable for this is an individually driven worm gear for individually engaging a toothed track or floating nut mounted on each leaf. Details of one such prior art leaf driving means are provided in U.S. Pat. No. 5,160,847, issued to Leavitt, et al., on Nov. 3, 1992. While providing a reduction in leakage through the arrangement of one layer over another and a shift of the blades in a lateral direction to cover gaps between blades in a lower layer, the prior art multiple layer multileaf collimator lacks preferred resolution in isolating the treatment area and avoiding undue exposure of healthy tissue or organs to the radiation therapy. The present invention improves resolution in a multiple layer multileaf collimator by providing a multiple layer multileaf collimator 4 comprising two layers of opposing pairs of elongated radiation blocking leaves, where the layers are not linked and can be rotated to within a desired angle, e.g., approximately between 0xc2x0 and 90xc2x0, of one another. In a preferred embodiment, a top layer is capably positioned substantially between about 0xc2x0 and 90xc2x0 relative to a bottom layer. FIG. 4 illustrates a three-dimensional view of two multileaf layers, 22 and 50, in accordance with a preferred embodiment of the present invention. For convenience of illustration, layer 22 is described as being provided in a manner equivalent to layer 22 of the prior art shown in FIG. 2a. As shown in the example configuration of FIG. 4, multileaf layer 50 is positioned to be substantially perpendicular to multileaf layer 22. Layer 50 suitably comprises a multileaf collimator that functions similarly to multileaf layer 22 as described above, however, the positioning of the multileaf layer 50 to a desired angle through a conventional motor/control mechanism (not shown) allows greater resolution of coverage for targets than typical sold block arrangements or even the parallel multiple multileaf arrangement of Yao. Further, it should be appreciated that while in the arrangement of Yao differing widths are used for the end and trimmer leafs as compared with the middle section leaves, this serves as one example of a suitable leaf set. Of course, the present invention is capably achieved with other leaf arrangements, including those having leaves of substantially equivalent widths. FIG. 5 illustrates more particularly coverage capabilities for a multiple layer multileaf collimator arrangement in accordance with the present invention. In FIG. 5, a partial top view of one-half of each multileaf layer 22 and 50 is shown, where a top multileaf layer 50 is positioned at a preferred angle of about 90xc2x0 (i.e., substantially perpendicular) relative to a bottom multileaf layer 22. As further shown in FIG. 5, the individual leaves of each layer, 30 in layer 22 and 24xe2x80x2 in layer 50, are separately movable via motors 40 attached to frame means 32 and 32xe2x80x2, respectively, operating as described above. The placement of multileaf layer 50 at an angular offset, e.g., of about 90xc2x0, allows the individual leaves 24xe2x80x2 to be moved in close proximity to and in a close correspondence with a target 60, e.g., a tumor, from multiple directions rather than being limited to merely equivalent directions as in the layer arrangement of Yao. Thus, the resolution of coverage for targets is improved, as well as gaining the advantage that because there is crossing over between the top and bottom layer, the leakage areas between leaves are protected. It should be appreciated that the multiple multileaf arrangement in accordance with the present invention is suitable for use with any type of multileaf design type or beam defining system, as is known and/or in use in the art. For example, the present invention is applicable in single focus and double focus multileaf collimators. An example of a single focus multileaf collimator is provided in the aforementioned U.S. Pat. No. 5,166,531, while an example of a double focus multileaf collimator is provided in U.S. Pat. No. 4,463,263 issued Jul. 31, 1984 to Brahme. Thus, the present invention is suitable with multileaf collimator designs that employ blades/leaves of varying thickness, size, depth, etc. Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.
	abstract	A method for protecting the components of the primary system of a boiling water reactor, especially against stress cracking corrosion, includes feeding a reducing agent into the primary coolant in order to reduce the number of substances having a oxidizing effect or in order to modify the electrochemical potential of the component surfaces covered with an oxide layer to negative values. An alcohol that can be oxidized in the conditions of a reactor is fed in as a reducing agent, preferably in a liquid form, into the primary coolant. The component surfaces are provided with a blank coating or a single intrinsic oxide coating.
	abstract	To establish a technique that enables sorting of the elevation and azimuth angle in the direction of emitting secondary electrons and obtaining images with emphasized contrast, in order to perform the review and analysis of shallow asperities and microscopic foreign particles in a wafer inspection during the manufacture of semiconductor devices, an electromagnetic overlapping objective lens is used to achieve high resolution, an electron beam is narrowly focused using the objective lens, an electric field for accelerating secondary electrons in the vicinity of a wafer in order to suppress the dependence on secondary electron energy of the rotation of secondary electrons generated by irradiation of the electron beam, a ring-shaped detector plate is disposed between an electron source and the objective lens, and the low angle components of the elevation angle of the secondary electrons, as viewed from the place of generation, and the high angle components are separated and also the azimuth components are separated and detected.
052884341	summary	FIELD OF THE INVENTION This invention relates to a process for dissolution and disposal of filters for use in hot cells and hazardous or other radioactive nuclear applications. In particular, a HEPA (high-efficiency particulate air) filter used to clean off-gas effluents is dissolved in an acid, complexed with chemicals, mixed with other nuclear wastes, and then solidified in a fluidized bed at 500.degree. C. BACKGROUND OF THE INVENTION Filters are used in hot cells or areas in which work is performed on equipment or substances that produce significant levels of radiation that may be threatening to humans. For instance, in hot cells, the work that is done is performed by electromechanical manipulators, master-slave manipulators, and overhead cranes, operated from remote locations by humans who are shielded from the radiation. Air in hot cells is circulated and filtered to prevent the release of radioactive materials to the environment. It is also necessary to filter the gases emanating from process equipment in hot cells. Such air or other gas is filtered to remove particulate matter that may be radioactive or hazardous. The filters and their housings are thus located in the hot cell and are radioactive or contaminated with radioactive materials or other hazardous elements. A method of recovering hazardous wastes collected on a phenolic resin filter used to filter fluid systems is disclosed in U.S. Pat. No. 4,995,916 issued Feb. 26, 1991. This method dissolves the phenolic fiber material and particulate contained in the filter cartridge by 8-12 molar nitric acid at temperatures of 160.degree.-190.degree. F. This patent is assigned to the U.S. Department of Energy. HEPA filters are disclosed in U.S. Pat. No. 4,773,922 issued on Sept. 12, 1988, and also assigned to the U.S. Department of Energy. A HEPA filter or complex of filters must be removed and replaced when particulate buildup creates an excessive pressure drop in the off-gas system. After replacement, the used filters require some form of regulated disposal method that prevents spread of the radioactive or hazardous particulates. Spent HEPA filters from nuclear facilities are typically classified as high-level, transuranic (TRU), and mixed waste, which is impossible to dispose of without processing. Because of the difference of the filter media from the HEPA filter of the present process, the above phenolic filter process is not appropriate for the HEPA filter dissolution. HEPA filter materials are primarily silicon (SiO.sub.2), boron (B.sub.2 O.sub.3), aluminum oxide (Al.sub.2 O.sub.3), and KEVLAR.TM.. As an alternative, a HEPA filter leach system may be used to "clean" the filter element; however, leaching tests of these HEPA filters in some cases has failed to remove enough mercury for the filters to meet EPA toxic concentration leach procedure (TCLP) test limits. Accordingly, it would be desirable to have an alternative to leaching. The present invention, filter media dissolution in an HF mixture, has been developed as a disposal method. SUMMARY OF THE INVENTION A process is disclosed for dissolving and calcining a HEPA filter: baking the HEPA filter at 500.degree.-550.degree. C. for about 3 hours; dissolving the HEPA filter media in a hydrofluoric (HF) acid solution forming an HF/filter solution; complexing the HF/filter solution with an aluminum nitrate (AlNO.sub.3) solution forming a complexed filter waste solution; mixing the complexed filter waste solution with a radioactive solution, forming a complexed filter/radioactive waste solution; performing a second complexing on the complexed filter/radioactive waste solution by addition of calcium nitrate (Ca(NO.sub.1).sub.2); forming a blended feed solution containing the filter waste solution, sodium waste, and fluorinel waste such that the ratio of fluorinel:Na waste is equal to or greater than 5.5:1; and then calcining the blended feed solution, thereby forming a calcined particulate and fines. Other objects, advantages, and capabilities of the present invention will become more apparent as the description proceeds.
	abstract	A transmission electron microscope has a target body position on the electron optical axis of the microscope, and an electrically conductive body off the axis of the microscope. The microscope also has an electron source for producing an axial electron beam. In use, the beam impinges upon a target body located at the target body position. The microscope further has a system for simultaneously producing a separate off-axis electron beam. In use, the off-axis electron beam impinges on the electrically conductive body causing secondary electrons to be emitted therefrom. The electrically conductive body is located such that the emitted secondary electrons impinge on the target body to neutralise positive charge which may build up on the target body.
	description	FIG. 1 shows the transverse horizontal section of the core 1 of a pressurized water nuclear reactor consisting of juxtaposed fuel assemblies 2 of straight prismatic shape with a square base, placed so that their axial or longitudinal direction is vertical, that is to say directed along the height of the core 1. Inside the core, which comprises 193 fuel assemblies, some of the fuel assemblies marked by. a cross are instrumented fuel assemblies, that is to say fuel assemblies whose instrumentation tube is able to take a thimble which in turn can take a mobile probe or a stationary detector for measuring neutron flux. Out of the 193 assemblies in the core, 58 assemblies are instrumented assemblies which are distributed throughout the core cross section. Of the 58 core instrumentation measuring channels, 42 channels, shown as a entire by the reference number 3, are connected to a computer 4, inside the computer room 5 of the nuclear power station, the said room being outside the reactor building in which is located the vessel containing the core 1 which is bounded by the safety containment 6. The computer 4 is the computer for the internal core instrumentation, which is generally denoted by the abbreviation RIC (reactor in-core). The RIC is used to carry out at regular intervals, for example every month, a neutron flux measurement in the core measurement channels using the mobile probes. In this way a flux map is made with reasonable accuracy. However, the RIC cannot be used to carry out continuous monitoring of the nuclear reactor core operation. The RIC comprises mobile measurement probes which are moved in the measurement channels. According to the invention, 16 neutron flux measuring channels, denoted generally by the reference number 7, from the 58 channels fitted with a thimble located inside the fuel assembly instrumentation tube forming the end of the measurement channel and extending over the entire height of the core, take a neutron flux detector which is kept permanently in the core during operation of the nuclear reactor. Each of the neutron flux detectors introduced in the end part of a measurement channel 7, inside the core 1 of the nuclear reactor, consists of a set of 8 self-powered neutron detectors which are fixed to the measurement rod in locations spaced apart over the length of the measurement rod so as to be distributed evenly over the entire height of the core. On the left of FIG. 1 is shown, schematically and on an enlarged scale, the measurement rod 8 of one of the measurement channels 7, which rod comprises eight self-powered neutron detectors 9 distributed along the length of the measurement rod or detector 8. The self-powered neutron detectors 9 are preferably self-powered neutron detectors whose transmitter is made of rhodium, so that under the effect of neutron radiation inside the core 1 of the nuclear reactor the self-powered neutron detectors produce an electrical signal which can be quickly used to provide an accurate measurement of the neutron flux, as will be explained hereinafter. The 16 measurement channels 7, enabling the process according to the invention to be implemented, are connected, on the outside of the reactor building bounded by the safety containment 6, via four conditioning units 15, to two cabinets 10a and 10b located in two protection rooms 11 of the nuclear power station. The four conditioning units are located in four separate protection rooms. Each of the cabinets 10a and 10b contains at least one unit for processing the neutron flux measurement signals and one unit for the acquisition of monitoring parameters from the nuclear reactor. The processing units of the cabinets 10a and 10b of the protection room enable various parameters for monitoring the nuclear reactor core operation to be provided, as will be explained in the rest of the text. The operating parameters are compared with limiting values, in order to determine if the parameters lie inside or outside a range corresponding to normal operation of the nuclear reactor core. The processing and acquisition units of the cabinets 10a and 10b are connected, inside the control room 12 of the nuclear reactor, to display panels or screens 13 which enable an alarm to be raised should a limiting value be exceeded by an operating parameter and which enable the parameters useful in the operation and monitoring of the nuclear reactor to be displayed. As can be seen on FIG. 2, each of the self-powered neutron detector rods 9 is connected to a signal conditioning unit 15, via a connection element 14. The plant comprises four connection elements 14, to each of which the self-powered neutron detectors of four measurement channels 7 are connected. Each of the connection elements 14 of the self-powered neutron detectors 9 is connected to one of the self-powered neutron detectors by a measurement wire and a control wire. The useful measurement signal is obtained, inside the corresponding conditioning unit 15, by subtraction of the signals provided by the measurement wire and the control wire. The measurement signal is transmitted, inside the corresponding conditioning unit 15, to an analogue filter 16 which enables the signal to be filtered and then transmitted to an analogue-to-digital conversion unit 17 in order to digitize the signal. The digitized signal is itself transmitted to a unit 18 which enables on-line acceleration processing of the flux measurements to be carried out. So, the self-powered neutron detector response, when it is subjected to a neutron flux and gamma radiation inside the core of the nuclear reactor, is produced from three components: two components of the response signal are due to electron production processes and therefore to the creation of an electric current, by radioactive beta disintegration, one of the processes having a half-life of 60 seconds and the other process having a half-life of about 4 minutes, for a rhodium self-powered neutron detector, an electron creation process by the Compton effect due to the secondary emission of gamma rays resulting from neutron capture and from irradiation by the gamma rays coming from the core, the response time of the self-powered neutron detector, that is to say the production of current by formation of electrons being very short and virtually instantaneous. The transfer function, which enables the electron emission and therefore the current produced as a function of neutron flux received by the self-powered neutron detector to be determined, is known. It is known how to isolate the component due to the Compton effect from the electric current produced. By using the inverse function of the transfer function or some other mathematical process, it is then possible to determine the neutron flux from the current generated only by the fast component. This procedure, carried out in the electronic processing units 18, which are part of the conditioning units 15, allows the response of the self-powered neutron detectors to be speeded up for determination of the neutron flux. This processing, which is called on-line inversion, enables the response time of the self-powered neutron detectors to be reduced from a time of around two minutes to one of around a few seconds. The accelerated current signal is transmitted to the processing units 19a and 19b fitted in the cabinets 10a and 10b of the protection room. The use of two identical cabinets 10a and 10b, each containing a processing unit 19a or 19b and a parameter acquisition unit 20a or 20b, enables the safety of the monitoring plant, which can continue to operate when one of the processing or acquisition units has become unavailable, to be increased. As will be explained hereinafter with regard to FIG. 3, the digitized signals from the neutron flux measurements are taken into account for determining, in the processing units, the neutron flux bulk distribution in the core in the form of a set of flux values at points distributed throughout the core, for example, in the case of a core containing 193 fuel assemblies at N points distributed along the instrumentation channels of each fuel assembly, that is to say 193xc3x97N points, N being determined according to the desired accuracy. From the flux or power distribution in the core, the processing unit determines operating parameters of the nuclear reactor core and in particular the parameters defined below: Plin: linear power density, that is to say the power per unit length the fuel elements of the core, CHR or DNB ratio: critical heating ratio defining the differences of thermal exchange conditions for the fuel elements, with respect to a critical boiling situation, PIax: axial power imbalance in the core, PIaz: azimuthal power imbalance in the core, NRM: negative reactivity margin. The core operating parameters are compared with limiting values defined during design of the nuclear reactor. This comparison enables margins to be defined with respect to the limiting values and, should a limiting value be exceeded, enables an alarm signal to be provided, which is transmitted to a display means 13 in the control room 12 of the nuclear reactor. The various calculated parameters, the flux distribution or even the calculated margins can also be displayed permanently on one or several screens 13 in the control room 12. The process according to the invention is characterized by the use of a reduced number of detectors, placed at fixed distances, for carrying out neutron measurements and for determining the flux and power distribution in the core. For example, in the case of the embodiment described, 16 detectors, each comprising eight self-powered neutron detectors distributed over the height of the core, are used to determine the flux and power distribution in the core of a nuclear reactor containing 193 fuel assemblies. In the case. of a core containing 193 fuel assemblies, the use of in-core mobile instrumentation capable of examining 58 assemblies such as those shown in FIG. 1 using mobile probes introduced periodically into the nuclear reactor core is known. This instrumentation acts as the reference instrumentation. Within the framework of the invention only 42 channels are used for the mobile instrumentation. In the case of in-core instrumentation, which would contains 58 detectors placed permanently in the core, and which would be used to monitor the nuclear reactor, the processing time to obtain the flux and power distribution in the core and the margin and alarm signals and various processing parameters of the core would be of the order of several minutes. Such a processing time is far too long for the monitoring tasks to be carried out satisfactorily. In the case of the monitoring process and device according to the invention, only 16 detectors distributed inside the core are used and in this case, the processing time is close to 30 seconds. Thus, a far more effective monitoring of the nuclear reactor core operation can be carried out. Furthermore, the use of suitable software in the processing units taking into account the accurate periodic readings of the flux values at certain points in the core from the fixed detectors enable the instantaneous flux and power distribution in the nuclear reactor core to be determined with great accuracy. The values of the core operating parameters provided by the processing units are therefore totally representative of the instantaneous state of the core. The flux distribution calculation is carried out using a neutron calculation software (or code) adapted to the reduced number of measurement detectors. The frequency of measurements and calculations leading to a value of core operating parameter or parameters being obtained, may be close to thirty seconds. It has been possible to determine that the maximum number of measurement detectors that can be used to implement the process according to the invention is close to 15% of the number of fuel assemblies. In other words, for a core containing close to 200 fuel assemblies, the maximum number of flux measurement detectors in a fixed position in the core is 30. As can be seen on FIG. 2, the results of calculations carried out in the processing units 19a and 19b are transmitted via a line 21 to a general control system of the nuclear power station denoted by the term controbloc. The acquisition units 20a and 20b enable the instantaneous values of several parameters, called parameters originating from the nuclear power station power unit plant, to be received in and transmitted to the control room. Units 22 called digital variable transfer units (DVTUs) enable data such as the temperatures and pressures in the primary circuit loops of the nuclear reactor and the power level defined by the thermohydraulic conditions to be transferred to the acquisition units. A unit 23 which is called the rod position processing logic (RPPL) enables the nuclear reactor reactivity parameters concerning the position of the various rod cluster control assemblies to be transmitted to the acquisition units. Units 24, which are called the RPN units or core instrumentation units, enable the value of the average core neutron power to be provided. Measurement units 25 (KRG units) enable the core output temperature values to be provided. Finally, a unit 26 comprises a unit for measuring the boron content of the cooling water of the nuclear reactor. The processing of parameters originating from the power unit plant in the processing unit (or computer) will be described hereinafter with respect to FIG. 3. The parameters originating from the power unit plant and the operating parameters from the acquisition and processing units as well as the flux measurements are transmitted to a local archiving system (LAS) 27 connected to a printer 28. FIG. 3 is a block diagram showing the three-dimensional neutron model 30, which allows an on-line calculation to be carried out, that is to say an instantaneous calculation, on the actual site of the nuclear reactor, of the neutron flux distribution in the core of the nuclear reactor and the core operating parameters such as the Plin, CHR or DNB ratio, PIax, PIaz and NRM parameters, mentioned hereinbefore. The three-dimensional neutron model 30 is used in the form of software which is installed in a computer on the nuclear reactor site and which allows the bulk neutron distribution in the core to be determined, in the form of a set of neutron flux values at various points distributed throughout the volume of the nuclear reactor core 1. For example, for a nuclear reactor having a core made up of 193 fuel assemblies arranged side by side, the neutron flux calculation is carried out at eight points of the central instrumentation tube of each fuel assembly, distributed evenly over the height of the nuclear reactor core. The neutron flux bulk distribution in the nuclear reactor core therefore consists of a set of 193xc3x97N neutron flux values, each one associated with a position of a point in the nuclear reactor core, N being chosen according to the required accuracy. Of the 193xc3x97N points distributed in the core, 16xc3x978 points correspond to positions in which the neutron flux measuring probes, forming the set of probes used within the framework of the monitoring process of the invention are arranged. The corresponding positions are denoted as instrumented positions, the 193xc3x97Nxe2x88x9216xc3x978 remaining positions being denoted as non-instrumented positions. The computer on which the neutron model 30 is used to carry out neutron flux calculations receives as input data, in an input module 31, the parameters originating from the nuclear reactor power unit plant, via the acquisition units 20a and 20b. The various parameters originating from the power unit plant which were mentioned hereinbefore have been represented by the references 22, 23, 24, 25 and 26 of the measurement and processing units enabling the parameters to be supplied to the acquisition units 20a and 20b. The neutron model 30, based on the neutron flux calculation code at any point in the core, is parameterized by input into the calculation code, at the module 30xe2x80x2, of defining parameters such as the nuclear fuel characteristics associated with enrichment in the core and the xenon concentration in the core. The calculated neutron flux values, shown at 32 in FIG. 3, are transmitted to a unit 33 for selecting flux values calculated at each of the 16xc3x978 instrumented positions. The values selected by the unit 33 are transmitted to a comparison module 35 which also receives the neutron flux measurements carried out by the self-powered neutron detectors and formatted in the corresponding conditioning units. The entire acquisition and conditioning means for neutron flux measurement signals have been shown as the module 34. The 16xc3x978 measured neutron flux values are compared with the 16xc3x978 calculated values, inside the comparison module 35 in which the differences between the calculated values and the measured values are calculated for all the instrumented positions. The results of the comparison, in the form of calculated differences, is transmitted via the line 35a to the computer using the calculation code based on the three-dimensional neutron model 30. Two modes for processing the differences can be used. In the first processing mode, the differences calculated for each instrumented position are processed by the computer which determines, by an extrapolation procedure, the corresponding values of the differences for each of the non-instrumented positions. For the set of points distributed throughout the core corresponding to the instrumented positions or to the non-instrumented positions, the values of the said differences are added algebraically to the flux values obtained by the calculation based on the parameters originating from the power unit plant, so as to obtain the measured value of the flux distribution at all the points in the core. From these measured values, at least one operating parameter mentioned hereinbefore is calculated in a module 36. The operating parameter is transmitted via the line 36a to a comparison unit 37 which transmits a control signal for an alarm device 38, should there be a significant difference between the value of the monitored parameter and a set value. According to a second processing mode, the values of the differences are transmitted to the module 30xe2x80x2, so as to modify the defining parameters of the calculation code, in a way that the difference between the measured and calculated values are minimized, at every point corresponding to an instrumented position. Determining the way in which the defining parameters of the calculation code are modified may require successive operations of determining the neutron flux values at the instrumented positions, while varying the defining parameters of the calculation code and while determining the modifications which minimize the differences with respect to the measurement values. In this way the calculation code is reset. Finally, a second on-line calculation of the instantaneous neutron flux distribution inside the core is carried out from the parameters originating from the power unit plant using the neutron flux calculation code which includes corrected defining parameters. From this instantaneous neutron flux distribution, the values of the core operating parameters are determined and then transmitted via the line 36a to the comparison unit 37. An alarm is raised should any limiting value be exceeded, as described previously. Parameters originating from the power unit plant are obtained and transmitted to the computer in a relative short time, of around 2 seconds. The neutron flux values in the various points of the core, which form the neutron flux bulk distribution, are calculated about every 30 seconds. To obtain a more accurate instantaneous value of the neutron flux bulk distribution in the core, it is possible to recalculate, approximately, using the instantaneous values of the parameters originating from the power unit plant, i.e. about every two seconds, the neutron flux values representing the instantaneous neutron flux bulk distribution in the nuclear reactor core. For this, the calculation code is used in a simplified way to modify the neutron flux values of the last bulk distribution calculated from the instantaneous values of the parameters originating from the power unit plant. In this way it is possible to obtain a f aster response in order to raise an alarm enabling a reduction in nuclear reactor power to be ordered. The nuclear reactor protection, resulting in the emergency shutdown of the reactor in order to reduce the power to zero power, is ensured by a protection system which comprises six-section multistage ex-core chambers arranged outside the nuclear reactor vessel. This protection system is calibrated using the RIC instrumentation system, once a month. The invention is not strictly limited to the embodiment which has been described. Thus it is possible to use a number of detectors other than 16 and generally a number of detectors which is less than about 15% of the number of fuel assemblies to determine the power distribution and the core operating parameters. Instead of self-powered neutron detectors comprising a transmitter made of a rhodium-based material, it is possible to use self-powered neutron detectors comprising a transmitter made of a cobalt-based material or of some other material. It would also be possible to use self-powered neutron detectors which ensure absorption of currents resulting from slow disintegration processes and which only provide currents resulting from fast processes. Such self-powered neutron detectors would mean that the use of an on-line measurement acceleration unit could be avoided. The frequency of measurements and calculations leading to the core operating parameter or parameters being obtained can be set to a value less than one minute, within the framework of the invention. The process and the device according to the invention are applicable to the monitoring of any nuclear reactor comprising a core formed by fuel assemblies into which it is possible to introduce internal flux measuring instrumentation.
	description	This application claims the benefit of U.S. Provisional Application No. 61/625,164 filed Apr. 17, 2012. U.S. Provisional Application No. 61/625,164 filed Apr. 17, 2012 is hereby incorporated by reference in its entirety. The following relates to the nuclear fuel arts, nuclear reactor arts, nuclear power generation arts, and related arts. A nuclear reactor core is typically constructed as an array of fuel assemblies (FA's) in which each FA is vertically coextensive with the height of the reactor core and the array of FA's spans the lateral dimensions of the reactor core. Each FA comprises an array of vertically oriented fuel rods held together by a structural skeleton comprising a set of horizontal spacer grids spaced apart along the vertical direction which are welded to guide tubes or other rod-like vertical elements. The upper and lower ends of the FA are capped by upper and lower end fittings (also sometimes called nozzles) connected to the guide tubes by fasteners, welding, or the like. Conventional spacer grids are constructed by interlocking straps, where each strap is machined (e.g. stamped) from a strip of metal, such as a nickel-chromium alloy (e.g., Inconel™) strip or a zirconium alloy (e.g., Zircaloy™) strip. The intersecting straps define openings, also called cells, through which fuel rods pass. The straps are machined or stamped to define dimples (i.e., “hard” stops, protrusions having high stiffness) and springs (i.e. “soft” stops, protrusions having low stiffness) in each cell to hold the fuel rod passing through the cell. Typically two dimples are formed from the straps forming two adjacent walls in each square cell. One dimple in each pair is located near the top of the grid strap and the other is located near the bottom of the grid strap. The opposite cell walls each contain a single spring which may either be formed from the strap that makes that cell wall, or in the case of a bi-metallic spacer grid, may be an insert made of a different material that is mechanically trapped or restrained by features formed from the strap that make up that cell wall. The springs are located at or near the mid-plane of the spacer grid, and are sized so that an interference condition exists when a fuel rod is inserted into the grid cell. This interference causes the springs to deflect backwards towards the cell walls on which they are located, preloading the fuel rod in two orthogonal directions against the opposing dimple pair and clamping it in position. The axial offset between the plane of action of the springs and the plane of action of the dimples creates restoring moments that cause the local vertical orientation of the fuel rod at the spacer grids to remain relatively fixed should lateral forces be applied to the fuel rod between any two axially adjacent spacer grids. Adverse handling conditions can produce high accelerations on the fuel rods which in turn may over-deflect the springs. Springs that are deflected past the normal fuel rod location may be plastically deformed and lose grip force on the fuel rod. Springs may also bottom out, allowing the fuel rod to contact the grid. The following discloses various improvements. In one embodiment, a spacer grid includes a plurality of intersecting straps having springs and dimples formed into the straps, the intersecting straps defining cells with the springs and dimples arranged to engage fuel rods passing through the cells. At least one of the springs in the spacer grid is cantilevered with a bridge region disposed between a distal end of the cantilevered spring and a base of the cantilevered spring. In accordance with another aspect, a spacer grid including a plurality of intersecting straps having springs and dimples formed into the straps, the intersecting straps defining cells with the springs and dimples arranged to engage fuel rods passing through the cells. At least one of the springs in the spacer grid is cantilevered with a first contact surface and a secondary contact surface formed by a bump and spaced apart from the first contact surface, the secondary contact surface having at least an order of magnitude higher stiffness than the first contact surface and located between a base of the spring and the first contact surface. In accordance with another aspect, a spacer grid including intersecting straps having springs and dimples formed into the straps, the intersecting straps defining cells with the springs and dimples arranged to hold fuel rods passing through the cells. At least one of the springs in the spacer grid is a cantilevered spring with a contact surface and a bump spaced apart from the contact surface and disposed along the cantilevered spring between the contact surface and a base of the cantilevered spring, the bump limiting travel of the spring. With reference to FIG. 1, an illustrative nuclear reactor 1 of the pressurized water reactor (PWR) variety is shown. The illustrative PWR 1 includes a nuclear reactor core 2 disposed in a pressure vessel which in the illustrative embodiment comprises a lower vessel portion 3 and an upper vessel portion 4 connected by a mid-flange 5. The reactor core 2 is disposed in the lower vessel portion 3, and comprises fuel rod containing a fissile material (e.g., 235U) immersed in primary coolant water. A cylindrical central riser 6 is disposed coaxially inside the cylindrical pressure vessel and a downcomer annulus 7 is defined between the central riser 6 and the pressure vessel. The illustrative PWR 1 includes internal control rod drive mechanisms (internal CRDMs) 8 that control insertion of control rods to control reactivity; however, the reactor can alternatively employ external CRDMs. In either case, guide frame supports 9 guide the translating control rod assembly (e.g., each including a set of control rods comprising neutron absorbing material yoked together by a spider and connected via a connecting rod with the CRDM). The illustrative PWR 1 employs internal steam generators 10 located inside the pressure vessel, but embodiments with the steam generators located outside the pressure vessel (i.e., a PWR with external steam generators) are also contemplated. The illustrative steam generators 10 are of the once-through straight-tube type with internal economizer, and are fed by a feedwater inlet 11 and deliver steam to a steam outlet 12. The illustrative PWR 1 includes an integral pressurizer 14 at the top of the upper vessel section 4 which defines an integral pressurizer volume 15; however an external pressurizer connected with the pressure vessel via suitable piping is also contemplated. The primary coolant in the illustrative PWR 1 is circulated by reactor coolant pumps (RCPs) comprising in the illustrative example external RCP motors 16 driving an impeller located in a RCP casing 17 disposed inside the pressure vessel. The illustrative PWR 1 also includes an optional support skirt 18. It is to be appreciated that the PWR 1 is merely an illustrative example—the disclosed spacer grids and fuel assemblies including same are suitably employed in substantially any type of PWR as well as in nuclear reactors of other types such as boiling water reactor (BWR) designs. With reference to FIG. 2, a representative fuel assembly 20 is diagrammatically shown with partial breakaway and the front top corner of the perspective view cut away to reveal internal components. The fuel assembly 20 is suitably employed as an element of the nuclear reactor core 2 disposed in the pressure vessel of FIG. 1. The fuel assembly 20 includes an array of vertically oriented fuel rods 22 each comprising a fissile material such as 235U. For example, each fuel rod may contain enriched uranium dioxide (UO2) or mixed UO2/gadolinium oxide (UO2—Gd2O3) pellets. Interspersed amongst the fuel rods 20 are guide tubes 24 that provide conduits for control rods, instrumentation, or so forth. The top of the fuel assembly 20 is terminated by an upper end fitting or nozzle 26 and the bottom of the fuel assembly 20 is terminated by a lower end fitting or nozzle 28. The vertical direction of the fuel assembly 20 is denoted as the vertical or “elevation” direction E in FIG. 2. The fuel assembly 20 is held together by a plurality of spacer grids including end grids 30 disposed near the top and bottom of the fuel assembly 20 and one or (typically) more mid-grids 32 disposed at spaced apart positions between the top and bottom of the fuel assembly 20. (Said another way, each end spacer grid 30 is closer to an end of the bundle of fuel rods 22 than the mid-grid 32). Illustrative FIG. 2 shows only two mid-grids 32, but typically additional mid-grids are present which are omitted in the cutaway illustration. The number of mid-grids, and the spacing of the end grids and mid grids along the height of the fuel assembly, is determined based on the total length of the bundle of fuel rods, the total number of fuel rods in the bundle, the structural characteristics of the fuel rods, applicable regulatory requirements, and so forth. As indicated diagrammatically in FIG. 1, the grids 30, 32 of all fuel assemblies typically are aligned with each other so that any contact between adjacent fuel assemblies is grid-to-grid contact. (Such uniformity among the fuel assemblies is also advantageous from a manufacturing standpoint). The grids 30, 32 comprise interlocking metal straps formed from metal sheets by stamping or other machining techniques. The metal may be a nickel-chromium alloy (e.g., Inconel), or a zirconium alloy (e.g., Zircaloy), or so forth. Inconel is stronger than Zircaloy; however, Zircaloy has a smaller neutron absorption cross-section as compared with Inconel. Thus, in some embodiments the end grids 30 are made of Inconel while the mid-grids 32 are made of Zircaloy. With reference to FIGS. 3-5, some design features of some illustrative spacer grids disclosed herein are shown. FIG. 4 shows a perspective view of an illustrative spacer grid 31 (where the grid 31 may in general serve as either one of the end grids 30 or one of the mid-grids 32 shown in FIG. 2). FIG. 3 shows an interior strap 40 of the grid 31, while FIG. 5 shows an outer strap 42 of the grid 31. Each standard cell defined by intersecting interior straps contains horizontally oriented dimple features (or stops) 44 at the top and bottom edges sandwiched around a pair of vertically-oriented cantilever spring features 46. The cantilever spring features 46, which are designed to have a large elastic deflection range compared with the dimples 44, are formed with their main surfaces inclined relative to the remainder of the vertical cell wall so as to create a substantial interference with the fuel rod. When the fuel rod is inserted into the fuel assembly during manufacturing, these dual spring features 46 are deflected back towards the vertical cell wall, creating a clamping force that pins the fuel rod against the opposing dimple pair 44. This same clamping action is simultaneously actuated at 90 degrees around the cladding by the spring and dimple features in the perpendicular cell walls. The outer straps 42 on the illustrative spacer grids 31 contain dimple features 44 only. This configuration has an advantage over grid designs that have spring features on the outer straps in that the material cutouts on the outer strap are minimized, enhancing the structural strength of the outer straps. The spring and dimple features are replaced in the guide tube cells with saddle features that position the control rod guide tubes accurately without generating any appreciable clamping force. Rather, the guide tubes are welded to the grids 31 to form (optionally along with the nozzles 26, 28) the structural skeleton of the fuel assembly 20. Optional integral tabs on the top and bottom edges of the interior grid straps in these special cells (not shown) are used to attach the mid-grids 32 to the control rod guide tubes permanently during fuel assembly manufacturing. With reference to FIGS. 6 and 7, the contact surfaces of the springs 46 of the interior straps 40 can have various shapes. In choosing the shape of the contact surfaces, factors such as fuel rod lead-in, ductility or brittleness of the material, and so forth are suitably taken into account. For example, if the end-grids 30 are made of Inconel, which is relatively ductile, the contact surfaces can be shaped as flat-topped domes 50 to provide good lead-in/fuel rod engagement surfaces for the springs. On the other hand, if the mid-grids 32 are made of less formable Zircaloy, then the contact surfaces can be shaped as more simple-to-manufacture hooks 52 formed by bending the free ends of the springs as to include a flat rod engagement portion and a distal “bent-back” portion that facilitates lead-in. The spacer grid 31 of FIGS. 3-5 is designed to avoid having springs in the outer straps 42, and all of the springs 46 in the spacer grid 31 face from the center of the grid outward. Accordingly, there is a transition point or points in the grid where the spring direction reverses. In the spacer grid 31, this spring direction transition occurs near the center of the grid; however, it may occur elsewhere in other spacer grid designs. With reference to FIGS. 8 and 9, a single fuel rod engagement portion is shown in front profile and side profile respectively, illustrating the dimples 44 and springs 46. Note that the dimples 44 shown in FIGS. 8 and 9 engage one cell (namely the cell “behind” in FIG. 8 or “to the right” in FIG. 9) while the springs 46 engage another cell (namely the cell “in front” in FIG. 8 or “to the left” in FIG. 9). The spacer grid 31 includes a plurality of intersecting straps 40, 42 having springs 46 and dimples 44 formed into the straps. The intersecting straps 40, 42 define cells with the springs and dimples arranged to engage (i.e., hold) fuel rods passing through the cells. The intersecting straps 40, 42 include (i) a first set of mutually parallel straps including a first transition strap and (ii) a second set of mutually parallel straps including a second transition strap, the second set of mutually parallel straps intersecting the first set of mutually parallel straps. The springs 46 formed into the interior straps 40 of the first set of mutually parallel straps (other than the first transition strap) face away from the first transition strap, and the springs 46 formed into the interior straps 40 of the second set of mutually parallel straps (other than the second transition strap) face away from the second transition strap. Similarly, the dimples 44 formed into the straps of the first set of mutually parallel straps (other than the first transition strap) face toward the first transition strap and the dimples 44 formed into the straps of the second set of mutually parallel straps (other than the second transition strap) face toward the second transition strap. With reference to FIG. 10, to utilize two grid transition straps to make the transition (one in each direction orthogonal to each other, i.e. the aforementioned first transition strap and second transition strap), the dual contact cantilever spring of FIGS. 8 and 9 is replaced in the transition straps with an “S” shaped, single contact spring configuration shown in FIG. 10 in which the directions of the upper and lower springs 46 are reversed. Additionally, there is no need for the dimples 44 on the grid straps of FIG. 10 as at the transition both sides engage the proximate fuel rods via the springs 46. In the transition strap of FIG. 10, one half of the springs face in one direction and the other half of the springs face in the opposite direction. In other embodiments the transition can be accommodated in other ways. For example, the strap with “S” shaped, single contact springs as per FIG. 10 can be replaced by two back-to-back straps without the dimples and with springs of the design of FIGS. 8 and 9, with the springs of the two back-to-back straps both facing outward in opposite directions. The cantilevered springs can have various configurations. With reference to FIG. 11, the spring 46 of FIGS. 8 and 9 is again shown in profile in FIG. 11 (similar to FIG. 9). The spring 46 has a dual cantilever design with a contact surface 54 that contacts a fuel rod. In FIG. 11, the spring 46 is shown in an unloaded or normally loaded state, in which the spring 46 is undeformed or only slightly deformed. Also shown in FIG. 11, is an overloaded spring 46′ (shown using a dashed lines). During nuclear reactor operation using springs such as those shown in FIG. 11, adverse handling conditions, seismic events, or other stresses can produce high accelerations on the fuel rods which in turn may over-deflect the springs 46 to the overdeflected configuration 46′. Springs 46′ that are deflected past the normal fuel rod location may be plastically deformed and lose grip force on the fuel rod. Tests performed by the inventors show that three-fourths of the design grip force could be lost from such over-deflection. With reference to FIG. 12, a second embodiment spring 47 is shown. The spring of FIG. 12 is designed to reduce or eliminate spring damage from handling loads. The spring 47 of FIG. 12 is a modified version of the spring shown in FIGS. 8, 9, and 11 having a secondary deformable region 48 formed at or near the base of the spring 47. The illustrative secondary deformable region 48 is formed as a bridge of the spring that runs approximately parallel with the plane of the strap 40 (although some deviation from parallel is contemplated). This bridge 48 generates a secondary deformable region (in effect, a secondary spring) that includes a second contact region in the form of an extra bump 55 in the spring (i.e., a proximate bump 55 that is more proximate to the base of the cantilevered spring compared with the spring contact surface 53 at the distal end of the spring 46 without the bridge, see FIG. 11). The bump 55 acts as a stop or travel limiter to prevent loss of grip force caused by excessive spring deflection. In general, the bump 55 is disposed closer to the base of the spring 47 than the contact surface 53 (i.e., between the base of the spring 47 and the distal contact surface 53) and is expected to exhibit greater stiffness compared with the distal end of the spring. The bump 55 and the contact surface 53 form two bumps or contact surfaces, with the contact surface 53 engaging the fuel rod in normal operation and the bump 55 engaging the fuel rod only during a deflection event (e.g., rough handling, seismic event or so forth). The springs 46, 47 have been fabricated, and tests applied 150% design load on the springs. The spring 46 (FIG. 11) allowed the simulated fuel rod to bottom out against the strap 40 (corresponding to overdeflecting even greater than the illustrative overdeflected spring 46′ shown in FIG. 11). The spring 47 of FIG. 12 which includes the travel limiting bumps 55 limited the over-deflection to one-half that of the spring 46. The spring 47 of FIG. 12 also retained 50% of its design grip force while the standard spring 46 retained only 25%. The travel limiting feature 55 of the spring of FIG. 12 makes the fuel assembly more tolerant of abnormal handling loads, seismic loading, or other mechanical stresses. It will be appreciated that the spring of FIG. 12 is an illustrative example, and the detailed shape of the spring and of the travel-limiting feature may vary while retaining the disclosed advantageous configuration including a bridge region 48 with a (second) proximate bump 55 of high stiffness to limit spring travel. The improved spring design may be employed in substantially any cantilevered spring arrangement, e.g. a dual cantilever spring as in FIG. 12, or in a single spring arrangement or an “S” spring arrangement (e.g., FIG. 10). FIG. 13 shows the spring of FIG. 12 under a force F sufficient to compress the spring 47. In the deflection state shown in FIG. 13, the plane of fuel rod, shown by dashed line 56, has not (yet) deflected far enough to engage the bump 55, but slightly more force would cause the fuel rod to engage the bump 55. As stated above, the bump 55 acts as a stop or travel limiter to inhibit further fuel rod movement and to prevent the spring 47 from over-deflection. The bump 55 is closer to the base of the cantilevered spring 47 than the distal contact surface 53 that engages the fuel rod during normal operation, and the bump 55 provides a secondary contact surface having a higher stiffness than the distal contact surface 53. In some embodiments, the secondary deformable region 48 including the bump 55 has at least an order of magnitude higher stiffness (e.g., at least an order of magnitude higher spring constant) as compared with the primary deformable region comprising the cantilevered contact surface 53. In one embodiment, the spring of FIG. 12 is only used on the outer-most of the interior straps 40. That is, there are exterior straps 42 having no springs and immediately inside those straps are the outer-most interior straps 40 bearing the springs 47 of FIGS. 12 and 13, with the remaining (i.e., further inward) straps 40 bearing the springs 46 of FIGS. 8, 9, and 11. Using the springs 47 with secondary deformable regions 48 only in the outer-most interior straps prevents overstressing the outermost springs if a fuel assembly is bumped. On the other hand, the spring 47 may add flow resistance when compared to the spring of FIGS. 8, 9, and 11, and hence in this embodiment the remaining (further inward) straps 40 use the springs 46 so as to provide enhanced primary coolant flow through the spacer grid. In some embodiments, the spring 47 may be made of Zircaloy. In such an embodiment, the bump 55 should be as close as practical to the base of the spring allowing a gradual arc to the bridge area 48 in order to have a large bend radius, as Zircaloy has a higher minimum bend radius than, e.g., Inconel. In other embodiments, the improved spring may be manufactured of Inconel or another metal that is robust in the radioactive nuclear reactor core environment. The spring embodiment 47 of FIGS. 12 and 13 includes a hooked shaped spring which allows for ease of manufacturing, particularly with more brittle materials such as Zircaloy. A spoon shaped embodiment, similar to FIG. 6, is alternatively contemplated, which may be advantageous with more ductile materials. Other shapes for the primary contact surface at the distal end of the cantilevered spring are also contemplated. With reference to FIGS. 14 and 15, an illustrative spacer grid design is shown as a diagrammatic overhead view using lines to represent straps viewed “on edge” from above (or below) the grid. Symbolic representations (e.g., hatching, cell labeling, line types, et cetera) shown in the key of FIG. 14 are used to identify relevant features such as guide tube locations, various types of fuel rod locations (differentiated based on number of springs), transition regions where springs transition from facing one direction to the opposite direction, and so forth. Cells designated for guide tubes are also labeled (where appropriate) to indicate transitions using the letter “T” along with a double-headed arrow indicating the transition direction, as defined in FIG. 14. In the example of FIGS. 15, it is assumed that the strap of FIG. 10 is employed at transitions so that some cells have missing springs (the number of missing springs in the cell being indicated by symbols defined in the key of FIG. 14). As set forth in the example of FIG. 15, by appropriate grid design the number of missing springs for any given cell along the transitions can be managed. With continuing reference to FIG. 15, the illustrative grid design 60 is shown. In this design, some fuel rod cells at the transitions have single contact springs in one direction and double contact springs in the orthogonal direction. Since the ideal configuration is a fuel rod cell with dual contact springs in both directions, adjacent grids on the fuel assembly (in the vertical or “elevation” direction E denoted in FIG. 2) are preferably flipped diagonally (i.e. rotated 180 degrees about diagonally opposite corners) relative to each other to decrease the number of fuel rods that have single contact springs at every grid elevation. Despite the grid rotations, there will still be a limited number of fuel rod cells in the fuel assembly 20 that have a single contact spring in at least one direction at every grid elevation. These locations are marked with a “O” in FIG. 15 (see key of FIG. 14). Three fuel rod cells near the center of the baseline grid 60 will have a single contact springs in both directions. These locations are marked with an “X”. Again, rotating adjacent grids will reduce, and in some embodiments eliminate, the number of fuel rods that have single contact springs in both directions. One cell of grid 60 will be occupied by an instrument guide tube. This cell is marked with an “I”. The illustrative baseline grid 60 includes the outer straps 42 and inner straps 40 of FIGS. 3-5, with no springs on the outer straps 42 and the springs 46 of FIGS. 8, 9, and 11 on inner straps 40. However, the outermost inner straps are different straps 40′ in that they include the springs 47 of FIGS. 12 and 13. (Straps 40′ are shown using thicker lines for emphasis in diagrammatic FIG. 15). Placement of these springs 47 at the outermost inner straps 40′ ensures that the travel limiters 48 are provided at these outermost inner straps 40′ that are likely to bear most of the force during a rough handling event, seismic event, or other mechanical overload event. The remaining inner straps 40, that is, the inner straps 40 that are inboard of the outermost inner straps 40′, bear the springs 46 that do not provide travel limiter protection but that do increase flow rate (as compared with springs 47). In the spacer grid design of FIG. 15, the springs 46 of the spacer grid have a lower spring constant (i.e. are less stiff) while the dimples 44 have a higher spring constant (i.e. are more stiff). In some embodiments, the springs have a spring constant that is no larger than one-half of the spring constant of the dimples. In some embodiments, the springs have a spring constant of 500 pounds/inch or less while the dimples have a spring constant of 1000 pounds/inch or higher. In some embodiments the travel limiters 48 provide at least an order of magnitude higher spring constant than the normally operating cantilevered spring surface 53. However, other spring constants and/or spring constant ratios are contemplated. The design of FIG. 15 is an illustrative example, and numerous alternative layouts are contemplated. Some alternative layouts maintain the basic spring and dimple design but change the arrangement of these features within the grid. Other alternative layouts includes changes to the basic spring geometry and changes to the baseline spacer grid structural arrangement. The preferred embodiments have been illustrated and described. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
051587394	claims	1. Device for dismantling an irradiated component of a nuclear reactor having at least one wall of tubular shape and having a vertically oriented axis, said device comprising; (a) a support; (b) means for fastening said support to an upper part of a tubular wall, said means comprising at least two flanging arms fixed to said support and radially disposed within said tubular wall when said device is in an operating position, and bearing and flanging jacks movable in a longitudinal direction at an outer end of said bearing and flanging jacks, and bearing devices each associated with a flanging arm and comprising a bearing arm mounted for pivoting movement about a horizontal axis on a corresponding flanging arm; (c) an actuating device for moving each said bearing arm between a low bearing position and a high withdrawal position; (d) a metal working machine for machining an upper surface of said tubular wall; (e) means for supporting said metal working machine on said support for rotation about an axis of said tubular wall; (f) means for driving said metal working machine in rotation about said axis of said tubular wall of said irradiated component; and (g) means for collecting and clearing away particles formed by machining of said tubular wall. 2. Device according to claim 1, wherein each of said bearing arms comprises a piece bearing on said upper surface of said tubular wall and having a substantially planar bearing surface, a compensating device being provided for adjusting a position of said bearing surface. 3. Device according to claim 1, wherein said metal working machine is fastened to an end of a supporting arm movable in a longitudinal direction in relation to said support of said dismantling device, said supporting arm extending radially relative to said tubular wall in said operating position of said dismantling device. 4. Device according to claim 1, wherein said means for collecting and clearing away particles of irradiated material obtained by machining comprise a frustoconical hopper fastened to an inside of said tubular wall underneath said metal working machine, so as to recover said particles and gather them in a central part of said hopper and a substantially vertical conveyor having a lower part located adjacent said central part of said hopper. 5. Device according to claim 4, comprising a vibrator in contact with a wall of said hopper, to assist movement of said particles towards said central part of said hopper. 6. Device according to claim 4, wherein said support is tubular and coaxial with said irradiated component when said device is in operating position, and conveyor being vertically disposed within said tubular support.
050227882	claims	1. A method for disposing waste material comprising the steps of: a. constructing an access tunnel into a subtending tectonic plate moving towards a subduction zone, the tunnel having a sidewall and a floor for the movement of material transporting vehicles thereon; b. forming at least one separate waste repository in the sidewall of the tunnel and emanating from said access tunnel; and c. depositing said waste material from inside the tunnel into said waste repository. 2. A method as in claim 1 wherein said tectonic plate comprises a sedimentary layer and an oceanic crust, said waste repositories being formed in the lower portion of said sedimentary layer. 3. A method as in claim 2 and further comprising forming waste repositories in said oceanic crust. 4. A method as in claim 1 wherein said access tunnel extends from an island to said tectonic plate. 5. A method as in claim 4 wherein said island is manmade. 6. A method as in claim 1 wherein said access tunnel extends from a non-descending plate to said tectonic plate. 7. A method as in claim 1 wherein said repositories extend substantially normal to said access tunnel. 8. A method as in claim 1 wherein said access tunnel extends from a caisson to said tectonic plate. 9. A method as in claim 1 wherein said repositories are of a volume to hold shielded waste material. 10. A method as in claim 9 wherein said waste material is radioactive material. 11. A method as in claim 10 wherein said waste material is divided into waste material having high radioactivity and waste material having lower radioactivity, said high radioactivity material being located further from said access tunnel within said repositories than said waste material having lower radioactivity. 12. A method as in claim 10 wherein said waste material is divided into waste material having high radioactivity and toxic waste, said toxic waste being located between said high radio activity, waste material and said access tunnel. 13. A method as in claim 1 and further comprising constructing said access tunnel to a size sufficient to allow simultaneous removal of the tailings obtained from forming said access tunnel and said waste repositories and to allow importation of wastes into said waste repositories.
	claims	1. A method of reductive stripping of plutonium from an organic non-water miscible phase comprising an extracting agent and plutonium at an oxidation state IV in an organic diluent, comprising:contacting the organic phase with an aqueous phase comprising a reducing agent capable of reducing plutonium(IV) to plutonium(III) and nitric acid; thenseparating the so contacted organic and aqueous phases;wherein the organic phase or the aqueous phase further comprises at least one anti-nitrous agent, the antinitrous agent being a hydroxyiminoalkanoic acid of general formula O═C(OH)—(R)—CH═N—OH where R is a straight-chain or branched alkylene group having at least 2 carbon atoms. 2. The method of claim 1, wherein R is an alkylene group having 2 to 12 carbon atoms. 3. The method of claim 2, wherein R is a straight-chain alkylene group having 3 to 8 carbon atoms. 4. The method of claim 3, wherein the hydroxyiminoalkanoic acid is 6 hydroxyiminohexanoic acid or 8-hydroxyiminooctanoic acid. 5. The method of claim 1, wherein the extracting agent is a tri-n-alkyl phosphate. 6. The method of claim 5, wherein the extracting agent is tri-n-butyl phosphate. 7. The method of claim 1, wherein the reducing agent is uranium(IV), hydroxylammonium nitrate, alkylated derivatives of hydroxylamine, ferrous sulfamate or sulfamic acid. 8. The method of claim 7, wherein the reducing agent is uranium(IV) or hydroxylammonium nitrate. 9. The method of claim 1, wherein the aqueous phase comprises from 0.02 mol/L to 0.6 mol/L of the reducing agent. 10. The method of claim 9, wherein the aqueous phase comprises from 0.05 mol/L to 0.4 mol/L of the reducing agent. 11. The method of claim 1, wherein the organic phase or the aqueous phase comprises from 0.01 mol/L to 3 mol/L of the hydroxyminoalkanoic acid. 12. The method of claim 11, wherein the organic phase or the aqueous phase comprises from 0.03 mol/L to 0.5 mol/L of the hydroxyminoalkanoic acid. 13. The method of claim 1, which is implemented in a PUREX method or a COEX method.
046876227	abstract	A nuclear event detector for sensing the occurrence of an ionizing radiation pulse and providing switched outputs in response to the sensing. The detector includes an ionizing radiation sensor which provides a sensor output signal when an ionizing radiation pulse incident thereon exceeds a predetermined threshold level. The detector further includes a pulse timer circuit which is responsive to the sensor output signal for providing a timing signal pulse of a predetermined duration. The detector also includes a latch circuit triggered by the output of the timer circuit which provides a flag signal indicating that an ionizing radiation pulse has been sensed. The latch circuit, timer circuit and sensor are part of a hybrid microcircuit and are disposed in a sealed enclosure with connectors extending from inside the enclosure to outside the enclosure. A first external connector is adapted for connection to a first electrical component for setting the threshold level. A second external connector is adapted for connection to a second electrical component for determining the duration of the timing signal pulse. When the threshold level is preset by the manufacturer, only connection to a second electrical component for determining the duration of the timer pulse is required. The detector includes test circuitry built inside the sealed package permitting all components of the detector to be operated under test.
056688474	abstract	In a radiation emitting device, particularly in a radiation treatment device, the actual radiation delivered to an object via a radiation beam is adjusted dependent on the dimensions of an opening in a plate arrangement provided between a radiation source and an object so that the radiation output has a constant wedge factor over an irradiation field, regardless of the size of the opening. The wedge factor is defined as the ratio between a reference radiation output along a reference axis of the beam with a predetermined physical wedge in the beam path and an actual radiation output of the beam in a substantiallylossless beam path.
	abstract	An architecture for an inertial confinement fusion system is disclosed. The system includes a fusion chamber for producing neutrons from a fusion reaction, and a laser system in which lasers are arranged about a vacuum chamber to provide energy to the fusion chamber to initiate the fusion reaction. The beam paths between the lasers and the fusion chamber are configured to prevent neutrons from the fusion chamber from reaching the laser system at a level that would preclude human access to the laser system.
	abstract	A radiation control system and method are provided in which radiation delivered to a patient and/or the operator of the equipment is minimized. The radiation control system may be used in a large variety of applications including applications in which radiation source is used to inspect an object, such as, for example, medical imaging, diagnosis and therapy, in manufacturing operation using radiation, in airports scanning systems, in different security setups, and in nuclear reactors automation and process control. The radiation control system and method may also be used with 3D imaging.
042004918	summary	This invention was made under contract with or supported by the Electric Power Research Institute, Inc. of Palo Alto, Calif. BACKGROUND OF THE INVENTION I. Field of the Invention This invention relates to measuring the power distribution of a nuclear reactor fuel element. In particular, the invention relates to a method and passive apparatus for analysis of power distribution history through the measurement of residual radiation along a fuel element. In order to verify the accuracy of nuclear calculations and to determine if anomalies occurred in the power production of the nuclear fuel, it is desirable to map the recent power distribution of a reactor and of the individual nuclear fuel elements. It has been found that the deposition of certain fission products in a fuel element or rod, specifically radioactive lanthanum-140 which is a fission product of barium, does not migrate within the fuel element and thus is representative of the recent reaction history of the nuclear fuel. The reaction history is directly correlated to the most recent power production, a consequence of the relatively short half-life of the parent reactant, barium-140. Thus, measurement of the radiation emission of lanthanum-140--which must be discriminated from other residual radiation--can be used to construct an accurate map of reactor power distribution. II. Description of the Prior Art In the past, gamma radiation from fuel elements has been measured by scanning each fuel element with collimated radiation detector capable of sensing radiation and of discriminating levels of energy. Typically, a sodium iodide scintillation type sensor or a germanium-lithium solid state sensor is used to detect gamma radiation, together with appropriate electronic and signal processing apparatus. There is, however, a substantial danger of exposure of the detector operator to dangerous levels of gamma radiation during measurement of the residual radiation of spent, yet radiating, fuel elements, since the detectors have in the past been manipulated by the operator in close proximity to the fuel elements. Therefore, a shielded detector system has been a requirement of prior art systems. Water has been the usual means of shielding the fuel element to be measured, so the prior art sensors were generally adapted to operate underwater. In summary, according to prior art methods, to determine a distribution history of a fuel element, each element was removed from the reactor, immersed in a shielding medium and slowly scanned by a sensor which generated exposure data one point at a time along one fuel element at a time. This technique has required extensive correction for radiation decay to account for scan time differences at different spatial locations along the fuel element. SUMMARY OF THE INVENTION In order to overcome the disadvantages of prior art detectors, a radiation detector of the present invention spatially discriminates in situ the distributed radiation of a spent nuclear reactor fuel element. A sensor according to the invention comprises a cylindrical casing or wand which enshrouds a material that converts incident gamma radiation having an energy level exceeding a predetermined threshold to a correspondingly distributed neutron radiation field. The incident gamma radiation is identifiable with a particular short lifetime reaction product representing recent power distribution, such as lanthanum-140. The converter material, which may be beryllium or deuterium or a compound thereof, sheaths a neutron field-sensitive activant, such as gold, in the form of a filament longitudinally disposed in the casing. The activant receives, and in essence stores along its length, information on the level and distribution of incident neutron radiation by creation of radioactive isotope characterized by a long lifetime of low level radiation which can later be measured by conventional low level and relatively safe radiation detection techniques. In operation, a wand according to the invention is placed alongside a spent fuel element within a reactor core and left for several hours to a few days to fully expose the activant. The wand is thereafter removed for analysis. One of the purposes of the present invention is to provide means for analyzing the power distribution history of a nuclear reactor fuel element in order to monitor the proper and efficient operation of a nuclear reactor. The present invention also provides means for measuring fission product power distribution history without danger of exposure of operators to radiation. According to the invention, the residual radiation of spent fuel elements can be measured and recorded by an in situ detector. Thus, measurements can be made with virtually no danger of exposure to dangerous levels of radiation. Another purpose of the invention is to provide means and a method for measuring the spatial distribution of residual short lifetime gamma radiation without compensation for time-related residual radiation decay. An advantage of the present invention in this instance is that distributed short lifetime residual radiation is simultaneously measured in a manner creating a relatively persistent spatial image more readily analyzed by conventional lower level radiation detection methods. Thus, the need to correct for time-related decay differences is eliminated. Other purposes and advantages of this invention will become apparent upon reference to the following detailed description and accompanying drawing.
043705553	abstract	A device for storing a source of photons and for irradiating a body by the radiation from said source, comprising. a body for biological protection provided with a cylindrical cavity of circular section and two so-called first and second passages respectively, these passages opening at one and the other of their ends in said cavity and on the outer wall of the body, PA0 a disc for biological protection, whose shape is complementary of that of the cavity of the body and presenting, on the one hand, a housing centered on an axis perpendicular to the axis of the cavity, this housing opening out on the side wall of the disc, PA0 a source of Y radiation contained in said housing, PA0 a precollimator disposed at right angles to said first passage, PA0 means for rotating said disc between a first position for which said source is opposite the precollimator and a second position for which the source is in stored position.
	summary
	summary
	abstract	An optical system comprises a Bragg reflector configured to diffract incident light having a wavelength between about 0.1 nm and about 0.7 nm. The optical system also comprises a diffraction grating comprising parallel lines engraved on a surface of the Bragg reflector. Specifically, the diffraction grating is configured to diffract incident light having a wavelength between about 0.6 nm and about 150 nm.
058752218	description	DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is seen a cross section 1 through a reactor core, in which square fuel elements 2 stand closely adjacent to one another in the manner of a checkerboard. With the exception of the edge regions, four such fuel elements each form a square, in which a respective measuring lance designated by (1), (2) . . . (28) is arranged only at one corner. A measuring lance of this type is therefore generally arranged at the common corner of four mutually abutting squares made up of four fuel elements each. For the evaluation of the signals of these measuring lances, once more with the exception of edge regions, four such squares are combined into a "region" (for example the adjacent, differently hatched regions 2', 2"), which thus register virtually the entire region of the core in the manner of a checkerboard. Since each measuring lance (reference numeral 3 in FIG. 2) comprises four sensors 4a, 4b, 4c and 4d arranged one above another in a sleeve pipe 5, four sensor signals are supplied to the entire device for monitoring the core via the corresponding measuring lines 6 of the measuring lances (1) . . . (28). Each of these measuring lines 6 thus carries the sensor signals assigned to one region. In FIG. 1, the individual measuring lances, respectively assigned to a region, are designated by one of the letters A, B, C and D, these letters specifying the assignment of the corresponding measuring lances and their sensor signals to a system of a total of p monitoring systems (here p=4). These monitoring systems operate redundantly and in each case supply their own monitoring signal and, if appropriate, alarm signal. These signals are only processed into an endstage monitoring signal or endstage output alarm signal in a system selection. The corresponding monitor monitoring the core therefore contains only systems which are respectively independent of one another (no sensor signal is processed in more than one system), and the regions monitored by the systems do not overlap. In the event of a failure of a measuring lance, although an entire region of 16 fuel elements is no longer monitored, only one of the redundantly operating systems is influenced thereby, while the other systems are not affected by the failure. Sensors of adjacent region are in this case also always assigned to different systems. These principles are also maintained in the case of other configurations of the core (for example larger cores) and of the measuring lances (for example 34 instead of 28 measuring lances). In the present case, the 28 measuring lances are distributed among systems having seven regions each (in general an arbitrary region will be designated by m and the total number of regions of a system p by M.sub.p. In the example, therefore, M.sub.p =7 applies to all the systems). In this assignment all the regions respectively register an identical number (namely four) of sensor signals, whereas in the general case for the individual regions, the number of sensor signals can also be different. This can primarily be provided if the above-mentioned "linear" assignment, in which each sensor is assigned to a maximum of one single system, is not performed. Each sensor signal is initially subjected to a plausibility control by means of a selection stage 8 in its region channel, firstly those sensor signals being separated out which lie outside the proper operating range of the sensors, as is also provided in the above-mentioned patent to Watford et al. From the remaining output signals from properly operating sensors, however, differing from this prior art, only a minimum number (here: two) is selected, to be specific generally the signals of the lowest sensors which are available. In general, the signals from sensors which are arranged linearly one above another specifically differ only little and, in particular, they show the same time profiles, virtually without a phase shift, which can be traced back to the local power pulsation in this region. The sensors are therefore in principle able to substitute for one another. Taking into account the lowest sensors (4a and 4b in FIG. 2), however, offers a slight advantage, since in the critical region of high power and low coolant throughput, the flux in the lower regions of the fuel elements executes more pronounced oscillations than in the upper regions. In other words, the corresponding extreme values (amplitudes) of the oscillation can be registered more distinctly. In particular, an analog filter 9' for the sensor signals can be connected upstream of the selection stage 8 which receives the sensor signals, whereby the sensor signals are subjected to a "2 out of 4" selection on processing in the component 10, which may simultaneously undertake a conversion of the analog input signals into digital output signals, so that instead of the analog filter 9' connected upstream, a digital filter 9 can also be connected downstream (in signal flow direction). In addition, in the case of this filter 9 a summation of the two output signals of the evaluation stage 8 is also performed, in order to obtain an instantaneous value for the flux into the appropriate region which is averaged over the model variation of the individual sensors. This corresponds to the summation of the sensor signals in the individual "cells" of the above-mentioned patent to Watford et al. However in the case of the prior art, the corresponding "cell signal" is formed from sensor signals which are also used in the monitoring of other regions and in other systems. Finally, in a standardization unit, a current measured value A(t)-A* is formed at the output of the filter 9 from the current signal A(t). The measured value can be standardized, for example, to the average signal level A* of this region. As described in the prior art, the average level can be formed by an integrator 10 in that the signal A(t) measured over a relatively long integration time period is integrated. This standardization supplies an alternatingly positive and negative measured value, so that the oscillation amplitudes lie symmetrically about a zero point and can be registered easily. However, digital signal processing makes it possible, also without great outlay, to register the amplitude of a half-period in each case, even in the case of otherwise standardized or unstandardized signals S. In that case, it may then be advantageous for the threshold values to be predefined as absolute values instead of relative values. Finally, the further processing of the signal S is suppressed as long as it lies under a threshold value A.sub.o for the normal signal noise, and therefore a determination of extreme values ("peaks" or "amplitudes"), which could be assigned to an oscillation, is not possible (threshold value element 11). With reference to FIG. 3, the region channel of a system p contains an evaluation stage 12, in which firstly, in a first computing stage, the point in time T.sub.n is recorded at which an initially increasing signal value S, which lies above the noise limit A.sub.o, has risen to an extreme value A.sub.n and drops once more (positive peak). As an alternative--or preferably in addition--a negative peak is also registered as the peak A.sub.n and its point in time T.sub.n, that is to say an extreme value which lies beyond the noise limit A.sub.o which is formed by an initially falling and then rising (negative) value of the signal S. This extreme value registration 13 is followed by a further plausibility check 14 which, for example, is constructed similarly to the description in the Watford et al. patent, and checks whether the time interval DT.sub.n, which can be registered in the extreme value monitoring 13, between the currently registered point in time T.sub.n and the previously registered point in time T.sub.n-1 can correspond to an oscillation within the critical frequency band between 0.3 and 0.7 Hz. A further evaluation element 15 additionally checks whether the registered time interval DT.sub.n virtually coincides with the last-registered time interval DT.sub.n-1. If this is not the case, then the registered peaks are not the amplitudes of an oscillation which is virtually undamped and could increase to hazardous extreme values; the further evaluation of the last-determined peak A.sub.n is then suppressed. If, on the other hand, these are values which can be assigned to the amplitude of an oscillating variable, then by means of a corresponding confirmation signal a subsequent computing element 16 is activated, which determines from the last-determined peaks their "rate of increase" ##EQU1## If, therefore, the respective signal value S can be described mathematically by a variable S(t).circle-solid.cos.OMEGA.T, then this rate of increase corresponds to the differential. ##EQU2## In the case of evaluating positive and negative extreme values, for example, it indicates the growth of the extreme value in each case following a half-period DT=T.sub.n -T.sub.n-1 of the oscillation. In the monitoring unit 17 ("checking"), a monitoring element 18 now forms a signal, in accordance with predetermined monitoring criteria which are described in more detail below, which signal indicates, for example as the binary signal in the state "0", that there is no hazardous oscillation corresponding to any of the monitoring criteria, whereas the state "1" of the corresponding monitoring signal sets off an alarm (item 19). This alarm signal, together with other information which, for example, identifies the region in which the monitoring criteria has responded, can be output to an display unit and/or stored in a memory for the purpose of documentation of the process. This construction of the region channel m is advantageously provided in each region channel, as is indicated at the top left in FIG. 4 in the field "system 1" for each region of the total number M1 of regions of the system p=1, and in the right field "system P" for all the regions (total number M.sub.p) of the system p=P. The linear alarm region signals (for example also entered into the element 19) represent a M.sub.p -multiple binary signal, corresponding to the number M.sub.p of the region channels, from which a N.sub.mp --multiple binary signal is formed in a region selection stage 20, in order to indicate that a bit corresponding to an alarm has been set at least in a number N.sub.mp of the regions of this system. In FIG. 4, the corresponding alarm region signals are combined once into a visual indication 21, where N.sub.m =1 is selected. This means that the visual alarm 21 is triggered as soon as the bit corresponding to the alarm is set in at least one region channel. Each system therefore contains a selection element in which N.sub.mp =1 is predetermined, i.e. a "1 out of 7" selection 22 (for example an OR element in digital evaluation) is executed, and the visual indication 21 is set, whereas if a second selection element 23 N.sub.mp =2 is set, a "2 out of 7" selection takes place. To be precise, an appropriate alarm bit in the region signal is only set if the monitoring criterion is satisfied respectively in at least two regions of the system, in order to rule out a false alarm as a result of processing errors. A system selection is now made in an output stage 24 which sets an alarm output signal if at least a minimum number N.sub.p from the total number P of the systems contains a set alarm signal. In this case, this system selection comprises a "1 out of 4" circuit 25 which is set to N.sub.p =1 and outputs an alarm signal (item 26) which is visually indicated in a display 27 and indicates that a critical oscillation has been discovered in one of the systems. A "2 out of 4" selection 28, set to N.sub.p =2, sets an alarm (item 27') which on the one hand can likewise be indicated in the display 27 and on the other hand acts on the reactor control 29 and there triggers a stabilization strategy which is stored in a memory 29' as an appropriate program. In general, in each system the processing elements of the region channel which are illustrated in FIGS. 2 and 3 can be implemented by means of a central computer with its own power supply, a central processing unit, an input module for 32 analog input signals and an appropriate output module for 32 digital signals, the computer being utilized to about 50% given an operating frequency of 32 MHz with the parallel processing of the 28 sensor signals, which are contained in the 32-bit input of the computer. An advantageous sampling rate for the input signals is 50 Hz or more, but at least 20 Hz should be ensured. The usual processing elements for the sensor signals offer sufficient space for the processor units of the systems. The output signals of these system processors can be connected to a commercially available microcomputer, in which the received region signals are processed and stored. This processor also contains the programs which are necessary to make the system selection and, in accordance with predefined strategies, to supply the signals which are necessary in the reactor control system for carrying out the respective stabilization measures. Optical fibers can advantageously be used as connecting lines. The stabilization measures are explained with reference to FIG. 5, which does not take into account a scale corresponding to the actual relationships. A course of the relative region measured value S is assumed and from its values which lie above the noise limit A.sub.o the rate of increase DA is determined if the oscillation exceeds a threshold value or limit value A.sub.lim. Here, the extreme case is assumed where, after a predefined maximum value A.sub.max of the amplitudes had been exceeded, a total SCRAM is initiated, a number N' (N'=2 here) oscillation periods being needed until it is sufficiently effective, whereas only a number N (for the purpose of illustration, N=3 is assumed here; in realistic conditions, N is very much larger) of oscillation periods has elapsed until the amplitudes of the relative measured value S pass through the region between A.sub.lim and A.sub.max. A curve 30 in FIG. 6 corresponds to the extreme case represented in FIG. 5 by the slope 30 (half envelope), further curves 34, 33, 32 and 31 being specified in FIG. 6 whose rate of increase DA is respectively lower by the factor 1/2, 1/3, 1/4 and 1/5. It can be seen from FIG. 6 that in the case of these rates of increase a SCRAM, which would be triggered when the threshold value A.sub.max were exceeded, is not yet necessary; instead the time or number N' of oscillation periods DT which is or are necessary for the effectiveness of the SCRAM permits the reactor to continue operating at power for a certain number N of periods. The number N can be seen from the point of intersection of the curves 32, 33. with the curve F(A.sub.4). For oscillations whose amplitudes grow still more weakly than the curve 32 when the threshold value A.sub.lim is exceeded, it can be assumed that such weakly increasing transient transitions inherently decay, so that it is provisionally not necessary to intervene in the reactor operation for a number N of operating periods, this number resulting from the point of intersection of the corresponding curves with the limit curve 35. An upper threshold value A4 in this case ensures that it is still possible, even in the case of an unchangingly growing amplitude, for a SCRAM to be initiated, the number N'=2 of oscillation periods still being available for its effectiveness. In FIG. 5, the relationship which is given by the curve F(A.sub.4) between the rates of increase DA and the periods N which are still available before the initiation of a SCRAM, following the exceeding of the threshold value A.sub.max are reproduced as a corresponding limit curve F(DA). A curve of this type--taking into account a sufficient safety margin--can be determined from model calculations for the behavior of the reactor under transient conditions and also from the comparison of such model calculations with actually observed reactor states and, for example, can be stored as a characteristic curve in a memory. It is then sufficient, when the threshold value A.sub.lim is exceeded, to make use of the respectively detected rate of increase in order to take the appropriate value N (that is to say the values N.sub.1, N.sub.2, N.sub.3, N.sub.4 for the curves 31, 32, 33, 34). When the amplitude value of A.sub.max is exceeded, a counter can be set to the appropriate value N, and counted down with each confirmation signal (FIG. 3). The reactor operation then does not need to be interrupted by a total SCRAM, provided the counter reading has not been counted down to zero. Here too, the total SCRAM only needs to be initiated when the amplitude threshold value A.sub.4 has been reached. As a rule, however, the oscillation has already inherently been damped within this time and decays once more, which can in particular be ensured by an alarm signal being set when the threshold value A.sub.max, is exceeded, in this alarm stage that alarm signal prevents only changes in the operating state being undertaken in the control system which could lead to an increase in power and hence to a further transient excitation of the oscillation. In this case, therefore, only if the threshold value A.sub.max is exceeded is a stabilization strategy simply followed which corresponds to a low-ranking alarm stage and does not require any interruption in the reactor operation, in particular no SCRAM, as long as a highest-ranking alarm stage with a total SCRAM is not present as a result of exceeding the curve given in FIG. 7 and/or exceeding the threshold value A.sub.4. However, it is also possible to dispense with a characteristic curve which, for each value DA, determines the corresponding time which is still available before a SCRAM (number of periods N), and instead to monitor the rate of increase DA by means of appropriate threshold value detectors for the exceeding of specific threshold values, as specified in FIG. 7 by DA.sub.1, DA.sub.2, DA.sub.3 and DA.sub.4. If, therefore, there is for example a rate of increase which lies below the threshold value DA.sub.1, it is then possible to wait for a corresponding number of periods N, in which no safety measures at all are yet necessary, that is to say no stabilization strategy with a special intervention in the reactor control is necessary. In the region between the threshold values DA.sub.1 and DA.sub.2 (alarm stage I), provision can, for example, be made for the reactor operation to be allowed to continue for a number N.sub.2 of oscillation periods, in which case it may be advantageous to prevent the reactor from being raised to increased power. In the alarm stage II, the duration for this reactor operation can be limited to a number N.sub.3 of reactor periods. It is also possible, in order to improve the damping, to provide for some of the control rods to be moved slowly into the reactor, which corresponds to a reduction in the reactor power, as is provided operationally when a lower power is demanded of the reactor. The threshold values DA.sub.3 and DA.sub.4 for the rate of increase determine an alarm stage III, in which the reactor can still run further for a number N.sub.4 of periods. It is also possible in this case to move some of the absorber rods in rapidly, which is referred to as a "partial SCRAM". Only when the threshold value DA.sub.4 is exceeded does a total SCRAM appear necessary in a highest-ranking alarm stage. A further variant of the invention is explained with reference to FIGS. 8 to 10. Rates of increase are shown in FIG. 8, in this case for the amplitudes of the relative region signal S, which correspond to the curves 32 and 33 of FIG. 6. These amplitudes are determined at the point in time at which they exceed the threshold value A.sub.lim. It is assumed that the alarm stage II has been detected by the monitoring stage and a stabilization strategy has been initiated in which the reactor power is to be stabilized by moving the control rods in slowly. In the envelope 33, the amplitudes which occur under these conditions are indicated by continuous lines. The stabilization strategy corresponding to alarm stage II--if it were maintained at amplitude values which lie above a threshold value indicated by A.sub.3 and illustrated by peaks which are drawn with dashed lines--would lead to a total SCRAM having to be initiated with the threshold value A.sub.4. However, a total SCRAM of this type should be avoided. Therefore, when the threshold value A.sub.3 is reached, a transition is made from the stabilization strategy discussed in conjunction with the alarm stage II in FIG. 7 (slow insertion of absorber elements) to a higher alarm stage with a higher-ranking stabilization strategy, namely the above-mentioned partial SCRAM. As a result, the oscillation is now damped more heavily, with the result that the amplitudes no longer increase and the threshold value A.sub.4 is not reached and, in turn, the total SCRAM is not initiated. The curve 32 shows that the threshold value A.sub.3 can also be set higher in this case, given a lower rate of increase, than in the case of a higher rate of increase. In this embodiment, therefore, it is not the rate of increase which is monitored for the exceeding of threshold values. Instead, the instantaneous detected rate of increase is used to predefine a threshold value for the amplitude values themselves. The dependency of the threshold value on the rate of increase can by contrast in turn be determined in accordance with a calibration curve, similar to FIG. 7, or the threshold value A.sub.3 can also be changed in discrete steps by means of an appropriate division of the region available for the rate of increase into individual alarm stages. This embodiment provides the advantage that changes in the decay rate of the oscillation, which occur during reactor operation even after the threshold value A.sub.lim has been exceeded, are taken into particular account. This is shown by the curve 40 in FIG. 8, in which it is initially assumed that the oscillation grows so weakly as it exceeds the threshold value A.sub.lim that an intervention in the reactor control system is not necessary. However, it is assumed that the operating personnel have performed an increase in the power at time t.sub.b via the operational reactor control system. As a result, the transiently excited oscillation is considerably amplified. This leads to the situation where the amplitude A, whose rise was initially low when it crossed over A.sub.lim and which has not triggered any alarm, now assume the value of curve 33, so that the amplitude A is now monitored with regard to its exceeding the threshold value A.sub.3. Also, the stabilization strategy ("partial SCRAM") which is proper in the alarm stage III is initiated. This results in the increasing oscillation being damped more heavily, so that even in this case the threshold value A.sub.4 is in practice no longer reached. The result, of course, is that a total SCRAM has been averted. In a similar manner to the threshold value A.sub.3 for the amplitude A, which leads to the initiation of the partial SCRAM, it is of course also possible for an appropriate threshold value A.sub.1 and A.sub.2 to be introduced for the lower-ranking stabilization strategies (blocking of an increase in power, alarm stage I; or slow introduction of additional absorber elements, alarm stage II). This is shown in FIG. 9 using an oscillation whose envelope increases at a relatively low rate. In this case the extreme values (amplitudes) of the oscillation lie on an envelope curve 41 and are monitored for exceeding the threshold values A.sub.1, A.sub.2, A.sub.3 which, in accordance with the high number N of oscillation periods which are available in the case of this rate of increase, lie relatively close to the threshold values A.sub.th and A.sub.max. When the threshold value A.sub.1 is exceeded, the first alarm stage is set, whose stabilization strategy provides only for the blocking of an increase in power. As a result, although the rate of increase is lowered, the oscillation is not yet sufficiently damped. When the threshold value A.sub.2 is exceeded, however, the power of the reactor is lowered and the oscillation is damped in such a way that further growth to the threshold values A.sub.3, A.sub.max, A.sub.th already no longer occurs. The curve 42 shown in FIG. 10 is based on a relatively high rate of increase DA, for which reason the threshold values A.sub.1, A.sub.2 and A.sub.3 are set lower in this case--depending on the detected rate of increase DA--than in FIG. 9. Hence, the alarm stage II (threshold value A.sub.2) is already reached relatively early, and the "partial SCRAM" provided in the alarm stage III as a result of exceeding the threshold value A.sub.3 is also performed earlier. This leads to the desired damping of the oscillation and prevents the threshold value A.sub.max from being exceeded. By this means, total shutdown is prevented even in this unfavorable case. The resetting of the respective alarm stages can be performed, for example, when the amplitude once more falls below the threshold value A.sub.lim. FIG. 11 illustrates an embodiment for the monitoring in the command channels of the system 1, the region selection stage for the alarm signals, which are set in the region signal by means of this monitoring, and the monitoring device in the corresponding system channel. In this case, the region monitoring in the first region of the channel 1 is illustrated in the fields in each case designated by "region 1", the region signal assigned to this first region and corresponding to the threshold value A.sub.1 being fed to a threshold value detector which sets a logic alarm signal "1" if the region signal S exceeds the threshold value A.sub.1. The threshold value is taken from a memory 52 for a characteristic curve. In accordance with the stored characteristic curve, this threshold value A.sub.1 corresponds to the value DA of the current rate of increase determined in the region channel 1 (component 16, FIG. 3). Using the logic output signal of the threshold value detector 51, on the one hand an indicator and/or memory unit 53 can be driven, which now forms an alarm region signal AA1, which is assigned to the first alarm stage, for the monitoring signal AA1, which is assigned to the first alarm stage and to the first region channel. In a similar way, the relative region signal S is performed in an evaluation unit 54 (not shown in more detail) with respect to the threshold value A2, and in a monitoring stage containing the threshold value detector 55, the characteristic curve memory 56 and the indicating and/or memory unit 57, with respect to the threshold value A.sub.3 and the alarm stage III. What is not shown is that the signal S can be monitored for the exceeding of a fixedly predefined threshold value A.sub.4 by means of a further threshold value detector. The corresponding elements are present in each region signal of the system and are also indicated for the last region "region M.sub.p " in the right-hand part of FIG. 11, using the reference symbols 51', 52'. . . 57'. The monitoring signals which are formed by the threshold value detectors 51, 51' in the individual region channels (i.e., a 7-bit signal in the case of M.sub.p =7) can be summed in a summing element 60. This signal thus indicates in how many region channels the corresponding threshold value detector 51 has set an alarm signal of stage I. If this number is greater than or equal to a predefined number N.sub.mp, then an appropriate interrogation unit 61 sets a corresponding alarm system signal. In this case, the interrogation unit 61 performs this interrogation twice, the minimum number N.sub.mp being set to 1 for a first alarm system signal AA1'. This signal AA1' can then be used to indicate, via a corresponding system selection (in the simplest case a summing element--not shown--for all the signals AA1' from all the redundantly operating system channels), whether and how many systems are generating the alarm stage I. In addition, in this system monitoring 61, N.sub.mp =2 is also set. A corresponding signal AA.sub.1 " is output if at least two regions report the alarm of stage I. This signal can be used in the system selection to form an alarm output signal from all the alarm signals which are generated in the redundantly operating systems. The alarm output signal can intervene in the control system of the reactor and there block an operational increase in the reactor power. In the simplest case it is sufficient if the system selection forms only a "1 out of 4" selection, i.e., it combines the appropriate signals AA1" of the four systems by means of an "OR" element. However, in order to reliably avoid unnecessary disturbances to the reactor operation, which could be produced by faulty processing in one of the systems, a minimum number N.sub.p for the system signals, in which the alarm stage I is set, is advantageously predefined for the intervention in the reactor operation. This can be carried out in a simple way in that the logic signals AA1" of the systems are added and produce the intervention in the reactor control system only if the sum is greater than or equal to 2. In a similar way, the monitoring signals assigned to the alarm stages II and III of the individual regions of the system can be processed via the summing elements 62, 64 into corresponding signals which, in the interrogation units 65, 66 for generating the alarm system signals assigned to these stages, supply AA3' and AA3". The lacuna! from the alarm signals AA2" of the four system signals are further processed (not illustrated) in the same way as was described with reference to the signals AA1", and form an alarm output signal assigned to this alarm stage II, which signal intervenes in the reactor operation in such a way that not only is an increase in the reactor power blocked but the reactor power is even reduced in accordance with the programs which are provided for normal reactor operation. In the same way as was described with regard to the signals AA1" of the first alarm stage, the alarm signals AA3" assigned to the alarm stage III are also further processed and form an alarm output signal assigned to this alarm stage III. The signal triggers a "partial SCRAM" in accordance with the stabilization strategy assigned to this alarm stage. Finally, it should be noted that the alarm signals formed by means of the fixedly set threshold value A.sub.4 are further processed in the same way, so that, in an emergency, a total SCRAM is triggered corresponding to the highest alarm stage. The invention therefore ensures on the one hand that the unstable state of the reactor is monitored with a sufficient redundancy in order to be able to make a reliable statement about the unstable state, given failure of individual sensors, measuring lances or computing elements; on the other hand the invention allows a minimum in intervention in the reactor operation in order to damp the instability. In this case, a total SCRAM is virtually ruled out in accordance with all experience and estimations, so that the fourth alarm stage--a total SCRAM--can be viewed as completely superfluous. The constructional elements provided for monitoring the threshold value A.sub.max and the transmission elements for an alarm signal assigned to this highest alarm stage are therefore described only as an option which may also be dispensed with.
	abstract	A method for producing an iodine radioisotopes fraction, comprising the steps of dissolving enriched uranium targets forming a slurry, filtering said slurry, absorbing salts of iodine radioisotopes on an aluminium resin doped with silver and recovering said iodine radioisotopes fraction, is disclosed. The recovery of the iodine radioisotopes fraction, in particular of I-131, comprises washing the aluminium resin doped in silver using a solution of NaOH and eluting of iodine radioisotopes by a solution of thiourea, and collecting an eluate containing said iodine radioisotopes in a thiourea solution.
	description	The present application is a continuation-in-part of U.S. Ser. No. 15/402,399, filed Jan. 10, 2017, and, through that application, claims the priority of U.S. Provisional Application Ser. No. 62/353,415, filed Jun. 22, 2016. Both of those applications are incorporated herein by reference. This invention was made with government support under contract number FA8650-13-C-7325, awarded by the United States Air Force. The U.S. Government has certain rights in the invention. The present invention relates to atomic interferometry, and, more particularly, to optical configurations that enable unprecedented precision and stability of atom interferometric measurements. Some of the most precise measurements of physical quantities currently available derive from atom interferometry. These include limits on composition-dependent gravitational forces (Einstein's principle of equivalence), measurements of the ratio h/m in an atom, and derivative determinations of the fine structure constant. Measurements of such exquisite precision, as well as accelerometer and gyroscopic applications, require stability in the face of external factors such as temperature or pressure variations and other mechanical or optical perturbations. Atom interferometry encompasses various classes of well-known techniques, and has been employed not only for fundamental measurements but for such practical applications as precision inertial sensing. Atom interferometry is based on tracking the center-of-mass motion of an ensemble of atoms by generating matter wave interference and measuring its phase shift. The matter wave interference may be created by applying light pulses that interact with the atoms via two-photon Raman transitions. Critical components of an atom interferometer include a source of atoms (thermal or cooled) in a vacuum chamber, a defined trajectory, and counter-propagating Raman beams that, along with the trajectory, define the inertially sensitive axes. As the term is used herein, an axis shall be designated “inertially sensitive” if motion about or along the axis by the atom interferometer results in a detectable interferometer signal. Depending on its configuration, an atom interferometer may be operated as an accelerometer, a gyroscope, or a combined accelerometer-gyroscope. In either of the latter two gyroscopic cases, a baseline set by launching the atoms at a finite velocity (typically on the order of m/s to hundreds of m/s) is necessary to provide rotational sensitivity. (Various publications treat the sensitivity-limiting parameters of an atom interferometer. Examples include Canuel et al., “Six-axis inertial sensor using cold-atom interferometry,” Phys. Rev. Lett., vol. 97, 010402 (2006)) where sensitivity was considered limited by the cold atom sources, and Sorrentino et al., “Sensitivity limits of a Raman atom interferometer as a gravity gradiometer,” Physical review A, vol. 89 (2014), and Yver-Leduc et al. “Reaching the quantum noise limit in a high-sensitivity cold-atom inertial sensor,” Journal of Optics B: Quantum and Semiclassical Optics, vol. 5, p. 5136 (2003), all of which are incorporated herein by reference. A cold atom interferometer for navigation applications was also recently addressed by Battelier et al., “Development of compact cold-atom sensors for inertial navigation,” arXiv preprint arXiv:1605.02454 (2016) (hereinafter, Battelier 2016), incorporated herein by reference. Since both accelerometer and gyroscope sensitivities scale quadratically with the time between interactions with the Raman pulses, there is a fundamental trade-off between sensitivity and sensor volume and bandwidth. In any practical configuration, external factors bearing on the relative optical phase of successive laser beams impinging on a probed ensemble of atoms give rise to measurement perturbations and drift, ultimately limiting system sensitivity. Thus, a configuration that, by its nature, provides for long-term stability of the relative phase of counterpropagating probe beams is particularly valuable. Such a configuration is taught for the first time herein. Magneto-optical traps (MOTs) are widely used as sources of cold, dense clouds of atoms, and, recently, of simple molecules as well. Double traps are used to generate cold atomic ensembles swapped between the traps and interrogated interferometrically during transit between the traps. Such a system is described, for example, by Rakholia et al., “Dual-axis high data-rate atom interferometer via cold ensemble exchange,” Phys. Rev. Appl., vol. 2, 054012 (2014) (hereinafter, Rakholia 2014), which is incorporated herein by reference. For practical applications in inertial navigation systems (such as gimbaled and, especially, strapdown platforms), it is desirable for the atom interferometer to have a long-term stability that exceeds the performance of state-of-the-art classical sensors. Additionally, the instrument needs to be portable, orientation-insensitive, and be operated to meet its sensitivity and short-term noise requirements, while minimizing the “dead time” associated with generating the atom source (e.g. loading atoms into magneto-optical traps) and the sampling time (set by time between Raman pulses). Mechanically rigid geometries that have been employed in single-trap designs do not lend themselves to double-trap implementation. The design of single MOTs employing micromirrors etched into monolithic structures, for example, has been driven largely by the goal of miniaturization and achieving a trap on a chip. Micromirrors etched into a pyramid, for example, have been used to achieve a tetrahedral four beam MOT, as described by Vangeleyn et al., “Single-laser, one-beam, tetrahedral magneto-optical trap,” Opt. Exp., vol. 17, pp. 13601-08 (2009), which is incorporated herein by reference. The proximity of two MOTs in such configurations does not allow for implementation of integral micromirror geometries as discussed above with respect to single traps. Typically, the proximity of the two MOTs, dictated by achievable magnetic field gradients, has been on the order of 20-50 mm. Therefore, dual MOT sensors have exclusively employed discrete beam-splitting and beam-turning optics deployed at a substantial distance from the traps. Performance of sensors based on two-trap MOTs may be limited by the stability of the respective traps. Consequently, a novel physical mechanism for ensuring the anti-symmetry of the MOTs, differing only in the sign of the wavevector of the launched atoms, while not limited by the structural rigidity of a supporting base, is highly desirable. Some steps addressing various of these limitations have already been suggested in the prior art. First, the dead time in the atomic measurement associated with generating the atom source can be reduced by running two reciprocal cold atom interferometers in a “launch-catch” configuration and recapturing the atoms (at rates up to ˜100 Hz) in between measurement cycles, as in Rakholia 2014. In that configuration, inertial sensitivity can be enhanced by applying Raman pules using physically separated Raman beams which extend the gyroscope baseline. However, that increases the complexity of distributing the Raman beams and maintaining phase stability. The overall dead time in the inertial measurement can be effectively eliminated by operating the atomic sensor in closed loop with classical sensors that are co-mounted on the same moving platform (as in Battelier 2016, for example). Finally, orientation-insensitivity under acceleration can be reduced by using counter-propagating Raman beams with identical effective k-vectors oriented perpendicular to the axis of launch. This requires a Raman geometry in which the two Raman frequency components are incident from opposite sides of the cell containing the ensemble of atoms rather than a geometry in which both components together pass through the cell and retro-reflect back through it. Propagation of beams of distinct wavelengths in orthogonal propagation modes of polarization-maintaining optical waveguide (such as optical fiber) has been the basis of various devices as described, for example, by Feng et al., “Single-Polarization, Switchable Dual-Wavelength Erbium-Doped Fiber Laser with Two Polarization-Maintaining Fiber Bragg Gratings,” Optics Express, vol. 16, pp. 11830-11835 (2008), which is incorporated herein by reference. Additionally, papers such as Ménoret et al., “A transportable cold atom inertial sensor for space applications,” International Conference on Space Optics, October 2010, Rhodes, Greece. pp. 1-4, (2010), and Ménoret et al., “Dual-Wavelength Laser Source for Onboard Atom Interferometry,” Opt. Lett., vol. 36, pp. 4128-4130 (2011), both incorporated herein by reference, teach the use of separate wavelengths generated within a fiber laser. However, two-trap atom interferometers have heretofore required that Raman beams of distinct wavelength be delivered separately because of the complexity entailed in combining and separating disparate wavelengths to multiple traps. In accordance with embodiments of the present invention, an improvement is provided to measurement methods that have steps of trapping an ensemble of atoms and measuring interference fringes between populations of internal states of a quantum system based on interaction of the ensemble of atoms with a plurality of counterpropagating optical beam pairs. The improvement entails steps of: coupling the plurality of counterpropagating beam pairs such that each pair of beams traverses the ensemble of atoms in parallel counterpropagating beam paths; interposing a beam-splitting surface common to the plurality of counterpropagating beam pairs; generating interference fringes between reflections of the plurality of parallel pairs of counterpropagating beams to generate a detector signal; and processing the detector signal to derive at least one of relative phase and relative alignment between respective pairs of the counterpropagating beams. In accordance with further embodiments of the present invention, processing the detector signal includes inferring relative alignment of the parallel pairs of counterpropagating beams from a depth of the interference fringes. Processing the detector signal may also include measuring phase shear across the plurality of parallel pairs of counterpropagating beams. In other embodiments of the present invention, detecting the interference fringes may include spatially resolving the interference fringes using a detector array. The methods may also include a step of feeding back the at least one of relative phase and relative alignment between respective pairs of the counterpropagating beams to an optical element for stabilizing the at least one of relative phase and relative alignment between respective pairs of the counterpropagating beams. In accordance with another aspect of the present invention, an atom interferometer is provided that has an ensemble of atoms successively launched between a pair of magneto-optical traps and a plurality of pairs of counterpropagating laser beams traverse the ensemble of atoms for probing quantum states characterizing the atoms. The atom interferometer also has a beam-splitting surface, common to the plurality of counterpropagating beam pairs, configured to reflect a portion of each of plurality of counterpropagating beam pair and a reflector for redirecting one of each pair of counterpropagating laser beams to form an interference pattern with the other of each pair of counterpropagating laser beams. A detector is configured to detect the interference pattern and generate a detector signal, and a processor is provided for receiving the detector signal and deriving a measure of at least of relative phase and relative spatial alignment of each pair of counterpropagating laser beams. In an alternate embodiment of the invention, the detector for detecting the interference fringes includes a detector array. In accordance with another aspect of the invention, an improvement is provided to an atom interferometer having at least one distinct ensemble of atoms. The improvement has a single polarization-preserving fiber coupled for propagation of a first laser beam characterized by a first Raman frequency and a second laser beam characterized by a second Raman frequency distinct from the first Raman frequency, from at least one source of the first and second laser beams. The improvement also provides a first parallel displacement beamsplitter for separating the first laser beam and the second laser beam coupled out of the polarization-preserving fiber into respective free-space-propagating parallel beams each respective free-space-propagating parallel beam traversing the at least one distinct ensemble of atoms. In further embodiments of the invention, there may be a reflector for turning the second laser beam into a direction antiparallel to the first laser beam, and the reflector may be a corner cube reflector. The improvement may also provide a second parallel displacement beamsplitter for creating a plurality of counterpropagating laser beam pairs. In accordance with yet another aspect of the invention, an atom interferometer is provided that has an ensemble of atoms successively launched between a pair of magneto-optical traps. The atom interferometer has a first plurality of laser beams, all characterized by a first Raman frequency, traversing the ensemble of atoms in a first set of parallel directions for probing quantum states characterizing the ensemble of atoms. It also has a second plurality of laser beams, all characterized by a second Raman frequency, traversing the ensemble of atoms in a second set of parallel directions substantially counterpropagating with respect to the first set of parallel directions. A first fiber collimator couples the first laser beam from optical fiber to free-space propagation substantially parallel to a baseplate and a first parallel displacement beam splitter splits the first laser beam into a plurality of parallel beam paths. A second fiber collimator couples the second laser beam from optical fiber to free-space propagation substantially parallel to the baseplate and a beam-turning optic steers the second laser beam in a path substantially parallel to the baseplate and substantially parallel to the plurality of parallel beam paths traversed by the first laser beam. A reflector is provided for turning the second laser beam into a direction substantially antiparallel to the plurality of parallel beam paths traversed by the first laser beam, while a second parallel displacement beam splitter splits the second laser beam into a plurality of parallel beam paths each counterpropagating on the plurality of parallel beam paths traversed by the first laser beam. In sime embodiments of the invention, the reflector may be a corner cube reflector. In accordance with a yet further aspect of the present invention, an improvement is provided to an atom interferometer of the sort having a first and a second MOT displaced with respect to each other by an inter-trap distance bisected by a center displaced from either MOT by a “center-to-trap distance,” with substantially orthogonal blue-detuned cooling beams traversing a first MOT in directions substantially opposing directions in which another pair of substantially orthogonal blue-detuned cooling beams traverse a second MOT, and substantially orthogonal red-detuned cooling beams traversing the first MOT in directions substantially opposing directions in which another pair of substantially orthogonal red-detuned cooling beams traverse the second MOT. The improvement has a first fiber collimator for coupling a first laser beam from optical fiber to free-space propagation in a first laser direction substantially parallel to a baseplate and displaced from the center by the center-to-trap distance and a second fiber collimator for coupling a second laser beam from optical fiber to free-space propagation substantially parallel to the baseplate, substantially orthogonal to the first laser direction, and also displaced from the center by the center-to-trap distance. The improvement also has a first pentaprism, disposed entirely within a sphere of radius no greater than three times the inter-trap distance about the center, for splitting the first laser beam into two orthogonal cooling beams, and a second pentaprism, disposed entirely within the sphere of radius no greater than three times the inter-trap distance about the center, for splitting the second laser beam into two orthogonal cooling beams. Additionally, in accordance with other embodiments, the improvement may also have a third pentaprism, disposed entirely within the sphere of radius no greater than three times the inter-trap distance about the center, for further splitting the first laser beam into two orthogonal cooling beams, and a fourth pentaprism, disposed entirely within the sphere of radius no greater than three times the inter-trap distance about the center, for further splitting the second laser beam into two orthogonal cooling beams. The following terms shall be given the indicated meanings unless the context dictates otherwise. As the term is used herein and in any appended claims, the term “propagation axis” shall designate the axis that includes a ray that constitutes the centroid of directions characterizing momenta of particles in a beam. The term “laser beam” shall refer to any output of a laser, irrespective of its degree of collimation. “Rayleigh range” is the distance along the propagation axis of a beam from the waist to the place where the area of the cross section is doubled. Novel concepts now described, may advantageously provide long-term stability and improved portability of an atom interferometer. The long-term stability of an atom interferometer depends on the intensity, polarization, frequency, and phase stability of the light fields, and the pointing stability of the optical beams. These optical stabilities may be advantageously improved in accordance with embodiments of the present invention, applicable in equal measure to systems using thermal beams or launched 2D MOTs, although systems employing MOTs in a reciprocal launch-catch configuration will be described here for heuristic convenience. In accordance with a preferred embodiment of the present invention, a cold atom accelerometer-gyroscope, designated generally by numeral 100 in the schematic cross-sectional depiction of FIG. 1, uses a pair of simultaneous atom-interferometers operating in a reciprocal “launch-catch” configuration. The physics of atom interferometry is well-known and need not be described here. The reader is referred to such tutorial monographs as P. R. Berman, ed., Atom Interferometry (Academic Press, 1997) and Barrett et al., “Mobile and remote inertial sensing with atom interferometers,” arXiv preprint arXiv:1311.7033 (2013), and Rakholia 2014, cited above, all of which are incorporated herein by reference. Typically, stimulated Raman transitions between hyperfine atomic levels in a π/2-π-−π/2 pulse sequence serve to coherently separate, redirect, and recombine atomic wavepackets from a cold atomic sample by imprinting a spatially-dependent phase of the light field on the atoms during each pulse. To first order, the resulting phase difference between the hyperfine levels is given byΔϕ=ke·(a−2v×Ω)T2,where ke is the effective Raman wavevector, T is the delay between pulses, and v,a, and Ω are the velocity, acceleration, and rotation vectors of the atoms relative to the platform, respectively. Δϕ provides acceleration and rotation, since the atomic physics dictate ke. Referring now to FIG. 1, the atom sources are a pair of magneto-optical traps (MOTs) 102, 104, formed within a common ultra-high vacuum cell (hereinafter, the “cell” or the “vacuum cell”) 106, each constitituting laser cooled and trapped sources of Cs atoms, which, after a brief static loading period, are launched towards each other by oppositely detuning the optical frequencies of the transverse cooling beams (L+ and L−, also referred to herein as “MOT beams”) to generate a moving molasses. MOTs 102 and 104, indicated in FIG. 1 by circles with arrows indicating launch direction, may be referred to herein, respectively, as MOT0 and MOT1. (MOT beams L0 are oriented out of the page and are not shown in FIG. 1, but are evident in FIG. 7A.) While operation with ensembles of cesium atoms is described herein, the invention described herein is not limited to cesium atoms and encompasses the use of any atoms. At the beginning of each measurement cycle, the atoms launched in the previous cycle are recaptured at the opposite MOT site. A cross section of the beam diagram through the cell 106 is shown. The overall size of the sensor head is driven by the size of this cell. This, in turn, is driven by MOT separation D and beam size requirements. MOT separation distance D may also be referred to herein as an “intertrap distance.” Greater MOT separations allow for a longer gyroscope baseline and sensitivity. Larger cell clear apertures allow for an improved detection signal-to-noise ratio (SNR) by allowing for larger MOT beam sizes, thereby improving trapping and recapture efficiency. Laser beams at Raman frequencies ω1 and ω2, which may be referred to herein as Raman beams, traverse an ensemble of atoms in cell 106 in counterpropagating directions. Large Raman beams are also required for high atom interferometer contrast and improved orientation insensitivity. Cell 106 depicted in FIG. 2 is coupled to vacuum system 201, which may include ion pump 205. The MOT separation D (shown in FIG. 1) is on the order of 60 mm, while and three parallel Raman beams 120, 122 and 124 are spaced by approximately 20 mm. A cell clear aperture of 15 mm allows 7.5-mm-diameter Raman and MOT beams (typically defined in terms of a e−2 diameter) to pass through the cell 106 with negligible wavefront distortion. Optical components, designated generally by numeral 320 in FIG. 3B, are all disposed outside vacuum cell 106. It is to be understood that the some or all of the sense head optical components may also be disposed within vacuum cell 106 within the scope of the present invention. For example, it could be especially beneficial to have the Michelson interferometer optics 600 (shown in FIG. 6 and described below) inside vacuum cell 106 in order to monitor the phase profile of the Raman light exactly as seen by the atoms and to remove spurious phase fluctuations caused by motion of the cell windows (not shown). An embodiment of the present invention is now described with reference to Figs. FIGS. 1, 2, 3A, 3B and 4. FIG. 3B shows a cross-sectional view of an embodiment in which two sensor heads 301 and 302 are mounted on either side of a monolithic baseplate 304, though, in other embodiments, only a single sensor head (otherwise referred to herein as a “sensor”) 301 need be provided. Sensor 301 may be seen more clearly in the perspective view of FIG. 3A. Monolithic basesplate 304 may be referred to herein as a “baseplate,” “optical baseplate,” “optical bench” or “bench.” Baseplate 304 may be about 20 inches in diameter, or smaller, within the scope of the present invention, and still allow for adequate beam diameters. A compact form factor for sensor 301 is preferred and may be achieved by using a two-layered optical design now described with reference to FIG. 3B. Referring to FIG. 3B, cell 106 is located on a top layer 310 near the center of the baseplate 304 and is suspended from above. The Raman beams 120, 122 and 124, state preparation and repump beams 105 are also on the top layer 310 in plane with the cell. The MOT beams L+, L− begin on the bottom layer 312 where they are routed and split into multiple components near the center of the baseplate 304 before being routed up to the top layer 312 and into the cell 106. The design shown in FIG. 3B, while densely packed, does not sacrifice access to the beams. Each beam has at least one area where it can be accessed from above for fine-tuning of optical alignment and polarization (by adjustment of Risley prism pairs, waveplates, etc.) before it enters the cell 106. An additional advantage of having all the optics for a single sensor 301 mounted on one side of the optical baseplate 304 is that it enables the use of the opposite side of the baseplate for another function. Our prototype is actually a pair of independent sensors with identical sensor heads oriented back-to-back on a single baseplate (see Figure: Two sensors (variation 1) in a back-to-back configuration on a single baseplate). This serves the purpose of validating the sensor stability, as both sensors experience the same common inertial input. Another option would be to have a pair of sensors on one baseplate with inertial sensitivity along different axes. Alternatively, the opposite side of the sensor baseplate could be used to house some portion of the laser system used to generate and feed light to the sensor head (such as the system-critical Raman laser system). Materials used for the sensor baseplate 304 and optics 320 are selected based on stability requirements as a matter of design choice. Disposition of optics 320 as describe below reduces dependence of the interferometer phase stability on the absolute stability of the baseplate 304 or optics mounting materials. Maintainance of interferometrically precise beam alignment in a laboratory environment using aluminum for the base material has been demonstrated, while other materials, including those that are more stable but difficult to manufacture (e.g., Zerodur®, beryllium, etc.) may be used for certain applications, within the scope of the present invention, to such portions of sensor 301 where the sensitivity is greatest, such as at the location of fiber collimators 401, 402 (shown in FIG. 4). For purposes of describing the present invention, it is assumed that all laser beams are supplied to the sensor head 301 via single mode polarization maintaining optical fiber 330 (shown in FIG. 3B). All laser sources (otherwise referred to herein as “sources”), optical switches, and modulators employed in are contained in one or more separate modules (or “laser modules”) 406, as known to persons of ordinary skill in the art. This has the advantage of modularity, i.e., separating the sensor head 301 and the laser modules according to logical function. Beams characterized by the same or distinct frequency may be derived from identical or multiple sources, within the scope of the present invention. The use of optical fiber 330 for coupling between module 406 and sensor head 301 also offers the advantage of cleaning the spatial mode of each beam before it reaches the sensor head, and it advantageously decouples the sensor head from mechanical instability upstream of the fiber. Assuming adequate stripping of fiber cladding modes, all pointing drift upstream of the fiber is converted by the fiber to intensity drift. A polarizer (or “cleanup polarizer”) 410 may be used at the output of each fiber 330 to clean the polarization state, thus converting any polarization drift upstream of the fiber to intensity drift. For all beams with a critical intensity stability requirement (particularly the Raman and cooling/launch beams), optical power is measured after cleanup polarizer 410 using a monitor detector (more particularly, a photodiode) 418, and stabilized by servoing back to a transducer (such as by RF attenuation of an accoustooptic modulator (AOM), not shown) located within laser module 406. One disadvantage of using optical fiber 330 to deliver light to the sensor head 301 is that each separate fiber is an additional source of phase drift and polarization drift, where the polarization drift becomes intensity drift after the cleanup polarizer 410. This drift introduces noise by fluctuations in thermal and mechanical stress on the fiber 330 caused by the environment. Even with active intensity stabilization, it is advantageous to limit these sources of non-common mode noise by using as few fibers as possible. In accordance with an embodiment of the present invention, a single delivery fiber 330 is employed for all common beams required by the sensor head. These beams are stabilized as needed, by feedback of intensity after polarizer cleanup, as described above, after the fiber 330 and before being split and routed via free-space optics within the sensor head 301 to their destinations at the vacuum cell 106. In particular, two polarizations of a single polarization preserving fiber 330 may be employed to deliver beams of distinct frequencies ω1 and ω2, in accordance with the present invention. A preferred embodiment of the invention uses a total of seven fibers per sensor to deliver the following beams: Raman frequency components ω1 and ω2, MOT L0, L+, and L− (3 beams), state preparation (optical pumping) beam 105, and hyperfine repump beam (not shown). The repump beam may optionally be supplied mixed with the MOT light in the L0 fiber (not shown), in which case these frequency components are then dichroically split again after the fiber for intensity monitoring. Measures have been described for mitigating the effects of beam misalignment and intensity and polarization drift upstream of the sensor head 301. Additionally, the atom interferometer phase is susceptible to differential phase noise introduced by fibers guiding the Raman frequency components ω1 and ω2. In accordance with an embodiment of the present invention, differential phase noise is mitigated this by monitoring the differential phase of the two Raman components within the sensor head 301 using Michelson interferometry, as described below. In accordance with another embodiment of the present invention, differential phase between Raman frequency components ω1 and ω2 is mitigated by carrying both Raman beams in cross-polarized propagation modes of a single fiber and splitting them within the sensor head 310. Even in this case, the Michelson interferometer 600 may advantageously be employed for monitoring differential phase or for actively stabilizing other sources of differential phase noise upstream of the fiber (such as within the Raman laser source module 406). Michelson interferometer 600 is described in detail below. Fiber phase noise is typically not a concern for the other laser systems. All methods for routing the various beams from their fiber collimators to the cell are left as matters of design choice and are within the scope of the present invention. The designs of FIGS. 1-4 depicted herein are provided solely as examples. Layout of a Raman beam system (or “Raman optical system”) 400, in accordance with an embodiment of the present invention, is now described with reference to FIG. 4. The setup shown in FIG. 4 advantageously produces three highly parallel ω1 beams counter-propagating with respect to three ω2 beams. In order not to limit system sensitivity, Raman beams ω1 and ω2 must meet specified alignment requirements such as: parallelism of neighboring beams, i.e., the three ω1 beams and the three ω2 beams, typically on the order of less than 20 gad; parallelism of counter-propagating beams, typically on the order of less than 500 gad. Additionally, it is desirable that wavefront distortion of Raman beams ω1 and ω2 be optically minimized in order to reduce variations in the phase observed by the atoms, especially when they are subject to cross-axis acceleration. In order to generate beams that are parallel with high stability, optical components are preferred for which the beam deflection angle is relatively insensitive to disturbances in the position and orientation of the optical component. Some of these components, such as the parallel displacement beamsplitters and corner-cube reflector, generate output beams that are parallel (or anti-parallel) to their input and are highly desensitized to angular motion of the optic relative to the input beam (they are insensitive to rotation of the optic about any axis). Others include the penta prism, which is insensitive to rotations of the optic within the plane of incidence (but more sensitive in the other direction), and Risley prism pairs which can generate arbitrary deflection angles that are relatively insensitive to the tip and tilt of the prisms. In cases where a corner-cube reflector is used, it is to be ensured that the effective region of the optic does not intersect with the edges or vertex of the cube, a circumstance that would degrade polarization and beam quality. For parallelism stability of counter-propagating beams, both Raman and MOT beams, sensor 301 is most susceptible to differential fluctuations between the angular orientations of the two fiber collimators 401 and 402. Such differential fluctuations may be advantageously reduced by co-locating the two fiber launch points (the loci of fiber collimators 401 and 402) on the optical bench 304. Penta prisms 416 are not necessary in all embodiments of the present invention, however they allow the footprint to be slightly reduced by bending the beams to one side. In an alternate embodiment of the invention, penta prisms are not employed but, instead, the beams are launched out of fiber 330 in a direction parallel to the propagation direction through cell 106. Penta prisms 416 may double as beamsplitters that direct a small amount of light to a monitor detector 418 for intensity monitoring and control. Flat beam pick-off optics might also be employed for that purpose. The use of a corner-cube 420 on the opposite side of the bench 304 (distal to fiber 330) to reflect Raman beam ω2 back towards ω1 introduces essentially no additional pointing error, regardless of the deformation of the bench 304. A second parallel displacement beamsplitter 430 splits the ω2 beam into three parallel beams, counterpropagating with respect to their ω1 beam counterparts. The angular stability of the three parallel Raman beams (ω1 or ω2) incident from either side of the cell 106 is governed by the stability of lateral displacement beamsplitters 500 (shown in FIG. 4) and Risley prism pairs 414, if used. (Lateral displacement beamsplitter 500 is depicted in detail in FIG. 5.) For this reason it is of paramount importance to mount the prisms in a way that minimizes internal stress on the optic, even at the expense of absolute mechanical stability. For example, soft, flexible urethane adhesive may be employed. Optics are mechanically retained on the surface of the baseplate using soft spring pressure from above. Three raised pads on the bench below provide the mechanical contact. The soft adhesive bonds the optic to the bench between these pads. Circular optics such as fiber collimators, Risley prisms, and wave plates are housed in V-grooves on the bench surface and retained with spring pressure and adhesive. As shown in FIG. 5, lateral displacement beamsplitter 500 splits incoming beam 501 into multiple, substantially parallel beams 503, 505 and 507. Any deviation from parallelism may be corrected by alignment of Risley prism pair 510. In accordance with principles of the present invention described herein, effects of platform deformation and optical mounting instabilities on the final beam parallelism are reduced. This allows for the use of less expensive and more machinable materials for baseplates and optical mounts than would otherwise be needed, thus, for example, aluminum might be used for both. Furthermore, optical components can be manufactured with such tight angular surface tolerances that for some applications it is possible to forgo active alignment of the beams entirely. In particular, lateral displacement beamsplitters of the type shown in FIG. 5, with output beams parallel to within 20 gad, can be manufactured using standard methods. Similarly, corner cube retroreflectors with angular beam deviations under 20 gad are readily achievable. Risley prism pairs can be used for fine-tuning of the optical alignment where needed. It is to be appreciated that while the optics described above generate deflection angles that are desensitized to rotations and displacements, the absolute lateral displacement of the beam through each optic is still fully sensitive to these motions. However, because the Raman system has no strict requirement for microscopic stability of beam centroid positions (side-to-side motions of the beams that are small with respect to the 7.5-mm beam size are acceptable), we are the possibility of lateral drifts resulting from platform instability is tolerable. The use of large Raman beams has the obvious advantage of providing more uniform illumination of the atoms in flight. This leads to improved phase stability under dynamics (especially under cross-axis acceleration) and higher phase contrast at finite temperature. Optically, the use of large beams simplifies the optical layout by reducing the need for additional lenses to position the beam waists at the atoms. In a preferred embodiment of the invention, 1/e2 beam diameters are 7.5 mm, leading to a Rayleigh range of over 50 m—much larger than the scale of the apparatus. This reduces the dependence of wavefront curvature on optical path length near cell 106, reducing the need for precise path length matching of all beams. All optical surfaces after the collimators are planar, thus avoiding any angular beam tilts that would result from lateral motion of powered (non-planar) optics. All optics must be specified to have sufficient clear aperture to prevent appreciable wavefront ripple due to diffraction effects. In a preferred embodiment of the invention, clear apertures of 15 mm or greater are used for the Raman optics. It is unusual to find off-the-shelf polarizers that have this large a clear aperture and that also exhibit exceptional surface quality and polarization extinction ratio. One solution for this problem is to use specially coated Brewster's angle plate polarizers which are easy to manufacture with high flatness and arbitrarily large clear aperture and only require a single custom coating. We also note that a pair of waveplates (half-wave 422 and quarter-wave 424) are used in front of the corner-cube 420 to correct polarization errors. Michelson interferometer 600 (shown in FIG. 4, and in detail in FIG. 6) is a subcomponent of the Raman optical system 400 that is used to monitor the relative phase stability between ω1 and ω2 as well as the spatial variation in the Raman beam wavefronts. The detected optical phase can also be stabilized by feeding back to a variable phase delay component (such as a piezo-mounted mirror). This utilization of a Michelson interferometer for phase detection and/or stabilization in close proximity to the atoms is equally useful for a variety of possible Raman beam configurations, including atom interferometer systems having 1, 2 or more fibers for Raman beam delivery and systems having retro-reflected Raman beams. For the Michelson detector optic 610, a single bonded optical component is employed, which includes a beamsplitter prism (or “beamsplitter surface”) 612, quarter wave plate 614, and retro-reflecting mirror surface (or “retro-reflecting surface”) 616 that extends across all three counter-propagating beam pairs (all shown in FIG. 6). All surfaces are preferably manufactured to exceptional surface regularity (<20 gad angle deviation between all beams). Polarizers 618 are rotated to fine tune the mixing of the two frequency components on the detectors 620 and compensate for any differences in relative beam power between the neighboring beams. The types of detectors 620 used depend upon the application. CCD cameras or other detector arrays may be used to monitor the fringes for initial alignment of the Raman system and characterization of the Raman optics. In some embodiments, three single photodiodes may be employed to measure the phase of each beam pair during the Raman pulses. Multi-pixel detectors (such as quad detectors or megapixel arrays) may be employed for in-situ monitoring of the spatial phase profile and phase shear across the beams, within the scope of the present invention. An added benefit of using a megapixel, or other large array, camera in the design is the use of this camera to detect the positions and sizes of the atom clouds in transit across the Raman beams. This information can be used to compensate for errors imprinted in the atomic phase that result from variations in the atom trapping location, trajectory, and spatial distribution. The measured optical phase is susceptible to relative motion between the beamsplitter surface 612 and the retro-reflecting surface 616. This would introduce drift in the phase measurement if these two surfaces belonged to separate optics. By combining these surfaces in a single prism joined together by optical contact bonds, the susceptibility of the measured phase difference to deformations of the baseplate or optical mounts is advantageously reduced. Furthermore, by specifying a fixed uniform angle of 45 degrees between these surfaces, the need for manual alignment of the two surfaces is eliminated. Angular alignment of the optic relative to the beams still needs to be mechanically stable to maximize contrast, but in principle all the information to determine relative beam parallelism and phase is still there even if the optic experiences a tilt error. Image capture and processing may be employed to extract this information if multiple fringes are visible. The absolute mechanical stability of the Michelson phase detection optics (polarizers, lenses 622, detectors 620) is not critical, because these optics appear downstream of the beamsplittng surface where interference occurs. A MOT subsystem 700, depicted in FIG. 7B, provides the beams for cooling and trapping of the two MOT clouds (labelled MOT 0 and MOT 1). Top and bottom views are provided in FIGS. 7A and 8, respectively. The MOT cooling beams also perform the functions of launching the atoms between the two trapping sites and illuminating the atoms at the end of the measurement cycle for state-dependent detection. Three fibers to deliver the MOT light: one 720 for the L0 beam which is oriented perpendicular to the launch trajectory and one each (722 and 724, respectively) for L+ and L− beams (blue-detuned and red-detuned, respectively, from atomic resonance) which contribute to the launch. After the brief (several millisecond) atom recapture and trapping phase, the MOT quadrupole magnetic field coils are turned off, and the L+ and L− light frequency is detuned by several linewidths in the positive and negative direction respectively. This generates moving molasses by cooling each cloud into a moving frame. The velocity vectors of the two clouds are oriented toward one-another due to the reversal of the orientations of the L+ and L− beams between the two traps. The 45-degree orientation of the L+/L− beams from the launch direction enables this reversal by allowing the two clouds to see different sets of launch beams. After state preparation and atom interferometry but before each cloud is recaptured at the opposite trapping site, the atomic states are detected by flashing on the L0 beams (one time without repump light followed by another time with repump light for state detection normalized to total population). The two traps require a total of 12 MOT beams incident on the cell from 12 directions (see Figure: Beam diagram through cell). As stated above, these 12 beams are delivered by three fibers for the L0, L+, and L− components respectively. The outputs of these fibers are intensity and polarization stabilized before being split into multiple beams, thus reducing non-common mode intensity fluctuations between the various beams. Because the MOT operates in a saturated regime and because the trapping locations are set by the magnetic field zero position rather than the beam positions, we are partially desensitized to fluctuations in intensity and lateral position of the MOT beams. Highly stable beam pointing directions are required, however, since launch trajectory is directly dependent on the k-vector orientations of the L+ and L− beams. One approach for splitting and routing all of these beams to the cell in a manner that is both compact and substantially reduces susceptibility of beam pointing direction to mechanical deformation of the optical baseplate 304 and mounts is shown in FIGS. 7A, 7B and 8. Only the L0 beams for MOT 0 and MOT 1 can be retro-reflected back through the cell 106 because they are never required to cool into a moving frame. These beams are split into only 2 components. The L+ and L− beams must be split into 4 components each. MOT fiber collimators 703 are confined to one side of the optical bench 304 in order to reduce susceptibility to non-common mode motions of the beams due to deformations of the bench between the fiber launch points. Similarly, all of the beamsplitters close to one-another and close to the fiber launch points near the center of the bench for this reason. Optical routing, as described above, advantageously allows placement of the requisite MOT beam optics on a single layer of a common stable baseplate 304. Differential motions of the beam components are also mitigated by using penta-prism beamsplitters rather than single-turn beamsplitters. The two L0 beam components are directed up (out of the plane of the baseplate) and into the cell using penta prisms 740, and are retro-reflected back through the cell by mirrors with quarter wave plates. Penta prisms 740 are disposed close to the MOTs, and no further than three times the intratrap distance D relative to center 742 of the sensor 301. After the beamsplitters, the k-vectors of all 8 L+/L− components are already in their final orientations except for one final reversal by 8 corner-cube reflectors 710 that bring the beams up to the level of the cell 106. Because these corner-cubes 710 preserve the orientations of the reflected beams, they can be positioned far out on the edges of the optical baseplate 304 without regard for potential non-common mode motions in their orientation. While the invention is described through the above-described exemplary embodiments, modifications to, and variations of, the illustrated embodiments may be made without departing from the inventive concepts disclosed herein. Furthermore, disclosed aspects, or portions thereof, may be combined in ways not listed above and/or not explicitly claimed. Accordingly, the invention should not be viewed as being limited to the disclosed embodiments.
042736706	description	DETAILED DESCRIPTION OF THE DRAWINGS So far as it is practical, the same elements or parts which appear in the different views of the drawings will be identified by the same numbers. With reference to FIG. 1, the apparatus illustrated by this drawing is representative of those used to process low radioactive aqueous waste containing dissolved and dispersed solids to a concentrated liquor, or bottoms, containing 25% by weight or more of solids. Although the subject invention pertains to an improved apparatus and method for the withdrawal of bottoms from such a representative system, a clear understanding of a source of such bottoms is believed to facilitate an understanding of the invention. As shown in the attached drawing, an aqueous radioactive waste stream at 60.degree. F. and 50 psia of low radioactivity and low solids, such 0.35% solids by weight, is fed at 33 gallons per minute by conduit 10 to pipe 11 which feeds the stream to recirculation pump 12. Pipe 14 conveys the stream from pump 12 to the liquor box 16 at the bottom of two-pass heater 15. The stream flows upwardly through one-half of the number of tubes 17 in heater 15 to liquor box 18 from which the stream is fed downwardly through the other one-half of the number of tubes 17 into liquor box 19. Heater 15 is supplied on the shell side with stream at 298.degree. F. and 65 psia by conduit 20 and the condensed steam is removed by conduit 21. The heated liquor at about 252.degree. F. is withdrawn from liquor box 19 by pipe 25 which feeds it to vapor body 26. The liquor boils in vapor body 26 at 15 psia and 213.degree. F., producing vapor at 16,472 pounds per hour which is fed to and through entrainment separator 28 on the top of the vapor body. The liquor is removed from the bottom of vapor body 26 by pipe 11 and is recirculated at 6000 to 8000 gallons per minute as described. After the liquor has been reduced to the desired solids concentration, which will generally be 27% solids by weight or higher, the product is removed at 218.degree. F. from conduit 14 through ram valve 60 using the method and apparatus provided by this invention and which are described subsequently in more detail. As the vapor flows upwardly in entrainment separator 28 it contacts mesh pad 30 which separates entrained liquid drops or mist and solids. The vapor leaves separator 28 at 213.degree. F. and 15 psia through conduit 35 which delivers it to the shell side of condenser 37. The water formed by condensing the vapor is removed at 16,272 pounds per hour from condenser 37 by conduit 38 at 212.degree. F. and 14.7 psia which delivers it to the shell side of subcooler 40. The cooled water or distillate which results from the vapor condensation is removed at 120.degree. F. and 29.5 gallons per minute by conduit 41 from the shell side of subcooler 40. Conduit 41 can deliver it to any suitable destination, such as for reuse in the plant. Cold water at 100.degree. F. is fed by conduit 44 to water box 45 at the top of subcooler 40. The cold water flows downwardly through the tubes 46 into water box 47 at the bottom from which it flows through conduit 48 to water box 49 at the bottom of condenser 37. The water flows upwardly from water box 49 through one-half of the number of tubes 50 in condenser 37 to water box 51 at the top. The water then flows from water box 51 downwardly through the other one-half of tubes 50 into water box 52 from which the cooling water at 121.degree. F. is removed by conduit 53. Withdrawal of the bottoms from the evaporator according to the invention is achieved using the apparatus shown in FIG. 2. Fast acting ram valve 60 is connected to conduit 14 and provides access thereto for removal of bottoms from the evaporator system. Extending from ram valve 60 is drain conduit 63 which communicates with pump 64. Rinse water supply conduit 66 communicates with drain conduit 63 near ram valve 60 so as to facilitate rinsing the drain conduit as will be subsequently described. A rinse water conduit valve 67 is positioned in conduit 66, desirably close to its juncture with drain conduit 63. Extending from the outlet of pump 64 is a delivery conduit 69 which communicates with bottoms collecting tank 70. Valve 71 regulates flow of bottoms by conduit 69 to bottoms tank 70. Vent 72 in the top of tank 70 provides a means for withdrawal of separated gases which must, of course, be properly handled if they are radioactive. Conduit 74 and valve 75 provide means for removing the collected bottoms from tank 70 for subsequent disposal. A branch conduit 77 having valve 78 therein communicates with feed tank 80. Low radioactive aqueous waste, collected from various sources, can be fed to feed tank 80 by conduit 82 through valve 83. Vent 85 in the top of feed tank 80 provides a means for removal and entry of air and other gases during filling and emptying of feed tank 80. Feed liquor withdrawal conduit 10 communicates with feed tank 80 through valve 87. Although not an essential part of the bottoms withdrawal apparatus, it is very advisable to position a block valve 91 in drain conduit 63 upstream but close to pump 64, and to position a block valve 92 in delivery conduit 69 downstream but close to pump 64. The block valves 91 and 92 can be used to isolate pump 64 thereby permitting its removal in case of failure. Although the apparatus as illustrated in FIG. 2 can be operated manually, it is clearly far more practical for it to be operated by automatic controls, including timers, electrically operated solenoid valves and such other conventional instrumentation as may be appropriate considering the radioactivity of the product being handled. Accordingly, the subsequent additional discussion of FIG. 2 will be as an automatic system. When the bottoms removal apparatus illustrated by FIG. 2 is not in operation it is maintained full of rinse or wash water which can be, if desired, the low radioactive liquor fed to the evaporator. When the density of the concentrated radioactive waste material or bottoms in the evaporator apparatus shown in FIG. 1 reaches a predetermined level, based on observation or according to a time cycle, the process sequencer 100 initiates control operations. At time zero, a 24-hour timer, which is part of the sequencer, sends a signal by line 110 which simultaneously opens block valves 91 and 92 and starts pump 64, and a signal by line 120 which opens ram valve 60 permitting bottoms to flow from conduit 14 to drain conduit 63. The 24-hour timer simultaneously also energizes a 0 to 30 minute timer and a separate 0 to 1 minute timer A. The 0-30 minute timer and timer A are part of the process sequencer. The valve 78 to the feed tank is simultaneously opened by a signal delivered to the valve by line 130. With pump 64 running, bottoms are withdrawn from the evaporator while simultaneously the wash or rinse water initially in conduits 63 and 69 is fed to feed tank 80. Timer A then times out in about 30 seconds, causing valve 78 to close and sending a signal by line 140 to valve 71, leading to bottoms tank 70, to open. Bottoms are removed from the evaporator for a 30 minute period, or such time as considered appropriate in view of the size of the evaporator, the concentration of the bottoms and the capacity of the bottoms withdrawal system. For a particular evaporator, a 30 minute cycle may cause the liquid level in the evaporator to drop 2 feet upon withdrawal of 400 to 600 gallons of bottoms with 2 inch diameter conduits 63 and 69. After 30 minutes, the 30 minute timer times out and a 0 to 10 minute timer is energized. The 0 to 10 minute timer sends a signal by line 150 to wash conduit valve 67, which is thereby opened. Wash water at about 40 to 50 psig thereby flows into conduits 63 and 69 while simultaneously bottoms are back flushed from the fast acting ram valve 60 into conduit 14 for a short time, i.e. 30 seconds, due to the lower pressure (25 psig) in conduit 14. At the same time, 0 to 1 minute timer A, as well as a 0 to 1 minute timer B, which are part of the sequencer, are energized. The 0 to 1 minute timer A times out in 30 seconds and bottoms tank valve 71 closes and valve 78 to the feed tank opens. In this way the bottoms at the front of the stream are directed to bottoms tank 70 and once that has been almost completed the flow is redirected to the feed tank which receives whatever small amount of bottoms are in the conduits as well as the conduit wash stream. The 0 to 1 minute timer B then times out in five seconds thereby sending a signal by line 120 to close ram valve 60. Subsequently, the 0 to 10 minute timer times out resulting in a signal being sent by line 150 to close wash conduit valve 67, a signal being sent by line 130 to close valve 78 leading to the feed tank 80, and a signal being sent by line 110 to shut off pump 64 and close block valves 91 and 92. At that point, the bottoms removal cycle is completed and remains on hold, ready for the next bottoms removal at a predetermined time.
	description	In ion implantation systems, an ion beam is directed towards a work piece (e.g., a semiconductor wafer, or a display panel) to implant ions into a lattice thereof. Once embedded into the lattice of the workpiece, the implanted ions change the physical and/or chemical properties of the implanted workpiece regions, relative to un-implanted regions. Because of this, ion implantation can be used in semiconductor device fabrication, metal finishing, and various applications in materials science research. During a typical implantation process, the ion beam has a cross-sectional area that is significantly smaller than the surface area of a workpiece to be implanted. Because of this, typical ion beams are scanned over the surface of the workpiece to achieve a specified doping profile in the workpiece. For example, FIG. 1A shows an end view of a conventional ion implantation system 100 where an ion beam 102 traces over a scan path 104 to implant ions into the lattice of a workpiece 106. During this tracing, the ion beam 102 is often scanned over a first axis 108 (e.g., electrically or magnetically scanned) while the workpiece 106 is mechanically translated over a second axis 110. However, the beam could also be electrically or magnetically scanned over both the first and second axes 108, 110 in other embodiments. Unfortunately, however, as the ion beam 102 traces over the scan path 104, the shape and/or cross-sectional area of the beam can vary somewhat, such as shown in FIGS. 1B-1F. For example, FIGS. 1B-1F show that as the beam 102 scans across the workpiece 106, the width of the beam can be larger near the center of the workpiece (central width Wc in FIG. 1D) and smaller near the edges (e.g., left and right widths, WL1, WR1 as shown in FIGS. 1B, 1F, respectively). If these variations in beam width are not accurately measured and accounted for, the doping profile actually formed in the workpiece 106 can differ from the specified doping profile. Such differences can result in the implanted workpiece not functioning as specified. In order to help ensure that the ions actually implanted into a workpiece are commensurate with a desired dosing profile, ion implanters often include a beam profiler. A beam profiler measures the flux or current of the ion beam at different regions on the scan path 104, and assembles these values to generate a beam profile. Although conventional beam profilers are known, conventional beam profilers require substantial mechanical assemblies and/or complex signal processing. Therefore, aspects of the present disclosure relate to improved beam profiling techniques. The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention, and is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. Rather, the purpose of the summary is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later. One embodiment relates to an ion implanter. The ion implanter includes an ion source to generate an ion beam, as well as a scanner to scan the ion beam generally in a propagation direction across a surface of a workpiece. The ion implanter also includes an array of absorption and radiation elements arranged to absorb energy of the scanned ion beam and radiate at least some of the absorbed energy away from the propagation direction. A detection element is arranged to detect energy radiated by the array of absorption and radiation elements and to determine a beam profile of the scanned ion beam based on the detected energy. The following description and annexed drawings set forth in detail certain illustrative aspects and implementations of the invention. These are indicative of but a few of the various ways in which the principles of the invention may be employed. The present invention will now be described with reference to the drawings wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures are not necessarily drawn to scale. Some embodiments of the present invention relate to improved beam profiling techniques. For example, to profile a scanned ion beam, many embodiments include a beam profiler that includes an array of absorption and emission elements arranged in the path of the scanned beam. As the beam impinges on the different absorption and emission elements, the impinged upon elements absorb energy and heat up. By measuring the temperatures of the individual absorption and emission elements (e.g., by snapping one or a series of infrared pictures), an infrared detector can determine the amount of beam current impingent on the various regions of the array, thereby allowing an accurate beam profile to be measured. FIG. 2 illustrates one embodiment of an ion implantation system 200 operable to carry out beam profiling techniques in accordance with some aspects of the invention. The ion implantation system 200 includes a source terminal 202, a beamline assembly 204, a scan system 206, and an end station 208, which are collectively arranged so as to inject ions (dopants) into the lattice of a workpiece 210 according to a specified dopant profile. In addition, the ion implantation system 200 includes a beam profiler 212, which includes of an array of absorption and radiation elements 214 and a radiation detector 216. During operation, an ion source 218 in the source terminal 202 is coupled to a high voltage power supply 220 to ionize dopant molecules (e.g., dopant gas molecules) and accelerate the ionized dopant molecules to form a pencil ion beam 222. To steer the pencil beam 222 from the source terminal 202 towards the workpiece 210, the beamline assembly 204 has a mass analyzer 224 in which a dipole magnetic field is established to pass only ions of appropriate charge-to-mass ratio through a resolving aperture 226. Ions having an inappropriate charge-to-mass ratio collide with the sidewalls 228a, 228b; thereby leaving only the ions having the appropriate charge-to-mass ratio to pass though the resolving aperture 226 and into the workpiece 210. The beam line assembly 204 may also include various beam forming and shaping structures extending between the ion source 218 and the end station 208, which maintain the pencil beam 222 in an elongated interior cavity or passageway through which the pencil beam 222 is transported to the workpiece 210. A vacuum pumping system 230 typically keeps the ion beam transport passageway at vacuum to reduce the probability of ions being deflected from the beam path through collisions with air molecules. Upon receiving the steered pencil beam 222, a scanner 232 within the scan system 206 laterally diverts or “scans” the pencil beam back and forth in time (e.g., in a horizontal direction), thereby providing a scanned ion beam 234. In some contexts, this type of scanned pencil beam may be referred to as a ribbon beam. In the illustrated embodiment, the scanner 232 is an electrical scanner that includes a pair of electrodes 236a, 236b arranged on opposing sides of the scanned beam 234. A control system 238 induces a change in a variable power source 240 to provide a time-varying current or voltage on the electrodes 236a, 236b, thereby inducing an oscillatory time-varying electric field in the beam path region and scanning the ion beam back and forth over a first axis in time. In other embodiments, the scanner 232 can be a magnetic scanner that provides a time-varying magnetic field in the beam path region, thereby scanning the ion beam over the first axis in time. In some embodiments, only a single electrode or magnet (rather than a pair of electrodes/magnets) can be used. The control system 238 can also control translational movement of a chuck, on which the workpiece is mounted, such that the ion beam tracers over a scan path (e.g., as shown in FIG. 1A). Downstream of the scanner 232, a parallelizer 242 can redirect the scanned ion beam 234 so that the scanned ion beam strikes a surface of the workpiece 210 at the same angle of incidence over the entire surface of the workpiece. To monitor the beam and help ensure proper calibration thereof, the beam profiler 212 includes an array of absorption and radiation elements 214, which are configured to absorb energy from the scanned beam 234 and radiate energy based on the energy absorbed. The radiation detector 216 detects this radiated energy and can determine a beam profile based on the detected energy. For example, in many embodiments, the individual absorption and radiation elements in the array 214 change their respective temperatures based on the energy they absorb from the scanned ion beam 234. When heated, the individual absorption and radiation elements radiate photons (e.g., infrared radiation), which are then detected by the detection element 216 (e.g., an infrared detector). For example, if the radiation detection element is an infrared camera, it can take a series of pictures of the array 214 in rapid succession to measure the temperature of the individual elements as the beam passes thereover. Because the temperature of the elements corresponds to the amount of beam energy they have absorbed from the beam, the elements' respective temperatures provides a good representation of the beam profile. In some embodiments, the ion implantation system can include a window 244 arranged between the radiation detector 216 and the array of absorption and radiation elements 214. This window 244 allows photons having the expected energy (e.g., photons in the infrared region of the spectrum) to pass there through, and can in some instances block photons of other energies. For example, for an infrared detector, a silicon window could be used, among others; while for a visible light detector, a glass window could be used, among others. FIGS. 3-4 show an array of absorption and radiation elements (e.g., array 214 of FIG. 2) in accordance with some embodiments. In these examples, the array 300 is made up of sixteen absorption and radiation elements 302a-302p arranged in a four-by-four grid. However, it will be appreciated that including more than sixteen absorption and radiation elements will provide a more accurate beam profile measurement, although fewer than sixteen absorption and radiation elements can also be included. In practice an array of hundreds or even thousands of absorption and radiation elements might be best for detailed profile measurements. The absorption and radiation elements 302a-302p have respective faces arranged at least approximately perpendicular to the beam's propagation direction 304, and are also arranged atop respective standoff members 306a-306p. The absorption and radiation elements and the standoff members can be made of the same material or of different materials, depending on the implementation. The absorption and radiation elements 302a-302p often have a surface area to volume ratio that is quite high. That is, a depth of an absorption and radiation element, as measured from the face, is substantially less than a length and/or width of the face. The absorption and radiation elements are typically made of a material with a low specific heat capacity (e.g., lower than 0.5 J/g K). This helps ensure that the absorption and radiation elements have a large beam collection area and small thermal mass, such that a small amount of beam current being absorbed corresponds to a large increase in temperature. The absorption and radiation elements are typically made of a material with a low thermal conductivity (e.g., lower than 2 W/cm K). Tantalum, tungsten, molybdenum, and/or some ceramics are good choices, among others. These also have the advantage that they have low sputter yields, thereby allowing the absorption and radiation elements to last longer. The standoffs 306a-306p are also thin and of poor thermal conductivity, such that the absorption and radiation elements thermally “float”. As shown in FIGS. 4-5, the array 300 can be positioned between a scanner, which diverts the beam, and a chuck 402. The chuck 402 is configured to hold a workpiece, and can often be translated along a second axis while the ion beam is scanned over a first axis. Thus, during beam profiling, the array 300 is inserted into the beam path to obtain a beam profile. After profiling is complete, the array 300 is removed or shuttered from the beamline (e.g., via a mechanical arm or assembly) and a workpiece can be placed in the chuck 402 and implantation can be carried out thereon. FIG. 6 shows a method in accordance with some embodiments. The method starts at 602, wherein an ion beam is generated. At 604, the ion beam is scanned over a scan path to provide a scanned ion beam. Despite being scanned, the ion beam still propagates generally along a propagation direction. At 606, the method uses an array of absorption and radiation elements to absorb energy of the scanned ion beam and radiate at least some of the absorbed energy away from the propagation direction. At 608, the method detects energy radiated by the array of absorption and radiation elements, and determines a beam profile of the scanned ion beam based on the detected energy. Although the invention has been illustrated and described with respect to one or more implementations, alterations and/or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, although some embodiments have been described above with respect to infrared radiation being radiated and detected to determine a beam profile, any other portion of the electromagnetic spectrum could also be used. For example, in other embodiments, the absorption and radiation elements could emit visible light or radio waves at a pre-determined wave length, and the radiation detector can be chosen appropriately to detect this pre-determined wavelength or spectrum of wavelengths. One advantage of infrared radiation is that it is relatively low-energy, and hence can be used to detect very low-intensity beams. In contrast, visible light is higher energy and a low-intensity beam may not be able to cause the structure to emit visible light. In addition, different types of end stations 208 may be employed in the ion implantation system 200. In some embodiments, a “batch” type end station can simultaneously support multiple workpieces on a rotating support structure, wherein the workpieces are rotated through the path of the ion beam until all the workpieces are completely implanted. A “serial” type end station, on the other hand, can be used in other embodiments. Serial type end stations support a single workpiece along the beam path for implantation, wherein multiple workpieces are implanted one at a time in serial fashion, with each workpiece being completely implanted before implantation of the next workpiece begins. In particular regard to the various functions performed by the above described components or structures (blocks, units, engines, assemblies, devices, circuits, systems, etc.), the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component or structure which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. The term “exemplary” as used herein is intended to imply an example, as opposed to best or superior. Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising”.
	abstract	An electron beam detecting device detects a state of an electron beam radiated by an electron beam radiation device. A plurality of wire electrodes, which are conductors, are disposed corresponding to a plurality of filaments, the wire electrodes being electrically insulated from each other, in the area in which the electron beams are radiated. The electrical current flowing through each of the wire electrodes is measured by an electric current measuring instrument (measuring unit). A CPU (determining unit) determines the radiation level of the electron beams by receiving a signal output by the electric current measuring instrument. The CPU judges that when the measuring instrument measures a decrease of the current value, an abnormal condition exists in the filament corresponding to the conductor with the lower current value.
055442137	abstract	V-shaped linear groove portions are formed at regular intervals and at three positions (with 120.degree. pitches) on a periphery, concentric with a ring-shaped support frame, of an X-ray mask to extend in the radial direction. On the other hand, corresponding mounts, as projecting portions, each having a spherical leading end are disposed at three positions on a mask chuck. The mask is held on the mask chuck at the three positions by engaging the corresponding V-shaped linear groove portions and the projecting portions.
	description	The present invention relates generally to ion implantation systems, and more particularly to uniform charge neutralization of an ion beam utilized in ion implantation systems. Ion implantation systems are used to dope semiconductors with impurities in integrated circuit manufacturing. In such systems, an ion source ionizes a desired dopant element, which is extracted from the source in the form of an ion beam of desired energy. The ion beam is then directed at the surface of a semiconductor workpiece in order to implant the workpiece with the dopant element. The ions of the beam penetrate the surface of the workpiece to form a region of desired conductivity, such as in the fabrication of transistor devices in the workpiece or wafer. The implantation process is typically performed in a high vacuum process chamber which prevents dispersion of the ion beam by collisions with residual gas molecules and which minimizes the risk of contamination of the workpiece by airborne particles. A typical ion implanter includes an ion source for generating the ion beam, a beamline system including mass analysis apparatus for mass resolving the ion beam using magnetic fields, and a target chamber containing the semiconductor workpiece to be implanted by the ion beam. For high energy implantation systems, an acceleration apparatus is provided between the mass analysis magnet and the target chamber for accelerating the ions to high energies. In order to achieve a desired ion implantation for a given application, the dosage and energy of the implanted ions may be varied. The ion dosage delivered controls the concentration of implanted ions for a given semiconductor material. Typically, high current implanters are used for high dose implants, while medium current implanters are used for lower dosage applications. The ion energy is used to control junction depth in semiconductor devices, where the energy levels of the beam ions determine the degree of depth of the implanted ions. The continuing trend toward smaller and smaller semiconductor devices requires a beamline construction which serves to deliver high beam currents at low energies. The high beam current provides the necessary dosage levels, while the low energy permits shallow implants. In addition, the continuing trend toward higher device densities on a semiconductor workpiece requires careful control over the uniformity of implantation beams being scanned across the workpiece. One effect during ion implantation of a semiconductor wafer with electrodes insulated by a gate oxide from the bulk semiconductor is the charging of the insulated feature by the charge of the beam ions. This effect, commonly referred to as charging, can be detrimental to the semiconductor circuit if the voltages of the insulated feature (e.g. the gate electrode) exceed the breakdown voltage of the insulator (e.g. the gate oxide) such that resultant damage to the gate oxide occurs. It can be appreciated that the charging rate and voltage increase with beam current, and that ion implantation with ever increasing beam currents represents an increasing processing challenge. To counteract the charging problem, the charging of the ion beam can be compensated for by providing electric charge of the opposite sign to the workpiece to be implanted. For a positive ion beam it is common practice to provide electrons in an amount equal to the amount of ions per unit time to the workpiece, i.e., to match the ion beam current with an equal electron current to the workpiece. This is typically brought about by devices generating electrons via electron generating processes such as thermionic emission, secondary emission, or discharge, and directing the electrons directly to the workpiece. These devices are typically designated electron guns, secondary electron flood, plasma electron flood, etc. Another continuing trend is toward larger semiconductor workpiece sizes, such as 300 mm diameter wafers. Coupled with higher device densities, the larger workpiece size increases the cost of individual workpieces. As a result, control over implantation uniformity with respect to ion beams and other parameters is more critical than ever in avoiding or mitigating the cost associated with scrapping workpieces. The ion beam is shaped according to the ion source extraction opening and subsequent shaping apparatus, comprising, for example, mass analyzers, resolving apertures, quadrupole magnets, and ion accelerators, by which an ion beam is provided to target workpieces or wafers. The beam and/or the target workpiece are translated with respect to one another to effect the ion beam scanning of the workpiece. Another technique used to limit beam blow-up in an ion beam is uniform charge neutralization utilizing electrons released into the ion beam. As for charge reduction, an electron discharge device typically involves making electrons utilizing ionization processes, energizing those electrons and colliding them with a gas. The energization can be done with a DC electric field (e.g., for a DC arc discharge) or a time varying electric field (e.g., for an AC arc discharge, an RF discharge, a microwave discharge, etc.). The type of discharge used is often based on the electrical characteristics that are desired (e.g., density distribution, densities achieved, etc.). Furthermore, microwave and RF discharges (e.g., RF plasma electron flood) can be scaled to large volumes but are more complicated and expensive to try to sustain, requiring matching circuits and costly high-frequency power generation. FIGS. 1-3, 4A, 4B, and 5-7 illustrate a prior art wafer charge compensation device described in U.S. Published Patent 2006/0113492. In this example, this prior art device is applied particularly to a single-wafer ion implantation system among beam processing systems each using a charged particle beam. FIGS. 1 and 2 are a plan view and a side view, respectively, showing a schematic structure of the single-wafer ion implantation system. The illustrated prior art ion implantation system comprises an ion source unit 11 (including ion source and extraction electrode), a mass analysis magnet device 12, a beam shaper 13, a deflector 14 for scanning, a P (i.e., parallelizing) lens 15, acceleration/deceleration electrodes 16, a deflecting energy filter 17, and a process chamber 18. In this prior art ion implantation system, ions generated in the ion source unit 11 are extracted through the extraction electrode (not illustrated) as an ion beam (hereinafter referred to as a “beam”). The extracted beam is subjected to a mass analysis in the mass analysis magnet device 12 so that only a necessary ion species is selected for implantation. The beam composed of only the necessary ion species is shaped in cross-section by the beam shaper 13. The beam shaper 13 is formed by a Q (quadrant or quadrupole) lens and so on. The beam having the shaped cross-section is deflected in an upward/downward direction in FIG. 1 by the deflector 14 for scanning. The deflector 14 has at least one shield upstream electrode 14-1 and at least one downstream shield electrode 14-2 that are disposed near the deflector 14 on its upstream and downstream sides, respectively. Although deflection scan electrodes are used as the deflector 14 for scanning in this embodiment, a deflection scan magnet may be used in place of them. The beam deflected by the deflector 14 for scanning is parallelized by the P-lens 15 formed by electrodes or a magnet so as to be parallel to an axis of a deflection angle of 0 degrees. In FIG. 1, a scan range by a reciprocal swinging beam by the deflector 14 is indicated by a thick black line and double broken lines. The beam from the P-lens 15 is accelerated or decelerated by one or more acceleration/deceleration electrodes 16 and sent to the deflecting energy filter 17. The deflecting energy filter 17 performs an energy analysis of the beam to thereby select only an ion species having a necessary energy. As shown in FIG. 2, only the selected ion species is deflected slightly downward in the deflecting energy filter 17. The beam composed of only the selected ion species is implanted into a wafer 19 that is a to-be-irradiated object introduced in the process chamber 18. The beam that is deviated from the workpiece 19 is incident on a beam stopper 18-1 provided in the process chamber 18 so that energy thereof is consumed. A transportation path of the beam is all maintained in a high-vacuum state. In FIG. 1, arrows shown adjacent to the wafer 19 represent that the beam is deflected for scanning in directions of these arrows, while, in FIG. 2, arrows shown adjacent to the wafer 19 represent that the wafer 19 is moved in directions of these arrows. Specifically, assuming that the beam is reciprocatingly deflected for scanning in, for example, x-axis directions, the wafer 19 is driven by a drive mechanism (not illustrated) so as to be reciprocated in y-axis directions perpendicular to the x-axis directions. This enables irradiation with the beam over the whole surface of the wafer 19. In the manner as described above, in the prior art ion implantation system shown in FIGS. 1 and 2, a beam having an elliptical or oval continuous cross-section that is long in one direction can be obtained by deflection a beam having a circular cross-section or an elliptical or oval cross-section and then bent at a uniform angle at any positions in a scan area thereof by the use of the deflecting energy filter serving as a later-stage energy analyzer and finally can be implanted into the wafer 19. A charge compensation device 30 according to this prior art is provided on the downstream side of the deflector 14 and, more specifically, on the downstream side of the deflecting energy filter 17. The charge compensation device is also called a plasma shower. The charge compensation device 30 is located outside the process chamber 18 in FIGS. 1 and 2 but may be disposed inside the process chamber 18. Referring to prior art FIGS. 3, 4A and 4B, a prior art ion source or charge compensation device 30 will be described. The prior art charge compensation device 30 comprises a first arc chamber 34 provided with a filament 31, a gas introduction port 32, and one or more first extraction holes 33, and a second arc chamber 35. The second arc chamber 35 has a second extraction hole 36 and is attached to a tubular or hollow cylindrical or rectangular member (flood box) 40 such that the second extraction hole 36 is exposed to an inner space 50 of the hollow cylindrical or rectangular member 40 and is faced on the reciprocal swinging beam of the scan area. The hollow cylindrical or rectangular member 40 may be part of a process chamber (not shown) on its inlet side or may be disposed in the process chamber. In any event, the second arc chamber 35 has a length approximately extending over the whole width of the hollow cylindrical or rectangular member 40. In FIG. 5, symbol SA denotes a scan range or area 50 (deflecting range or area) by the beam in the hollow cylindrical or rectangular member 40. In this embodiment, the second extraction hole 36 is realized by a plurality of holes 36 arranged at intervals in a direction of the length of the second arc chamber 35 in the scan area SA. Alternatively, the second extraction hole 36 may be realized by a single slit extending over the scan area SA. In the case of either the plurality of holes or the single silt, the opening distribution or shape of the second extraction hole 36 is configured to correspond to a second plasma density distribution in the second arc chamber 35. That is, it is desirable that the opening density be high at a portion where the plasma density is low while the opening density is low at a portion where the plasma density is high. Specifically, when the second extraction hole 36 is realized by the plurality of holes, the interval of the holes is shortened at the portion where the plasma density is low while the interval of the holes is increased at the portion where the plasma density is high. On the other hand, when the second extraction hole 36 is realized by the single slit, the width of the slit is increased at the portion where the plasma density is low while the width of the slit is reduced at the portion where the plasma density is high. The first arc chamber 34 is attached to a wall of the second arc chamber 35 such that the first extraction hole 33 is exposed or opened up to the second arc chamber 35 at a position near an intermediate portion in the length direction of the second arc chamber 35. At a boundary portion between the first and second arc chambers 34 and 35, there is provided a first extraction electrode 37 having a hole at a position corresponding to the first extraction hole 33. However, the first extraction electrode 37 may be omitted. In this case, a second arc voltage, which will be described later, is supplied between the first and second arc chambers 34 and 35 for producing second plasma in the second arc chamber 35. A plurality of permanent magnets 38 are disposed at wall surfaces of the second arc chamber 35 excluding those regions where the first arc chamber 34 and the second extraction hole 36 are respectively provided. That is, the permanent magnets 38 are arranged at intervals at each of the upper and lower wall surfaces, the left and right wall surfaces, and the both-side end wall surfaces of the second arc chamber 35. The permanent magnets 38 serve to form confinement magnetic fields (cusp magnetic fields for confinement) in the second arc chamber 35. Therefore, all the permanent magnets 38 are disposed with their magnetic poles directed toward the inside of the second arc chamber 35 and with the magnetic poles of the adjacent permanent magnets 38 being opposite to each other. In FIG. 5, magnetic fluxes forming the confinement magnetic fields are partly shown by arrows. FIGS. 6 and 7 show an arrangement of the permanent magnets 38 at one of the both-side end wall surfaces of the second arc chamber 35. Herein, since the shape of the end wall surface is square, a plurality of square frame-shaped permanent magnets 38 having different sizes are disposed concentrically and a square permanent magnet 38 is disposed in the innermost-side frame-shaped permanent magnet 38. These permanent magnets 38 are also disposed with their magnetic poles directed toward the inside of the second arc chamber 35 and with the magnetic poles of the adjacent permanent magnets 38 being opposite to each other. The permanent magnet 38 may have another polygonal shape including a triangular shape. If the shape of the end wall surface is circular, the permanent magnet 38 may have an annular shape. Note that the first and second arc chambers 34 and 35 are supported by an arc chamber support 39 (FIG. 3). The power is supplied to the filament 31 through a filament feed 41 attached to the arc chamber support 39. In FIGS. 1 and 2, the charge compensation device 30 is disposed at a position where the beam is deflected slightly downward. On the other hand, in FIG. 5, the hollow cylindrical or rectangular member 40 is illustrated in the horizontal state. In order to dispose the charge compensation device 30 as shown in FIGS. 1 and 2, the whole device is inclined so as to match a deflection angle of the beam. A gas such as Argon is introduced into the first arc chamber 34 through the gas introduction port 32. A power is supplied from a filament power supply 42 to the filament 31 disposed in the first arc chamber 34 to heat the filament 31 to a high temperature to thereby generate electrons via thermionic emission. The thermionically emitted electrons are accelerated by a first arc voltage supplied between the filament 31 and the first arc chamber 34 from a first arc power supply 43. The accelerated electrons collide with the introduced gas so that the first plasma is produced in the first arc chamber 34. The first arc chamber 34 is provided with one or more first extraction holes 33 and the first extraction electrode 37 is disposed on the outside thereof. By supplying a first extraction voltage between the first extraction electrode 37 and the first arc chamber 34 from a first extraction power supply 44, first electrons are extracted from the first arc chamber 34. The second arc chamber 35 having the length corresponding to the scan area SA is introduced with a neutral gas ejected from the first extraction hole 33 without ionization in the first arc chamber 34 and with the first electrons extracted from the first arc chamber 34. Even if a material of the filament 31 should be scattered due to evaporation or the like, since the size of the first extraction hole 33 is small, the scattered material stays within the first arc chamber 34 and thus is not introduced into the second arc chamber 35. The first electrons introduced into the second arc chamber 35 are accelerated by a second arc voltage supplied between the second arc chamber 35 and the first extraction electrode 37 from a second arc power supply 45. The accelerated electrons collide with the gas introduced from the first arc chamber 34 so that dense second plasma is produced in the second arc chamber 35. Since the plurality of permanent magnets 38 are arranged at the wall surfaces of the second arc chamber 35 to form the confinement magnetic fields, it is possible to suppress the loss of electrons at those wall surfaces and improve the plasma uniformity in the scan direction in the second arc chamber 35. In order to keep the temperature of the permanent magnets 38 below their Curie temperature, i.e. prevent thermal demagnetization of the permanent magnets 38, the second arc chamber 35 is cooled by water cooling or the like. The second arc chamber 35 is provided with the second extraction hole 36 at the position facing a beam passing region. In this embodiment, as described before, the second extraction hole 36 is in the form of the plurality of holes arranged corresponding to the scan area SA of the beam. Alternatively, the second extraction hole 36 may be realized by an opening in the form of the single slit extending over the scan area SA, which has also been described before. The second arc chamber 35 is configured so as not to allow leakage of the gas from other than the second extraction hole 36, thereby preventing a reduction in gas pressure within the second arc chamber 35 to enhance the plasma production efficiency. When the beam passes near the second extraction hole 36, second electrons are extracted from the second arc chamber 35 by the positive potential of the beam. The extracted second electrons collide with a neutral gas ejected from the second extraction hole 36 without ionization in the first and second arc chambers 34 and 35. As a result, plasma (plasma bridge) is formed between the beam (reciprocal swinging beam) and the second arc chamber 35 (precisely the second extraction hole 36). The second electrons in the second arc chamber 35 are autonomously supplied to the beam through the plasma bridge. Since the second extraction hole 36 exists in the region corresponding to the scan area SA, even when the position of the beam moves by deflecting for scanning, the plasma bridge is constantly formed between the beam and the second arc chamber 35 to thereby achieve the autonomous electron supply. The second arc chamber 35 is configured so as to be supplied with a second extraction voltage between itself and the ground potential from a second extraction power supply 46. With this configuration, it is possible to adjust the amount and energy of electrons supplied to the beam. The current value (arc current) between the second arc power supply 45 and the second extraction power supply 46 may be measured and fed back so as to control the power supplies to achieve a constant arc current. The second extraction hole 36 and the scan area by the beam thereabout are covered with the hollow cylindrical or rectangular member 40. The potential of the hollow cylindrical or rectangular member 40 may be set different from that of the second arc chamber 35 to enable an adjustment of the amount of second electrons extracted from the second arc chamber 35 and supplied to the wafer or may be set equal to that of the second arc chamber 35 to achieve a simple structure. Inner walls 50 (surfaces in contact with the beam) of the hollow cylindrical or rectangular member 40 are formed serrated to thereby prevent adhesion of insulating stains to the whole surfaces of the inner walls. Further, on the beam upstream side of the hollow cylindrical or rectangular member 40 is disposed a bias electrode 48 that can be applied with a negative voltage from a bias power supply 47. This makes it possible to prevent scattering of electrons in the beam upstream direction and efficiently transport electrons toward the downstream side (toward the wafer). The hollow cylindrical or rectangular member 40 is further provided with magnetic shielding to thereby shield an external magnetic field, for example, a magnetic field from the deflecting energy filter 17. This is because when the external magnetic field is strong, electrons wind around the lines of magnetic field thereof so that the electrons are lost before reaching the wafer. With the foregoing structure, the second extraction hole 36 exists in the region corresponding to the scan area SA. Accordingly, when the plasma is produced in the second arc chamber 35, even if the position of the beam moves by deflecting for scanning, the plasma bridge is constantly formed between the beam and the second arc chamber 35 to thereby carry out an equilibrium electron supply. In addition, since the confinement magnetic fields are generated inside the second arc chamber 35, the loss of electrons at the inner wall surfaces of the second arc chamber 35 is reduced. This makes it possible to improve the plasma production efficiency and uniformity of the plasma within the second arc chamber 35, thereby enabling a sufficient supply of electrons to the beam somewhat regardless of the scan position of the beam. However, this plasma source arrangement relies on diffusion and does not warrant equal plasma properties of the plasma in the second arc chamber; it can also be relatively expensive, due to the use and arrangement of magnets and design details. Accordingly, it is desirable to provide charging prevention and improved uniform charge neutralization devices and methodologies by which uniform ion beams may be provided for implanting semiconductor workpieces that is less costly and difficult to fabricate. The following presents a simplified summary in order to provide a basic understanding of one or more aspects of the invention. This summary is not an extensive overview of the invention, and is neither intended to identify key or critical elements of the invention, nor to delineate the scope thereof. Rather, the primary purpose of the summary is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later. The present invention is directed to methods and apparatus for implanting workpieces using an ion beam, by which the above mentioned and other shortcomings associated with the prior art may be overcome or mitigated. In particular, the invention provides implantation systems wherein a relatively wide ion beam, such as a ribbon beam or a pencil beam scanned into a time-averaged ribbon beam, is produced by an ion source, which is then charged neutralized. According to one aspect of the invention, a plasma electron flood system, comprising a housing with a discharge chamber configured to contain a gas, and comprising an elongated extraction slit, a cathode and a plurality of anodes residing therein. The elongated extraction slit is in direct communication with an ion implantation system wherein the cathode emits electrons that are drawn to the plurality of anodes through a potential difference therebetween. A fraction of the emitted electrons are released through the elongated extraction slit as a band of electrons for use in neutralizing an ion beam traveling within the ion implantation system. Another implementation of the invention involves an ion implantation system comprising an ion source that produces a relatively wide ion beam along a longitudinal path, a mass analyzer that provides a magnetic field across the path so as to deflect ions of the beam at varying trajectories according to mass. An end station receives the mass analyzed ion beam from the beamline system and supports at least one workpiece along the path for implantation using the mass analyzed ion beam. A discharge chamber within the housing comprises a plurality of anodes, a cathode and an elongated extraction slit and the cathode emits electrons that are drawn to the plurality of anodes through a potential difference between them. The elongated extraction slit emits a portion of the electrons as an elongated band into the ion beam. Yet another aspect of the invention provides a method of introducing electrons into an ion beam, comprising energizing a cathode within a discharge chamber, biasing the cathode, a discharge chamber housing and an anode and emitting electrons through an elongated extraction slit into the ribbon ion beam. Another aspect of the present invention provides a method of implanting a workpiece using a static or time-averaged ribbon ion beam in an ion implantation system, comprising creating a ribbon ion beam and mass analyzing the ribbon ion beam. The method further providing an elongated band of electrons to the ribbon ion beam and providing the mass analyzed ribbon ion beam to at least one workpiece so as to implant the at least one workpiece with ions from the ribbon ion beam. In another implementation of the invention, involves an ion implantation system for implanting a workpiece using an ion beam, comprising means for creating a ribbon ion beam, means for mass analyzing the ribbon ion beam, means for providing an elongated band of electrons to the mass analyzed ribbon ion beam, means for providing the mass analyzed ribbon ion beam to a workpiece so as to implant the workpiece with ions from the ribbon ion beam. To the accomplishment of the foregoing and related ends, the following description and annexed drawings set forth in detail certain illustrative aspects and implementations of the invention. These are indicative of but a few of the various ways in which the principles of the invention may be employed. Other aspects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings. The present invention will now be described with reference to the drawings wherein like reference numerals are used to refer to like elements throughout. The invention provides methods and systems for provision of a plasma electron flooded ion beam for ion implantation of workpieces such as semiconductor workpieces. One implementation of the invention is illustrated and described hereinafter with respect to the drawing figures. The illustrations and following descriptions are exemplary in nature, and not limiting. Thus, it will be appreciated that variants of the illustrated systems and methods and other such implementations apart from those illustrated herein are deemed as falling within the scope of the present invention and the appended claims. Referring initially to FIG. 8 the figure illustrates an exploded partial view of the invention which provides a plasma electron flood system (PEF) 800 comprising a housing 802 configured to contain a gas introduced by e.g., a valve (not shown) within a discharge chamber 816. The housing 802 of the PEF system 800 has a cross-section of dimensions 818 by 820 with desired cutouts (e.g., inner diameter 822) that can be extruded to any desired extruded length 824, for example 300 or 450 millimeters. It should be appreciated that the housing 802 can also be machined, laser cut, and the like. The plasma electron flood system 800 further comprises an elongated extraction slit 806, a cathode assembly 808, a plurality of anodes 810 and an elongated cathode filament 814, residing therein. In this embodiment, the elongated extraction slit 806 is formed within a slit plate 812 and the elongated extraction slit 806 can be in direct communication with an ion implanter (not shown). The cathode assembly 808 is energized to emit electrons from a cathode filament 814 that are drawn to the plurality of anodes through a potential difference therebetween. The electrons are released through the elongated extraction slit 806 as approximately an electron band for use in neutralizing a ribbon ion beam traveling within the ion implanter. The inventors recognized that by introducing electrons in this manner there would be an equal path length for electrons to reach a pencil, wide or ribbon ion beam in contrast to the unequal path length there is with point-source type technology, and that the charge neutralization would be more uniform across the width of the ion beam, for example. To minimize contamination within the discharge chamber 816 and thus the ribbon ion beam, the cathode filament 814 and the plurality of anodes 810 can comprise graphite. It will be appreciated that tungsten (W), molybdenum (Mo), and tantalum (Ta) and other refractory materials commonly used in this technology can also be used. In one embodiment, referring to FIGS. 8 and 9A, the plurality of anodes 810 (FIGS. 8 and 9A) are configured using reflex geometry, i.e., a relatively small anode area such that electrons accelerated toward the anodes 810 have a low probability of intercepting the anodes 810. The transit time of primary electrons from the cathode filament 814 to the anodes 810 is increased which enhances the numbers of electron-neutral collisions, thus the electron generation and the discharge density of the plasma, which lets the plasma electron flood system 800 operate at low pressures within the discharge chamber 816. The discharge chamber 816 can have a large diameter 822 (e.g., 100 mm or greater), wherein the cathode filament 814 has a diameter of 0.9 mm, for example. The cathode filament 814 current can be set at 40 A, with a resultant cathode filament 814 temperature of approximately 2500° C. and a relatively low self-magnetization (e.g., less than 100 Gauss). There can be three anodes 810, for example, each having a diameter of 3 mm and therefore the anodes 110 are small enough in diameter to create a reflex geometry and yet large enough to ensure plasma discharge stability. The gas comprises Xenon, for example, and operates at about 5×10−5 to 1×10−4 Torr partial pressure within the discharge chamber 116 of the plasma electron flood system 100. Alternatively to Xenon the gas can also comprise Argon. With the cathode 810 at the same electrostatic potential as the housing 102, for example, the primary electrons are confined electrostatically, which in turn increases both the plasma confinement and thus plasma density. The plasma electron flood system 800 can operate as a DC discharge at low pressures in a Townsend discharge mode, wherein electrons are injected from the cathode filament 814 in order to sustain the ongoing discharge. Thereby the pressure of the Xenon gas can be kept low (e.g., less than 5e-5 Torr), for example, which can reduce the partial pressure of Xenon in the system and can minimize some the detrimental effects of charge exchange the ion beams experience at higher pressures (e.g., greater than 5e-6 Torr). Biasing the anodes 810 electrically positive and electrically grounding the cathode filament 814 and housing 802 provides electron energy filtering so that only collisional or thermalized electrons can leave the discharge chamber 816 through the elongated extraction slit opening 806, for example. Referring now to FIG. 9B (not drawn to scale), the housing 802 (FIG. 1) can be configured so that an electron elongated extraction slit 806 is transverse to the direction of propagation of an ion beam 802, for example as illustrated, such that the elongated band of extracted electrons is provided into the ribbon ion beam transverse to the length of the ribbon ion beam, as illustrated in FIG. 9B. This ensures uniformity of charge neutralization, allowing electrons 902 to exit from the plasma electron flood system (PEF) 950 all along the elongated extraction slit 806 in a slit plate 812. It should be appreciated that the elongated extraction slit 806 in the slit plate 812 can be an integral part of the PEF 900 (FIG. 9) rather than as illustrated, for example. The length of the slit 916 can be made to match the width 910 of the ribbon ion beam 904, for example to aid ion beam uniformity. In addition, the length of the slit 916 can be made automatically adjustable, based upon the wafer size, utilizing masking or other techniques that are well known by those of skill in the art, for example. Referring to FIG. 10, the invention provides an ion implantation system 1000 comprising an ion source 1002 for producing an elongated (e.g., a pencil ion beam, a ribbon-shaped, etc.) ion beam 1004 along a longitudinal beam path. The ion beam source 1002 includes a plasma source 1006 with an associated power source 1008 and an extraction apparatus 1010, which may be of any design by which the elongated ribbon ion beam 1004 of large aspect ratio is extracted, for example. The following examples are provided to more fully illustrate the invention, but are not to be construed as limiting the scope thereof. For instance, the plasma source 1006 may comprise a relatively long plasma confinement chamber from which the ribbon-beam 1004 can be extracted using a high aspect ratio extraction slit in the extraction apparatus 1010. The ribbon-beam 1004 comprises a transverse width and a transverse height defining a first aspect ratio, wherein the transverse width is much larger than the transverse height. For example, the width of the elongated ion beam 1004 extracted from the plasma source 1006 can be approximately 400 mm, for example and the height can be 10 mm, for example. The formation of ribbon ion beams and other type ion beams is well known by those of ordinary skill in the art. A beamline system 1012 is provided downstream of the ion source 1002 to receive the beam 1004 therefrom, comprising a mass analyzer 1014 positioned along the path to receive the beam 1004. The mass analyzer 1014 operates to provide a magnetic field across the path so as to deflect ions from the ion beam 1004 at varying trajectories according to mass (e.g., charge to mass ratio) in order to provide an elongated mass analyzed ion beam 1004 having a second aspect ratio and profile substantially similar to the first aspect ratio. An end station 1022 is provided in the system 1000, which receives the mass analyzed ion beam 1004 from the beamline system 1012 and supports one or more workpieces such as semiconductor workpieces along the path for implantation using the mass analyzed ion beam 1004. The end station 1022 includes a target scanning system 1020 for translating or scanning one or more target workpieces and the elongated ion beam 1004 relative to one another. The target scanning system 1020 may provide for batch or serial implantation. In accordance with another aspect of the present invention, FIG. 11 illustrates an exemplary method 1100 for transferring a plurality of electrons created within a plasma chamber into a ribbon ion beam associated with a plasma flood electron system 100 (FIG. 1). The system 100 illustrated in FIG. 1, for example, can be operated in accordance with the method 1100 of FIG. 11. It is noted that acts performed within the plasma flood electron system 100 (FIG. 1) can be performed concurrently (in parallel) or in series. It should also be noted that while exemplary methods are illustrated and described herein as a series of acts or events, it will be appreciated that the present invention is not limited by the illustrated ordering of such acts or events, as some steps may occur in different orders and/or concurrently with other steps apart from that shown and described herein, in accordance with the invention. In addition, not all illustrated steps may be required to implement a methodology in accordance with the present invention. Moreover, it will be appreciated that the methods may be implemented in association with the system 100 illustrated and described herein as well as in association with other systems not illustrated. As illustrated in FIG. 11, the method 1100 begins at 1102 a ribbon ion beam is created using techniques that are well known by those of skill in the art. The invention provides an ion source 1002 (FIG. 10) for producing an elongated (e.g., a ribbon-shaped, etc.) ion beam 1004 (FIG. 10) along a longitudinal beam path. The ion beam source 1002 (FIG. 10) includes a plasma source 1006 (FIG. 10) with an associated power source 1008 (FIG. 10) and extraction apparatus 1010 (FIG. 10), which may be of any design by which the elongated ribbon ion beam 1004 of large aspect ratio is extracted, for example. As discussed supra, the following examples are provided to more completely illustrate the invention, but are not to be construed as limiting the scope thereof. For instance, the plasma source 1006 may comprise a relatively long plasma confinement chamber from which the ribbon ion beam 1004 can be extracted using a high aspect ratio extraction slit in the extraction apparatus 1010. The ribbon-beam 1004 comprises a transverse width and a transverse height defining a first aspect ratio, wherein the transverse width is much larger than the transverse height. For example, the width of the elongated ion beam 1004 extracted from the plasma source 1006 can be approximately 400 mm, for example and the height can be 10 mm, for example. At 1104 the ribbon beam is mass analyzed to select ions of a desired charge-to-mass ratio. The mass analysis apparatus for mass resolving the ion beam uses magnetic fields. The mass of an ion relative to the charge thereon (e.g., charge-to-mass ratio) affects the degree to which the ions are accelerated both axially and transversely by an electrostatic or magnetic field. Therefore, the beam which reaches a desired area of a semiconductor wafer or other target can be made very pure since ions of undesirable molecular weight will be deflected to positions away from the beam and implantation of other than desired materials can be avoided. The mass analyzer can employ a mass analysis magnet(s) creating a dipole magnetic field to deflect various ions in an ion beam via magnetic deflection in an arcuate passageway that will effectively separate ions of different charge-to-mass ratios. Mass analysis techniques are well known by those of skill in the art. Continuing at 1106 a cathode and a plurality of anodes within the discharge chamber of the plasma flood electron system 800 (FIG. 8) are energized. The cathode 810 current can be set at 40 A, with a resultant cathode 810 temperature of approximately 2500° C. and a relatively low self-magnetization (e.g., less than 100 Gauss). The plurality of anodes 810 (e.g., three) can each of the anodes having a diameter of 3 mm, for example. The gas within the plasma chamber 816 can comprise Xenon, for example, and can operate at about 5×10−5 to 1×10−4 Torr within the plasma chamber 116 (FIG. 1) of the plasma electron flood system 800 (FIG. 8). Components 810, 802 and 814 can be biased electrostatically to provide electrostatic confinement of the discharge plasma and energy filtering of the electrons leaving through the extraction slit 806; for example, the cathode 810 (FIG. 8) and the discharge chamber housing 802 can be biased to ground potential and the anodes 810 (FIG. 1) can be biased to 100 Volts. An electron leaving the cathode 810 (FIG. 8) will have close to zero (0) electron-Volts initial kinetic energy, when it reaches the anode 110 (FIG. 1) it will have gained 100 electron-Volts of kinetic energy (100 eV). If the electron collides with an atom on the path to the anode, it can acquire at most a kinetic energy of 100 eV plus the energy of the atom, for example 1 eV; and therefore will have a total maximum energy of 101 eV. Such an electron or any electron acquiring a total energy larger than 100 eV could leave the discharge chamber through the extraction slit, loosing 100 eV of energy and leaving with typically 1 eV of kinetic energy, for example. At 1106 numerous such electrons, typically referred to as collisional, thermalized or secondary electrons are delivered in this manner into the ribbon ion beam 202 (FIG. 2). The collisional electrons are particularly useful to neutralize the ion beam 202 prior to implantation in a workpiece. Thus electrons created within the discharge chamber can be introduced into the ribbon ion beam as an elongated band of electrons passing through the elongated slit. As both anode and cathode can be subject to sputtering and evaporation the cathode filament 814 can comprise graphite, and both tungsten (W), molybdenum (MO), and tantalum (Ta) are optional materials, for example. Thereby the risk of wafer contamination from cathode material can be minimized. The anodes 810 can comprise graphite, or aluminum (Al), both materials with little contamination risk to silicon wafer, or molybdenum (Mo), and tungsten (W), and the like. At 1108 the mass analyzed ribbon ion beam is provided to at least one workpiece so as to implant the at least one workpiece w/ions, wherein the method ends. Although the invention has been illustrated and described above with respect to a certain aspects and implementations, it will be appreciated that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, circuits, systems, etc.), the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure, which performs the function in the herein illustrated exemplary implementations of the invention. In this regard, it will also be recognized that the invention includes a computer-readable medium having computer-executable instructions for performing the steps of the various methods of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms “includes”, “including”, “has”, “having”, “with” and variants thereof are used in either the detailed description or the claims, these terms are intended to be inclusive in a manner similar to the term “comprising”.
	description	This is a continuation of application Ser. No. 10/878,528 filed 29 Jun. 2004, now U.S. Pat. No. 6,927,391 which is a continuation of application Ser. No. 09/960,479 filed 24 Sep. 2001, now U.S. Pat. No. 6,781,125, which claims priority to Japanese Patent Application No. 2000-340387 filed 02 Nov. 2000 and No. 2000-344226 filed 07 Nov. 2000, the contents of which are incorporated herein by reference in their entirety. The present invention relates to an apparatus system used as observation, analysis and evaluation means in research and development and manufacturing of an electronic device such as a semiconductor device, liquid crystal device and a magnetic head, a micro-electronic device or the like which require observation and analysis of not only a surface of an object to be observed but also an inner section near the surface. In manufacturing of a semiconductor device such as a semiconductor memory typified by a dynamic random access memory, a microprocessor and a semiconductor laser, and electronic parts such as a magnetic head, a product property is inspected for quality control of a product during a manufacturing process or at completion of the process. In the inspection, measurement of manufacturing dimension, defect inspection of a circuit pattern, or analysis of foreign materials are carried out. For that purpose, various means are prepared and used. Particularly, when there is a wrong portion within the product, a minute processing and observation apparatus is increasingly used which comprises a combination of a focused ion beam (FIB) apparatus and an electron microscope. This apparatus is disclosed in JP-A-11-260307 specification. In the specification, disclosed is a technique of carrying out section processing of a sample by an FIB apparatus and observing an exposed section by an electron microscope disposed slantingly above the sample. As another technique of observing the sample section, invented and used is a method of taking out of a processing and observation apparatus a minute sample, which is a cut-out minute area of micron orders including an observation region, and moving the minute sample to a separately prepared apparatus to be reprocessed into an optimum shape and observed and analyzed. This method is disclosed in JP-A-5-52721 specification. This is a method of cutting out part of a sample and observing its section, where a tip of a probe driven by a manipulator is positioned on a minute sample cut by an FIB, the probe and minute sample are connected by a deposition gas, and the minute sample is transferred in the connected condition. The above described conventional methods have the following problems. First, to observe a section of a hole or groove of the sample formed by FIB processing, a sample stage is inclined to thereby observe a section of an inner wall of the hole or groove in a slanting direction. In that case, an adjustment range of inclination of the sample stage is limited by constraints in structure due to a working distance of an FIB apparatus, presence of an objective lens, or size of a sample stage, and larger inclination cannot be allowed. Thus, vertical observation of the section of the inner wall of the hole or groove is impossible. The vertical observation of the section is indispensable in confirmation of processing properties such as dry etching, planarization, thin film forming, or the like in process development or the like of semiconductor device manufacturing, but the above described known apparatuses cannot cope with the vertical observation. Second, a reduction in resolution resulting from the slant observation becomes a serious problem. When slantingly emitting an electron beam to a wafer surface from above and to observe a section of an inner wall of a hole or groove, observation resolution in a direction perpendicular to the wafer surface, that is, of the section of the inner wall of the hole or groove is reduced. A reduction rate reaches approximately 15% at an angle of 30°, and 30% at an angle of around 45°, which is most frequently used. Miniaturization of recent semiconductor devices has reached the limit, and measurement of the dimension or shape with accuracy below a few nano meters is required. Required observation resolution is less than 3 nm, which falls below a technical limit area of a scanning electron microscope. In addition, with high resolution of such degree, depth of focus is extremely shallow and focusing is achieved only in a range below some ten percent of 1 μm, so that an appropriate observation range of a vertical section of the device at the time of slant observation is often less than half of a required area. This problem can be solved by vertical observation. The vertical observation enables superior observation in focus on the whole observation area. Third, the observation section exists on a wall surface of a minute hole or groove formed in the wafer, so that numeral density of secondary electrons coming out of the hole are reduced in comparison with those on the surface of the wafer. Thus, secondary electron detecting efficiency is reduced and it causes a reduction in S/N of a secondary electron image, inevitably resulting in a reduction in accuracy of the section observation. Miniaturization of LSI patterns progresses at a rate of 30% reduction every a few years without stop, and higher resolution is increasingly required in the observation apparatus. Moreover, even if surface distribution of an atomic property X-ray excited by emitting an electron beam is measured by an X-ray detector to carry out elementary analysis (EDX analysis), enlargement of an X-ray generation area due to the electron beam entering into the sample causes surface resolution of analysis to be approximately 1 μm though the electron beam has a diameter equal or less than 0.1 μm, which is insufficient for analysis of the LSI element section having a minute structure. Fourth, cases where the vertical observation of the section is indispensable include evaluation of workmanship of etching, implantation of grooves or holes, planarization or the like in wafer process. In order to accurately measure a dimension and shape of a processed section, a sample of a chip size including a section to be observed has been determined and observed by a scanning electron microscope for general purpose in the past. However, accompanying with miniaturization progress of devices and enlargement of diameter of the wafer, sometimes failure is resulted since it is considerably difficult to accurately break an element circuit pattern at a position to be observed. However, failure in creating an evaluation sample is not allowed because of poor supply capacity or increased price of the wafer for evaluation. Fifth, with the technique disclosed in JP-A-5-52721 specification, it is possible to obtain sufficient level of observation and analysis accuracy such as resolution, but the sample has to be manufactured in the conventional apparatus, taken out of the apparatus, and introduced into the separately prepared observation and analysis apparatus, thus there is a problem of requiring hours of time for taking out the minute sample, processing, observation and analysis. Further, in a case where the sample exposed to the air is degraded by oxidation or moisture adsorption, it is difficult to avoid the degradation. Section observation of the semiconductor device has been recently considered to be important as an advantageous inspection technique in manufacturing the semiconductor, and a desirable throughput in that case at present is observation and analysis of more than a few positions per hour, and processing at much higher speed will be desired in the future. Contrary to the desire, the problem of extremely low throughput of the conventional method has not been solved. In view of the above problems, the present invention has its object to provide a method and apparatus for processing and observing a minute sample, which can vertically observe an inner section of the sample to be observed, and can carry out observation and analysis with high resolution, high accuracy and high throughput without degradation resulting from exposure to the air and without failure. Another object of the present invention is to provide a minute sample processing apparatus which requires minimum capacity of a vacuum container and a reduced occupying area and has high operability even when the apparatus is intended for a large sample. Still another object of the present invention will be described in embodiments described hereinafter. In order to attain the above object, there is provided a minute sample processing apparatus, including: a focused ion beam optical system comprising an ion source, a lens for focusing an ion beam and an ion beam scanning deflector; an electron beam optical system comprising an electron source, a lens for focusing an electron beam and an electron beam scanning deflector; a detector for detecting a secondary particle emitted from the sample; and a sample stage on which the sample is placed, wherein the apparatus further comprises a probe for supporting a minute sample cut out by emitting the ion beam to the sample, and a mechanism for operating the probe. Further, in order to attain another object, there is provided a charged particle beam apparatus, including: a sample stage for placing a sample in a vacuum container; a charged particle source; a irradiation optical system for irradiating a charged particle beam from the charged particle source to the sample; a secondary particle detector for detecting a secondary particle generated from the sample by applying the charged particle beam to the sample; a needle member whose tip is capable of coming into contact with the sample; a probe holder for holding the needle member; an introduction mechanism capable of introducing and extracting the probe holder into and from the vacuum container; and a moving mechanism having a mechanism of slanting the probe holder to a surface of the sample stage. Structure and technical effects for achieving other objects of the present invention will be described in embodiments described hereinafter. A structure and an operation of a minute sample processing and observation apparatus according to the present invention will be described. (Embodiment 1) A structure and an operation of a first embodiment of an apparatus of the invention will be described with reference to FIGS. 1, 2 and 3. FIGS. 1 and 2 show a whole structure of the apparatus and FIG. 3 shows structures of a focused ion beam optical system, scanning electron microscope optical system and around a sample stage in detail. Shown in this embodiment is a wafer corresponding apparatus in the minute sample processing and observation apparatus of the present invention. FIG. 3 shows a schematic bird's eye section of FIG. 1, and there are some differences between the figures, though not essential, in orientations or details of apparatuses for convenience in description. In FIG. 1, around a center of an apparatus system are appropriately located a focused ion beam optical system 31 and an electron beam optical system 41 above a vacuum sample chamber 60. A sample stage 24 on which a wafer 21 to be a sample is placed is located inside the vacuum sample chamber 60. Two optical systems 31 and 41 are adjusted in such a manner that their respective central axes intersect at a point on a surface or near the surface of the wafer 21. A mechanism for moving the wafer 21 backward and forward, and right and left with high accuracy is provided in the sample stage 24, and is controlled in such a manner that a designated position on the wafer 21 falls immediately below the focused ion beam optical system 31. The sample stage 24 has functions of rotational, vertical and slanting movements. An exhaust apparatus (not shown) is connected to the vacuum sample chamber 60 and the chamber 60 is controlled so as to have an appropriate pressure. The optical systems 31, 41 also individually comprise respective exhaust systems (not shown) and they are maintained at appropriate pressures. A wafer introducing device 61 and wafer conveying device 62 are provided within the vacuum sample chamber 60. A wafer transferring robot 82 and a cassette introducing device 81 are disposed adjacent to the vacuum sample chamber 60. Provided on the left side of the vacuum sample chamber 60 is an operation controller 100 for controlling the whole apparatus and a series of processing of sample processing, observation and evaluation. Next, an outline of an operation of introducing the wafer in this embodiment will be described. When a wafer cassette 23 is placed on a table of the cassette introducing device 81 and an operation start command is issued from the operation controller 100, the wafer transferring robot 82 pulls out a wafer to be a sample from a designated slot in the cassette, and an orientation adjustment device 83 shown in FIG. 2 adjusts an orientation of the wafer 21 to a predetermined position. Then, the wafer transferring robot 82 places the wafer 21 on a placement stage 63 when a hatch on an upper portion of the wafer introducing device 61 is opened. When the hatch is closed, a narrow space is formed around the wafer to be a load lock chamber, and after air is exhausted by a vacuum exhaust device (not shown), the placement stage 63 is lowered. Next, the wafer conveying device 62 takes up the wafer 21 on the placement stage 63 and places it on the sample stage 24 at a center of the vacuum sample chamber 60. The sample stage 24 is provided with means for chucking the wafer 21 according to need in order to correct a warp or prevent vibration of the wafer 21. A coordinate value of an observation and analysis position on the wafer 21 is input from the operation controller 100, and the sample stage 24 is moved and stopped when the observation and analysis position of the wafer 21 falls immediately below the focused ion beam optical system 31. Next, a process of sample processing, observation and evaluation will be described with reference to FIG. 3. In the minute sample processing and observation apparatus of the present invention, the focused ion beam optical system 31 comprises an ion source 1, a lens 2 for focusing an ion beam emitted from the ion source 1, an ion beam scanning deflector 3 or the like, and the electron beam optical system 41 comprises an electron gun 7, electron lens 9 for focusing an electron beam 8 emitted from the electron gun 7, an electron beam scanning deflector 10 or the like. The apparatus is further provided with a secondary particle detector 6 for detecting a secondary particle from the wafer by applying a focused ion beam (FIB) 4 or the electron beam 8 to the wafer 21, the movable sample stage 24 on which the wafer 21 is placed, a sample stage controller 25 for controlling a position of the sample stage for determining a desired sample position, a manipulator controller 15 for moving a tip of a probe 72 to an extracting position of a minute sample, extracting the minute sample and controlling a position or direction optimum for observation and evaluation of a determined position of the minute sample by applying the focused ion beam 4 (FIB) or electron beam 8 to the minute sample, an X-ray detector 16 for detecting an atomic property X-ray excited at the time of applying the electron beam 8, and a deposition gas supplying device 17. Next, an outline of the process of sample processing, observation and evaluation after introducing the wafer in this embodiment will be described. The sample stage is first lowered and the probe 72 is horizontally (in X and Y directions) moved relative to the sample stage 24 with the tip of the probe 72 separated from the wafer 21, and the tip of the probe 72 is set in a scanning area of the FIB 4. The manipulator controller 15 which is a mechanism for operating the probe stores a positional coordinate and then evacuates the probe 72. The focused ion beam optical system 31 applies the FIB 4 to the wafer 21 to form a rectangular U-shaped groove across an observation and analysis position p2 as shown in FIG. 4. A processing area has a length of about 5 μm, width of about 1 μm and depth of about 3 μm, and is connected to the wafer 21 at its one side surface. Then, the sample stage 24 is inclined, and an inclined surface of a triangular prism is formed by the FIB 4. In this condition, however, the minute sample 22 is connected with the wafer 21 by a support portion S2. Then, the inclination of the sample stage 24 is returned, and thereafter, the probe 72 at the tip of the manipulator 70 is brought into contact with an end portion of the minute sample 22. Then, the deposition gas is deposited on a contact point 75 by application of the FIB 4, and the probe 72 is joined to and made integral with the minute sample 22. Further, the support portion S2 is cut by the FIB 4 to cut out the minute sample 22. The minute sample 22 is brought into a condition of being supported by the probe 72, and ready is completed that a surface and an inner section of the minute sample 22 for the purpose of observation and analysis is taken out as an observation and analysis surface p3. Next, as shown in FIG. 5(b), the manipulator 70 is operated to lift the minute sample 22 up to a level apart from the surface of the wafer 21. If necessary, the observation section p3 of the minute sample 22 may be additionally processed to a desired shape by appropriately adjusting the application angle of the FIB 4 with rotating operation of the manipulator. As an example of the additional processing, there is a finishing processing for forming an observation section p2 slantingly formed by tapering of the beam of the FIB 4 to be a real vertical section. In section processing/observation having been performed hitherto, an observation surface has to be a side wall of a hole dug by the FIB, while in the apparatus of this embodiment, the sample can be additionally processed after being lifted, with the observation surface thereof appropriately moved. Therefore, it becomes possible to form a desired section appropriately. Then, the minute sample 22 is rotated, and the manipulator 70 is moved in such a manner that the electron beam 8 of the electron beam optical system 41 substantially vertically enters into the observation section p3 to control attitude of the minute sample 22, and then stopped. Thus, even in case of observing a section of the sample, detection efficiency of a secondary electron by the secondary particle detector 6 is increased as much as in the case of observing an outermost surface of the wafer. Observation condition of the observation and analysis surface p3 of the minute sample 22 is greatly improved. A reduction in resolution which has been a problem in the conventional method can be avoided. The angles of the observation and analysis surfaces p2, p3 can be adjusted to desirable angles, and therefore, it becomes possible to perform more exact observation and analysis. With this, direction of observation of the inner section of an object sample can be freely selected. Consequently, there can be provided a minute sample processing and observation apparatus which permits observing a shape and dimension of etching or planarization, an implanting condition, coating thickness or the like with high resolution by substantially vertically observing the section, and achieving measurement and evaluation with high accuracy. In this embodiment, the resolution can be improved by transferring a minute sample by movement of the manipulator 70 immediately below the electron beam optical system 41 to reduce a working distance. In an apparatus, like this embodiment, in which an ion beam optical system and an electron beam optical system are disposed in one vacuum container, a space in the vacuum container is limited, and it is difficult to bring a large sample close to the electron beam optical system. However, by positioning a cut-out minute sample below the electron beam optical system as is in this embodiment, such a problem can be solved. Further, the minute sample 22 is observed and analyzed while being placed in the sample chamber of a vacuum atmosphere without taken out of the apparatus, so that observation and analysis of the inner section of the sample to be observed and analyzed can be achieved with high resolution, high accuracy and an optimum angle without contamination or deposition of foreign materials resulting from exposure to the outside atmosphere. In addition, observation and analysis can be achieved with high throughput of processing more than a few positions per hour. This method also allows observation to be carried out simply by lifting and appropriately positioning the minute sample, which permits facilitating operation and reduction in operation time. In this embodiment, the section of the semiconductor sample cut by FIB application is moved substantially perpendicularly to the optical axis of the scanning electron microscope to be observed. Thus, an extremely meritorious effect is exerted in such a case of observing a thin film layer formed in the semiconductor sample. For example, wiring formed in the semiconductor wafer has been often formed from copper or the like these days. Metal such as copper tends to be diffused in the semiconductor wafer to degrade the property of the semiconductor, so that it is necessary to form a barrier metal around the wiring to prevent diffusion. The barrier metal is an extremely thin film with a thickness on the order of 0.01 μm to 0.02 μm when the wiring has a thickness of 0.1 μm to 0.2 μm, and is formed from metal such as tantalum. In an inspection process of the semiconductor wafer, whether a barrier metal is formed appropriately or not is an important inspection item. When the electron beam is slantingly emitted with respect to the observation section as in the conventional section processing and observation, a distance that the electron beam interferes in the sample is increased to reduce the resolution of the scanning electron microscope and to sometimes make it difficult to observe the barrier metal. Further, since the barrier metal is the thin film as described above, the electron beam entering into the barrier metal sometimes interferes adjacent other material areas. In such a case, there is a possibility of detecting information on other materials from a position where materials constituting the barrier metal only should exist. Thus, information on the copper of the adjacent wiring is detected regardless of the barrier metal being appropriately formed, which leads to a possibility of obtaining an inspection result that function as the barrier metal is not effected. This presents a problem especially in an EDX analysis for analyzing composition of a sample by detecting a property X-ray specific to material which is resulted from the electron beam application. The metal which forms the wiring or barrier metal is sometimes corroded or oxidized at its surface when made in contact with the air, thus making it difficult to observe the section. In this embodiment, for solving the above two problems together, observation by the scanning electron microscope capable of non-destructive observation with high resolution can be achieved in a vacuum atmosphere where the sample is cut out, and the electron beam application perpendicularly to the sample section is permitted. With this structure, it become possible to carry out section processing and observation of the semiconductor element which is becoming increasingly more minute with high resolution and accuracy. Further, also in a case an additional processing is effected after observation by the scanning electron microscope, the minute sample can be positioned below the optical axis of the FIB without being exposed to the air. Therefore, there is no possibility that a position to be additionally processed is hidden by the oxide film and alignment of processing positions becomes impossible. Further, in this embodiment, the minute sample 22 having the observation and analysis surface p3 can be inclined or moved in various ways by the manipulator 70. Thus, it becomes possible, for example, to provide a hole in the observation section p2 and to also confirm three-dimensional fault forming condition in the sample. In the example shown in FIG. 3, the manipulator 70 and the electron beam optical system 41 are provided opposite to each other with respect to the FIB 4. However, in order to reduce the number of operation of the manipulator 70 or the like to minimize processing/observation time, it is preferable that a relative angle between the manipulator 70 and the electron beam optical system 41 is set close to 90° in a surface perpendicular to the application direction of the FIB 4. The reason is that by setting so, it is sufficient that the manipulator 70 simply carries out an operation of lifting the minute sample 22 from the wafer 21, operation of rotating the probe 72 in such a manner that the observation section p2 is perpendicular to the electron beam 8, and other fine adjustment operations. Used in the above description is an example of lifting the minute sample 22 from the wafer 21 by the manipulator 70, but not limited to this. The wafer 21 may be lowered to thereby consequently lift the minute sample 22. In this case, the sample stage 24 is provided with a Z-axis moving mechanism for moving the wafer 21 in a Z direction (an optical axis direction of the FIB 4). With this structure, it becomes possible to perform cutting out and lifting of the minute sample 22 in a condition where the optical axis of the electron beam optical system 41 is located in the portion of the wafer 21 to be the minute sample 22. In this case, the process from cutting out the minute sample 22 by the FIB 4 to observing the observation section p2 can occur with confirmation by the electron microscope without frequent changes of electron beam application positions during the process. By the electron beam optical system 41, an electron microscope image of the surface of the wafer 21 slantingly viewed can be obtained. A section to be processed or processing arrival position by the FIB 4 is superposed on the electron microscope image to be model displayed, then the section processing condition by the FIB 4 can be easily confirmed. In order to display the section to be processed in a superposed manner on the electron microscope image, animation showing a portion to be a section is displayed on the electron microscope image in the superposed manner based on a processing depth to be set and a dimension in the electron microscope image calculated from magnification. If the processing depth is calculated in real time based on current and acceleration voltage of the FIB, material of the sample and the like, and an animation showing the present processing depth are displayed in an interposed manner on the electron microscope image, it becomes easy to confirm progress of the processing. The electron beam optical system 41 of this embodiment is disposed in a bird's eye position with respect to the wafer 21, and the electron microscope image becomes a bird's eye image. Therefore, by displaying also the above-described animation into three-dimensional display together with the electron microscope image, it is possible to confirm the processing condition more clearly. Further, this embodiment has a function of setting a position of the section processing on a scanning ion microscope image (SIM image) formed on the basis of the secondary electron obtained by scanning the wafer 21 with the FIB. However, it is possible to provide also a sequence where other setting and operation of the apparatus (driving of the sample stage and determination of the processing position by the ion beam) are automatically carried out based on inputs of the section position and the processing depth. In this case, a portion to be an upside of the observation section p3 is first designated on the SIM image, and the processing depth (a dimension in the depth direction of the observation section p3) is set. Based on these two settings, the forming angle of the inclined portion of the minute sample 22 and the observation and analysis surface p3 are automatically determined, and the subsequent processing is automatically carried out by the settings. It is also possible to provide a sequence where the subsequent processing is automatically carried out by setting the observation and analysis surface p3 (rectangular area) on the SIM image and setting the processing depth. In this embodiment, after the minute sample 22 is lifted, the probe 72 is operated so that the observation section p3 is appropriately positioned with respect to the electron beam 8. In FIG. 4, for example, when simply rotating the probe 72, the minute sample 22 is rotated around an attachment point to the probe 72. Therefore, the observation section p3 includes components of not only a rotation around a longitudinal axis of the minute sample 22 but also a rotation around an axis in the application direction of the FIB 4. Imparting a mechanism for removing the rotational components to the manipulator or manipulator controller, and operating the manipulator in timing compliant with the rotation of the probe 72 or timing different from the rotational operation allow the observation section p3 to be accurately positioned in a surface perpendicular to the optical axis of the electron beam 8. The same effect can be obtained by disposing the probe 72 to have an angle slightly larger than 90° to the electron beam optical system 41 in the surface perpendicular to the optical axis of the FIB 4. In this case, the effect is achieved by disposing the probe 72 to a rotational component around the axis in the application direction of the focused ion beam plus 90° with respect to the electron beam optical system 41. Including the rotational component around the axis in the application direction of the FIB 4 is resulted from the rotation axis of the probe 72 being inclined with respect to the observation and analysis surface p2 and the observation section p3. That is, the above problem can be solved by forming the probe 72 such that the rotation axis becomes parallel to the observation and analysis surface p2 and observation section p3. Therefore, in a case of the apparatus having a mirror structure as shown in FIG. 3, the rotation axis of the probe 72 is preferably formed in parallel with the surface of the wafer 21 (perpendicular to the optical axis of the FIB 4). By curve the tip of the probe 72, even a probe having the rotation axis parallel to the surface of the wafer 21 can support the minute sample 22. Further, it is preferable to form the rotation axis of the probe 72 so as to be perpendicular to the electron beam optical system 41 so that the sample can be moved below the optical axis of the electron beam 8 by rotation and parallel movement of the probe. Specific examples of the structure of the probe will be further described in detail in a description on a subsequent embodiment. If a mechanism to transfer a driving power from the manipulator controller 15 to a probe having a rotation axis with a different height from a probe holder 71 and parallel to the wafer 21 is provided, alignment of the observation section p3 with the electron beam 8 can be carried out without moving the minute sample 22 on a large scale. The minute sample 22 in a suspended condition by the probe 72 is susceptible to vibration, thus in observation and analysis with high magnification and in a locating environment of much vibration, the minute sample 22 may be grounded on a safe position on the wafer 21 or grounded on a minute sample port provided on a space around the wafer on the sample stage to thereby substantially restrain the vibration of the minute sample, permitting superior observation and analysis. FIG. 18 shows an example thereof such that earthquake resistance is improved by grounding the cut-out minute sample 22 on the wafer 21. In adopting such a method, it is preferable to make a sequence in advance such that the grounding position of the minute sample matches the optical axis of the electron beam 8. In creating the minute sample 22 shown in FIG. 4, the minute sample 22 is processed into pentahedron. This achieves creating of the minute sample especially with reduced waste in processing and in a reduced period of time for separation of the minute sample. It is needless to say that the same effect of the present invention can be obtained by forming the minute sample 22 into tetrahedron (not shown) or a shape close to tetrahedron which can minimize processing time because of the least processing surface. In the EDX analysis in which the electron beam 8 is scanned on the minute sample 22, elementary analysis accuracy is improved by forming the minute sample 22 thinner in the electron beam application direction than an entry distance of about 1 μm by the electron beam application. The EDX analysis is carried out using a detector of an X-ray generated from the minute sample resulting from the electron beam application. Forming the minute sample to be a thinner film permits avoiding enlargement of an X-ray generation area resulting from entry of a charged particle beam, thus enabling the elementary analysis with high resolution. By applying the analysis thus far described to the semiconductor wafer with or without pattern, the analysis can be used in an inspection of a semiconductor manufacturing process to contribute to improvement of manufacturing yield by early detection of failure and quality control in a short period of time. (Embodiment 2) A structure and an operation of a minute sample processing and observation apparatus according to a second embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. 7 is a plan view of FIG. 6, and there are some differences between the figures in orientations or details of apparatuses for convenience in description but they are not essential differences. In this apparatus, a focused ion beam optical system 31 is vertically disposed and a second focused ion beam optical system 32 is located at an angle of approximately 40° at the upper part of a vacuum sample chamber 60 disposed in the central part of the apparatus system. An electron beam optical system 41 is slantingly located at an angle of approximately 45°. Three optical systems 31, 32, 41 are adjusted in such a manner that their respective central axes intersect at a point around a surface of a wafer 21. Similarly to the apparatus of the first embodiment, inside the vacuum sample chamber 60 is located a sample stage 24 on which the wafer 21 to be a sample is placed. The sample stage 24 in this embodiment has functions of horizontal (X-Y), rotational and vertical movements, but a slanting function is not necessarily required. Next, a sample creating operation by this apparatus will be described with reference to FIG. 4. An FIB 4 is applied from the focused ion beam optical system 31 to the wafer 21 to form a rectangular U-shaped groove across an observation and analysis position p2 as shown in FIG. 4. This is identical to the first embodiment. Then, an inclined surface of a triangular prism is formed by processing with the FIB 4 from another focused ion beam optical system 32. In this condition, however, the minute sample 22 and wafer 21 are connected with each other by a support portion. Then, a minute sample is cut out using the FIB 4 from the focused ion beam optical system 31 similarly to the first embodiment. That is, a probe 72 at a tip of a probe holder 71 of a manipulator 70 is brought into contact with an end portion of a minute sample 22, and then deposition gas is deposited on a contact point 75 by application of the FIB 4, where the probe 72 is joined to and made integral with the minute sample 22, and the support portion is cut by the FIB 4 to cut out the minute sample 22. Subsequent steps of observation and analysis of the minute sample 22 are identical to the first embodiment. As described above, also in this embodiment, high speed observation and analysis with high resolution can be achieved similarly to the first embodiment. In this embodiment, slanting of the sample stage can be eliminated especially by using two focused ion beam optical systems. Omitting the slanting mechanism of the sample stage can improve positioning accuracy of the sample stage more than a few to ten times. In a manufacturing site of LSI devices, it has come into practice in recent years that various wafer inspection and evaluation apparatus carry out a foreign material inspection and defect inspection, that a property and coordinate data of a wrong portion on the wafer are recorded, and that subsequent apparatus for a further detail inspection receives the coordinate data to determine a designated coordinate position and to carry out observation and analysis. High positioning accuracy permits automation of determining the observation position of the wafer 21 and simplification of its algorithm. This can substantially reduce required time, which permits obtaining high throughput. Further, the sample stage having no slanting mechanism is compact and lightweight and can easily obtain high rigidity to increase reliability, thus permitting superior observation and analysis and miniaturization or a reduction in cost of the apparatus. Imparting a swinging function to the focused ion beam optical system 31 to be appropriately moved between the vertical and inclined positions permits processing identical to the second embodiment without slanting the sample stage 24, and thus the effect of the present invention can be obtained. (Embodiment 3) A structure and an operation of a minute sample processing and observation apparatus according to a third embodiment of the present invention will be described with reference to FIGS. 8 and 9. FIG. 9 is a plan view of FIG. 8, and there are some differences between the figures in orientations or details of apparatuses for convenience in description but they are not essential difference. In the apparatus of this embodiment, a focused ion beam optical system 33 is slantingly located at an angle of approximately 45° at an upper portion of a vacuum sample chamber 60 disposed at the central part of the apparatus system. An electron beam optical system 42 is also slantingly located at an angle of approximately 45°. Two optical systems 33, 42 are adjusted in such a manner that their respective central axes intersect at a point around a surface of a wafer 21. Similarly to the apparatus of the first embodiment, inside the vacuum sample chamber 60 is located a sample stage 24. Further, similarly to the second embodiment, the sample stage 24 has no slanting function. Next, processes of sample processing, observation and evaluation after introducing the wafer will be described with reference to FIG. 19 also. The sample stage is first lowered to move a probe 72 horizontally (in X and Y directions) relative to the sample stage 24 with the tip of the probe 72 separated from the wafer 21, and the tip of the probe 72 is set in a scanning area of the FIB 4. The manipulator controller 15 stores a positional coordinate and then evacuates the probe 72. The sample stage is oriented in such a manner that an intersection line of a vertical plane containing an optical axis of a focused ion beam optical system 33 and a top surface of the wafer is superposed on an observation section of a sample to be formed. Then, an FIB 4 is applied to the wafer 21 for scanning to form a vertical section C1 having a length and depth required for the observation. Then, an inclined cut section C2 which intersects a formed section is formed. When forming the inclined cut section C2, the sample stage is rotated around a horizontal axis up to a position where an inclination angle of an inclined surface is obtained to determine the orientation. Next, an inclined groove is formed by the FIB 4 in parallel with a vertical cut line. Further, an end C3 is cut orthogonal to the groove. A processing area has a length of about 5 μm, width of about 1 μm and depth of about 3 μm, and is connected to the wafer 21 in a cantilevered condition of a length of about 5 μm. Then, the probe 72 at the tip of a manipulator 70 is brought into contact with an end portion of a minute sample 22, and then deposition gas is deposited on a contact point 75 by application of the FIB 4, where the probe 72 is joined to and made integral with the minute sample 22. Then, the other end C4 supporting the minute sample is cut by the FIB 4 to cut out the minute sample 22. The minute sample 22 is brought into a condition of being supported by the probe 72, and ready to be taken out with a surface and an inner section for the purpose of observation and analysis as an observation and analysis surface p3 is completed. Processing thereafter is substantially identical to the first embodiment except that an orientation of the sample stage 24 is also required to be appropriately adjusted when setting the optimum orientation of the minute sample for processing and observation by the focused ion beam optical system or observation by electron beam optical system, and thus description thereof will be omitted. As described above, also in this embodiment, high speed observation and analysis with high resolution can be achieved similarly to the first embodiment. This embodiment has a feature that one focused ion beam optical system is inclined with respect to the sample stage to thereby cut out and extract the minute sample from the wafer without imparting a slanting function to the sample stage. Generally, a large number of devices are required to be mounted around the optical system, causing lack of spaces, and a large total mass of the devices makes difficult design of a mounting substrate including ensuring rigidity. Maintenance thereof is also a matter of concern. This embodiment eliminates the need for a slanting mechanism of the sample stage, and requires only one focused ion beam optical system, which can provide a simple, compact and lightweight structure and reduced cost. (Embodiment 4) An outline of structure of a minute sample processing and observation apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. 10. In this embodiment, a second sample stage 18 and second sample stage controller 19 for controlling an angle, a height and the like of the second sample stage are added to a basic structure of the minute sample processing and observation apparatus shown in FIG. 3. The process from applying an ion beam from the focused ion beam optical system 31 to a wafer to extracting a minute sample from the wafer is identical to the first embodiment. In this embodiment, the extracted minute sample is fixed to the second sample stage for observation and analysis instead of observation and analysis in the supported condition by the manipulator. FIG. 11 shows a condition of the minute sample 22 fixed to the second sample stage 18. A member with a flattened surface is used for a minute sample fixed portion of the second sample stage 18 in this embodiment, but flatness does not matter. A bottom surface of the minute sample is brought into contact with the second sample stage 18, and deposition gas is deposited on a contact point between the second sample stage 18 and minute sample 22 with the FIB 4 to fix the minute sample 22 to the second sample stage 18 with an assist deposition film 76. In order to prevent inconvenience of attachment of foreign materials to the surface of the observation section or destruction of the surface of the observation section when creating the minute sample 22 or depositing the deposition gas, an application angle of the FIB 4 may be appropriately set in parallel to the observation section of the minute sample by operating the second sample stage to create a desired observation section by applying the FIB 4. By locating the second sample stage shown in FIG. 12, a plurality of minute samples can be collectively handled. By repeating operation of extracting the minute sample 22 from the wafer 21 to fix it to an appropriate position on the second sample stage 18 beside the first sample stage, section observation and elementary analysis of the plurality of samples can be carried out with the wafer 21 fixed to the sample stage 24, and distribution of a section structure throughout the wafer 21 can be efficiently examined. In FIG. 12, when fixing the plurality of minute samples in a line to the second sample stage 18 and carrying out observation and analysis in a condition where both of a stopping orientation of the sample stage 24 and an angle of the second sample stage 18 are adjusted so as to locate the minute sample 22 at an appropriate angle to the electron beam 8, the plurality of minute samples can be observed and analyzed successively or repeatedly with compared to one another, thereby permitting detailed and efficient examinations of the section structure and elementary distribution throughout the wafer 21. The second sample stage 18 shown in FIG. 13 is a rotatable column sample stage such that a minute sample group can be arranged on its outer peripheral surface, and a larger number of minute samples can be handled at a time than in the case of FIG. 12. By detaching the minute samples 22 to be recovered in a designated position in a sample recovery tray and providing identification means for the minute samples, the minute samples 22 can be taken out again for observation and analysis when a detailed evaluation is required afterward. As described above, also in this embodiment, secondary electron detecting efficiency can be obtained as high as in the case of observing the wafer surface, an angle for observation and analysis can be adjusted to a desirable angle including vertical observation, observation can be carried out with placed in a sample chamber of a vacuum atmosphere, and the like, therefore, observation condition of the minute sample 22 is greatly improved to permit avoiding a reduction in resolution which has been a conventional problem and carrying out optimum, exact observation and analysis promptly with high speed and high efficiency. As a result, superior observation and analysis can be carried out with high throughput. By separating the minute sample from the manipulator to be fixed to the second sample stage, vibration isolating mechanism of the sample stage which holds the introduced sample and vibration isolating mechanism of the second sample stage to which the minute sample is fixed can be shared. (Embodiment 5) Details of the probe for lifting the minute sample from the wafer, which has been described in the former embodiments and a driving mechanism for driving the probe will be described below. FIG. 16 is an explanatory view of the embodiment. In this embodiment, an example where the probe for lifting the minute sample from the wafer and the like and a holder for holding the probe are detachably mounted to a sample chamber (vacuum container) will be described. An optical system 226 comprising an ion source 225, beam limiting aperture 228, focusing lens 229, deflector 230 and objective lens 231 are basically the same as in FIG. 3, and an FIB 227 is adjusted which is applied along an optical axis 224. Further, the apparatus shown in FIG. 16 is provided with a sample holder 233a for holding a wafer 217 and a stage 234 for moving the sample holder in X-Y directions. The apparatus is further provided with a secondary electron detector 237 for detecting a secondary electron discharged from the sample resulting from application of the FIB 227, a deposition gas source 238 for blasting a deposition gas concurrently with application of the ion beam and a vacuum container 206 for maintaining high vacuum in the sample chamber. An output of the secondary electron detector 237 is amplified by an amplifier (not shown) and then stored in an image memory (not shown) and displayed on an image display apparatus 238. A central processing unit 240 controls various components of the apparatus shown in FIG. 16 via an FIB controller 236, a probe position controller 223, and stage position controller 235. Details of a probe moving mechanism 201 (manipulator) which is controlled by the probe position controller 223 will be described with reference to FIGS. 17 and 18. An air lock chamber 202 provided in the probe moving mechanism 201 is coupled to a base flange 205 via bellows 204 absorbing a moving amount of a probe 203. The base flange 205 is fixed to a vacuum container 206 with a vacuum seal 207 interposed therebetween. A closable air lock valve 208 is disposed at an end of the air lock chamber 202, and opened/closed by rotating a cylindrical air rock valve opening/closing mechanism 209. Shown in FIG. 17 is a condition where the air lock valve 208 is opened and a probe holder 210 is introduced into the vacuum container 206 in such a manner that its central axis is inclined to a surface of the wafer 217. An air rock chamber outer cylinder 211 in which the air lock valve 208 and air rock valve opening/closing mechanism 209 are accommodated has a concentrical hollow double structure, and one end of the hollow portion communicates with the air lock chamber 202 and the other end communicates with an exhaust pipe 212. The above structure eliminates the need for compact bellows for the air lock chamber 202 which has been conventionally required, permitting simplification, miniaturization and reduction in cost of the probe moving mechanism 201. On a fixed side flange 213 of the bellows 204, a current introduction terminal 214 having a sealing function is disposed. By connecting via a lead wire 216 a vacuum side of the current introduction terminal 214 to a probe holder 249 which holds the probe 203 and is formed from an insulating material with conduction at portions in contact with the probe 203 and probe holder stopper 215, power can be supplied from an air side to the probe 203. To one end of the air rock chamber outer cylinder 211, a Y-axis stage 219a is fixed where a Y-axis linear guide 218a is fixed in parallel with the surface of the wafer 217 as shown, and coupled to a Y-axis base 220 via the Y-axis linear guide 218a as shown in FIG. 18. Linear driving of a Y-axis is carried out using a Y-axis linear actuator 221a held by the Y-axis base 220. An output shaft of the Y-axis linear actuator 221a is coupled to a Y-axis stage 219a via a Y-axis lever 222a. The Y-axis base 220 is coupled to a Z-axis stage 219b. The Z-axis stage 219b is coupled to an X-axis stage 219c via a Z-axis linear guide 218b disposed perpendicularly to the surface of the wafer 217 having a phase 90° different from the Y-axis linear guide 218a as shown. The linear driving of the Z-axis stage 219b is carried out using a Z-axis linear actuator 221b held by the X-axis stage 219c. An output shaft of the Z-axis linear actuator 221b is coupled to the Z-axis stage 219b via a Z-axis lever 222b. Similarly, the X-axis stage 219c is coupled to the base flange 205 via an X-axis linear guide 218c disposed in parallel with the surface of the wafer 217 having a phase 90° different from the Y-axis linear guide 218a as shown. The linear driving of the X-axis stage 219c is carried out using an X-axis linear actuator 221c held by the base flange 205. An output shaft of the X-axis linear actuator 221c is coupled to the X-axis stage 219c via an X-axis lever 222c. As described above, coupling the X-, Y- and Z-axes to the respective linear actuators via the respective levers can eliminate projections at the linear actuators and achieve miniaturization of the probe moving mechanism 201. The probe moving mechanism 201 of this embodiment has a width of 172 mm in the X-axis direction and a height of 165 mm in the Z-axis direction which are substantially identical to the width and height of the used linear actuator. Introduction of the probe holder 210 into the vacuum container 206 according to this embodiment adopts the following procedures. The probe holder 210 is inserted in front of the air lock valve 208. In this condition, the air lock chamber 202 is kept to be sealed by the vacuum seal 207 arranged in an outer cylinder of the probe holder 210. After the insertion, air in the air lock chamber 202 is exhausted to be a vacuum from the exhaust pipe 212 through a hollow portion of the air lock chamber outer cylinder 211. After confirming that a pressure in the air lock chamber 202 reaches a predetermined pressure, the air lock valve 208 is opened using the air lock valve opening/closing mechanism 209, and the probe holder 210 is introduced into the vacuum container 206. The above described operations allow the probe 203 to be introduced into the vacuum container 206 without the vacuum container 206 being exposed to the air. Extracting the probe holder 210 from the vacuum container 206 can be carried out by the procedure in the reverse order of the insertion. That is, the probe holder 210 is once extracted in front of the air lock valve 208, then the air lock valve 208 is closed using the air lock valve opening/closing mechanism 209. Confirming the closure, the air in the air lock chamber 202 is leaked from the exhaust pipe 212. After confirming an atmospheric pressure, the probe holder 210 is taken out of the probe moving mechanism 201. Adopting the above structure allows replacement of the probe 203 which is a consumable supply to be carried out without the vacuum container 206 being exposed to the air. As shown in FIG. 16, by structuring the probe holder 210 in such a manner that a substantially central axis of the probe holder 210 enters slantingly to the wafer 217 (in this embodiment, enters at an angle of 30°), the probe holder 210 can reach near the optical axis 224 of the charged particle beam optical system with a minimum length, which permits providing the probe holder 210 with high rigidity and remarkably facilitating handling of the few μm sample piece 232 and operations of making the tip of the probe into contact with a predetermined position on an electron element having a submicron wiring. Machine parts such as the bellows 204 for absorbing the mounting amount of the probe 203 are not positioned lower than the surface of the wafer 217, so that the probe moving mechanism 201 has no influence on the size of the vacuum container 206, and the vacuum container 206 may be a minimum size determined within a movement range of the wafer 217. Minimizing the vacuum container 206 which determines the size of the apparatus can provide a sample creating apparatus for samples with large diameters mounted with a probe moving mechanism, which permits reduction in occupying area, weight and cost and also miniaturization of exhaust means. In this embodiment, the entering angle of the probe holder 210 is 30°, but not limited to this. The same effect can be obtained by inserting the probe holder 210 slantingly to the vacuum container 206 in such a manner that the probe 203 is within a range of being displayed by the image display apparatus 238. By arranging the probe moving mechanism 201 in a position where a distance to the intersection point of the center of the base flange 205 which couples the probe moving mechanism 201 to the vacuum container 206 and a vertical line of the optical axis 224 is below ½ of the horizontal movement range of the sample stage 234, below 150 mm in this embodiment, the probe holder 210 can be introduced into the vacuum container 206 with a minimum length at a desired angle, and freedom of a layout of the apparatus can be increased while permitting the vacuum container 206 to be miniaturized. Moreover, by adopting the structure where the respective linear actuators of the probe moving mechanism 201 slantingly entering in the vacuum container 206 and the respective stages are coupled via the levers, the probe moving mechanism 201 can eliminate projections, thus imposing no limitation in the layout to other measurement instruments arranged in the vacuum container 206, preventing problems of unexpected interference or the like and achieving miniaturization of the apparatus. Creating the sample using this apparatus is carried out by the following procedures. The ion beam 227 emitted from the ion source 225 is focused on a predetermined position on the stage 234 by passing through the optical system 226. The focused ion beam, that is, FIB 227 is spattered in the form of scanning the surface of the wafer 217 to carry out fine processing of the sample piece (not shown). On the stage 234, the wafer 217 and the sample holder 233a for holding the extracted sample piece are placed, and the stage position controller 235 determines a position to be FIB processed and extracted. The probe 203 mounted on the probe moving mechanism 201 is moved to an extracting position on the wafer 217 independently of the stage 234 by the probe position controller 223. Operations of movement and processing are carried out while observing by scanning with the FIB around the extracting position of the wafer 217 by the FIB controller 236, detecting the secondary electron from the wafer 217 by the secondary electron detector 237, and displaying the obtained secondary particle image on the image display apparatus 238. For extracting the sample piece, the FIB processing is carried out while changing the attitude of the wafer 217 to cut out the sample piece in the form of a wedge, and deposition gas is supplied to the contact portion of the sample piece where the probe 203 is made into contact with using the deposition gas source 239, and an ion beam assist deposition film is formed to thereby attach the probe 203 to the sample piece. The prove 203 is then raised from the wafer 217 by the probe position controller 223, and moved to a position of the sample holder 233b on the stage 234. The probe 203 is lowered, contact between the wedge portion of the sample piece attached to the probe 203 and the surface of the sample holder 233b is confirmed, and a side surface of the sample piece is attached to the sample holder 233a by the ion beam assist deposition film. The tip of the probe 203 is cut from the sample piece 232 by the FIB and moved to a next sample extracting position by the probe position controller 223. The above processes make it possible to extract the sample piece 232 at a desired position from the wafer 217 and move it to the sample holder 233b. The above operations are collectively controlled by a central processing unit 240. This embodiment adopts the ion beam assist deposition film as the attaching means between the probe 203 and the sample piece 232, but there is no problem in electrostatic attaching means using an attaching force by static electricity, and the same effect can be obtained as this embodiment in that case. However, attachment by the assist deposition film is desirable for attaching the probe to the accurate position. In this embodiment, the probe moving mechanism is structured to be slantingly inserted, thereby permitting miniaturization of the sample chamber (vacuum container) in comparison with a probe moving mechanism which is inserted horizontally of the wafer surface disclosed in JP-A-11-56602 specification. For example, when the sample is the semiconductor wafer with the large diameter and the probe moving mechanism is tried to be horizontally introduced, the machine parts such as bellows for absorbing the moving amount of the probe are inevitably positioned lower than the surface of the wafer, therefore the machine parts have to be placed in a position which has no interference with the stage on which the wafer is placed, that is, out of the movement range of the stage. This inevitably causes upsizing of the vacuum container, but the present invention can achieve miniaturization of the vacuum container, and the resultant reduction in an occupying area and cost and miniaturization of a vacuum exhaust pump. There have been needs for extending the probe from the side wall of the vacuum container to the predetermined position (around the optical axis of the charged particle beam) and thereby providing a long support member for supporting the probe, causing a problem of degraded rigidity. This embodiment can also solve the problem to thereby facilitate positioning the prove in the predetermined position. (Embodiment 6) FIG. 19 is a sectional view of a sample creating apparatus of a sixth embodiment using a slantingly entering sample stage fine moving device 241. Described in the former embodiment has been the example of providing an electron beam barrel in the same sample chamber as the ion beam barrel and observing the sample cut out by the electron beam barrel. However, described in this embodiment is an example of transferring a cut-out sample to other analyzer using a side entry type sample stage and observation is carried out. The side entry type sample stage means a stage to be inserted from the side of a charged particle beam barrel or the sample chamber, and details thereof will be described below. FIG. 20 is an enlarged view of portions around the probe 203 in FIG. 19, and FIG. 21A is a vertical sectional view and FIG. 21B is a horizontal sectional view of a side entry type sample stage 242 used in FIG. 19. First, the side entry type sample stage 242 will be described with reference to FIG. 21. A sample locating portion 243 to which a sample piece 232 is attached is held by a sample holder 233a. A projection 245 is provided on an end surface of a driving shaft 244 side of the sample holder 233a. The shape of the projection 245 does not matter. Arranged in a position on an end surface of a vacuum side of the driving shaft 244 is a rotation shaft 246, of which free end is eccentric from a rotational central axis of the driving shaft 244, in contact with a surface of the projection 245 with an attitude in parallel with the central axis of the driving shaft 244. When a knob 247 of the driving shaft 244 is rotated, the rotation shaft 246 is eccentrically rotated and the projection 245 with which the free end of the rotation shaft 246 is in contact is rotationally moved around a rotation bearing 273 depending on an eccentric amount and a rotation amount of the rotation shaft 246. That is, the sample holder 233a is rotationally moved. In this embodiment, rotation at 230° is possible. A part of an outer cylinder 248 of the sample holder 233a portion is cut out and it facilitates attachment of the sample piece 232 to a sample locating portion 243 and forming of the sample piece 232 by the FIB. Using the same mechanical system and control system as the probe moving mechanism 201 shown in FIGS. 17 and 18 for a sample stage fine moving mechanism 241 for driving the side entry type sample stage 242 and a sample stage position controller 278 improves productivity and reduces cost of the apparatus, and also improves maintainability and operability. Sample creation using the sample creating apparatus according to this embodiment takes the following steps. The operations of introducing and extracting the side entry type sample stage 242 into and from the vacuum container 206 are the same as the operations of the probe holder 210 in the above described probe moving mechanism 201. Before extraction of the sample piece 232 at a desired position from the wafer 217, the same processes as the fifth embodiment are adopted. After extraction of the sample piece 232, the side entry type sample stage 242 is inserted into the vacuum container 206 without being exposed to the air. In this case, similarly to the fifth embodiment, by structuring the side entry type sample stage 242 in such a manner that a substantially central axis of the side entry type sample stage 242 slantingly enters with respect to the wafer 217, the size of the vacuum container 206 can be minimized, and the side entry type sample stage 242 can reach near an intersection point of the optical axis 224 of the FIB 227 and the wafer 217 with a minimum length. In this embodiment, the side entry type sample stage 242 slantingly enters at an angle of 30° to the surface of the wafer 217, but not limited to 30°. The same effect can be obtained by slantingly inserting the side entry type sample stage 242 into the vacuum container 206 in such a manner that the sample holder 233a exists within a range of being displayed by an image display apparatus 238. By this structure, for the same reason as the probe moving mechanism 201 in the fifth embodiment, the sample stage fine moving mechanism 241 has no influence on the size of the vacuum container 206 and the vacuum container 206 can be a minimum size which is determined by a movement range of the wafer 217. By arranging the sample stage fine moving mechanism 241 in a position where a distance to an intersection point of a center of the base flange 205 which couples the sample stage fine moving mechanism 241 to the vacuum container 206 and a vertical line of the optical axis 224 is below ½ of the horizontal movement range of the sample stage 234, below 150 mm in this embodiment, the side entry type sample stage 242 can be introduced with a minimum length at a desired angle, and freedom of a layout of the apparatus can be increased while permitting the vacuum container 206 to be miniaturized. After insertion of the side entry type sample stage 242, the knob 247 is turned to rotate the sample locating portion 243 held by the sample holder 233a at an angle in parallel with the wafer 217 as shown in FIG. 20, that is 30° in this embodiment. Then, the probe 203 holding the sample piece 232 is driven by the probe moving mechanism 201 and the probe position controller 223 shown in FIG. 19, and the minute sample piece 232 is attached to the sample holder 233a by forming a deposition film. After attachment, the sample holder 233a is again rotated to the position in parallel with the axis of the side entry type sample stage 242, and the side entry type sample stage 242 is then extracted from the vacuum container 206 by the above described means, and for example, mounted to a TEM apparatus (not shown) to thereby carry out TEM observation. The rotation of the sample holder 233a is used for fine rotational adjustment of the sample piece 232 in the TEM observation to permit more reliable analysis. By adopting the structure according to this embodiment, the FIB apparatus can be realized which has the vacuum container 206 with the size restricted to the same size as in the fifth embodiment, the probe moving mechanism 201 which can extract the sample piece 232 at a desired position on the wafer 217 and the side entry type sample stage 242 which can be mounted to various analyzers. By using this FIB apparatus, it becomes possible to transfer the sample piece 232 at a desired position of the wafer 217 with a large diameter to the sample holder 233a in the vacuum container 206, and further, by taking out the side entry type sample stage 242 on which the sample holder 233a is placed without being exposed to the air, prompt mounting on various analyzers and evaluation become possible. Further, by adopting a sample stage fine moving device with the same manner as the probe moving mechanism 201, improvements of productivity, maintainability, and operability of an apparatus can be realized. (Embodiment 7) FIG. 22 is a sectional view of a sample creating apparatus of still another embodiment. The embodiment differs from the sixth embodiment in that it uses a probe moving mechanism 201 having a probe holder 210 in which freedom of rotation around a Y-axis shown by the coordinate system shown in FIG. 16 is added to a probe 203 shown in FIG. 23, and a sample stage fine moving mechanism in which freedom of rotation around a central axis of a side entry type sample stage 242 is added to a sample holder 233a shown in FIG. 24. The structure of the probe holder 210 will be described with reference to FIG. 23. FIG. 23A shows the probe 203 in a projected condition, and FIG. 23B shows the probe 203 accommodated in an outer cylinder 248. The probe 203 is fixed to a probe holder 249 through a leaf spring 252, and the probe holder 249 is held in an inner cylinder 251 which linearly moves through a bearing 250. The inner cylinder 251 is inserted into an outer cylinder 248 with freedom in a rotating direction being limited, and pressed against a driving shaft 253 via a bearing 254. An end of the probe holder 249 is connected to a helical compression spring 259, and the other end of the helical compression spring 259 is coupled to the driving shaft 253. A rotation center of the bearing 250 is inclined to a center line of the probe holder 210 at an insertion angle of the probe holder 210. This allows the probe 203 to be rotationally moved in parallel with the surface of the wafer 217 in the vacuum container 206. If such a probe is applied to the apparatus described in the first embodiment, observation by a scanning electron microscope capable of non destructive observation with high resolution becomes compatible with application substantially in a vertical direction to the sample section. As is the apparatus of the present invention, in an apparatus handling large samples, a probe and a moving mechanism of the probe must be disposed above the samples. However, the probe and the probe moving mechanism disclosed in FIG. 23 permit rotation of a cut out minute sample around a rotation axis parallel to a sample surface. The driving shaft 253 is inserted into the outer cylinder 248 with a bearing 255 for rotation and linear moving and a vacuum seal (not shown) interposed. An end of the driving shaft 253 projects from the outer cylinder 248. A gear 256b is fixed to the projected portion of the driving shaft 253, and a minute feeding mechanism 257 which is an actuator of linear movement is pressed against an end surface of the driving shaft 253. Another gear 256a in mesh with the gear 256b is arranged in parallel with the driving shaft 253, and a knob 247 for rotary movement is fixed to the gear 256a. It is needless to say that the gears 256a, 256b are held via rotatable members, though not shown. The above is the basic structure of the probe holder 210 having two degrees of freedom of rotation and accommodation of the probe 203. Next, operations will be described. The driving shaft 253 is linearly moved using the minute feeding mechanism 257. The linear movement of the driving shaft 253 is transferred to the outer cylinder 248, thus the probe 203 held by the probe holder 210 is linearly moved without rotation. By this structure, accidents such as damages of the minute probe 203 can be prevented in operations such as inserting or extracting the fine probe holder 210 into or from the vacuum container 206, and an operator can easily use the apparatus. The probe 203 is rotationally moved by turning the knob 247, rotationally moving the driving shaft 253 via the gears 256a, 256b. Since freedom of rotation of the inner cylinder 251 is limited, the rotary movement of the driving shaft 253 does not cause rotary movement of the inner cylinder 251. An elastic deformation by the helical compression spring 259 changes a direction of the rotary movement, but the rotary power is transferred to the probe holder 249, and the probe holder 249 held via the inner cylinder 251 and bearing 250 for rotation is rotationally moved. As described above, by simple operations of linear and rotary movements of a single driving shaft 253, the probe 203 can move linearly and rotationally. Next, the fine moving mechanism of the side entry type sample stage 242 to which freedom of rotation is added will be described with reference to FIG. 24. The respective moving mechanisms of the X-, Y- and Z-axes are of the same type as the probe moving mechanism 201 shown in FIGS. 17 and 18, and only different points will be described below. In this embodiment, the difference from the sixth embodiment is that a gear 261a is disposed on a grip 260 of a side entry type sample stage 242, and a gear 261b in mesh with the gear 261a and a driving source 262 for rotatably driving the gear 261b are disposed on a Y-axis stage 219a. By the structure of this embodiment, the side entry type sample stage 242 can be inclined at a desired angle by rotationally moving the sample holder 233a portion together with the whole side entry type sample stage 242. Further, by using the gears 261a, 261b as transferring media of the rotary power, the gear 261a coupled to the side entry type sample stage 242 can be coupled to the gear 261b coupled to the driving source 262 using no mechanical parts such as screws with no bars in inserting and extracting the side entry type sample stage 242. FIG. 25 shows operations of processing the sample piece 232 by the sample creating apparatus of FIG. 22. Sample creating by the sample creating apparatus of this embodiment will be described with reference to this figure. The same steps as the fifth embodiment are adopted before the step (a) for extracting the sample piece 232 from the wafer 217. When analyzing an outermost surface of the wafer 217, as described in the sixth embodiment, the sample piece 232 is transferred on a sample locating portion 243 rotationally moved in parallel with the surface of the wafer 217 without rotating the probe 203. When analyzing the wafer 217 in the depth direction, the sample piece 232 is extracted from the wafer 217 and then the probe 203 is rotated at an angle of 90°, and the X-, Y- and Z-axes are driven if necessary, and the sample piece 232 is attached by the ion beam assist deposition film to the sample locating portion 243 which has been rotationally moved in parallel with the surface of the wafer 217 (FIG. 25(b)). After the sample piece 232 is transferred to the sample locating portion 243, the probe 203 is linearly moved using the minute feeding mechanism 257 so as to be accommodated in the outer cylinder 248. Then, the knob 247 is turned to reset the inclined sample holder 233a holding the sample locating portion 243 (FIG. 25(c)). Then, the driving source 262 is driven, and the sample holder 233a is rotationally moved in such a manner that the sample locating portion 243 is opposed to the FIB 227, and the sample piece 232 is forming worked by the FIB 227 (FIG. 25(d)). In this case, during the steps of processing, by rotating and inclining the sample holder 233a to have a position in FIG. 25(b), it is possible to observe the condition of the observation surface at any time through an image display apparatus 238 for displaying secondary particle images from the sample surface. After forming worked, it is possible to carry out analysis by extracting the side entry type sample stage 242 from the vacuum container 206 and mounting it as it is on an analyzer such as TEM. According to the sample creating apparatus of this embodiment, analysis of the outermost surface layer and in the depth direction of the wafer 217 is possible, and further, a wide range of sample analyses is possible because of having the same structure as the side entry type sample stage 242 capable of being mounted to various analyzers, thereby greatly enlarging a range of utilization as the sample creating apparatus. In the above embodiment, description has been made on creation and observation of the TEM sample as an example for convenience in description, but not limited to the TEM. It is apparent that the sample surface can be easily analyzed or observed by configuring the apparatus so as to be mounted to any one of the focused ion beam apparatus, transmission electron microscope, scanning electron microscope, scanning probe microscope, Auger electron spectroscopic analyzer, electron probe X-ray microanalyzer, electronic energy deficiency analyzer, secondary ion mass spectroscope, secondary neutron ionization mass spectroscope, X-ray photoelectron spectroscopic analyzer, or electrical measuring apparatus using a probe. In the charged particle beam apparatus having the ion beam barrel and electron beam barrel as described in the first embodiment, the ion beam barrel and electron beam barrel are relatively inclined to the sample placing surface of the sample stage. The sample piece is separated from the sample placed on the sample stage by the ion beam, and is joined in an deposited manner by the ion beam and gas to a needle member mounted to the tip of the probe and is extracted. The extracted sample piece is moved below the electron beam rotated such that the electron beam can be applied to a predetermined portion. The secondary electron from the sample may be detected by the detector to obtain a scanning electron microscope image. In the sample creating apparatus described above, the description has been made specially on the FIB 227 only for convenience in description, but the same effects can be obtained as the present invention even in, for example, a sample creating apparatus using a projection ion beam which is configured by replacing a deflector 230 and objective lens 231 with a mask plate and projection lens, or a sample creating apparatus using a laser beam which is configured by replacing an ion source 225 with a laser source. Moreover, there is no problem of making a sample creating apparatus having a structure in which an optical system of a scanning electron microscope is added to the above described sample creating apparatus. In that case, by using the probe moving mechanism 201 having freedom of rotation around the Y-axis shown in the seventh embodiment of the present invention, it becomes possible to observe the sample piece 232 with high resolution by opposing the sample piece 232 together with the probe to the optical system of the scanning electron microscope after the sample piece is taken out of the wafer 217. (Embodiment 8) FIG. 26 is a sectional view of an embodiment where a probe moving mechanism 201 according to the present invention is applied to a failure inspection apparatus. In the figure, an electron beam 266 emitted form an electron gun 265 passes through an electron beam optical system 267 and is focused on a surface of a wafer 217 placed on a stage 234. The stage 234 is controlled by a stage position controller 235 to determine position of an element to be evaluated on the wafer 217. In this figure, only two probe moving mechanisms 201 are shown, but another two probe moving mechanisms 201 are arranged opposite in the direction perpendicular to the sheet surface, thus the failure inspection apparatus is provided with four probe moving mechanisms 201. A probe 203 arranged in each of four probe moving mechanisms 201 is moved to the position of the evaluation element on the wafer 217 by the probe position controller 223 capable of being driven independently of the stage 234. Movement is carried out with confirming in such a manner that an electron beam controller 271 scans around the evaluation element on the wafer 217 with an electron beam 266, and that a secondary electron from the wafer 217 is detected by a secondary electron detector 237 to display an image of the element portion on an image display apparatus 238. In this embodiment, a power supply 269 is connected to each probe 203 so that voltage can be applied to a minute portion of the wafer 217 with which applied to a minute portion of the wafer 217 with which the probe 203 comes into contact. At the same time, an amperemeter 270 is also connected to each probe 203 so that a current flowing in each probe 203 can be measured. As an example of an evaluation method, a case in a MOS device formed on the wafer 217 is described. First, three probes 203 are brought into contact with a source electrode, a gate electrode and a drain electrode, respectively. The source electrode is grounded using the probe 203, and while exciting voltage of the gate electrode as a parameter by the probe 203, a relationship between a drain voltage and a drain current flowing between the source and a drain by the probe 203. This provides an output property of the MOS. These operations are collectively controlled by the central processing unit 240. As the moving mechanism of each probe 203, the probe moving mechanism 201 of the slant entering type shown in FIGS. 17 and 18 is used, so that an inspection of the wafer 217 with a large diameter can be achieved with a compact apparatus. Further, since the structure of probe moving mechanism 201 is one that the replacement or the like of the probe 203 can be easily carried out, and therefore, an operating rate of the apparatus can be improved. (Embodiment 9) FIG. 27 is a sectional view of a probe moving mechanism 201 of the present invention. In this figure, an FIB 227 emitted from the ion source 225 is focused on a desired position on the stage 234 by passing through an optical system 226. The focused ion beam, that is, FIB 227, is spattered in the form of scanning the surface of the wafer 217 to carry out fine processing. On the stage 234, the wafer 217, semiconductor tip, or the like, are placed and the stage position controller 235 determines an observation position on the wafer 217. The probe 203 mounted on the probe moving mechanism 201 is moved to the observation position on the wafer 217 by the probe position controller 223 which can drive independently of the stage 234. Movement and processing are carried out while observing in such a manner that the FIB controller 236 scans around the observation position on the wafer 217 with the FIB, that a secondary electron from the wafer 217 is detected by a secondary electron detector 237, and that an obtained secondary particle image is displayed on an image display apparatus 238. A power supply 269 is connected to the probe 203 so that voltage can be applied to a minute portion of the wafer 217 with which the probe 203 is brought into contact. In observation, a groove is provided around a circuit by the FIB so as to electrically isolate the circuit to be observed from other circuits. The voltage applied probe 203 is brought into contact with an end of the circuit, and a position is observed which is considered to be connected to the circuit in design. When connected without any break, a contrast is changed (brightened), so that failure of the circuit can be determined. These operations are collectively controlled by the central processing unit 240. As the moving mechanism of the probe, the probe moving mechanism 201 of the slant entering type shown in FIGS. 17 and 18 is used, so that an inspection of the wafer 217 with a large diameter can be achieved with a compact apparatus. Further, since the structure of probe moving mechanism 201 is such that the replacement or the like of the probe 203 can be easily carried out, and therefore, an operating rate of the apparatus can be improved. The same effects as the present invention can be obtained in, for example, a sample creating apparatus using a projection ion beam which is structure by replacing a deflector 230 and an objective lens 231 with a mask plate and a projection lens, or a sample observing apparatus using a laser beam which is structured by replacing an ion source 225 with a laser source.
052271218	description	DESCRIPTION OF THE PREFERRED EMBODIMENT Outline of Contents I. Overview Description of Control Complex PA0 II. Panel Overview PA0 III. DIAS PA0 IV. DPS PA0 V. Control Room Integration PA0 VI. Panel Modularity PA0 APPENDIX (Validity Algorithm) PA0 1. Conditions that may cause a trip in less than 10 minutes. PA0 2. Conditions that may cause major equipment damage. PA0 3. Personnel/Radiation hazard. PA0 4. Critical Safety Function violation. PA0 5. Immediate Technical Specification Action Required. PA0 6. First-Out Reactor/Turbine Trip. PA0 1. Conditions that may cause a trip in greater than 10 minutes. PA0 2. Technical specification action items that are not Priority 1. PA0 3. Possible equipment damage. PA0 1. Sensor deviations. PA0 2. Equipment status deviations PA0 3. Equipment/process deviations not critical to operation. A. Alarm and Messages PA1 B. Indicator PA1 C. CRT PA1 D. Controller PA1 E. Display Formats PA1 F. Display Integration PA1 A. Discreet Indicators PA1 B. Validity Algorithm Summary PA1 C. Alarm Processing and Display PA1 A. CRT PA1 B. IPSO PA1 Pump: A hollow pump indicates that the pump has been activated by the operator ot automatic control signal. A solid pump indicates that the pump has been deactivated by the operator or automatic control signal. PA1 Valve: A hollow valve indicates that the valve is fully open and a solid valve indicates that the valve is fully closed. A valve not fully open or closed has a mixed solid/hollow shape, i.e., left side solid/right ride hollow. PA1 Valve Open and Operable--Red Color Coding. PA1 Valve Closed and Operable--Green Color Coding. PA1 Non-Instrumented Valve--Grey Color Coding (Position is Operator Inputted). PA1 Valve Not Operable--Grey Color Coding with Alarm Coding. PA1 Loss of Indication--Grey Color Coding with Alarm Coding and mixed hollow/solid shape. PA1 The critical function information provided on the 1st level display page that is associated with the critical function. PA1 Information related to success path availability and performance of the success paths that can support that critical function. PA1 High level information presented using a mimic format with the critical function/success path related information. PA1 A time trend of the most representative critical function parameter. PA1 1. RCP 1A PA1 2. RCP 1B PA1 3. RCP 2A PA1 4. RCP 2B PA1 5. RCP SealBleed PA1 6. RCS PA1 7. T.sub.hot PA1 8. T.sub.cold PA1 9. Pressurizer Pressure PA1 10. Pressurizer Level PA1 1. When validation fails and a "FAULT SELECT" sensor is selected for the "process representation". PA1 2. When the "Valid" output does not correlate to the PAMI sensor(s). PA1 1. The "process representation" is always displayed on the applicable DIAS display and/or CRT page(s) where a single "process representation" is needed as opposed to multiple sensor values. Each plant process parameter is evaluated individually to determine the type of display required and location (DIAS and CRT or CRT only). PA1 2. The "process representation" is always a "valid" value unless there is a: PA1 Both of these are explained below. PA1 3. The "process representation" is always used for alarm calculations and trending (where a single value is normally trended). This can be "valid" , "fault select" or "operator select" data, depending on the results of the algorithm calculations as described below. PA1 4. Using a menu on DIAS or the CRT, the operator may view any of the values (A,B,C,D or calculated output) without changing the "process representation". PA1 5. A "Fault Select" value will be displayed automatically as the "process representation" when the validation algorithm is unable to yield "valid" data. The "fault select" value is the output of the sensor closest to the last "valid" signal at the time validation initially failed. On DIAS (if applicable), this information will be labeled "fault select". On the CRT(s) graphic pages, this information is preceded by an asterisk() to indicate suspect data. The "fault select" "process representation" is automatically returned to a "valid" process representation" when the validation algorithm is able to calculate "valid" data. PA1 6. An "operator select" sensor may be selected for the "process representation" only when there is a: PA1 The "operator select" "process representation" will replace the "valid" or "fault select" "process representation". On DIAS (if applicable), this information will be labeled "operator select". On the CRT(s), this information will be preceded by an asterisk() on graphic displays and labelled "operator select" in the data base. The "operator select" "process representation" is automatically replaced by the calculated "valid" signal when both the "Validation Fault" and the "PAMI Fault" clear. PA1 1. Normal operation PA1 2. Heatup/cooldown. PA1 3. Cold shutdown/refueling. PA1 4. Post-trip. PA1 1. Unacknowledged Alarm--If there is an unacknowledged alarm associated with an alarm tile, the alarm tile will flash at a fast rate (i.e., 4 times/sec using a 50/50 duty cycle as depicted by the long rays in FIG. 9). This condition takes precedence over all other alarm tile states for group alarms. PA1 2. Cleared Alarm/Return to Normal (Reset Alarm)--When an alarm condition clears, the corresponding alarm tile flashes at a slow rate (i.e., 1 time/sec using a 50/50 duty cycle as depiected by the short rays in FIG. 9) until this condition has been acknowledged. This condition takes precedence over the remaining two states for grouped alarms. PA1 3. Alarm--If an alarm condition exists and alarm states 1 and 2 above do not exist, then the alarm tile is lit without flashing (as depicted by the absence of rays in FIG. 9). PA1 4. No Alarm--If there is no alarm condition associated with an annunciator tile, then the alarm tile is not lit (not depicted in FIG. 9). To indicate that the alarm tile's bulb is functioning, a lamp test feature is provided. PA1 A) First Level Display Page Set (Major Plant System/Function Groupings 142 PA1 B) Control Room Workstation 144 PA1 C) Alarm tiles 146 PA1 1) The operator selects the "Alarm List" menu option 140 (FIG. 4) followed by the "Elec." menu option 148 (FIG. 12). This accesses the categorized alarm listing of the type shown in FIG. 14 beginning with the electrical alarms. PA1 2) If the operator wishes to view alarms associated with a specific alarm, e.g., RCPIA, he selects the following menu options from page 84 (FIG. 4 and 12): PA1 A. Categorized Alarm List--The operator selects "Alarm List" followed by the tile, e.g., "RCPIA", menu option. The categorized alarm list is accessed with RCPIA alarms at the top of the page. PA1 B. Alarm Messages--The operator can use the alarm tile menu options in the same method that the control panel alarm tiles are used. The selection of an alarm tile menu option provides the alarm message and a menu with display pages that can provide supporting information about the alarm condition. PA1 1) Alarm acknowledgement via the annunciator tiles--Alarms can be acknowledged by depressing alarming/unacknowledged annunciator tiles or a CRT annunciator tile representation. This action changes the annunciator tile from a flashing condition to a solid condition when all alarm conditions associated with the tile have been acknowledged and silences any audible sound (described later) associated with the alarm condition. Alarm messages are viewed on the message window (when using the physical tile) and the workstation's CRT message line (see FIG. 16). PA1 2) Alarm acknowledgement using alarm listing pages--Alarms can be acknowledged on the categorized listing by touching alarm tile touch targets associated with the alarm tile categories (see FIG. 14). Upon touching the alarm tile's representation, all alarms associated with that tile are acknowledged. This means of alarm acknowledgement may be the most useful for acknowledging multiple alarms remote to the operator's location. PA1 1. Unacknowledged Priority 1 or 2 Alarms. PA1 2. An Alarm Reminder Tone for Priority 1 or 2 Unacknowledged or Cleared Conditions. PA1 3. Cleared Priority 1 Alarms, or Cleared Priority 2 Alarms. PA1 new/unacknowledged priority 2, 3 and operator aid features change from a fast flash rate to a steady highlighted condition, i.e., tiles and CRT alarm representations. PA1 Any cleared alarm conditions, i.e., slow flash rate, are not presented as alarm information. PA1 Any new alarm condition or cleared alarm condition coming in after the "STOP FLASH" button has been activated, is normally displayed to the operator (i.e., flashing). However, the operator may redepress the alarm "STOP FLASH" button to suppress these conditions. PA1 1) Primary Systems (example, see FIG. 19) PA1 2) Secondary Systems PA1 3) Power Conversion PA1 4) Electrical Systems PA1 5) Auxiliary Systems PA1 6) Critical Functions PA1 1) The next higher level (when applicable) display page in the hierarchy, item (c). This feature is more meaningful on a 3rd level display page since the next higher level page is a level 2 display page which is not normally on the menu. PA1 2) Display pages of systems that are connected to or support the process of the presently displayed page (h,i). PA1 3) All six first level display pages (b,c,d,e,f,g). PA1 4) The IPSO display page (a). PA1 5) The last page viewed on the monitor (j). PA1 (1) Display Page Access Using Alarm Tiles--This mechanism for display page access may be most useful for obtaining display pages associated with the workstation's process. By pressing a workstation alarm tile from display 78, such as 80 (FIG. 15), region 4 of the workstation CRT's display page menu changes to a new menu with display page options associated with the alrm tile's descriptor. For example, as shown in FIG. 23 an RCP1A alarm tile provides menu options associated with RCP 1A. The desired display page will then be a direct access menu option. PA1 (2) Accessing CRT Information from the Discrete Indicators--Each discrete indicator 82 such as shown in FIG. 7, has a CRT access touch target 158. This button provides for access to supporting information for the process parameter that is presently displayed on the discrete indicator. By touching the CRT target on the discrete indicator, region 4 of the menu options on the workstation's CRT changes to menu options containing display pages with supporting and diagnostic information associated with the process parameter. PA1 (3) Display Page Access Using a Display Page Directory --Any display page of the display page hierarchy can be accessed using the presently displayed menu. For example, if the operator is viewing the Feedwater System display page and wants to access the CVCS display page, the following sequence takes place (refer to FIGS. 22 and 4): The operator selects "by touch" the "DIRECTORY" menu option (option 1 in region 2 on FIG. 22) followed by the "PRIMARY" menu option (option b in region 3 on FIG. 22). This accesses the primary section of the display page hierarchy from the display page library (see FIG. 4). Each display page within the primary section of the display page hierarchy is a touch target on this display page, and now the operator can select the CVCS display page. Any page in the display page hierarchy can be accessed using this feature. The "DIRECTORY" menu option is followed by the desired hierarchy associated with one of the six first level display pages, menu options b,c,d,e,f or g on FIG. 22. PA1 Failure to satisfy the safety function status checks, (post-trip). PA1 Poor performance of a success path/system that is being used to support a critical function. PA1 An undesirable priority 1 deviation in a power production function (pre-trip). PA1 Unavailability of a safety system (less than minimum availability as defined by Reg. Guide. 1.47). PA1 (a) Feedwater and Condensate System Status Information (i.e., operational status, alarm status) PA1 (b) Steam Generator Levels, Dynamic Representation PA1 (c) Steam Generator Safety Valve Status PA1 (d) Atmospheric Dump Valve Status PA1 (e) Main Steam Isolation Valve Status PA1 (f) Turbine Bypass System Status PA1 (a) Plant net electric output, digital value. PA1 (b) Alarm information for deviations in important processes associated with the main turbine and turbine generator. PA1 (c) Power distribution operational and alarm status to the plant busses and site grid. PA1 (a) Circulation water system status. PA1 (b) Alarm information for critical deviations in condenser pressure conditions. PA1 Containment Isolation Actuation PA1 Safety Injection Actuation PA1 Main Steam Isolation PA1 Containment Purge Isolation PA1 High Containment Airborne Radiation PA1 High Activity Associated, with Any Release Path PA1 High Coolant Activity PA1 (a) Diesel Generator Status PA1 (b) Status of Power Distribution within the Power Plant PA1 (c) Instrument Air System Status PA1 (d) Service Water System Status PA1 (e) Component Cooling Water System Status PA1 CCW--Component Cooling Water PA1 CD--Condensate PA1 CI--Containment Isolation PA1 CS--Containment Spray PA1 CW--Circulating Water PA1 EF--Emergency Feedwater PA1 FW--Feedwater PA1 IA--Instrument Air PA1 SDC--Shutdown Cooling PA1 RCS--Reactor Coolant PA1 SI--Safety Injection PA1 SW--Service Water PA1 TB--Turbine Bypass PA1 Yes, go to step 2 PA1 No, go to step 5 PA1 If all deviation checks are satisfactory do the following: PA1 If any deviation checks are unsatisfactory, the following occurs: PA1 a. Yes, Output the "PAMI" message and if not previously present, remove the "PAMI Fault Operator Select Permissive", clear the "PAMI Fault" alarm if present, go to step 6. PA1 b. No, Perform the following: PA1 Note: A validation fault enables one Operator Select Permissive and failure of the "valid" algorithm output to deviation check satisfactorily against "PAMI" gives the other Operator Select Permissive. PA1 If there is no Operator Select permissive, output the "calculated signal", as the "process representation", go to step 9. PA1 If there is an Operator Select permissive, go to step 7. PA1 Note: This step outputs the "calculated signal" as the "process representation" when the operator has the option to select a sensor, but does not use that option. PA1 No, go to step 10 ("bad" sensor evaluations are not performed when the "process representation" is from a "fault select" sensor). PA1 Yes, Deviation check all "bad" sensors (A, B, C, D) against the "valid", or "operator select" signal by the following methods: PA1 Yes, Output the message "Out-of-Range" along with the "process representation" signal. On the CRT place an asterisk () preceding the "process representation". Go to step 1 and repeat the algorithm. PA1 No, go to step 1 and repeat the algorithm. PA1 a. Steps 1-5 (Determination of "Calculated Signal" and Faults) of the generic validation algorithm are modified to account for the following (steps 1-8 perform these functions): PA1 b. The (Determination of "Calculated Signal" and Faults) and the remainder of the generic validation algorithm (steps 6-10) are performed independently for each of the cold legs (1A, 1B, 2A, 2B). PA1 c. Two additional algorithms were added: PA1 A--1st narrow range sensor (safety) (465.degree.-615.degree. F.) PA1 B--2nd narrow range sensor (safety) (465.degree.-615.degree. F.) PA1 C--wide range sensor (PAMI) (50.degree.-750.degree. F.) PA1 D--wide range sensor in opposite cold leg (i.e., when discussing loop 1A, this will be the wide range sensor in loop 1B, PAMI) (50.degree.-750.degree. F.) PA1 Cold leg 1A, 1B, 2A and 2B temperature "calculated signal" will be calculated using sensors, A,B,C. A validation attempt will be made using narrow range sensors, if that is unsuccessful, the cold leg "calculated signal" will be validated using wide range sensors. In the event that validation fails using both narrow and wide range sensors, the the algorithm will select the sensor closest to the last "valid" signal as the "fault select" "calculated signal". PA1 2. "Process Representation" selection (steps 9, 10) (similar to steps 6 and 7 of the generic validation algorithm). PA1 3. PAMI Check of "operator select" sensor (step 11) (identical to step 8 of the generic validation algorithm). PA1 4. Bad Sensor Evaluation and Range Check (step 12, 13) (similar to steps 9, 10 of the generic validation algorithm. PA1 Yes, go to step 2 PA1 No, go to step 5 PA1 If both deviation checks are satisfactory, go to step 4 to see if the average is in range. PA1 If any deviation checks are unsatisfactory go to step 5. PA1 The average or selected sensor goes in-range at 96% and 4% of narrow range. PA1 The average or selected sensor goes out-of-range at 98% and 2% of narrow range. PA1 If in-range, clear the "Validation Fault" alarm, if present, disable the "Validation Fault Operator Select Permissive", and output the average or selected narrow range sensor as the "valid" "calculated signal". Go to step 6. PA1 If out-of-range, attempt the wide range validation, go to step 7. PA1 If either sensor A or B passes the deviation check, the algorithm selects the sensor (A or B) that is closest to C. This sensor is elected for further checks. The sensor that deviates the most from sensor C is flagged as a "bad" sensor, if not previously "bad" and its associated sensor deviation alarm is generated if not previously generated. Go to step 4. PA1 If both A and B do not deviation check against C, go to step 7 and attempt wide range validation. PA1 If satisfactory, do the following: PA1 If unsatisfactory, do the following: PA1 Note: To validate the single wide range sensor in a cold leg, the algorithm deviation checks it against the wide range sensor in the other cold leg of that loop (i.e., if in loop 1, 1A wide range sensor is deviation checked against the 1B wide range sensor). PA1 If the deviation check is satisfactory, select C sensor as "valid", "calculated signal and do the following". PA1 If the deviation check is unsatisfactory, validation fails, go to step 8. PA1 If the previous scan was not "fault select", a validation fault has just occurred. Do the following: PA1 If the previous scan was "fault select", validation had failed previously and the algorithm has already picked a "fault select" sensor. Continue to output the signal from the "fault select" sensor as the "calculated signal", go to step 9. PA1 Note: To simplify the discussion of the cold leg (1A,1B,2A or 2B) "process representation" inputs to the loop 1 or loop 2 algorithm, A will designate the input from leg 1A or 2A and B will designate the input from leg 1B or 2B leg T.sub.c. PA1 No, output the "process representation" from step 2 as "fault select", go to step 6. PA1 Yes, output the "process representation" from step 2 as "fault select", go to step 6. PA1 No, output the "process representation" from step 2 as "operator select", go to step 6. PA1 a. Steps 1-5 (Determination of "Calculated Signal" and Faults) of the generic validation algorithm are modified to account for the following. PA1 b. The remainder of the generic algorithm (steps 6-10) are renumbered to account for additional steps in the (Determination of "Calculated Signal" and Faults). They are almost identical with the minor modifications described with each step. PA1 P--101A--A PA1 P--101B--B PA1 P--101C--C PA1 P--101D--D PA1 P--100X--E PA1 P--100Y--F PA1 P--103--G PA1 P--104--H PA1 P--105--I PA1 P--106--J PA1 P--190A--K PA1 P--190B--L PA1 Yes, go to step 2 PA1 No, go to step 5 and attempt (0-1600 psig range validation) PA1 If all deviation checks are satisfactory, go to step 4 to see if the average is in range. PA1 If any deviation checks are unsatisfactory, the following occurs: PA1 The average goes in-range at 96% and 4% of narrow range. PA1 The average goes out-of-range at 98% and 2% of narrow range. PA1 If in-range, do the following: PA1 If out-of range, attempt the (0-1600 psig) range validation, go to step 5. PA1 Yes, go to step 6 PA1 No, go to step 9 and attempt (0-4,000 range validation) PA1 If all deviation checks are satisfactory, go to step 8 to see if the average is in range. PA1 If any deviation checks are unsatisfactory, the following occurs: PA1 The average goes in-range at 96% and 4% of the 0-1600 psig range. PA1 The average goes out-of-range at 98% and 2% of the 0-1600 psig range. PA1 If in-range, do the following: PA1 If out-of-range, attempt the 0-4000 psig range validation, go to step 9. PA1 Yes, go to step 10. PA1 No, (0-4000 psig) range validation is not possible, go to step 13. PA1 If both deviation checks are satisfactory, do the following: PA1 If either deviation check is unsatisfactory, go to step 13. PA1 Method (a) (within sum of 1/2 0-4000 psig range instrument uncertainty, plus process variation, plus instrument position constant). PA1 Method (b) (within sum of 1/2 0-4000 psig range instrument uncertainty, plus process variation). PA1 No, do the following: PA1 If the previous scan was not "fault select", a validation fault has just occurred, do the following: PA1 Note: "Out-of-range" informs the operator that the actual pressure may be higher or lower than the sensor is capable of measuring. 1. Mode and Equipment Dependance PA2 2. Subfunction Grouping PA2 3. Shape and Color Coding PA2 4. Alarms on CRT PA2 5. Determining Alarm Conditions PA2 6. Acknowledging Alarms PA2 a. "Fault Select" value or PA2 b. "Operator Select" value. PA2 a. "Validation Fault" or PA2 b. "PAMI Fault". PA2 "Alarm Tiles 150" PA2 "Primary 152" PA2 Note: A sensor is "good" if it was not declared a "bad" sensor on the previous scan or a "suspect" sensor on a previous pass. PA2 a. Clear the "Validation Fault" alarm, if previously present PA2 b. Clear the permissive that allows the operator to select a sensor after a validation fault (i.e., "Validation Fault Operator Select Permissive"), if previously present. PA2 c. Declare any "suspect" sensor "bad" and output a sensor deviation alarm on that sensor. PA2 d. Output the average as the "valid" "calculated signal". PA2 e. Go to step 4 PA2 a. The sensor with the greatest deviation from the average is flagged as "suspect", then the algorithm checks to see if this the first or second pass on this scan. PA2 Note: The "PAMI Fault Operator Select Permissive" allows the operator to select any sensor for the "process representation" when the "calculated signal" (i.e. algorithm's "valid" output) does not agree with the PAMI sensor(s). PA2 Remove the "PAMI" message PA2 Generate a "PAMI Fault" alarm PA2 Enable the "PAMI Fault Operator Select Permissive" PA2 Go to step 6. PA2 If the previous scan was not "fault select", a "validation fault" has just occurred. Do the following: PA2 If the previous scan was "fault select", validation had failed previously and already picked a "fault select" sensor. Continue to output the "fault select" sensor as the "calculated signal", go to step 6. PA2 Note: it is important that the sensor initially fault selected be retained since over time other failed sensors may erroneously appear more accurate. PA2 Deviation check "bad" sensors to be (within sum of instrument range uncertainty and expected process variation). PA2 Note: "Out-of-range" informs the operator that the actual process value may be higher or lower than the sensor is capable of measuring. In the case of process measurements with multiple ranges of sensors this check will cause the selection of sensors in a new range. PA2 Note: On the RCS panel, RCP Differential Pressure, SG Differential Pressure and Pressurizer Level Reference Leg Temperature use this generic validation algorithm directly. The T.sub.cold, T.sub.hot, Pressurizer Level and Pressurizer Pressure algorithms this generic algorithm with additional steps and minor modifications to accommodate: PA2 1. Only 3 cold leg sensors PA2 2. There are wide and narrow range temperature sensors in the same cold leg. PA2 1. An algorithm that averages the 2 cold leg "process representation" to get a loop T.sub.cold "process representation" (1A and 1B for loop 1 and 2A and 2B for loop 2) PA2 2. An algorithm that averages the 2 cold loop "process representation" to get an RCS T.sub.cold "process representation" (loop 1 and loop 2). PA2 Note; A sensor is "good" if it was not declared a "bad" sensor on the previous scan. PA2 Note: Hysteresis is needed to prevent frequent shifts at end-of-range. Out-of-range occurs at 98% and 2% to insure that no out-of-range sensors are used to calculate a "valid" output (i.e.: worst case sensors would read 100% or 0%). PA2 a. Disable the "PAMI fault operator select permissive" PA2 b. Output the "PAMI" message with the "valid" "calculated signal". PA2 c. Clear the "PAMI Fault" alarm, if present. PA2 d. Go to step 9. PA2 a. Remove the "PAMI" message PA2 b. Enable the "PAMI Fault Operator Select Permissive". PA2 a. Clear the "Validation Fault" alarm, if present PA2 b. Disable the "Validation Fault Operator Select Permissive", if it was enabled. PA2 c. Go to step 9. PA2 a. Generate a "validation fault" alarm. PA2 b. Enable the "Validation Fault Operator Select Permissive". PA2 c. Deviation check all sensors (A, B, C) against the last "valid" signal. Select the sensor that deviates the least from the last "valid" signal as the "fault select" sensor. PA2 d. Output the signal from the "fault select" sensor as the leg T.sub.c "calculated signal". PA2 e. Go to step 9. PA2 1. The algorithm averages the "process representation" inputs from the A and B cold legs and outputs the average as the loop (1 or 2) T.sub.c "process representation". PA2 2. The algorithm checks to see if A and B are "valid" PA2 3. The algorithm checks to see if A or B is "operator select". PA2 4. The algorithm checks to see if A or B is "fault select". PA2 5. Deviation check A and B against the average. (Within sum of 1/2 wide range instrument uncertainty and expected process variation). PA2 6. The algorithm checks to see if A and B are narrow range. PA2 7. The algorithm checks to see if either or both inputs is out-of-range. PA2 8. The algorithm checks to see if A and B inputs are PAMI. PA2 1. Three sensor ranges (0-1600 psig), (1500-2500 psig) and (0-4000 psig). PA2 Note: A sensor is "good" it was not declared a "bad" sensor on the previous pass or a suspect sensor on a previous pass. PA2 The sensor with the greatest deviation rom the average is flagged as a "suspect" sensor, then the algorithm checks to see if this the first or second pass on this scan. PA2 Note: Hysteresis prevents frequent range shifts. Out-of-range occurs at 98% and 2% to insure that no out-of-range sensors are used to calculate a "valid" output (i.e., worst case sensors would read 100% and 0%). PA2 a. Clear the "Validation Fault" alarm, if previously present. PA2 b. Remove the "Validation Fault Operator Select Permissive". PA2 c. Output the average as the "valid" "calculated signal". PA2 d. Go to step 12. PA2 The sensor with the greatest deviation from the average is flagged as a "suspect" sensor, then the algorithm checks to see if this is the first or second pass on this scan. PA2 Hysteresis prevents frequent range shifts. Out-of-range occurs at 98% and 2% to insure that no out-of-range sensors are used to calculate a "valid" output (i.e., worst case sensors would read 100% or 0%). PA2 a. Clear the "Validation Fault" alarm, if previously present. PA2 b. Remove the "Validation Fault Operator Select Permissive". PA2 c. Output the average as the "valid" "calculated signal". PA2 d. Go to step 12. PA2 a. Clear the "validation fault" alarm, if previously present. PA2 b. Remove the "Validation Fault Operator Select Permissive", if previously present. PA2 c. Go to step 12. PA2 Yes, do the following: PA2 a. Remove the "PAMI" message, if previously present. PA2 b. Generate a "PAMI Fault" alarm, if not previously present. PA2 c. Enable the "PAMI Fault Operator Select Permissive" PA2 d. Go to step 14. PA2 a. Generate a "Validation Fault" alarm. PA2 b. Deviation check all sensors (A,B,C,D,E,F,G,H,I,J,K or L) against the last "valid" signal. Select the sensor that deviates the least from the last "valid" signal as the "fault select" sensor. PA2 c. Output the signal from the "fault select" sensor as the pressurizer pressure "calculated signal". PA2 d. Enable the "Validation Fault Operator Select Permissive". PA2 e. Go to step 14. I. OVERVIEW DESCRIPTION OF CONTROL COMPLEX FIG. 1 shows a control room complex in accordance with the preferred embodiment of the present invention. The heart of the main control room 10 is a master control console 12 which allows one person to operate the nuclear steam supply system from the hot standby to the full power condition. It should be appreciated that the control room, equipment and methods described herein, may be advantageously used with light water reactors, heavy water reactors, high temperature gas cooled reactors, liquid metal reactors and advanced passive light water reactors, but for present purposes, the description will proceed on the basis that the plant has a pressurized water NSSS. For such an NSSS, the master control console 12 typically has five panels, one each for the reactor coolant system (RCS) 14, the chemical volume and control system (CVCS) 16, the nuclear reactor core 18, the feed water and condenser system (FWCS) 20, and the turbine system 22. As will be described more fully below, the monitoring and control for each of these five plant systems, is accomplished at the respective panel in the master control console. Immediately overhead behind the core monitoring and control panel 18, is a large board or screen 24 for displaying the integrated process status overview (IPSO). Thus, the operator has five panels and the overhead IPSO board within easy view while sitting or standing in the center of the master control console 12. To the left of the master control console is the safety related console 26, typically including modules associated with the safety monitoring, engineered safeguard features, cooling water, and similar functions. To the right of the master control console is the auxiliary system console 28 containing modules associated with the secondary cycle, auxiliary power and diesel generator, the switch yard, and the heating and ventilation system. Preferably, the plant computer 30 and mass data storage devices 32 associated with the control room are located in distributed equipment rooms 31 to improve fire safety and sabotage protection. The control room complex 10 also has associated therewith, a shift supervisor's office 34, which has a complete view of the control room, an integrated technical support center (TSC) 36 and viewing gallery outside the control area, and other offices 38 in which paper work associated with the operation of the plant may be performed. Similarly, desk, tables, and the like 40 are located on the control room floor for convenient use by the operators. A remote shut-down room 42 (FIG. 2) is also available on site for post-accident monitoring purposes (PAM). FIG. 2 is a schematic of the information links between the plant components and sensors, which for present purposes are considered conventional, and the various panels in the main control room. It is evident from FIG. 2 that information flows in both directions through the dashed line 46 representing the nuclear steam supply system and turbo generating system boundary. NSSS status and sensor information 48 that is used in the plant protection system 50 and the PAMS 58, passes directly through the NSSS boundary 46. Control signals 52 from the power control system pass directly through the NSSS boundary. Other control system signals 60,62 from the engineered safeguard function component control system 56 and the normal process component control system 64, are interfaced through the NSSS boundary via remote multiplexors 6. Each of the plant protection system, ESF component control system, process component control system, power control system and PAMs, is linked to the main control room 42, to each other, to the data processing system (DPS) 70 and to the discrete indication and alarm system (DIAS) 72. FIG. 2 illustrates one significant aspect of the present invention, namely, the integration of monitoring, control and protection information, during both normal and accident conditions, so that the operator's task in determining an appropriate course of action is considerably simplified. The way in which this is accomplished will be described in the following sections. II. PANEL OVERVIEW FIGS. 3(a) and 3(b) are schematics of a sit/stand panel such as the reactor coolant system panel 14 from the master control console 12 in accordance with one embodiment of the invention. FIGS. 3(c) and 3(d) show an alternative embodiment for stand up only. The substantially flat upper portion or wall 74 of the panel is vertically oriented and the substantially flat lower or desk portion 76 is substantially horizontal, with the monitoring and alarm interfaces carried by the upper portion, and the control interfaces carried on the lower portion. A. Alarm and Messages The alarm functionality (see FIGS. 9, 15-18) includes alarm and message (A+M) interface 78 having a multiplicity of tiles 80 each having a particular acronym or similar cue 81 associated therewith, whereby an alarm condition is indicated by the illumination of that tile and the generation of an accompanying audible signal. The operator is required to acknowledge the alarm by either pushing the tile or some other interface provided for that purpose. The number of tiles associated with a particular panel is dependent on the number of different alarm conditions that can arise with respect to the monitored system, e.g, the reactor coolant system. Typically, hundreds of such tiles are associated with each panel. The alarms are prioritized into three (3) alarm classes (Priority 1, Priority 2, and Priority 3, prompting immediate action, prompt action and cautionary awareness). This RCS panel alarms are equipment status and mode dependent (Normal RCS, Heatup/Cooldown, Cold Shutdown/Refueling and post Trip). When a high priority alarm actuates coincidentally with a low priority alarm on the same parameter, the lower priority alarm is automatically cleared. On improving conditions, the higher priority alarm will flash and sound a reset tone. The operator will acknowledge that the higher priority alarm has cleared. If the lower priority alarm still exists, its alarm window or indicator will turn on in the acknowledged state after the operator acknowledges that the higher priority alarm has cleared. B. Indicator The second monitoring interface are the process variable indicators, for example reactor coolant hot and cold leg temperatures, pressurizer level and pressure, and other RCS parameters. Discrete indicators 82 (see also FIGS. 7 and 8) provide an improved method of presenting the RCS panel parameters. Some RCS panel parameters require continuous validated display and trending on the master control console. Plant process and category 1 parameters like pressurizer level and RCS cold leg temperature fall into this category. Other RCS panel parameters are used less frequently. The discrete indicators 82 provide indication on parameters needed for operation when the Data Processing System (CRT information displays) is unavailable. These include Regulatory Guide 1.97 category 1 and 2 parameters, associated with priority 1 or priority 2 alarms, other parameters needed for operation due to inaccessibility of local gages and parameters that the operator must view for surveillance when the Data Processing System is unavailable for a period of up to twenty-four (24) hours. These less frequently viewed parameters would be available on discrete indicators, with a menu available by operator selection. The menu would show alphanumeric listings of available data points. Lastly, parameters displayed on process controllers need not be available on discrete indicators. C. CRT Additionally, a CRT display 84 generates an image of the major vessels, pipes, pumps, valves and the like associated with, e.g., the reactor coolant system, and displays the alarms and values of the parameters which may be shown in bar, graph, trend line or other form on the other displays 78,82 (see FIGS. 4-6, 10, 12-14 and 19-23). From this CRT, the operator has access to all NSSS information. The information is presented in a three level structured hierarchy that is consistent with the operator's system visualization. FIG. 4 illustrates the NSSS primary side page directory 84, which accesses all CRT pages related to the functions of the RCS panel. D. Controller In the control portion 76 of the panel 14, a plurality of discrete, on-off switches 86 are provided at the left, for example, each switch pattern being associated with a particular reactor cooling pump whose operating parameters are displayed immediately above it, and analog control interfaces which can be in the form of conventional dials or the like (not shown), or touch screen, discrete control as indicated at 88. Process controllers are provided on the RCS panel to provide the operator with the ability to automatically or manually control process control loops. The process controllers allow control of throttling or variable position devices (such as electro-pneumatic valves) from a single control panel device. Process controllers are used for closed loop control of the following RCS panel process variables: pressure level, pressurizer pressure, RCP Seal Injection Flow and RCP Seal Injection Temperature. Process controllers are designed for each specific control loop utilizing the a consistent set of display and control features. In a conventional control room, each process control loop has its own control device, usually referred to as a MANUAL/AUTO Station. For example, the RCP Seal Injection Sub-System has five process control loops, a seal injection flow control loop for each of the four RCPs and a seal injection temperature control loop for the entire sub-system. These five control loops each have their own MANUAL/AUTO station which occupy a large amount of control panel space and make cross loop comparisons cumbersome. Although these five process loops are controlled independently, process variations in one controlled parameter affect the other four process parameters. Conventional MANUAL/AUTO stations make it difficult for the operator to simultaneously interact with the five MANUAL/AUTO stations. The RCS panel process controllers for similar processes (related by function or system) are operated from a single control station, called a process controller. This single control station saves panel space, accommodates convenient cross channel checking and allows easier control loop interaction for multiple related controls. Component control features (i.e., actuation of switches controls) provide the primary method by which the operator actuates equipment and systems on the RCS panel. The RCS panel has forty-three components controlled from momentary type switches Each switch contains a red status indicator for active or open and a green status indicator for inactive or closed. Blue status indicator lights/switches are used to indicate and select automatic control or control via a process controller. In addition to color coding, the red switch is always located above the green switch to reinforce color distinction. Each switch generates an active control signal when depressed and is inactive when released. Each switch is backlit to indicate equipment status/position. E. Display Formats Process display formats use standard information placement for similar processes and equipment. Fluid system piping representations are where possible standardized, top to bottom, left to right, with avoidance of crossovers. Incoming and outgoing flow path connections are placed at the margins. Related data are grouped by task and analysis specifications for comparison, sequence of use, function, and frequency. Process representations/layout are based on the operator's process visualization to maximize the efficiency of his data gathering tasks. The operator's visualization of a system is often based on diagrams used with learning materials and plant design documentation associated with system descriptions. Graphic information is presented on display page formats to aid in rapid operator comprehension of processes. Graphic information includes the use of bar graphs, flow charts, trends, and other plots, (e.g., Temp. vs. Press.). Bar graphs are primarily used to represent flows, pressures and levels. Since level corresponds to a tank, the bar graph is placed with consistent spatial orientation with respect to the tank symbol. Level bar graphs are oriented vertically. Flow bar graphs when used are oriented horizontally. Bar graphs are also helpful for comparison of numeric quantities. Flowcharts are used when they aid in the operator's process visualization. Flowcharts are helpful for understanding control system processes such as the Turbine Control System. Operator's learning materials for process control systems are frequently in a flowchart format, and thus a similar format on a display page is easy to comprehend. Trends are used on display page formats when task analysis indicates that the operator should be informed about parameter changes over time. Additionally, the operator is able to establish trends of any data base points in the plant computers data base. In some situations, task analysis may indicate that more than one trend is important to monitor process comparisons. In other situations such as heatup/cooldown curves, two parameters may be placed on the different ordinate axis of a graph. When more than one trend curve occupies the same coordinate axes, two ordinate vertical axes can be used for parameters that have different units. Scale labels are divisible by 1, 2, 5 or 10. Tick marks between scale labels are also divisible by 1, 2, 5 or 10. Trended information is typically presented on display pages with a scale of 30 minutes. However, the operator is able to adjust the scale to suit his needs. Logarithmic axes may be established using multiples of 10. If full range is less than 10, an intermediate range label is located to fall near the middle of the scale. Different colors are used for trends occupying the same coordinates. When multiple curves use a common scale, the scale is gray the curves are color coded. When multiple ordinate scales are used, they are color coded in correspondence to the curve. The colors used for trends will not include the alarm color or normal status color to avoid associating process parameter with normal or alarm conditions. Color is used to aid the operator in rapidly discriminating between different types of information. Since the benefits of color coding are more pronounced with fewer colors, coding on informational displays (i.e., IPSO, CRTs, alarm tiles) is limited to seven colors. In addition, color coded information has other representational characteristics to aid in discrimination of data and discrimination by color deficient observers. The following colors are used in the information display to represent the following types of information. The colors used have been carefully selected to yield satisfactory contrast for red-green deficient color observers. ______________________________________ Color Representation Characteristics ______________________________________ Black Background color. Green Component Off/Inactive, Valve Closed and Operable. Red Component On/Activated, Valve Open and Operable. Yellow Alarm Status-Good attention-getting color. Grey Text, labels, dividing lines, menu options, piping, inoperable and non-instrumented valves, graph grids, and other applications not covered by other coding conventions. Light Blue Process parameter values. White System's response to operator touch, e.g., menu selection until appropriate system response occurs. ______________________________________ Shape coding is used in the information system to aid the operator to identifying component type, operational status, and alarm status. Component shape coding is based on symbology studies which included shape coding questionnaires given to nuclear power plant personnel. FIGS. 5 and 6 show the shapes used to represent components in the control room. An attribute of shape, hollow/solid, is reflective of the status of the component. Hollow shape coding indicates that the component is active, whereas solid shape coding is used to represent inactive components. An example of shape coding for a pump and valve is described as follows. Information coding on valves is provided by these additional characteristics/representations: F. Display Integration Information associated with safety related concerns is integrated as a part of the control room information to allow the operator to use safety related information, where possible, during normal operation. This is a better design from a human factors view than that of previous control rooms because in stressful situations, people tend to use information that they are most familiar with. In many situations, safety related parameters are only a subset of the parameters that monitor a particular process variable Operators of present control room designs typically use control or narrow range indications during process control and should use separate safety related indications when monitoring plant safety concerns In this invention, the parameters typically used for monitoring and control are validated for accuracy against the safety related parameter(s), where available. If a parameter deviates beyond expected values from the associated safety related information, a validation alarm is presented to the operator. In response to an alarm condition, the operator can review the individual channels associated with the parameter on either a diagnostic CRT page or the discrete indicator displaying that parameter. At this time, he can select the most appropriate sensor for display. The operator is informed when the validation algorithm is able to validate the data. The resultant output of the validation algorithms are used on IPSO, the normally displayed format of a discrete indicator, and the higher level display pages on the CRT display system that contain the parameter. The Regulatory Guide 1.97 category 1 information is also displayed, by discrete indication display, at a single location on the safety monitoring panel. Critical Function and Success Path (availability and performance) information is accessible throughout the information hierarchy (see FIGS. 10, 24, 25, 26, 27, 32-35). Alarms provide guidance to unexpected deviation in critical functions as well as success path unavailability or performance problems. Priority 1 alarms alert the operator to the inability to maintain a critical function as well as the inability of a success path to meet minimum functional requirements Lower priority alarms provide subsystem/train and component unavailability or poor performance. IPSO provides overview information that is most useful for operator assessment of the Critical Functions. Priority 1 alarms associated with the Critical Functions or Success Paths supporting the critical function are presented on IPSO critical function matrix. Supporting information relating to these alarm conditions is available by using the alarm tiles or the critical function section of the CRT display page hiearchy. The critical function section of the display page hierarchy contains the following information: Level 1 Display Page--"Critical Functions": this page provides more detail on the critical function matrix presented on IPSO. Specifically, more detail on alarm conditions (descriptor, priority). This will help guide the operator to the appropriate level two critical function display page. A 2nd level page exists for each of the 12 critical functions. Each page contains: The 3rd level display pages in the critical function hierarchy are a duplicate of display page existing elsewhere in the hierarchy. For example, a safety injection display page display page under Inventory Control also exists within the primary section of the display page hierarchy. III. DISCRETE INDICATOR AND ALARM SYSTEM A. Discrete Indicators The discrete indicators 82 provide an improved method of presenting safety related parameters. Major process parameters such as Regulatory Guide 1.97 Category 1, require continuous validated display and trending on the master control console. The discrete indicators also provide indication and alarms on parameters needed for operation when the Data Processing System (DPS) is unavailable. These include Regulatory Guide 1.97 Category 1, 2 and 3 parameters, parameters associated with priority 1 or priority 2 alarms, and other surveillance related parameters. Though the DPS is a highly reliable and redundant computer system, its unavailability is considered for a period of up to twenty-four hours. The less frequently viewed parameters are available on discrete indicators, with a menu available by operator selection. Each discrete indicator has the capability to present a number of parameters associated with a component, system, or process. The discrete indicators present various display formats that are based on fulfilling certain operator information requirements. When monitoring or controlling a process such as pressurizer pressure, it is desirable that the operator use a "process representation" value in the most accurate range. For this type of information, the discrete indicator 82, such as shown in FIGS. 7 and 8, presents a bold digital value 90 in field 92 and an analog bar graph 94 of the validated average of the sensors in the most accurate range. The preferred validation technique is described in the Appendix, and validated status is indicated in field 96. This validated data is checked against post-accident monitoring indication (PAMI) sensors when applicable. When in agreement with the PAMI, as shown at field 98 the indicator may be used for post-accident monitoring. This has the advantage of continuing to allow the operator to utilize the indicator he is most familiar with and uses on a day-to-day basis. The operator, upon demand, can display any individual channel on the discrete indicator digital display, by touching a sensor identification such as 102. The use of validated parameters is a benefit to operators by reducing their stimulus overload and task loading resulting from presentation of multiple sensor channels representing a single parameter. When the parameter cannot be validated, the discrete indicator displays the sensor reading that is closest to the last validated value. A validation alarm is generated for this condition. The discrete indicator continues to display this sensor's value until the operator selects another value for indication. The field 96 on the discrete indicator that usually read "VALID" displays "FAULT SEL" in reverse image. This indicates that the value is not validated and has been selected by the computer. In this circumstance, the operator should review the available sensors that can be used for the "process representation". If the operator makes a sensor selection (which is enabled by a validation fault or failure of the "VALID" signal to agree with PAMI), the field 96 with "FAULT SEL" will be replaced by the message "OPERATOR SELECT", which is displayed in reverse image. When the validation algorithm can validate the data and all faults have cleared, the validation fault alarm will clear and the algorithm will replace the "FAULT SELECT" or "OPERATOR SELECT" "process representation" in field 92 with the "VALID" "calculated signal". Parameters that are required for monitoring the overall performance of plant processes or responding to priority 1 or 2 alarms are provided on discrete indicators. The most representative process parameter is the normally displayed value. Through menu options, the operator can view the other process related parameters. There are ten discrete indicators provided for the RCS panel. The indicators are: FIG. 7 illustrates that two related discrete indicators can be shown on a single display 82. On the left side of whereas at the right, pressurizer level is shown the display 82 validated pressurizer pressure is shown. The pressure display includes the following: digital "process representation" value 90 with units of measurement (2254 psig), quality 96 of the display (VALID), indication 98 that the display is acceptable for post accident monitoring (PAMI), bar chart 94 with the process value, a 30 minute range (1500-2500) and units of measurement for the bar chart (psig). In the upper right hand corner of the PRESS display, there are two buttons, "CRT" and "MENU". When touched, the selected button backlights, indicating selection. When the operator removes his hand, the actual selection is processed. The "CRT" button changes the CRT 84 menu options on the CRT located at the same panel as the discrete indicator where the button is pushed, e.g., RCS panel 14 as shown in FIG. 3. This "CRT" option identifies the CRT pages most closely associated the parameters on the discrete indicator. The "MENU" button selects the discrete indicator menu (FIG. 8). The upper section of the menu page is early identical to the normal display, It contains the digital "process representation" value 96 with units of measurement (2254 psig), quality of display (valid), indication that the display is acceptable for post accident monitoring (PAMI), CRT and MENU buttons. The lower section of the menu page contains selector buttons, such as 102, for all sensor inputs and "calculated signals" of this discrete indicator. The selector buttons 102 backlight when touched, indicating selection. When the operator removes his finger, the actual processing of the selection takes place. There are 13 buttons for pressure: four for 0-1600 psig pressurizer pressure: p-103, p-104, p-105 and P-106; six for 1500-2500 psig pressure: P-101A, P-101B, P-101C, P-101D, P-100X and P-100Y; two for 0-4000 psig RCS pressure: P-190A and P-190B; and one for the "calculated signal" pressure: CALC PRESS. When selected, the "CALC PRESS" button displays the "calculated signal" (i.e. the output of the algorithm). The "calculated signal" of the algorithm can be a a "valid" signal. If the algorithm were to fail and select an individual sensor for the "calculated signal", the "valid" message would be replaced by the message "fault select". This message "fault select" would be displayed in reverse image on the discrete indicator. This message would be displayed on the discrete indicator any time "CALC PRESS" is selected until the algorithm outputs a "VALID" signal to replace the "FAULT SELECT" sensor. To change the display, the operator would touch the button containing the sensor he wished to view. For example: by touching the button marked "P-103", the digital display would display the output from the 0-1600 psig range sensor P-103. The message "VALID" below the digital value would be replaced by the message "P-103". Additionally, the "PAMI" message would be removed because P-103 is not a PAMI sensor. The button "ANAL/ALARM OPER SEL" selects the signal used for the "process representation" in DIAS. It selects whatever sensor is displayed on the digital display. The signal select button gives the operator the option to "operator select" any of the sensors for analog display and alarm processing when a fault exists, such as: If a fault were present and the operator elected to select P-103 for the "process representation", he would select the menu, select P-103 for display and then touch the "ANAL/ALARM OPER SEL" button. The message infield 96 below the digital display would read "P-103 OP SEL" in reverse image. Any time P-103 was selected for display, it would have the message "OP SEL" displayed in reverse image, indicating that the output from P-103 is being used for the "process representation" After selecting an "operator select" sensor for the "process representation", it is expected that the operator will depress the button marked "ANALOG DISPLAY". This would return to the analog 94 and trend display 104 (FIG. 7) for the operator selected sensor with the message "OP SEL" in reverse image. The "ANAL/ALARM OPER SEL" button is not normally displayed on the discrete indicator menu page; it automatically displays when the "operator select permissive" is enabled after a fault. The "ANAL/ALARM OPER SEL" button is removed from the menu page when the "operator select permissive" is disabled after all faults are corrected. The button "ANALOG DISPLAY" removes the menu page and replaces it with the bar graph (analog) and trend display for whatever sensor or "calculated signal" is currently selected as the "process representation" (normally the "valid" "calculated signal" output). Other validated process parameter discrete indicators operate in an identical manner. Menu driven discrete indicators contain all level 1 and 2 displays for a functional group of indication. B. Validation Algorithm Summary To reduce an operator's task loading and to reduce his stimulus overload, a generic validation algorithm is used. This algorithm takes the outputs of all sensors measuring the same parameter and generates a single output representative of that parameter, called the "Process Representation". A generic validation approach is used to ensure that it is well understood by operators. This avoids an operator questioning the origin of each valid parameter. This generic algorithm averages all sensors [(A,B,C and D) (sensor quantity may be parameter specific)] and deviation checks all sensors against the average. If the deviation checks are satisfactory, the average is used as the "Process Representation" and is output as a "valid" signal. If any sensors do not successfully pass the deviation check against the average, the sensor with the greatest deviation from the average is taken out and the average is recalculated with the remaining sensors. When all sensors used to generate the average deviation check satisfactorily against the average, this average is used as the "valid process representation". This "valid process representation" is then deviation checked against the post-accident monitoring system sensors (if present). If this second deviation check is satisfactory, the process representation" is displayed with the message "Valid PAMI" (Post-Accident Monitoring Indication), indicating that this signal is suitable for monitoring during emergency conditions, since it is in agreement with the value as determined by the PAMI sensors. As long as agreement exists, this indicator may then be utilized for post-accident monitoring rather than utilizing the dedicated PAMI indicator. This provides a Human Factors Engineering advantage of alliowing the oerator to use the indicator he normally uses for any day-to-day work and which he is most familiar with. The validation process, as described, reduces the time an operator takes to perform the tasks related to key process related parameters. To insure timely information, all validated outputs are recalculated at least once every two seconds. Additionally, redundancy and hardware diversity are provided in the calculating devices insuring reliability. The following section describes the algorithm and display processing on the DIAS and CRT displays. It should be appreciated that the discrete validation is accomplished using a generic algorithm that is applicable to different parameters. In this manner, the operators understand how the validated reading has been determined for every parameter and, again, this reinforces their confidence. This algorithm always has an output and allows the operator selection for display when validation is not possible. The discrete indicators continuously display all vital information yet allow easy access via a function or organized menu system to enable the operator to access less frequently needed information. There is no need for separate backup displays, since the backups are integrated in the subsidiary levels of retrieval. Such displays vastly reduce the amount of indicator locations required on the panel and yet provide all vital indication in a easy to use format, thereby reducing stimulus overload. The Appendix in conjunction with FIGS. 37 and 38 provide additional details on the preferred implementation of the algorithm. C. Alarm Processing and Display Another feature of the monitoring associated with each panel, is the reduction of the numer of alarms that are generated, in order to minimize the operator information overload. Cross channel signal validation is accomplished prior to alarm generation, and the alarm logic and set points are contingent on the applicable plant mode. The alarms are displayed with distinct visual cueing in accordance with the priority of the required operator response. For example, priority 1 dictates immediate action, priority 2 dictates prompt action, priority 3 is cautionary, and priority 4, or operator aid, is merely status information. The types of alarm conditions that exist within each category are described below: Priority 1 Priority 2 Priority 3 The alarms are displayed using techniques that help the operator quickly correlate the impact of the alarm on plant safety or performance. These techniques include grouping of displays which highlight the nature of the problem rather than the symptom denoted by the specific alarm condition. Another is the fixed spatial dedication of alarm displays allowing pattern recognition. Another is the plant level pictorial overview display on the IPSO board which shows success paths and critical functions impacted by the priority 1 alarms. To insure that all alarms are recognized by the operator without task overload, all alarms can be either individually acknowledged, or acknowledged in small functionally related groups. All alarms can be acknowledged at any control panel. Momentary audible alerts for alarm state changes require no operator action to silence. Periodic momentary audible reminders are provided for unacknowledged conditions. The operator can affectuate a global alarm stop flash which will automatically resume in time, to allow for deferred acknowledgement. In addition to alarms, an information notification category "Operator Aids" has been established for information that may be helpful for operations but is not representative of deviations from abnormal conditions. Conditions classified as "Operator Aids" include: channel bypass conditions, approach to interlocks and equipment status change permissive. Some parameters have more than one alarm on the same parameter (i.e., Seal Inlet Temperature Hi Hi and Hi). To limit the operator's required response, the lower priority is automatically cleared without a reset tone or slow flash rate when the higher priority alarm actuates after actuation of the lower priority alarm. The Hi Hi alarm will be acknoweldged by the operator; therefore, the operator acknowledgement of the cleared lower priority alarm is unnecessary. When the condition improves to the point where the higher priority alarm clears, the condition will sound a reset tone and the alarm window will flash slowly. The operator will acknowledge that the higher priority alarm has cleared. If the lower priority alarm condition still exists, its alarm tile or indicator will turn on in the acknowledged state after the operator acknowledges that the higher priority alarm has cleared. If the condition improves such that it clears both the high and low priority alarms before operator acknowledgement, then operator acknowledgement of the cleared high priority alarm will also clear the lower priority condition. 1. Mode and Equipment Dependancy A key feature of the alarm system is its mode dependent and equipment status dependent logic. These features combine to greatly reduce the number of alarms received during significant events and limit those alarms to conditions that actually represent process or conditions that actually represent process or component deviations pertinent to the current plant state. Mode and equipment dependency is implemented both through alarm logic changes and setpoint changes. An alarm of mode dependency is the reduction in the low pressurizer alarm setpoint to avoid a nuisance alarm on a normal reactor ring. Equipment dependent logic is used to actuate a low flow alarm only when an upstream pump is supposed to be operating. Four modes have been selected which correspond to significant changes in the alarm logic based on the plant state. These modes are: The alarm modes are manually entered by the operator with the exception of the post-trip mode. Upon a reactor trip, the alarm logic automatically switches to the post-trip mode with no operator action required. All equipment dependent alarm features are actuated automatically without operator action. 2. Subfunction Grouping The RCS panel has over 200 conditions that can cause an alarm. To reduce the operator's stimulus overload due to the quantity of alarms and improve his alarm comprehension, many alarms are grouped into subfunctional groups 108, 110, 112 (FIG. 15). The subfunctional group alarm tiles have a variety of related subfunctional group alarm messages that are read on the panel alarm message window 114 (adjacent to the alarm tile) or CRT. In cases where key process related parameters are alarmed, there is a single alarm message for each alarm tile (i.e., RCS Pressure Low). This single alarm message allows the operator to quickly identify the specific process related problem. As shown in FIG. 16, some alarms are grouped by similar component rather than process function, and are augmented by a message such as 116. As shown in FIG. 9, each alarm tile can be in one of the following states: 3. Shape and Color Coding Alarm information is identified by a unique tile color, preferably yellow 118. The parameter/component descriptor or concise message 120 within the tube is shown in blue. Grey color coding is used for the tile color 122 for Return to Normal conditions. Shape coding is used to identify alarm priority, i.e., 1, 2 or 3. A single bright color is used for alarm information to maximize the attention-getting quality of this information. The shape coding used for identifying alarm priorities uses representational features of decreasing levels of salience. Shape coding of alarm priorities also allows retention of priority information for Return to Normal conditions. For priority 1 alarms, the alarm tiles, mimic diagram components, symbols, process parameters, and menu option fields have their descriptor presented in reverse image (i.e., blue letters 12 on a yellow 118 solid rectangular background 124) using the alarm color coding. The descriptor is presented in blue to provide good contrast for readability. In addition, the alarm tiles and menu option fields on the CRT use the same representation. For priority 2 alarms, the alarm tiles, mimic diagram parameters, components, menu options, and symbols have a thin (1 line) box 126 using the yellow alarm color code around their descriptor, which is blue. For priority 3 alarms, the alarm tiles, mimic diagram parameters, components, menu options, and symbols have brackets 128 around their descriptors 120. For all alarms, English Descriptors on the CRT's message line are also represented with the alarm representation formats when they are in alarm. 4. Alarms on CRT Each CRT page in the data processing system provides the operator with an overview of the existence of any unacknowledged alarm conditions and a general overview of where they exist within the plant. The standard menu provided with each display page contains the IPSO and all first level display pages as menu options (see FIG. 10 menu region 130). These menu option fields provide the existence of unacknowledged alarms in their sector of the display page hierarchy and their alarm status/priority by using the alarm highlighting feature as described above. If an alarm tile (i.e., in the DIAS) is in alarm, a first level display page menu option field, such as 132, in the menu options 130 shows that an alarm condition exists in an associated area of the display page hierarchy. The alarm tiles in menu 130 are categorized into the first level display page set corresponding to the console groupings or by critical function, as shown in FIG. 11. In addition to alarm information represented on the first level display page menu options, the following display page features are also used to represent the existence of alarms. Display page menu options 134 that provide access to levels 2 and 3 display pages are lit with the above described alarm representation if information on the corresponding page is in alarm (e.g., if an unacknowledged alarm exists, the display page menu option is highlighted to show the highest priority unacknowledged condition). The operator can by selecting option 136, level 2 display page directory containing a pictorial diagram of the level 3 display pages in a hierarchical format associated with a first level display page (see FIGS. 12 and 15). Each of the level 2 and 3 display pages represented on this diagram provide alarm notification if information on that display page is in an unacknowledged alarm state. This alarm information is most useful for determining where alarms exist within an area of the display page hierarchy. For example, the operator would be notified by the display page menu 130 (FIG. 10) that an unacknowledged alarm(s) exists in the auxiliary systems by grey alarm shape coding (return to normal) and slow flashing of alarm coding on the "PRI" menu option field. He can then access that directory/hierarchy to see what page(s) contains alarm information by touching the menu option "DIRECTORY 136" followed by "PRI". When the Primary display directory comes up (FIG. 12), the field(s) representing the display page(s) that contains the alarm condition(s) (such as PZR LEVEL 138) will be highlighted. The desired page that contains the alarm information (similar to FIG. 15) is accessed by touching the flashing field. The descriptors of components and plant data on the process display pages of the CRT (FIG. 13) are alarm coded and flashed to provide indication of alarms and their acknowledgement status. A component's descriptor can provide this alarm information if a parameter associated with the component is in alarm. This is true even if the parameter in alarm is not represented on the display pages, e.g., low pump lube oil pressure is represented by alarm coding of the associated component's symbol. To view the exact information that is in alarm, the operator can access a lower level display page, or use the alarm system features that are described later. 5. Determining Alarm Conditions and Acknowledging Alarms With reference again to FIG. 16, each category 1 and 2 alarm annunciator tile in the DIAS may notify the operator of more than one possible alarm condition. To quickly determine the actual alarm condition, a message window 114 is provided in the display area 78 on the panel. By depressing an unacknowledged alarming annunciator tile, such as 134, an English description 116 of the specific alarm condition is provided on the message window 114. The alarm tile 134 remains flashing until all alarm conditions associated with the alarm tile have been acknowledged. The English descriptors of additional alarms can be accessed by redepressing the alarm tile 134. At the same time that a message appears on the message window of a DIAS alarm display 78, an alarm message is presented on another filed 132 at the bottom of the display page 84 on the panel CRT (see FIG. 13). The CRT alarm message contaings the following information: Time, Priority, Severity (e.g., Hi, Hi-Hi), Descriptor, Setpoint, and real time process value (coded as described to show the alarm priority and alarm condition). If additional unacknowledged alarms exist that are associated with the tile, the number of additional unacknowledged alarms is specified within a circle 136 at the right hand side of the message area (see FIG. 13). In addition to this alarm message, menu options/fields appear on the display page menu (Region 4) and provide direct access to the display pages that can be used to obtain supporting or diagnostic information of the alarm condition. The display regions are shown in FIG. 22. The alarm tiles that are in alarm on the DIAS display 78 of a given panel can be accessed and acknowledged on any CRT panel by procedure similar to accessing and acknowledging the alarms via the alarm tiles. By selecting the "Alarm Tiles" menu option followed by an alarming display page menu option, i.e., first level display page set (region 3), the alarm tiles that are in alarm, that are associated with the display page, are provided in region 4 of the display page menu. One tile is depicted and is a touch target that provides access to other tiles. The operator acknowledges and reviews these CRT alarm tiles by touch and obtains alarm messages and supporting display page touch targets in the same format as described above. This means of responding to alarming alarm tiles is most useful for responding to alarms at workstations that are remote to the operator's location. All alarm conditions associated with an annunciator tile in the DIAS display are held in a buffer. The buffer containing alarm conditions is arranged in the following format: ______________________________________ 1. First-In Unacknowledged 2. . . . . . N Last-In Unacknowledged N+1 First-In Cleared/Return to Normal N+2 . . . . . . . n Last-In Cleared/Return to Normal n+.sup.1 Acknowledged Alarms n+2 . . . . . ______________________________________ Depressing an alarm tile provides access to the alarm condition that is at the top of the buffer. Acknowledging unacknowledged alarms moves these alarm conditions to the bottom of the buffer. Acknowledging cleared alarms drops them from the buffer. Previously acknowledged alarm(s) (n+1,n+2, . . . ) can be reviewed when there are no unacknowledged or cleared unacknowledged alarm conditions present. Upon reviewing these alarms, they move to the bottom of the buffer. Alarm messages for priority 3 alarms and operator aids are only generated by the computer and only appear on the message line 132 of the CRT page (FIG. 3); there will be no English descriptor provided on the message window of the DIAS display 78. One annunciator tile is provided at each annunciator workstation for all priority 3 alarms and 1 alarm tile is provided on the workstation for operator aids that are associated with these workstation. When an alarm condition changes priority, the following changes occur in the alarm handling system. When a higher priority alarm comes in on the same parameter, the previous alarm is automatically cleared (i.e., no operator acknowledgement necessary since he will need to acknowledge the higher priority condition) without a reset tone or slow flash rate. When an alarm condition improves to the point where the high priority alarm clears, the operator will need to acknowledge that the higher priority alarm has cleared; however, if the lower priority alarm still exists, it will turn on (upon operator acknowledgement of the higher priority cleared condition) and automatically go to the acknowledged state (i.e., no operator action required). The new lower priority alarm condition will be observed by the operator when reading the alarm message in response to clearing the highest priority alarm. The invention provides a means of listing, and categorizing alarms, and accessing supporting display pages. In this system accessible from the fields 138 of the DIAS display 78 and 140 of the CRT display 84 shown in FIGS. 15 and 13, respectively, alarms are provided on alarm listing display pages. The categories of alarms in this listing are as follows (see FIG. 14): A workstation's alarm tiles in alarm are listed by priority. Alarms associated with the alarm tiles are listed as they are contained in the alarm tile's alarm buffer. These alarm categories provide alarm data consistent with operator's information needs in response to alarm conditions. When accessing the Categorized Alarm Listing 78 via page 84 (FIGS. 4 and 12), the operator can easily select the data in the category he wishes to see. Using the "Alarm List" menu option 14--(FIG. 4) followed by a display page feature that represents alarm condition(s) (FIG. 12), the operator can view the specific alarm conditions that he is interested in (FIG. 14). Three examples of accessing alarm data in the categorized list from page 84 (FIG. 4) follow. The display page's menu changes to a representation of the alarm tiles that are in alarm and are associated with the Primary Systems (see FIG. 14). At this time, the operator can request one of two different types of information formats associated with the displayed alarm tiles: Alarm information is also provided on all process display mimic diagrams which contain a component or parameter which is in an alarm condition. Color, and shape coding is used to indicate alarm conditions, as described earlier. Parameters in alarms that are associated with a component can cause the represented component's descriptor to be highlighted to indicate an alarm condition if the parameter is not visible on the display page, e.g., pump lube oil pressure may not be listed on a level two display page, so the pump's descriptor may be alarm coded. If the operator desires to see the exact alarm condition associated with a component, he would access the appropriate lower level display page. Alternatively, he could touch the "Alarm Tiles" menu option followed by touching the component's descriptor and respond to the alarm using alarm tile representations. This action also accesses menu options associated with display pages that provide more detail about the component. The following means of alarm acknowledgement is provided with the invention. Each of these methods of alarm acknowledgement clears unacknowledged alarm indicators in the other alarm formats. When an alarm condition clears, the operator needs to be notified. Notification is accomplished by flashing the annunciator tiles and associated process display page information at a slow rate. Acknowledging or resetting the cleared alarm indications takes place in a mechanism similar to acknowledgement of new alarms, i.e., touching an alarm tile or CRT alarm representation/feature. Distinct sounds/tones are provided in the control room to indicate the following alarm information: An audible alarm, tone 1 or 3, is only present for 1 second and tone 2 will repeat periodically, once every minute, until all new or cleared alarms are acknowledged. In situations where multiple unacknowledged alarms exist, the operator needs to direct his attention at the highest priority new alarm conditions. In this situation, all other unacknowledged alarms, i.e., new priority 2, 3 and all cleared alarm conditions, are added noise that distracts the operator from most important alarm conditions. In the control room, a "STOP FLASH" and "RESUME" button exists at the MCC, ACC and ASC. When the "STOP FLASH" button is depressed, the alarm system's behavior exhibits the following characteristics: The alarm reminder tone informs the operator about any unacknowledged new or cleared alarm conditions that exist. To identify these conditions for acknowledgment, the operator selects a "resume" button which returns all unacknowledged and cleared conditions to their normal representational alarm status. The alarm suppression button is backlit after selection to show that the alarm suppression feature is active. So that the operator can provide quick, direct access to supporting information thereby enhancing the operator response to alarm conditions, a single operator action provides alarm acknowledgement, display of alarm parameters, and selection options for CRT display pages appropriate for the alarm condition. The invention provides redundancy and diversity in alarm processing and display such that the operators have confidence in intelligent alarm processing techniques and such that plant safety and availability are not impacted by equipment failures. Priority 1 and 2 alarms are processed and displayed by two independent systems. Two-system redundancy is invisible to the operators through continuous cross-checking and integrated operator interfaces. FIGS. 16-18 show a schematic alarm response using the tiles in accordance with the invention. The illustrated group of tiles is associated with the reactor coolant pump seal monitoring in the reactor cooling system panel shown in FIG. 3. The priority 2 seal/bleed system trouble alarm is illuminated to alert the operator, who then can read a more complete message in the message window, which indicates a high control bleed-off pressure. Such a message is provided for priority 1 and 2 alarms. The same message in more complete form is displayed on the panel CRT. The CRT also identifies menu options that indicate useful supporting display pages. Alternatively, the operator may directly access a listing of all the alarms in a particular group. Thus, overview of the alarm conditions is provided with the tiles, and the detail is provided with the associated messages. A given alarm is rendered more or less important at a particular point in time, depending on the equipment status and the mode of operation of the NSSS. Alarm handling is reduced by validation of the parameter signals, and clearing automatically lower priority alarms when one of the higher priority alarms is actuated on the same condition. IV. DATA PROCESSING SYSTEM A. The CRT Display The CRT shown 84 in the center of the panel in FIG. 3 is part of the data processing system which processes and displays all plant operational data. Thus, it is linked to all other instrumentation and control systems in the control room. FIGS. 2, 28 and 30 schematically show the relationship of the data processing system with the control system, plant protection system, and discrete indication and alarm system. The data processing system 70 receives from the control system 64, the same sensor data that is used by the control system for executing the control logic. Likewise, it receives from the discrete indication and alarm system 72 the validated sensor data that is used by the discrete indication and alarm system for generating the discrete alarms and displays. The plant protection system 50 does not use internally validated data for its trip logic, and this "raw" signal is for each channel passed along to the data processing system 70 which performs its own signal validation logic 154 on the plant protection system signals, and passes on the internally validated signal to the validated signal comparison logic 156. In that functional area, the validated signals from the control system 64, the plant protection system 50 and the discrete indication and alarm system 72 are compared and displayed on the CRT 84. It should be appreciated that both the validated signal from the comparison logic 156 and the validated signal from the plant protection system are available for display on the CRT 84. Thus, the CRT display within each panel includes signal validation and all CRTs in the plant are capable of accessing any information available to the other CRTs in the plant. Moreover, on any given CRT, the alarm tile images from any other panel may be generated and the alarms acknowledged. Detailed display indicator windows may be accessed as well. The CRTs have a substantially real time response, with at most a two-second delay. The CRT display pages contain all the power plant information that is available to the operator, in a structured, hierarchic format. The CRT pages are very useful for information presentation because they allow graphical layouts of power plant processes in formats that are consistent with operator visualization. In addition, CRT formats can aid operational activities, where appropriate, by providing trends, categorized listing, messages, operational prompts, as well as alert the operator to abnormal processes. The primary method the operator obtains information formats on the CRTs is through a touch screen interface which operates in a known manner. The touch screens are based on infrared beam technology. Horizontal and vertical beams exist in a bezel mounted around the face of each color monitor. When the beams are obstructed by the user, the coordinates are cross-referenced with the display page data base to determine the selected information. Messages and Supporting Display page option touch targets can be accessed onto panel CRTs by touching other panel features, e.g., discrete indicators and alarm tiles. IPSO is available as a display page and forms the apex of the display page hierarchy (see FIGS. 10, 22 and 24). Three levels exist below IPSO, where each level of the hierarchy provides consistent information content to satisfy particular operational needs. The structure of the hierarchical format is based on assisting the operator in the performance of his tasks as well as providing quick and easy access to all information displayed via the CRTs. The display formats on the top level provide information for general monitoring activities, while the lowest level formats contain information that is most useful for supporting diagnostic activities. Level 1 display pages provide information that is most useful for general monitoring activities associated with a major plant process. These display pages inform the operator of major system performance and major equipment status and provide direction to lower level display pages for supportive or diagnositc information. The level 1 display pages are as follows: Level 2 display pages provide information that is most useful for controlling plant components and systems. These pages contain all information necessary to control the system's processes and functions. Parameters which must be observed during controlling tasks appear on the same display, even though they may be parts of other systems. Proposed operating procedures or guides for controlling components are utilized for determining which parameters to display. FIG. 20 is a sample display for Reactor Coolant Pump 1A and 1B Control. The operator would normally monitor the "Primary System" display page to assess RCS performance. If the operator wishes to operate or adjust RCP 1A or 1B, the operator would access the control display page. All information for Reactor Coolant Pump Control is on the control display to preclude unnecessary jumping between display pages. Level 3 display pages provide information that is most useful for diagnostic activities of the component and processes represented in level 2 display pages. Level 3 display pages provide data useful for instrument cross-channel comparisons, detailed information for diagnosing equipment or system malfunctions, and trending information useful for determining direction of system performance changes, degradation or improvement. FIG. 21 shows a diagnostic display of the Seal and Cooling section of RCP1A; the pump portion, the supporting oil system, and the motor section are presented on a separate display page due to display page information density limits. Display page access is accomplished through the use of menus placed on the bottom of the display pages. Each display page contains one standard menu format that provides direct, i.e., single touch, access to all related display pages in the information hierarchy. The menu has fields (see FIG. 10) where display page title are listed. By selecting a field (a thru j), the specified display page is accessed. The menu option fields associated with a display page includes the following (see FIG. 22). To access a display page described by a menu option, the operator would select the menu option (a-k) by touching the desired menu option field on the monitor. The menu option is highlighted (using black letters on a white background) until the display page appears. Since the menu options provide direct access to a minimum set of display pages in the display page hierarchy, alternate means are available for quickly accessing other display pages. Three options are available to the operator: In addition to the menu options described above, menu options exist for "LAST PAGE", "ALARM LIST", "ALARM TILES", "OTHER", and horizontal paging options ("Keys") The "LAST PAGE" (option j on FIG. 22) provides direct access to the last page that was on the monitor. This is very useful to operators for comparison of information between two display pages, or retrieval of information that the operator was previously involved with. The "ALARM LIST" (option n on FIG. 22) provides for quick access to the alarm listing display pages. The "ALARM TILES" (option m on FIG. 22) provides for quick access toi alarm tile representations of active alarm tiles in the area above Region 4 (see FIG. 23) of the workstation's CRT menu. This allows an operator to access alarm information associated with specific tiles on any workstation's CRT. This method of alarm access is further described in Section 5 of this document. The "OTHER" (option k on FIG. 22) provides access to display pages or information that does not fall into the categories of information described by the presently displayed menu options. B. IPSO Another part of the data processing system is the integrated process status overview (IPSO board). Although the number of displays and alarms stimulating the operator at any one time can be considerably reduced using the panels having the discrete alarm, discrete display, and CRT displays described above, the number of stimuli is still relatively high and, particularly during emergency operations, may cause delay in the operator's understanding of the status and trends of the critical systems of the NSSS. A single display is needed that presents only the highest level concerns to the operator and helps guide the operator to the more detailed information as it is needed. Although some attempts have been made in the past to present a large board or display to the operator, such displays to date have not included a significant consolidation of information in the nature to be described below. The IPSO board presents a high level overview of all high level concerns including overview of the plant state, critical safety and power functions, symbols representing key systems and processes, key plant data, and key alarms. IPSO information includes trends, deviations, numeric values of most representative critical function parameters, and the existence and system location of priority 1 alarms including availability and performance status for systems supporting the critical functions. This is otherwise known as success path monitoring. The IPSO board also can identify the existence and plant area location of other unacknowledged alarms. Thus, IPSO bridges the gap between an operator's tendency toward system thinking and a more desirable assessment of critical functions. This compensates for reduction in the dedicated displays to help operators maintain a field plant conditions. It also helps operators maintain an overview of plant performance while being involved in detailed diagnostic tasks. IPSO provides a common mental visualization of the plant process to facilitate better communication among all plant personnel. In FIG. 25, the condition illustrated is a reactor trip. At the instance illustrated, the temperature rise in the reactor is 27.degree. and the average temperature rise is higher than desired and rising as indicated by the arrow and "+". The pressurizer pressure is higher than desired, but it is falling. Likewise, the steam generator water level is higher than desired but falling. FIG. 24 shows a CRT display page hierarchy wherein the IPSO is at the apex, the first level display page set contains generic monitoring information for each of the secondary, electrical, primary, auxiliary, power conversion and critical function systems, the second level of display pages relates to system and/or component control, and the third level of display pages provides details and diagnostic information. IPSO is a continuous display visible from any control room workstation, the shift supervisor's office, and Technical Support Center. The IPSO is centrally located relative to the master control console. The IPSO also exists as a display page format that is accessible from any control room workstation CRT as well as remote facilities such as the Emergency Operations Facility. The IPSO large panel format is 4.5 feet high by 6 ffet wide. Its location, above and behind the MCC workstation, is approximately 40 feet from the shift supervisor's office (the furthest viewable point). One of the beneficial aspects of IPSO is the use of IPSO information to support operator response to plant disturbances, particularly when a disturbance effects a number of plant functions. IPSO information supports the operator's abaility to respond to challenges in plant power production as well as safety-related concerns. IPSO supports the operator's ability to quickly assess the overall plant's process performance by providing information to allow a quick assessment of the plant's critical safety functions. The concept of monitoring plant power and safety functions allows a categorization of the power and safety-related plant processes into a manageable set of information that is representative of the various plant processes. The critical functions are: ______________________________________ Critical To: Function Power Safety ______________________________________ 1. Reactivity Control X X 2. Core Heat Removal X X 3. RCS Heat Removal X X 4. RCS Inventory Control X X 5. RCS Pressure Control X X 6. Steam/Feed Conversion X 7. Electric Generation X 8. Heat Rejection X 9. Containment Environment Control X 10. Containment Isolation X 11. Radiological Emissions Control X X 12. Vital Auxiliaries X X ______________________________________ A 3.times.4 alarm matrix block 160 containing a box 162 for each critical function exist in the upper right hand corner of IPSO (see FIG. 25 and the CRT display of IPSO in FIG. 10). The matrix provides a single location for the continuous display of critical function status. If a priority 1 alarm condition exists that relates to a critical function, the corresponding matrix box 164 will be highlighted in the priority 1 alarm presentation technique. Critical Function alarms are representative of one of the following priority 1 conditions: The 3.times.4 matrix representation is an overview summary of the 1st level critical function display page information (FIG. 32). The operator obtains the details associated with critical function and Success Path alarms in the Critical Function section of the display page. Each critical function can be maintained by one or more plant systems. Information on IPSO is most representative of the ability of supporting systems to maintain the critical functions. For some critical functions, the overall status of the critical function can be assessed by a most representative controlled parameter(s). For these critical functions, the process parameter's relationship to the control setpoint(s) and indication of improving or degrading trends is represented on IPSO to the right of the parameter's descriptor. An arrowhead as explained in FIG. 26 is used if the integral of the parameter's value is greater than an acceptable narrow band control value, indicating that the parameter is moving toward or away from the control setpoint. The arrowhead's direction, up or down, indicates the direction of change of the process parameter. If these parameters deviate beyond normal control bounds, a plus or minus sign is placed above or below the control setpoint representation. The following bases were used for the selection of parameters or other indications that are used on IPSO to provide the monitoring of the overall status of the critical functions. 1. Reactivity Control Reactor power is the only parameter displayed on the IPSO as a means of monitoring reactivity. Using Reactor Power, the operator can quickly determine if the rods have inserted. He can also use Reactor Power to determine the general rate and direction of reactivity change after shutdown. Reactor Power is displayed on IPSO with a digital representation 166 because a discrete value of this parameter is most meaningful to both operators and administrative personnel. The IPSO also provides an alarm representation on the reactor vessel if there is a priority 1 alarm condition associated with the Core Operating Limit Supervisory System. 2. Core Heat Removal A representative Core Exit Temperature 168 and Subcooled Margin 170 are the parameters presented on IPSO for determining if Core Heat removal is adequate. If Core Exit Temperature is within limits, then the operator can be assured of maintaining fuel integrity. The Subcooling Margin is used because it gives the operator the temperature margin to bulk boiling. Core Exit Temperature is represented on IPSO by using a dynamic representation (i.e., trending format), since there is a distinct upper bound that defines a limit to core exit temperature, and setpoints for representational characteristics can be easily defined. Subcooled Margin is also represented on IPSO using a dynamic representation since there is a lower bound which defines an operational limit for maintaing subcooling. 3. RCS Heat Removal T.sub.H, T.sub.C, S/G Level 172, and T.sub.ave 174 are used on IPSO to provide the operator the ability to quickly assess the effectiveness of the RCS Heat Removal Function. In order to remove heat from the Reactor Coolant, S/G Level must be sufficiently maintained so that the necessary heat transfer can take place from the RCS to the steam plant. A dynamic representation is used so the operator can observe degradiations or improvements in deviant condition at a glance. T.sub.H and T.sub.C are used on IPSO because they are needed by the operator to determine how much heat is being transferred from the reactor coolant to the secondary system. A digital value of these parameters is used since a quick comparison of these parameters is desired for observing the delta T. In addition, an indication of their actual values are used often and would be helpful to an operator in locations where the discrete indicator displaying T.sub.h and T.sub.c is not easily visible. T.sub.ave is presented on IPSO using a dynamic representation to allow quick operator assessment of whether this controlled parameter is within acceptable operating bounds. 4. RCS Inventory Control Pressurizer Level 176 is presented on the IPSO using a dynamic representational indication to allow the operator to quickly access if the RCS has the proper quantity of coolant and observe deviations in level indicative of improving or degrading conditions. 5. RCS Pressure Control Pressurizer Pressure 178 and Subcooled Margin is used as the indications on IPSO to determine the RCS Pressure Control. A dynamic representation is used on IPSO to notify the operator of changing pressure conditions that may indicate RCS depressurization or over pressurization. A dynamic representation is used on IPSO for saturation margin. A saturation condition in the RCS can adversely affect the ability to control pressure by the pressurizer. Also, if pressure is dropping, the subcooled margin monitor representation on IPSO depicts a decrease in the margin to saturation. 6. Steam/Feed Conversion The processes associated with Steam/Feed Conversion can be quickly assessed by providing the following information on IPSO: 7. Electric Generation The processes associated with Electric Generation can be quickly assessed by providing the following information on IPSO: 8. Heat Rejection The processes associated with heat rejection can be quickly assessed by providing the following information on IPSO: 9. Containment Environment Control Containment Pressure and Containment Temperature are the parameters which are used on the IPSO to monitor the control of the Containment Environment. These are presented on IPSO using a dynamic representation to allow assessment of trending and relative values. The Containment Pressure variable is used on the IPSO to warn the operator about an adverse overpressure situation which could be the result of a break in the Reactor Coolant System. The Containment Temperature also helps indicate a possible break in the Reactor Coolant System; it also can indicate a combustion in the Containment Building. 10. Containment Isolation The Containment Isolation Safety function is monitored on the IPSO with a Containment Isolation system symbol representation. This symbol will be driven by an algorithm which presents the effectiveness of the following containment isolation situations when the associated conditions warrant containment isolation: 11. Radiological Emissions Control Radiation symbols exist on IPSO which presents notification of high radioactivity levels such as inside containment, and (2) radiation associated with radioactivity release paths to the environment. These symbols will only be presented on IPSO when high radiation levels exist. These indications are presented in the alarm color in a location relative to the sensor in any of the following situations occurs: 12. Vital Auxiliaries Vital Auxiliaries are monitored on IPSO by providing the following information: The systems represented on IPSO are the major heat transport path systems and systems that are required to support the major heat transport process, either power or safety related. These systems include systems that require availability monitoring per Reg. Guide 1.47, and all major success paths that support the plant Critical Functions. The following systems have dynamic representations on IPSO: System Information presented on IPSO includes systems operational status, change in operational status (i.e., active to inactive, or inactive to active) and the existence of a priority one alarm(s) associated with the system. Alarm information on systems can also help inform an operator about success path related Critical Function alarms. Priority 1 alarm information is also presented on IPSO by alarm coding the descriptors of the representative features on IPSO as described above. V. INTEGRATION OF CONTROL ROOM FIG. 27 presents an overview of the integrated information presentation available to the operator in accordance with the invention. From the integrated process status overview or board, the operator may observe the high priority alarms. If the operator is concerned with parameter trends, he may view the discrete indicators. If he is interested in the system and component status, he may view the settings on the system controls. Thus, the IPSO information is displayed either on the board or at the panel CRT, and the other information from the operator's panel or any other panel, is available to the operator on his CRT. From the IPSO overview, the operator may navigate through the CRT or DIAS display pages. Moreover, the operator has direct access to either of these types of information from any of the control panels and when a system control is adjusted or set, the results are incorporated into the other alarm and display generators in the other panels. As shown in FIGS. 2 and 28-31, in general overview, the integration of the system means that each panel including the main console, the safety console, and the auxiliary console, includes a CRT 84 which is driven by the data processing system 70. The data processing system utilizes the plant main computer and, although being more powerful, it is not as reliable as the DIAS 72 computers (which may be distributed microprocessors-based or mini-computer based). Also, it is slower because it is menu driven and performs many more computations. It is used primarily for conveying the most important information to the operator and thus important alarm tiles can be viewed on each CRT and acknowledged from any CRT. Any information available on one CRT is available at every other CRT. The indicator and alarm system 72 for a given panel is related to the controls, but the discrete (i.e., quick and accurate) aspects of the alarms and indicator displays 78,82 and controls of that panel are not available at any other panel. Basically, information is categorized in three ways. Category 1 information must be continuously displayed at all times and this is accomplished in DIAS 72. Category 2 information need not be continuously available, but it must nevertheless be available periodically and this is also the responsibility of DIAS 72. Category 3 information is not needed rapidly and is informational only, and that is provided by the DPS 70. In the event of the failure of DPS, some essential information is provided by DIAS. The DPS and DIAS are connected to the IPSO board by a display generator 180. From the IPSO, the operator can obtain detailed information either by going to the panel of concern, or paging through the CRT displays. It should be appreciated that DIAS and DPS do not necessarily receive inputs for the same parameters, but, to the extent they do receive information from common parameters, the sensors for these parameters are the same. Moreover, the validation algorithms used in DIAS and DPS are the same. Furthermore, the algorithms used for the discrete alarm tiles and the discrete indicators include as part of the computation of the "representative" value, a comparison of the DIAS and DPS validated values. FIG. 29 is a block diagram representing the discrete indicator and alarm system in relation to other parts of the control room signal processing. The DIAS system preferably is segmented so that, for example, all of the required discrete indicator and discrete alarm information for a given panel N is processed in only one segment. Each segment, however, includes a redundant processor. The information and processing in DIAS 1 is for category 1 and 2 information which is not normally displayed directly on IPSO. IPSO normally receives its input from the DPS. However, in the event of a failure of DPS, certain of the DIAS information is then sent to the IPSO display generator for presentation on the IPSO board. It should also be appreciated that both DIAS and the DPS utilize sensor output from all sensors in the plant for measuring a given parameter, but that the number of sensors in the plant for a given parameter may differ from parameter to parameter. For example, the pressurizer pressure is obtained from 12 sensors, whereas another parameter, for example, from the balance of plant, may only be measured by two or three sensors. Some systems, such as the plant protection system, do not employ validation because they must perform their function as quickly as possible and employ, for example, a 2 out of 4 actuation logic from 4 independent channels. In the event the validation for a given parameter differs as determined within two or more systems, an alarm or other cue will be provided to the operator through the CRT. One of the significant advantages of the present invention is that the DPS need not be nuclear qualified, yet it can be confidently used because it obtains parameter values from the same sensors as the nuclear qualified DIAS. These are validated in the same manner and a comparison is made between the validated DPS parameters and the validated DIAS parameters, before the DPS information is displayed on the CRTs or the IPSO. The nuclear qualification of the alarm tiles and windows, and the discrete indicator displays in the DIAS are preferably implemented using a 512.times.256 electroluminescent display panel, power conversion circuitry, and graphics drawing controller with VT text terminal emulation, such as the M3 electroluminescent display module available from the Digital Electronics Corporation, Hayward, Calif. The control function of each panel is preferably implemented using discrete, distributed programmable controllers of the type available under the trademark "MODICON 984" from the AEG Modicon Corporation, North Andover, Mass., U.S.A. Thus, the computational basis of the DIAS is with either distributed, discrete programmable microprocessors or mini computers, whereas the computational basis of the DPS is a dedicated main frame computer. The ESF control system and the process component control system are shown schematically in FIG. 31, whereas the plant protection system is preferably of the type based on the "Core Protection Calculator" system such as described in U.S. Pat. No. 4,330,367, "System and Process for the Control of a Nuclear Power System", issued on May 18, 1982, to Combustion Engineering, Inc., the disclosure of which is hereby incorporated by reference. Another aspect of integration is the capability to display the critical functions and success path in IPSO as described above. Since the major safety and power generating signal and status generators are connected to both DIAS and DPS, the operator may page through the critical functions in accordance with the display page hierarchy shown in FIGS. 32 through 35. In FIG. 33, the operator is informed that the emergency feed is unavailable in the reactant coolant system. In FIG. 34, the operator is informed that the emergency feed is unavailable and the reactor is in a trip condition. Under these circumstances, the operator must determine an alternative for removing heat from the reactor core and by paging to the second level of the critical function display page which, although shown for inventory control (FIG. 35), would have a comparable level of detail for heat removal. This type of information with this level of detail and integration is available for all critical functions under substantially all operating conditions, not only during accidents. VI. PANEL MODULARITY It should be appreciated that, as mentioned above, the discrete tile and message technique significantly reduces the surface area required on the panel to perform that particular monitoring function. Similarly, the discrete display portion of the monitoring function, including the hierarchical pages, is condensed relative to conventional nuclear control room systems. The control function on a given panel can be consolidated in a similar fashion. Thus, a feature of the present invention is the physical modularity of each panel constituting the master control console, and more generally, of each panel in the main control room. In essence, the space required for effective interface with the operator for a given panel, becomes independent of the number of alarms or displays or controls that are to be accessed by the operator. For example, as shown in FIG. 3, six locations on each side of the CRT may be allocated for alarm and indicator display purposes. Preferably, the top two on each side are dedicated to alarms 78 and the other four on each side dedicated to the indicator display 82. An identical layout is provided for each panel in the control room. This permits significant flexibility and cost savings during the construction phase of the plant because the hardware can be installed and the terminals connected early in the construction schedule, even before all system functional requirements have been finalized. The software based systems are shipped early with representative software installed to allow preliminary checking of the control room operations. Final software installation and functional testing are conducted at a more convenient point in the construction schedule. This method can accelerate plant construction schedules for the instrumentation and control systems significantly. Since the instrumentation and control requirements for a given plant are often not finalized until late in the plant design schedule, the present invention will in almost every case significantly reduce costly delays during construction. This is in addition to the obvious cost savings in the ability to fabricate uniform panels, both in the engineering phase normally required to select the locations of and lay out the alarms and displays, and in the material savings in fabricating more compact panels. Furthermore, such modularity in the plant facilitates the training of operators and, when operators are under stress during emergencies, should reduce operator error because the functionality of each panel is spatially consistent. Thus, each modular control panel has spatially dedicated discrete indicators and alarms, preferably at least one spatially dedicated discrete controller at 88, a CRT 84, and interconnections with at least one other modular control panel or computer for communication therewith. For example, communication via the DPS includes, among other things, the ability to acknowledge an alarm at one panel while the operator is located at another panel, and the automatic availability at every other panel of information concerning the system controlled at one panel. FIG. 36 (a) illustrates the conventional sequence for furnishing instrumentation and control to a nuclear power plant and 36(b) the sequence in accordance with the invention. Conventionally, the input and outputs are defined, the necessary algorithms are then defined, and these specify the man machine interface. Fabrication of all equipment then begins and all equipment is installed in the plant at substantially the same time before system testing can begin. In contrast, the modularity of the present invention permits fabrication of hardware to begin immediately in parallel with the definition of the input/output. Likewise, the hardware can be installed and generically tested in parallel with the definition of the man machine interface and the definition of the algorithms that are plant specific. The hardware and software are then integrated before final testing. In a conventional nuclear installation, the equipment is installed during the fourth year of the entire instrumentation and control activity, whereas with the present invention, equipment can be installed during the second or third year. With further reference to FIG. 2, the process component control system and the engineered safety features component control system 56 use programmable logic controllers similar to the Modicon equipment mentioned above including input and output multiplexors and associated wires and cabling, all of which can be shipped to the plant before the plant specific logic and algorithms have been developed. This equipment is fault tolerant. The data processing system 70 uses redundant plant main frame computers, along with modular software and hardware and associated data links. Such hardware can be delivered and the modular software that is specific to the plant installed, just prior to integration and system testing. The DIAS 72 also uses input/output multiplexors and a fault tolerant arrangement, with programmable logic processors or mini-computers, with the same advantages as described with respect to the process control and engineered safety features control systems. APPENDIX Detailed Examples of Validation Algorithm This Appendix describes the details of the generic validation and display algorithm implemented in the DPS and DIAS. ______________________________________ Definition of Terms Used in Discussion ______________________________________ PAMI - Post Accident Monitoring Instrumentation. Instrument - The performance accuracy of a sensor and its Uncertainty transmitter (i.e., if accuracy is .+-.1%, the instrument uncertainly is 2%). Expected Process - The difference in temperature (or other Variation unit of measurement) between sensors measuring the same process parameter due to expected variation in the the process temperature (or other unit of measurement) at different sensor locations. Calculated Signal - A single signal that the algorithm calculates to represent all sensors measuring the same parameter. Process - A single signal that is output for displays Representation and alarms where a single value is needed as opposed to multiple sensor values. The "process representation" will always be the "calculatad signal" unless a failure has occurred. After a failure it may be the output of a single sensor selected by the operator or algorithm. Valid - A "calculated signal" that has been verified to be accurate by successfully deviation checking all of its inputs with their average. Valid PAMI - A "valid" "process representation" that deviation checks successfully against the "PAMI" sensors. Validation Fault - A failure of the validation and display algorithm to calculate a "Valid" "Calculated Signal". PAMI Fault - A failure of the "Calculated Signal" to deviation check successfully against the "PAMI" sensors. Fault Select - The "calculated signal" that is the output of the sensor closest to the last "valid" signal at the time validation initially failed. Operator Select - A "process representation" that is the output of the sensor that the operator has selected after a "PAMI Fault" or a "Validation Fault". Good - A label given to a sensor that deviation checks successfully against the "Operator Select" or "Valid" "Process Representation". Bad - A label given to a sensor that fails to deviation check successfully against the "Valid" "Process Representation". Suspect - A label given to the "good" sensor that deviates the most from the average "calculated signal" when any deviation check fails. "Validation Fault - The permissive that allows the operator to Operator Select select an individual sensor as the "Process Permissive" Representation" when the algorithm is unable to calculate a "valid" signal. "PAMI Fault - The permissive that allows the operator to Operator Select select an individual sensor as the "Process Permissive Representation" when the "valid" "calculated signal" does not deviation check successfully against "PAMI" indication. ______________________________________ Validation and Display Algorithm The sensor inputs (A, B, C, D) are all read and stored at the time the algorithm begins. The algorithm uses these stored inputs to perform all steps (1-10), which comprise a scan. When the algorithm is repeated (after step 10), the sensor inputs are read and stored again, for use on the new scan. Determination of "Calculated Signal" and Faults (Steps 1,2,3,4,5) Validation Attempt (Steps 1, 2, 3) 1. The algorithm checks to see if there are 2 or more "good" sensors. 2. The algorithm averages all "good" sensors (A,B,C,D). Go to step 3. 3. Deviation check all good sensors against the average (within sum of 1/2 instrument uncertainty and expected process variation). If the first pass, the algorithm is repeated, beginning at step 1. PA4 Note: If the deviation check fails on the first pass, the algorithm has used one or more bad sensors to calculate the average. Performing a second pass eliminates the one bad sensor or determines that multiple sensors are bad. PA3 If it is the second pass validation fails, go to step 5. PA4 Note: Failing to pass the deviation check on the second pass indicates that there are two or more simultaneous sensor failures. The algorithm cannot be sure to correctly eliminate only the bad sensors, therefore the algorithm must fail. This insures that the algorithm does not calculate a incorrect "valid" signal for this case. Normally without two or more simultaneous failures, the algorithm will detect multiple non-simultaneous deviations, sequentially eliminate them from the algorithm and still determine a "valid" signal. PA3 a. Generate a "Validation Fault" alarm PA3 b. Declare all "suspect" sensors "good". PA4 Note: This step insures that the algorithm will attempt to validate using all sensors not previously determined "bad" on the next validation attempt. PA3 e. Enable the permissive for the operator to select an individual sensor output for "process representation", the ("Validation Fault Operator Select Permissive"). PA3 d. Deviation check all sensors against the last "valid" signal. Select the sensor that deviates the least from the last "valid" signal as the "fault select" sensor. PA3 e. Output the signal from the "fault select" sensor as the "calculated signal". PA3 f. Go to step 6. PA3 a. Remove "bad" data flags and make them "good" on all sensors passing the deviation check, if present and clear its associated sensor deviation alarm. PA3 b. Maintain "bad" data flags on all sensors failing the deviation check. PA3 c. Go to step 10. PA3 1. Different numbers of sensors PA3 2. Multiple sensors ranges PA3 3. Data reduction in related process measurements. PA3 Note: This feature allows the operator to select another sensor for the cold leg "process representation" when the algorithm's "valid" output does not correlate with postaccident monitoring indication (sensor c). PA3 Yes, output average as "valid", go to step 5. PA3 No, go to step 3. PA3 Yes, go to step 4. PA3 No, output the average as "fault select", go to step 5. PA3 Yes, output the average as "fault select", go to step 5. PA3 No, output the average as "operator select", go to step 5. PA3 If the deviation checks are satisfactory, clear the "T.sub.c Cold Leg (1A/1B or 2A/2B) Temp Deviation" alarm, if present, go to step 6. PA3 If either deviation check is unsatisfactory, generate the "T.sub.c Cold Leg (1A/1B or 2A/2B) Temp Deviation" alarm, go to step 6. PA3 Yes, output the average as narrow range, go to step 7. PA3 No, output the average as wide range, go to step 7. PA3 If either or both are out-of-range, output this T.sub.c loop "process representation" signal with the message "out-of-range", go to step 8. PA3 If both are in-range, this T.sub.c loop "process representation" is not output with the message, "out-of-range", go to step 8. PA3 Yes, output the "PAMI" message with the loop (1 or 2) T.sub.c "process representation", the loop T.sub.c algorithm is repeated, go to step 1. PA3 No, do not output the "PAMI" message with the loop (1 or 2) T.sub.c "process representation", the loop T.sub.c algorithm is repeated, go to step 1. PA3 If the first pass, the algorithm is repeated, beginning at step 1. PA4 Note: If the deviation check fails on the first pass, the algorithm has used one or more bad sensors to calculate the average. Performing a second pass eliminates the one bad sensor or determines that multiple sensors are bad. PA3 If it is the second pass, the (1500-2500) range validation fails, go to step 5 to attempt 0-1600 psig range validation. PA4 Note; Failing to pass the deviation check on the second pass indicates that there ar two or more simultaneous (1500-2500) range sensor failures. The algorithm cannot be sure to correctly eliminate only the bad sensors, therefore the (1500-2500) range validation must fail. The 0-1600 psig range validation is attempted. This insures that the algorithm does not calculate an incorrect signal for this case. Normally without two or more simultaneous failures, the algorithm will detect multiple non-simultaneous deviations, sequentially eliminate them from the algorithm and still determine a "valid" signal. PA3 If the first pass, the 0-1600 psig range algorithm is repeated, beginning at step 5. PA4 Note: If the deviation check fails on the first pass, the algorithm has used one or more bad sensors to calculate the average. Performing a second pass eliminates the one bad sensor or determines that multiple sensors are bad. PA3 If it is the second pass, the 0-1600 psig range validation fails, go to step 9 to attempt 0-4000 psig range validation. PA4 Note: Failing to pass the deviation check ion the second pass indicates that there are two or more simultaneous 0-1600 psig range sensor failures. The algorithm cannot be sure to correctly eliminate only the bad sensors, therefore the 0-1600 psig range validation must fail. The 0-4000 psig range validation is attempted. This insures that the algorithm does not calculate an incorrect signal for this case. Normally without two or more simultaneous failures, the algorithm will detect multiple non-simultaneous deviations, sequentially eliminate them from the algorithm and still determine a "valid" signal. PA3 a. Output the "PAMI" message, if not previously present. PA3 b. Remove the "PAMI Fault Operator Select Permissive", if previously present. PA3 c. Go to step 14. PA3 Note: The (0-4000 psig) wide range sensors (K and L) are not located on the pressurizer, as are the other pressure sensors. The K and L sensors are positioned at the discharge of the reactor coolant pumps (RCPs) where they measure RCS pressure. During normal operation the pressure at this location is much higher (approximately 110 psi for a System 80 plant) than at the pressurizer, where sensors (A, B, C, D, E, F, G, H, I and J) are located. An additional deviation acceptance criteria (called instrument position constant) will be sued when deviation checks are made with or against the K and L (0-4000 psig range) sensors. Valid--PAMI Check (Step 4) 4. (Step applicable if process has a Category 1 PAMI Sensor. If there is no PAMI sensor(s) in this process, the step is not performed, go to step 6. Does the "valid" signal deviation check against the PAMI sensor(s) Failed Validation (Step 5) 5. The algorithm checks to see if the "calculated signal" on the previous scan was a "Fault Select" sensor. "Process Representation" Selection (Steps 6, 7) 6. The algorithm checks to see if there is either the "Validation Fault Operator Select Permissive" or the "PAMI Fault Operator Select Permissive". 7. Check to see if the operator has selected a sensor as the "process representation". Yes, output the signal from the selected sensor as the "process representation", go to step 8. No, output the "calculated signal" as the "process representation", go to step 9. PAMI Check of "Operator Select" Sensor (Step 8) 8. Does the "operator select" sensor deviation check against the PAMI sensor (within sum of PAMI instrument uncertainty and expected process variation). Yes, output the "PAMI" message on the "process representation" display. No, remove the "PAMI" message on the "process representation" display. Bad Sensor Evaluation (Step 9) 9. Is the "process representation" "valid" or "operator select". Range Check (Step 10) 10. The algorithm checks to see if the "process representation", is at or above the maximum numerical range, or at or below the minimum numerical range for the sensors. T.sub.cold Validation Algorithm (FIG. 37) There are 12 sensors used to measure cold leg temperatures in the RCS. During most operational sequences, the operator is looking for a single "process representation" of all cold leg temperatures in the RCS. This value will be provided in the DIAS with a display labeled "RCS T.sub.cold ". For consistency, this value, which is determined by DIAS, is also used on the Integrated Process Status Overview (IPSO) board. To insure reliability, DPS compares DIAS's RCS T.sub.cold "process representation" with its own RCS T.sub.cold and alarms any deviations (DPS/DIAS RCS T.sub.c Calculation Deviation). A three step validation algorithm is used to determine this value: 1. Determine a "process representation" temperature in each of the 4 cold legs (1A, 1B, 2A, 2B) through a combination of deviation checking and averaging (the details are described later). 2. From the results in step 1, determine a T.sub.cold "process representation" for each RCS loop (loop 1 and loop 2) by averaging the corresponding A, B data. 3. From the results in step 2, determine a RCS T.sub.cold (process representation" for normal display and alarms by averaging loop 1 and 2 data. The three step process determines "valid" "process representation" temperatures for cold legs 1A, 1B, 2A and 2B, cold loop 1 and 2 and RCS T.sub.c. for situations when a "valid" cold leg "process representation" temperature cannot be calculated the algorithm will select the sensor closest to the last "valid" signal as the "fault select" "process representation" temperature. This automatic fault selection insures a continuous output of the RCS T.sub.cold "process representation" for display and alarms. After a failure the operator may select an individual sensor for that cold leg (1A, 1B, 2A, 2B) "process representation". This selection will allow calculation of loop 1, loop 2 and RCS T.sub.cold "process representation", with "operator select" data. The following section describes the algorithm and display processing on the DIAS and CRT displays. 1. The leg 1A, 1B, 2A, 2B, loop 1, 2 and RCS T.sub.cold "process representation" shall always be displayed on the applicable DIAS display and/or CRT page(s) where a single "process representation" is needed as opposed to multiple sensor values. 2. The T.sub.cold algorithm and display processing is identical to the generic validation algorithm with the following modifications: 3. Using a menu (as described in the generic validation algorithm) on DIAS or the CRT the operator may view any of the 12 sensor values or 7 "calculated signals". These selections include the following: ______________________________________ T-112CA/122CA 465-615.degree. F. T.sub.cold Loop 1A/2A T-112CB/122CB 465-615.degree. F. T.sub.cold Loop 1B/2B T-112CC/122CC 465-615.degree. F. T.sub.cold Loop 1A/2A T-112CD/122CD 465-615.degree. F. T.sub.cold Loop 1B/2B T-111CA/111CB/ 50-750.degree. F. T.sub.cold Loop 1A/1B/2A/2B, 123CA/123CB PAMI Loop 1A Tc Calculated Signal Loop 1B Tc Calculated Signal Loop 2A Tc Calculated Signal Loop 2B Tc Calculated Signal Loop 1 Tc Calculated Signal Loop 2 Tc Calculated Signal RCS Tc Calculated Signal ______________________________________ Validation Algorithms Note: To simplify the discussion of sensor tag numbers, the following letters will be used to designate sensors in a cold leg. The algorithms described below are calculated and displayed independently by both DPS and DIAS. Method to Determine Cold Leg 1A, 1B, 2A, or 2B T.sub.cold "Process Representation" The determination of the Cold Leg "Process Representation" will be performed in four parts: 1. Determination of "calculated signal" and faults, as described below (steps 1-8): Cold Leg (1A, 1B, 2A or 2B Validation and Display Algorithm Determination of "Calculated Signal" and Faults (Steps 1-8) Narrow Range Validation Attempt (Steps 1-5) 1. The algorithm checks to see if there two "good" narrow range sensors (A and B). 2. The algorithm averages A and B, go to step 3. 3. Deviation check both "good" narrow range sensors (A and B) against the average (within sum of 1/2 narrow range uncertainty and expected process variation) Range Selection (Step 4) 4. The algorithm checks to see if the average or selected narrow range sensor is in-range. 5. The algorithm deviation checks narrow range sensors (A and B) against sensor C (within sum of wide range instrument uncertainty and expected process variation). Valid PAMI Check (Step 6) 6. The algorithm checks to see if the "valid" average or selected sensor deviation checks satisfactorily against the PAMI sensor (C). (Within sum of 1/2 wide range uncertainty and expected process variation). Wide Range Validation Attempt (Step 7) 7. Deviation check C against D (within sum of wide range instrument uncertainty and expected process validation). Failed Validation (Step 8) 8. The algorithm checks to see if the "calculated signal" on the previous scan was a "fault select" sensor. T.sub.c Leg (A or B) "Process Representation" Selection (Steps 9, 10) 9. Step 9 is identical to step 6 of the generic validation algorithm. 10. Step 10 is identical to step 7 of the generic validation algorithm except for the following. The operator may select any sensor A, B or C form that cold leg or A, B, C from the opposite cold leg (A or B) as the "process representation". PAMI Check of "Operator Select" Sensor (Step 11) 11. This step is identical to step 8 of the generic validation algorithm. Bad Sensor Evaluation (Step 12) 12. This step is identical to step 9 of the generic validation algorithm except that wide range instrument uncertainties are used on all deviation checks except when narrow range sensors are being deviation checked against a narrow range signal, in this case narrow range instrument certainties will be used. Range Check (Step 13) 13. This step is identical to step 10 of the generic validation algorithm. Method to Determine Loop 1 and 2 T.sub.cold "Process Representation" The loop 1 and 2 T.sub.c "process representation" will be calculated by averaging the "process representation" from the A and B cold legs (1A and 1B for loop 1), (2A and 2B for loop 2). Method to Determine RCS T.sub.cold The RCS T.sub.cold "process representation" will be calculated by averaging the "process representation" inputs from loop 1 and 2 T.sub.cold. 5. The algorithm checks to see if signal 1 or 2 is "fault select". Range Check 6. This step is identical to step 10 of the generic validation algorithm. Go to step 1 and repeat the algorithm. Pressurizer Pressure Validation Algorithm (FIG. 38) There are 12 sensors used to measure pressurizer and RCS pressure. During most operational sequences, the operator is looking for a single "process representation" of all pressurizer/RCS pressure readings. This value will be provided in DIAS with a display labeled "PRESS". For consistency, this value, which is determined by DIAS, is also used on the IPSO board. To insure reliability, DPS compares DIAS's Press "process representation" with its own Press "process representation" and alarms any deviations (DPS/DIAS Press Calculation Deviation). The algorithm determines a "valid" "process representation" for pressurizer/RCS pressure. For situations when a "valid" pressure "process representation" cannot be calculated, the algorithm will select the sensor closest to the last "valid" signal as the "fault select" "process representation" pressure. This automatic fault selection insures continuous output of the pressurizer/RCS "process representation" pressure for displays and alarms. After a failure the operator may select an individual sensor for the pressure "process representation" as the "fault select" "process representation". The following section describes the algorithm and display processing on the DIAS and CRT displays. 1. The "process representation" pressure shall always be displayed on the applicable DIAS display and/or the CRT page(s) where a single "process representation" is needed as opposed to multiple sensor values. 2. The pressure algorithm and display processing is identical to the generic validation algorithm with the following modifications: 3. Using a menu (as described in the generic validation algorithm) the operator may view any of the 12 sensors values or single "calculated signal". These selections include the following: ______________________________________ P-103, 104, 105, 106 0-1600 psig Pressurizer Pressure P-101A, 1O1B, 101C, 1500-2500 psig Pressurizer Pressure 1010, 100X, 100Y P-190A, 190B 0-4000 psig RCS Pressure, PAMI CALC PRESS Calculated Signal ______________________________________ Validation Algorithm To simplify the discussion of sensor tag numbers, the following letters will be used to designate pressure sensors: The algorithm described below is calculated and displayed independently by both DPS and DIAS. The pressurizer pressure "calculated signal" will be calculated using sensors A, B, C, D, E, F, G, H, I, J, K and L. An attempt will be made to use the narrow 1600-2500 psig range sensors (A, B, C, D, E and F) (pressure is normally in this range). If pressure is outside the 1500-2500 psig range, the 0-1600 psig range sensors (G, H, I and J) will be used. If pressure cannot be calculated using these sensors, the 0-4000 psig range sensors (K and L) will be used. In the event that the validation fails all of these three ranges, the algorithm will select the sensor closest to the last "valid" signal as the "fault select" "calculated signal". This "fault select" "calculated signal" will be used as the "process representation" until the operator selects an "operator select" sensor to replace it or the algorithm is able to validate data. Pressurizer Pressure Validation and Display Algorithm Determination of Calculated Signal and Faults (Steps 1-13) 1500-2500 Psig Range Validation Attempt (Steps 1-4) 1. The algorithm checks to see if there are 2 or more "good" (1500-2500 psig narrow range) sensors. 2. The algorithm averages all "good" (1500-2500) range sensors (A, B, C, D, E and F). Go to step 3. 3. Deviation check all "good" (1500-2500) range sensors against the average (within sum of 1/2 narrow range uncertainty and expected process variation). Range Selection (Step 4) 4. The algorithm checks to see if the average is in-range. 0-1600 psig Range Validation Attempt (Steps 5-8) 5. The algorithm checks to see if there are 2 or more "good" 0-1600 psig range sensors (G, H, I and J). 6. The algorithm averages all "good" 0-1600 psig range sensors (G, H, I and J). Go to step 7. 7. Deviation check all "good" 0-1600 psig range sensors against the average (within sum of 1/2 of the 0-1600 psig range uncertainty and expected process variation). Range Selection (Step 8) 8. The algorithm checks to see if the average is in-range. 0-4000 Psig Range Validation Attempt (Steps 9, 10, 11) 9. The algorithm checks to see if both of the 0-4000 psig range sensors (K and L) are "good". 10. The algorithm averages K and L, the 0-4000 psig range sensors. Go to step 11. 11. Deviation check K and L against the average (within sum of 1/2 0-4000 psig range uncertainty and expected process variation). Valid-PAMI Check (Step 12) 12. Does the "valid" "calculated signal" deviation check against the PAMI sensors. Use method a if the "valid" "calculated signal" is in the 1500-2500 psig or 0-1600 psig range, and method b if in the 0-4000 psig range. Failed Validation (Step 13) 13. The algorithm checks to see if the "calculated signal" output of the previous scan was a "fault select" sensor. Pressurizer Pressure "Process Representation" Selection (Steps 14, 15) 14. Step 14 is identical to step 6 of the generic validation algorithm. 15. Step 15 is identical to step 7 of the generic validation algorithm. PAMI Check of "Operator Select" Sensor (Step 16) 16. Step 16 is identical to step 8 of the generic validation, except that the deviation criteria are the same as those specified in step 12 of this pressurizer pressure validation and display algorithm. Bad Sensor Evaluation (Step 17) 17. This step is identical to step 9 of the generic validation algorithm, except that the deviation criteria checks are the same as those specified in step 12 of this pressurizer pressure validation and display algorithm. Range Check (Step 18) 18. The algorithm checks to see if the "process representation" is at or above the maximum numerical range (1600 psig for the 0-1600 psig sensors, 2500 psig for the 1500-2500 psig sensors and 4000 psig for the 0-4000 psig sensors) or at or below the minimum numerical range (0 psig for the 0-1600 psig and 15-4000 psig sensors and 1500 psig for the 1500-2500 psig sensors). Yes, Output the message "Out-of-Range" along with the "process representation" signal. On the CRT place an asterisk () preceding the "process representation". Go to step 1 and repeat the algorithm. No, go to step 1 and repeat the algorithm.
043483534	abstract	A reusable system for removably attaching the lower end 21 of a nuclear reactor fuel assembly duct tube to an upper end 11 of a nuclear reactor fuel assembly inlet nozzle. The duct tube's lower end 21 has sides terminating in locking tabs 22 which end in inwardly-extending flanges 23. The flanges 23 engage recesses 13 in the top section 12 of the inlet nozzle's upper end 11. A retaining collar 30 slides over the inlet nozzle's upper end 11 to restrain the flanges 23 in the recesses 13. A locking nut 40 has an inside threaded portion 41 which engages an outside threaded portion 15 of the inlet nozzle's upper end 11 to secure the retaining collar 30 against protrusions 24 on the duct tube's sides.
	summary
	description	This application is a U.S. National Stage Application of International Application No. PCT/EP2011/051017 filed Jan. 26, 2011, which designates the United States of America, and claims priority to DE Patent Application No. 10 2010 006 434.3 filed Feb. 1, 2010. The contents of which are hereby incorporated by reference in their entirety. This disclosure relates to a method and a device for producing a 99mTc reaction product. 99mTc is used in medical imaging in particular, for example in SPECT imaging. A commercially available 99mTc-generator is an instrument for extracting the metastable isotope 99mTc from a source containing decaying 99Mo, for example with the aid of solvent extraction or chromatography. 99Mo in turn is usually obtained from a method which uses highly enriched uranium 235U as a target. 99Mo is created as a fission product by irradiating the target with neutrons. However, as a result of international treaties, it will become ever more difficult in future to operate reactors with highly enriched uranium, which could lead to a bottleneck in the supply of radionuclides for SPECT imaging. U.S. Pat. No. 5,802,438 discloses a method for producing 99mTc by irradiating a Mo-metal target in the surroundings of a reactor. HU 53668 (A3) and HU 37359 (A2) describe methods in which 99mTc is obtained with the aid of sublimation processes. In one embodiment, a method for producing a reaction product containing 99mTc may comprise: providing a 100Mo-metal target to be irradiated, irradiating the 100Mo-metal target with a proton beam having an energy suitable for inducing a 100Mo(p, 2n)99mTc nuclear reaction, heating the 100Mo-metal target to a temperature of over 300° C., and obtaining the 99mTc made in the 100Mo-metal target in a sublimation-extraction process with the aid of oxygen gas, which is routed over the 100Mo-metal target forming 99mTc-technetium oxide in the process. In a further embodiment, the method further comprises feeding the obtained 99mTc-technetium oxide to an alkaline solution, more particularly to a sodium hydroxide solution, or to a salt solution to form 99mTc-pertechnetate. In a further embodiment, the 100Mo-metal target is available in the form of a film, in the form of a powder, in the form of tubules, in the form of a grid structure, in the form of spheres or in the form of metal foam. In a further embodiment, the 100Mo-metal target is held by a thermally insulating mount. In a further embodiment, heating of the 100Mo-metal target is achieved by the irradiation by the proton beam. In a further embodiment, the heating is brought about with the aid of current conducted through the 100Mo-metal target. In a further embodiment, the heating is brought about by heating a chamber, more particularly a ceramic chamber, in which the 100Mo-metal target is arranged. In another embodiment, a device for producing a reaction product containing 99mTc may comprise: a 100Mo-metal target, an accelerator unit for providing a proton beam which can be directed at the 100Mo-metal target, the proton beam having an energy which is suitable for inducing a 100Mo(p, 2n)99mTc nuclear reaction when the 100Mo-metal target is irradiated by the proton beam, a gas supply line for routing oxygen gas onto the irradiated 100Mo-metal target for forming 99mTc-technetium oxide, and a gas discharge line for discharging the sublimated 99mTc-technetium oxide. In a further embodiment, the device may further comprise a liquid chamber with an alkaline solution, more particularly with a sodium hydroxide solution, or a salt solution into which the 99mTc-technetium oxide can be routed for the formation of 99mTc-pertechnetate. In a further embodiment, the 100Mo-metal target is available in the form of a film, in the form of a powder, in the form of tubules, in the form of a grid structure, in the form of spheres or in the form of metal foam. In a further embodiment, the 100Mo-metal target is held by a thermally insulating mount. In a further embodiment, the device includes a circuit for conducting current through the 100Mo-metal target. In a further embodiment, the 100Mo-metal target is arranged in a heatable chamber, more particularly a ceramic chamber. Some embodiments provide a method and a device by means of which a reaction product containing 99mTc can be obtained. In some embodiments, a method for producing a reaction product containing 99mTc may comprise the following steps: providing a 100Mo-metal target to be irradiated, irradiating the 100Mo-metal target with a proton beam having an energy suitable for inducing a 100Mo(p, 2n)99mTc nuclear reaction, with a 100Mo(p, 2n)99mTc nuclear reaction being induced by the irradiation, heating the 100Mo-metal target to a temperature of over 300° C., more particularly of over 400° C., obtaining the 99mTc made in the 100Mo-metal target in a sublimation-extraction process with the aid of oxygen gas, which is routed over the heated 100Mo-metal target forming 99mTc-technetium oxide in the process. The 99mTc-technetium oxide can be discharged by the gas flow of the oxygen gas and thus be e.g. transported away from the 100Mo-metal target. Certain embodiments are based on the discovery that 99mTc can be obtained directly in a 100Mo-metal target if the 100Mo-metal target is irradiated by a proton beam with a suitable energy, e.g. in a region between 20 MeV and 25 MeV. Thus, the 99mTc is obtained directly from a nuclear reaction occurring as a result of the interaction of the proton beam with the molybdenum atoms, according to the nuclear reaction 100Mo(p, 2n)99mTc. The 99mTc produced in this manner is extracted with the aid of a sublimation process. To this end, the 100Mo-metal target with the 99mTc is heated to a temperature of over 300° C. If oxygen gas is now routed to the 100Mo-metal target, the 99mTc reacts with the oxygen, forming 99mTc-technetium oxide in the process, e.g. according to the equation 2Tc+3.5O2->Tc2O7. The molybdenum of the target likewise reacts with the oxygen, forming a molybdenum oxide in the process, e.g. by forming MoO3. However, since the molybdenum oxide is substantially less volatile than the technetium oxide, the technetium oxide is transported away by the oxygen gas routed over the 100Mo-metal target and can be discharged. Here, the proton irradiation and the extraction of 99mTc by the oxygen gas with optional heating of the 100Mo-metal target can occur at the same time or alternately in succession. Accelerating protons to the aforementioned energy usually requires only a single accelerator unit of average size, which can also be installed and used locally. Using the above-described method, 99mTc can be made locally in the vicinity or in the surroundings of the desired location of use, for example in the surroundings of a hospital. In contrast to conventional, non-local production methods which are accompanied by the use of large installations such as in nuclear reactors and the distribution problems connected therewith, a local production solves many problems. Nuclear medicine units can plan their workflows independently from one another and are not reliant on complex logistics and infrastructure. The proton beam may be accelerated to an energy of between 20 MeV and 25 MeV. Restricting the maximum energy to no more than 35 MeV, more particularly to 30 MeV and most particularly to 25 MeV, avoids too high an energy of the particle beam triggering nuclear reactions which lead to undesired reaction products, e.g. other Tc isotopes than 99mTc, which should then be removed again in a complicated manner. The 100Mo-metal target can be designed in such a way that the emerging particle beam has an energy of at least 5 MeV, more particularly at least 10 MeV. This makes it possible to keep the energy range of the proton beam in a region in which the occurring nuclear reactions remain controllable and in which undesired reaction products are minimized. In one embodiment, the following step is additionally carried out: feeding the obtained 99mTc-technetium oxide, which was transported away, to an alkaline solution, more particularly to a sodium hydroxide solution, or to a salt solution, more particularly a sodium salt solution, to form 99mTc-pertechnetate. This may provide an advantageous reaction product containing 99mTc because 99mTc-pertechnetate can easily be distributed and processed and can be a starting point for the production of radiopharmaceuticals, e.g. SPECT tracers. In the case of a sodium hydroxide solution, the reaction equation is: Tc2O7+2NaOH->2NaTcO4+H2O. Excess O2, which originates from the oxygen gas and was routed through the liquid, can be cleaned and returned to the gas supply, e.g. within a closed loop. In one embodiment, the 100Mo-metal target is available in the form of a film, more particularly as a stack of films of a plurality of films arranged one behind the other in the beam direction. This makes it possible to obtain 99mTc in a particularly effective fashion and, moreover, it is easier to heat the 100Mo-metal target to the temperature required for sublimation. Alternative forms are possible, for example, the 100Mo-metal target can be available in the form of a powder, in the form of tubules, in the form of a grid structure, in the form of spheres or in the form of metal foam. To this end, the 100Mo-metal target can be held by a thermally insulating mount, e.g. epoxy resin strengthened by G20. Heating to the desired temperature can already be achieved by proton beam irradiation because the proton beam on its part transfers thermal energy onto the 100Mo-metal target. Optionally, the temperature of the 100Mo-metal target can be set by matching the energy and/or intensity of the proton beam and/or the strength of the gas flow, which can e.g. be controlled by a valve, to one another or by controlling one or more of these variables. Heat supply by the proton beam and heat dissipation by the mount and by convection cooling can thus be matched to one another. This enables the equilibrium temperature to be set in the 100Mo-metal target. In particular, the 100Mo-metal target can be heated by proton beam irradiation only. Additional heating devices are not mandatory. In an alternative and/or additional embodiment, the 100Mo-metal target can be heated with the aid of a current which is conducted through the 100Mo-metal target, i.e. it can be heated with the aid of a circuit, e.g. by the Ohmic heating occurring in this case. The temperature to be achieved can be set in a simple manner by controlling the electric circuit. In an alternative and/or additional embodiment, the 100Mo-metal target can be arranged in a chamber, e.g. in a ceramic chamber, which is heated specifically for heating the 100Mo-metal target. This can also be used to reach or set the temperature required for the sublimation. In some embodiments a device for producing a reaction product containing 99mTc may comprise: a 100Mo-metal target, an accelerator unit for providing a proton beam which can be directed at the 100Mo-metal target, the proton beam having an energy which is suitable for inducing a 100Mo(p, 2n)99mTc nuclear reaction when the 100Mo-metal target (15) is irradiated by the proton beam (13), a gas supply line for routing oxygen gas onto the irradiated 100Mo-metal target for forming 99mTc-technetium oxide, a gas discharge line for discharging the sublimated 99mTc-technetium oxide. In one embodiment, the device can furthermore comprise: a liquid chamber with an alkaline solution, more particularly with a sodium hydroxide solution, or a salt solution into which the 99mTc-technetium oxide can be routed for the formation of 99mTc-pertechnetate. The device can furthermore comprise a heating device for heating the 100Mo-metal target to a temperature of over 400° C. FIG. 1 shows one embodiment of a device for producing 99mTc-pertechnetate. An accelerator unit 11, e.g. a cyclotron, accelerates protons to an energy of approximately 20 MeV to 25 MeV. The protons are then, in the form of a proton beam 13, directed at a 100Mo-metal target 15, which is irradiated by the proton beam. The 100Mo-metal target 15 is designed such that the emerging particle beam has an energy of approximately at least 10 MeV. Illustrated here is a 100Mo-metal target 15 in the form of a plurality of metal films 17, arranged one behind the other in the beam direction and arranged perpendicular to the beam propagation direction. As illustrated in FIG. 4, the area of the film 17 is greater than the cross-sectional profile of the proton beam 13. The metal films 17 are held by a thermally insulating mount 19 which, for example, can be manufactured in large parts from epoxy resin strengthened by G20. The proton beam 13 interacts with the 100Mo-metal target 15 as per the 100Mo(p, 2n)99mTc nuclear reaction, from which 99mTc then emerges directly. Here, the proton beam 13 is controlled in terms of its intensity such that so much thermal energy is transferred to the metal films 17 during the irradiation that the metal films 17 moreover heat up to a temperature of over 400° C. Oxygen gas is routed over the 99mTc from an oxygen source via a valve 21 which controls the gas flow. At such temperatures, the 99mTc made in the metal films 17 reacts with the oxygen and makes 99mTc-technetium oxide, e.g. according to the equation 2Tc+3.5O2->Tc2O7. The 100Mo likewise reacts with the oxygen forming a molybdenum oxide in the process, e.g. forming 100MoO3. Since the MoO3 is significantly less volatile than the technetium oxide, the technetium oxide is transported away by the oxygen gas routed over the 100Mo-metal target 15 and can be discharged. The gas flow, the energy transmitted by the proton beam 13 and the heat loss through the mount 19 of the 100Mo-metal target 15 are matched to one another such that the temperature required for the sublimation-extraction process is reached and maintained. The gas containing technetium oxide is subsequently routed into a liquid column 23 containing a salt solution or alkaline solution and effervesced there such that 99mTc-pertechnetate is formed by a reaction of the technetium oxide with the solution, e.g. sodium pertechnetate in the case of a sodium hydroxide solution or a sodium salt solution. In the case of a sodium hydroxide solution, the reaction equation can, for example, be: Tc2O7+2 NaOH->2NaTcO4+H2O. Subsequently, the 99mTc-pertechnetate now made can be used as starting point for the production of radiopharmaceuticals, e.g. of SPECT tracers. The O2 rising in the liquid column 23 can be routed back to the supplying gas inlet in an e.g. closed loop 25. FIG. 2 shows another embodiment that substantially corresponds to the embodiment shown in FIG. 1. This embodiment has a device 27, by means of which electric current can be conducted through the metal films 17, i.e. the metal films 17 are part of a circuit. The current which flows through the metal films 17 heats the metal films 17 by resistance heating. The temperature to which the metal films 17 are heated can thus be controlled in a simple manner, and so the metal films 17 reach a temperature required for the sublimation-extraction process. FIG. 3 shows a further embodiment, in which, compared to the embodiment shown in FIG. 1, a heating device 29 is arranged in the irradiation chamber, the latter being able to be made of e.g. ceramics, by means of which heating device the temperature required for the sublimation-extraction process is produced. Embodiments shown in FIG. 1 to FIG. 3 for heating the metal films 17 can also be combined with one another. In FIGS. 1-3, the 100Mo-metal target is embodied as metal film. Other embodiments are possible, e.g., as shown in FIGS. 5-9. In FIG. 5, the 100Mo-metal target is embodied as a multiplicity of tubules. In FIG. 6, the 100Mo-metal target is available in powder form. In FIG. 7, the 100Mo-metal target is shown as a multiplicity of spheres. In FIG. 8, the 100Mo-metal target is shown in the form of a metal foam block. In FIG. 9, the 100Mo-metal target is shown in the form of a grid. What is common to all these embodiments is that the 100Mo-metal target 15 has a large surface area, which can react with the supplied oxygen gas. This leads to an efficient extraction of the 99mTc-technetium oxide. FIG. 10 shows a schematic diagram of example steps of a method according to one embodiment. Initially, a 100Mo-metal target is provided (step 41). The target is subsequently irradiated by a proton beam which was accelerated to an energy of 10 MeV to approximately 25 MeV (step 43). After irradiation of the target, the target is heated to a temperature of over 400° C. (step 45) in order, with the aid of a sublimation-extraction process, to extract the 99mTc made in the target. To this end, oxygen gas is routed over the target (step 47), the forming 99mTc-technetium oxide being sublimated and discharged (step 49). 99mTc-pertechnetate can be obtained from the 99mTc-technetium oxide with the aid of a sodium hydroxide solution or a sodium salt solution (step 51). 11 Accelerator unit 13 Proton beam 15 100Mo-metal target 17 Metal film 19 Mount 21 Valve 23 Liquid column 25 Loop 27 Circuit 29 Heating device Step 41 Step 43 Step 45 Step 47 Step 49 Step 51
	claims	1. An unlatching tool configured for actuating a movable section of a control rod drive shaft in a pressurized water reactor, the unlatching tool extending longitudinally along a center axis and comprising:a base;an outer assembly rotatably fixed to the base;an inner support assembly non-rotatably fixed to the base;a gripper assembly movably coupled to the base and configured for gripping the movable section of the control rod drive shaft;a latch rotatably coupled to the inner support assembly for rotation about a latch axis extending parallel to a center axis of the unlatching tool; anda latch actuator fixed to the outer assembly and configured for rotating the outer assembly in a first rotational direction about the center axis of the unlatching tool such that the latch is rotated about the latch axis radially inward with respect to the center axis of the unlatching tool,the outer assembly being configured such that an inner circumferential surface of the outer assembly contacts a tip of the latch to hold the latch against an outer circumferential surface of a stationary section of the control rod drive shaft. 2. The unlatching tool as recited in claim 1 wherein the outer assembly includes a window extending circumferentially between a first circumferential edge and a second circumferential edge of the outer assembly, the outer assembly configured for contacting a portion of an outer surface of the latch to force the latch radially inward with respect to the center axis during the rotation of the outer assembly in the first rotational direction about the center axis of the unlatching tool by the latch actuator. 3. The unlatching tool as recited in claim 2 wherein the outer assembly is configured for contacting a further portion of the outer surface of the latch to force the latch radially outward with respect to the center axis by rotating the outer assembly in a second rotational direction about the center axis of the unlatching tool by the latch actuator. 4. The unlatching tool as recited in claim 1 wherein the latch actuator includes a fixed portion fixed to the outer assembly and a movable portion movable radially with respect to the center axis. 5. The unlatching tool as recited in claim 4 wherein the base includes a slot formed therein receiving a contact end of the movable portion, the latch actuator including a spring biasing the movable portion toward the slot. 6. The unlatching tool as recited in claim 5 wherein the slot includes an unlatching stop for holding the latch in an unlatched orientation and a latching stop for holding the latch in the latched orientation, the movable portion being movable radially outward with respect to the center axis to further compress the spring to allow for the latch actuator to be movable in the slot between the unlatching stop and the latching stop. 7. The unlatching tool as recited in claim 1 wherein the unlatching tool comprises a mechanical actuator fixed to the base and configured to raise and lower the gripper assembly. 8. The unlatching tool as recited in claim 7 wherein the mechanical actuator is a screw jack. 9. The unlatching tool as recited in claim 1 wherein the gripper assembly is configured such that raising of the gripper assembly forces grippers of the gripper assembly radially inward with respect to the center axis. 10. A method for actuating a movable section of a control rod drive shaft comprising:installing the unlatching tool as recited in claim 1 on the control rod drive shaft;latching the unlatching tool to the stationary section of the control rod drive shaft; andraising a rod connected to the gripper assembly to cause the gripper assembly to grip the movable section and move the movable section upward. 11. The method as recited in claim 10 wherein the installing of the unlatching tool on the control rod drive shaft includes contacting and opening a c-ring of the control rod drive shaft with a lower edge of the gripper assembly. 12. The method as recited in claim 10 wherein the latching of the unlatching tool to the stationary section of the control rod drive shaft includes actuating the latch actuator to move the latch into contact with the outer circumferential surface of the stationary section of the control rod drive shaft. 13. The method as recited in claim 12 wherein the actuating of the latch actuator includes forcing the latch actuator radially outward with respect to the center axis and moving the latch actuator circumferentially. 14. The method as recited in claim 12 wherein the latch actuator is fixed to an outer section of the unlatching tool, the actuating of the latch actuator including rotating the outer section in the first rotational direction. 15. The method as recited in claim 14 further comprising unlatching the unlatching tool from the stationary section of the control rod drive shaft by rotating the outer section in a second rotational direction opposite of the first rotational direction. 16. The method as recited in claim 14 wherein an axial position of the latch remains constant during the rotating of the outer section in the first rotational direction. 17. The method as recited in claim 14 wherein the latch rotates about the latch axis extending parallel to the center axis of the unlatching tool during the moving of the latch into contact with the outer circumferential surface of the stationary section of the control rod drive shaft. 18. The method as recited in claim 14 wherein the actuating of the latch actuator includes contacting an outer surface of the latch with a circumferential edge of a wall portion of the outer section to force a contact surface of the latch radially inward with respect to the center axis toward the stationary section of the control rod drive shaft. 19. The method as recited in claim 18 wherein the actuating of the latch actuator includes contacting the tip of the latch with an inner circumferential surface of the wall portion to force the contact surface of the latch radially inward with respect to the center axis into contact with the stationary section of the control rod drive shaft.
	claims	1. A method of irradiating an isotope in a commercial nuclear reactor that has a moveable in-core detector system including detectors that travel in retractable thimbles that extend from a seal table, outside the nuclear reactor, up into a pressure vessel of the nuclear reactor and through instrument thimbles within fuel assemblies supported within a reactor core, the moveable in-core detector system further including a multi-path selector, positioned on an upstream side of the seal table, that selects the retractable thimbles through which the detectors travel, the method comprising the steps of:providing an elongated, hollow, target specimen cable sized to travel in one of the retractable thimbles with the target specimen cable being sealed at a lead end and having a removable plug that is configured to fit into a trailing end, the target specimen cable having a length sufficient to extend out of the seal table when the target specimen is fully inserted in a preselected, substantially fully extended retractable thimble;loading one or more target specimens through the trailing end into a forward location in the hollow of the target specimen cable;closing off the trailing end with the removable plug;identifying the preselected retractable thimble that extends into the instrument thimble into which the target specimen cable is to be loaded;inserting the lead end of the target specimen cable into the preselected retractable thimble;driving the target specimen cable through the retractable thimble and into the instrument thimble to an elevation that places the target specimen at a predetermined elevation;irradiating the target specimen at the predetermined elevation for a preselected period of time; andwithdrawing the target specimen cable from the instrument thimble after the preselected period of time and out of the preselected retractable thimble to a processing area where it can be loaded into a shielded transportation cask. 2. The method of claim 1 wherein the driving step is performed manually. 3. The method of claim 2 wherein the withdrawing step is performed manually. 4. The method of claim 1 wherein the inserting step is performed downstream of the multi-path selector and upstream of the seal table. 5. The method of claim 1 wherein the driving step comprises inserting the target specimen cable through the retractable thimble into the instrument thimble until the lead end of the target specimen cable reaches the sealed end of the retractable thimble causes the inserting step to cease, then withdrawing the target specimen cable to an axial elevation that places the target specimen at the predetermined elevation. 6. The method of claim 1 including the steps of partitioning the target specimen cable into different axial compartments and loading different target specimens in at least some of the compartments. 7. A method of irradiating an isotope in a commercial nuclear reactor that has a moveable in-core detector system including detectors that travel in retractable thimbles that extend from a seal table, outside the nuclear reactor, up into a pressure vessel of the nuclear reactor and through instrument thimbles within fuel assemblies supported within a reactor core, the moveable in-core detector system further including a multi-path selector, positioned on an upstream side of the seal table, that selects the retractable thimbles through which the detectors travel, the method comprising the steps of:providing an elongated, hollow, target specimen cable sized to travel in one of the retractable thimbles with the target specimen cable being sealed at a lead end and having a removable plug that is configured to fit into a trailing end, the target specimen cable having a length sufficient to extend out of the seal table when the target specimen is fully inserted in a preselected, substantially fully extended retractable thimble;loading one or more target specimens through the trailing end into a forward location in the hollow of the target specimen cable;closing off the trailing end with the removable plug;identifying the preselected retractable thimble that extends into the instrument thimble into which the target specimen cable is to be loaded;inserting the lead end of the target specimen cable into the preselected retractable thimble;driving the target specimen cable through the retractable thimble and into the instrument thimble to an elevation that places the target specimen at a predetermined elevation;sealing an outside of the target specimen cable to the seal table with a compression fitting to lock the target specimen cable in place;irradiating the target specimen at the predetermined elevation for a preselected period of time; andwithdrawing the target specimen cable from the instrument thimble after the preselected period of time and out of the preselected retractable thimble to a processing area where it can be loaded into a shielded transportation cask. 8. The method of claim 7 including the step of removing any excess material from the target specimen cable that extends approximately more than three inches above the compression fitting. 9. The method of claim 8 including the step of inserting the removable plug into the trailing end of the target specimen cable. 10. The method of claim 8 wherein the withdrawing step includes the steps of: releasing the compression fitting; attaching temporary tubing to the preselected retractable thimble above the seal table; and extending the temporary tubing to a staging area where the target specimen cable can be offloaded. 11. The method of claim 10 including the steps of: winding the target specimen cable that is offloaded into a coiled specimen cable; and loading the coiled target specimen cable into a transportation cask. 12. The method of claim 11 wherein the step of winding the target specimen cable includes the step of winding the target specimen cable around a spindle; and cutting the target specimen cable in segments. 13. The method of claim 12 wherein separate segments are wound around different spindles.
046630864	description	EXAMPLE 1 This example illustrates the treatment of cation exchange resins AMBERLITE IR 120 H. The resins are transferred by means of a hydroejector using demineralized water into a treatment vessel, equipped with a mechanical stirrer and a device for the ultrasonic detection of the solid-liquid interface level. After decanting the resin mixture for a period which can extend to between 24 and 48 hours, depending on whether the resins are in ball or ground form, the supernatant water is eliminated, either by pumping, or by vacuum siphoning. Complementary resin quantities are again transferred and the decanting, pumping and vacuum siphoning operations are repeated until the volume V of the decanted resins reaches 50% of the volume of the vessel. A 0.37 mol.l.sup.-1 barium nitrate solution is prepared in an auxiliary vessel and into the treatment vessel is introduced a volume V of said solution, i.e. a volume identical to that occupied by the decanted resins. This is all stirred for 2 hours. Decanting is then allowed to continue for 1 hour and the supernatant solution is eliminated by means of a pump, a vapour ejector, or by vacuum siphoning. In this case, the volume of the eliminated solution corresponds to 1.22 V, which shows that not only the pretreatment solution, but also a certain quantity of the water absorbed by the resins, is eliminated, said quantity representing 14% of the initial volume of the decanted humid resins. This operation is repeated 3 times to obtain a Ba.sup.++ saturation level of the resins close to 100%, due to the Ba(NO.sub.3).sub.2 concentration of the solution (0.37 mol.l.sup.-1) and the contacting time. The saturation treatment leads to a salting out of 10 to 15% of the initial activity of the resins. In addition, the supernatant radioactive solution is returned to the head of the liquid effluent treatment station, either upstream of an evaporator, or upstream of a chemical coprecipitation chain. Following decanting and eliminating then of the supernatant solution, the pretreated resins are washed with demineralized water also using a washing water volume equal to 0.65 V, i.e. identical to that of the pretreated, decanted resins. The pH of the resin suspension is adjusted to 7.5.+-.0.2 with the aid of a barium slurry containing 300 g.l.sup.-1 of Ba(OH.sub.2). This washing operation is repeated four times, whilst checking the NO.sub.3.sup.- concentration of the washing waters after each operation until a NO.sub.3.sup.- concentration of the washing waters below 2 g.l.sup.-1 is obtained. Thus, it is necessary to wash the pretreated resins before conditioning them in bitumen, because if the excess barium nitrate were added to the dry extract of the resins, this would have the disadvantage of increasing not only the volume of the final residue, but also of aiding the leaching of this soluble salt in water. The transfer and washing waters are very slightly radioactive and are returned to the effluent treatment station, where their degree of radioactivity was checked. The pretreated, washed resins are then resuspended in demineralized water using 0.4 to 0.45 V of water for a proportion of 0.6 to 0.55 V of the resin mixture. The suspension of the pretreated organic resins is then passed to the bituminizing installation, which is of the four screw drying extruder type. The properties of the coatings leaving the bituminizing installation are then checked. Table 1 gives the results obtained in connection with the hourly evaporation capacity of the extruder and the composition of the coating obtained during a bituminizing operation performed with resins in ball form. The swelling properties in water of the coatings obtained are then evaluated. These have been cast and solidified in the form of cylindrical test pieces with a diameter of 48 mm and a height of 90 mm. In order to determine the swelling in water, the coatings are immersed in non-renewed ordinary or demineralized water and periodically the percentage volume increase of the coatings is measured as a function of the immersion time in days. The volume ratio between the water and the coatings is 4.5 and the surface/volume ratio of the coatings 10.5 cm.sup.-1. The results obtained are given in curves 1 of FIGS. 1 and 2, which represent the volume increase percentage of the coatings as a function of the time in days. FIG. 1 illustrates the results obtained with ordinary water and FIG. 2 the results obtained with demineralized water. On the basis of these results, it can be seen that the swelling of the coatings after 365 days immersion in ordinary water is 4.2% by volume or 4.45% by weight and that it is 5.0% by volume or 5.1% by weight after 365 days immersion in demineralized water. EXAMPLE 2 Cation exchange resins AMBERLITE IR 120H are treated as in example 1, but using aqueous 1.5 mol.l.sup.-1 barium acetate solution instead of aqueous 0.37 mol.l.sup.-1 barium nitrate solution. A 1.5 mol.l.sup.-1 barium acetate solution is prepared in an auxiliary vessel and into the treatment vessel is introduced a volume V of said solution, i.e. a volume identical to that occupied by the decanted resins. The mixture undergoes stirring for 2 hours making it possible to obtain a Ba.sup.2+ saturation level of the resins exceeding 90% due to the Ba(CH.sub.3 COO).sub.2 concentration of the solution (1.5 mol.l.sup.-1) and the contacting time. Decanting is then allowed to take place for 1 hour and the supernatant solution is eliminated by means of a pump, a vapour ejector or vacuum siphoning. In this case, the volume of the solution eliminated corresponds to 1.34 V, which shows that not only has the pretreatment solution been eliminated, but also a certain amount of the water absorbed by the resins, said quantity representing 21% of the volume of the decanted humid resins. Following decanting and elimination of the supernatant solution, the pretreated resins are washed with demineralized water using a washing water volume equal to 0.83 V, i.e. identical to that of the pretreated, decanted resins. The pH of the suspension of resins is adjusted to 7.5.+-.0.2 with the aid of a barium slurry containing 300 g.l.sup.-1 of Ba(OH).sub.2. This washing operation is repeated three times whilst checking the CH.sub.3 CO.sub.2.sup.- concentration of the washing waters after each operation until a CH.sub.3 CO.sub.2.sup.- concentration thereof below 2 g.l.sup.-1 is obtained. The operation is continued as in example 1 and bituminizing is carried out under the same conditions using a blown MR 90/40 bitumen. The properties of the coatings leaving the bituminizing installation are then checked. The results obtained are given in curves 2 of FIGS. 1 and 2, which show the volume increase percentage of the coatings as a function of the time (in days) during which they were immersed in non-renewed ordinary water (FIG. 1) or in non-renewed demineralized water (FIG. 2). On the basis of FIGS. 1 and 2, it can be seen that the swelling of the coatings after 120 days immersion in ordinary water is 2.45% by volume or 3.4% by weight and that the swelling after 120 days immersion in demineralized water is 4.9% by volume of 5.0% by weight. EXAMPLE 3 In this example, as in example 1, balls of AMBERLITE IR 120H resin are treated, but using a 1.5 mol.l.sup.-1 soda solution in place on the barium nitrate solution which has the effect of bringing the resins into Na.sup.+ form. The pretreated resins are coated with MR 90/40 bitumen under the same conditions as in example 1, followed by the determination of the properties of the coating obtained as in example 1. The results obtained are given in table 1 and in curves 3 of FIGS. 1 and 2, which represent the volume increase percentage of the coatings as a function of the time in days during which they were immersed in renewed ordinary water (FIG. 1) or renewed demineralized water (FIG. 2). It can be seen from these results that the swelling of the coatings after 15 days immersion in demineralized water or ordinary water is very significant. Thus, swelling is 38.7% by volume or 25.1% by weight in the case of demineralized water and 50.1% by volume or 45.6% by weight in the case of ordinary water. Thus, in the process of the invention, the choie of salt for the pretreatment has a very significant effect on the results obtained. EXAMPLE 4 This example illustrates the treatment of anion exchange resins AMBERLITE IRN-78L. Using the operating procedure of the preceding examples, in this case use is made of AMBERLITE IRN-78L resin balls using a 1.5 mol.l.sup.-1 sodium nitrate solution and washing the NO.sub.3.sup.- -saturated resins with demineralized water until a supernatant product is obtained, whose salinity is below 2 g.l.sup.-1. The pretreated resins are coated in blown bitumen MR 90/40 under the same conditions as in the preceding examples, followed by the determination of the properties of the coatings obtained. The results obtained are given in table 1 and in curves 4 of FIGS. 1 and 2, which represent the volume increase percentage of the coatings as a function of the time in days during which they were immersed in non-renewed ordinary water (FIG. 1), or in non-renewed demineralized water (FIG. 2). The results show that the swelling of the coatings after 365 days immersion is 9.5% by volume or 6.1% by weight in the case of ordinary water and 7.2% by volume or 7.1% by weight in the case of demineralized water. EXAMPLE 5 Anion exchange resins AMBERLITE IRN-78L are treated as in example 4, but using an aqueous 1.5 mol.l.sup.-1 barium acetate solution. The operating procedure is identical to that of example 4. The results obtained with the coatings leaving the bituminizing installation are given in table 1 and in curves 5 of FIGS. 1 and 2. It can be seen that the swelling of the coatings after 55 days immersion in demineralized water is 1.7% by volume of 4.9% by weight and that swelling after 55 days in ordinary water is 1.2% by volume or 4.6% by weight. TABLE 1 __________________________________________________________________________ Evaporation capacity of Composition of the coating Suspension of AMBERLITE the extruder during Coating casting in % by weight resins in ball form, which bituminizing (in kg .multidot. h.sup.-1 temperature bitumen MR90/40 (B) have undergone bituminizing. of water) (in .degree.C.) dry extract (ES) water __________________________________________________________________________ Ex. 1 IR12OH resins pre- 160 165 54.1 (B) treatment reagent 44.4 (ES) Ba(NO.sub.3).sub.2 1.5 (H.sub.2) Ex. 2: IR12OH resins pre- 54.2 (B) treatment reagent 162 158 44.5 (ES) Ba(CH.sub.3 CO.sub.2).sub.2 1.3 (H.sub.2 O ) Ex. 3: IR12OH resins pre- 55.7 (B) treatment reagent 143 159 43.0 (ES) NaOH 1.3 (H.sub.2 O) Ex. 4: IRN-78L resins pre- 51.9 (B) treatment reagent 144 160 46.7 (ES) NaNO.sub.3 1.4 (H.sub.2 O) Ex. 5: IRN-78L resins pre- 55.6 (B) treatment reagent 147 165 43.1 (ES) Ba(CH.sub.3 CO.sub.2).sub.2 1.3 (H.sub.2 O) __________________________________________________________________________
046613102	abstract	The dynamic logic of each channel of a multichannel protection system for a nuclear power plant provides a trip logic path and a global bypass logic path by which pulse signals from a clock source may be transmitted to a dc-to-dc power converter which energizes the undervoltage coils for a pair of contactors in the reactor trip switchgear. Each of the logic paths is constructed of basic logic units which in turn, each include a toroidal core of rectangular hysteresis loop magnetic material having a control winding which must be energized by a dc current in order for pulses applied to an input winding to appear at an output winding. Blockage of pulses through any one of the serially connected basic logic units in a logic path terminates the flow of pulses to the converter through that logic path. The control windings of corresponding logic units of the trip logic path in each channel are energized by one of a set of redundant sensors which monitor one of a plurality of reactor trip parameters. Dynamic voting logic appropriate for existing conditions is implemented in part by microprocessors in each channel which gather status information from the other channels through isolated, fiber optic, multiplexed data links and provide the switching logic for alternate paths for energization of the individual basic logic unit control windings, so that for instance, coincidence of trip signals from corresponding sensors in at least two out of four unbypassed channels is required to trip the reactor switchgear. Local bypasses provide additional energization paths for the control windings of basic logic units associated with sensors which are out of service or being repaired. Pulses propagate through the basic logic units of the global bypass path when an entire channel is taken out of service for treating or maintenance. Interlocks between logic units in the trip logic and global bypass logic paths permit only one path to deliver pulses to the converter at any given instant.
059873990	summary	The present invention is related generally to a method and system for performing high sensitivity surveillance of various processes. More particularly the invention is related to a method and system for carrying out surveillance of any number of input signals and one or more sensors. In certain embodiments high sensitivity surveillance is performed utilizing a regression sequential probability ratio test involving two input signals which need not be redundant sensor signals, nor have similar noise distributions nor even involve signals from the same variable. In another form of the invention a bounded angle ratio test is utilized to carry out ultrasensitive surveillance. Conventional parameter-surveillance schemes are sensitive only to gross changes in the mean value of a process or to large steps or spikes that exceed some threshold limit check. These conventional methods suffer from either large numbers of false alarms (if thresholds are set too close to normal operating levels) or a large number of missed (or delayed) alarms (if the thresholds are set too expansively). Moreover, most conventional methods cannot perceive the onset of a process disturbance or sensor deviation which gives rise to a signal below the threshold level or an alarm condition. Most methods also do not account for the relationship between a measurement by one sensor relative to another sensor measurement. Another conventional methodology is a sequential probability ratio test (SPRT) which was originally developed in the 1940s for applications involving the testing of manufactured devices to determine the level of defects. These applications, before the advent of computers, were for manufactured items that could be counted manually. As an example, a company manufacturing toasters might sell a shipment of toasters under the stipulation that if greater than 8% of the toasters were defective, the entire lot of toasters would be rejected and replaced for free; and if less than 8% of the toasters were defective, the entire lot would be accepted by the company receiving them. Before the SPRT test was devised, the purchasing company would have to test most or all items in a shipment of toasters being received. For the toaster example, testing would continue until at least 92% of the toasters were confirmed to be good, or until at least 8% of the toasters were identified to be defective. In 1948 Abraham Wald devised a more rigorous SPRT technique, which provided a formula by which the testing for defective manufactured items could be terminated earlier, and sometimes much earlier, while still attaining the terms of the procurement contract with any desired confidence level. In the foregoing example involving toasters, if the purchasing company were receiving 100 toasters and four of the first eight toasters tested were found to be defective, it is intuitively quite likely that the entire lot is going to be rejected and that testing could be terminated. Instead of going by intuition, however, Wald developed a simple, quantitative formula that would enable one to calculate, after each successive toaster is tested, the probability that the entire lot is going to be accepted or rejected. As soon as enough toasters are tested so that this probability reaches a pre-determined level, say 99.9% certainty, then a decision would be made and the testing could cease. In the 1980s, other researchers began exploring the adaptation of Wald's SPRT test for an entirely new application, namely, surveillance of digitized computer signals. Now, instead of monitoring manufactured hardware units, the SPRT methodology was adapted for testing the validity of packets of information streaming from real-time physical processes. See, for example, U.S. Pat. Nos. 5,223,207; 5,410,492; 5,586,066 and 5,629,872. These types of SPRT based surveillance systems have been finding many beneficial uses in a variety of application domains for signal validation and for sensor and equipment operability surveillance. As recited hereinbefore, conventional parameter-surveillance schemes are sensitive only to gross changes in the process mean, or to large steps or spikes that exceed some threshold limit check. These conventional methods suffer from either large false alarm rates (if thresholds are set too close) or large missed (or delayed) alarm rates (if the threshold are set too wide). The SPRT methodology therefore has provided a superior surveillance tool because it is sensitive not only to disturbances in the signal mean, but also to very subtle changes in the statistical quality (variance, skewness, bias) of the monitored signals. A SPRT-based system provides a human operator with very early annunciation of the onset of process anomalies, thereby enabling him to terminate or avoid events which might challenge safety guidelines for equipment-availability goals and, in many cases, to schedule corrective actions (sensor replacement or recalibration; component adjustment, alignment, or rebalancing; etc.) to be performed during a scheduled plant outage. When the noise distributions on the signals are gaussian and white, and when the signals under surveillance are uncorrelated, it can be mathematically proven that the SPRT methodology provides the earliest possible annunciation of the onset of subtle anomalous patterns in noisy process variables. For sudden, gross failures of sensors or system components the SPRT methodology would annunciate the disturbance at the same time as a conventional threshold limit check. However, for slow degradation that evolves over a long time period (gradual decalibration bias in a sensor, wearout or buildup of a radial rub in rotating machinery, build-in of a radiation source in the presence of a noisy background signal, etc), the SPRT methodology can alert the operator of the incipience or onset of the disturbance long before it would be apparent to visual inspection of strip chart or CRT signal traces, and well before conventional threshold limit checks would be tripped. Another feature of the SPRT technique that distinguishes it from conventional methods is that it has built-in quantitative false-alarm and missed-alarm probabilities. This is important in the context of safety-critical and mission-critical applications, because it makes it possible to apply formal reliability analysis methods to an overall expert system comprising many SPRT modules that are simultaneously monitoring a variety of plant variables. A variety of SPRT-based online surveillance and diagnosis systems have been developed for applications in utilities, manufacturing, robotics, transportation, aerospace and health monitoring. Most applications to date, however, have been limited to systems involving two or more redundant sensors, or two or more pieces of equipment deployed in parallel with identical sensors for each device. This limitation in applicability of SPRT surveillance tools arises because the conventional SPRT equation requires exactly two input signals, and both of these signals have to possess identical noise properties. It is therefore an object of the invention to provide an improved method and system for surveillance of a wide variety of industrial, financial, physical and biological systems. It is another object of the invention to provide a novel method and system utilizing an improved SPRT system allowing surveillance of any number of input signals with or without sensor redundancy. It is a further object of the invention to provide an improved method and system utilizing another improved SPRT type of system employing two input signals which need not come from redundant sensors, nor have similar noise distributions nor originate from the same physical variable but should have some degree of cross correlation. It is still another object of the system to provide a novel method and system selectively employing an improved SPRT methodology which monitors a system providing only a single signal and/or an improved SPRT methodology employing two or more input signals having cross correlation depending on the current status of relationship and correlation between or among signal sets. It is also a further object of the invention to provide an improved method and system employing a bounded angle ratio test. It is yet another object of the invention to provide a novel method and system for surveillance of signal sources having either correlated or uncorrelated behavior and detecting the state of the signal sources enabling responsive action thereto. It is an additional object of the invention to provide an improved method and system for surveillance of an on-line, real-time signals or off-line accumulated sensor data. It is yet a further object of the invention to provide a novel method and system for performing preliminary analysis of signal sources for alarm or state analysis prior to data input to a downstream SPRT type system. It is still an additional object of the invention to provide an improved method and system for ultrasensitive analysis and modification of systems and processes utilizing at least one of a single signal analytic technique, a two unique signal source technique and a bounded angle ratio test. It is an additional object of the invention to provide a novel method and system for generating an estimated signal for each sensor in a system that comprises three or more sensors. It is still another object of the invention to provide an improved method and system for automatically swapping in an estimated signal to replace a signal from a sensor identified to be degrading in a system comprising three or more signals. Other objects, features and advantages of the present invention will be readily apparent from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings described below.
050376020	claims	1. A system for producing radionuclides for use with positron emission tomography (PET), said system comprising: a source of ions for producing a .sup.3 He.sup.++ beam at a low energy; radio frequency quadrupole (RFQ) accelerator means for accelerating said .sup.3 He.sup.++ beam to an energy level of about 8 MeV; and a target system having a selected target compound therein irradiated with said accelerated .sup.3 He.sup.++ beam to produce at least one radionuclide having application to PET. low energy beam transport means for coupling the .sup.3 He.sup.++ beam from said source of ions to said RFQ accelerator; and high energy transport means for directing the accelerated .sup.3 He.sup.++ beam from said RFQ accelerator to said target system. (a) accelerating a beam of .sup.3 He.sup.++ ions with a RFQ accelerator to a energy level of about 8 MeV; (b) irradiating a target compound with the accelerated .sup.3 He.sup.++ beam to produce at least one radionuclide having application to PET; (c) processing the radionuclide obtained in step (b) to produce a desired precursor containing said radionuclide; and (d) preparing a suitable radiopharmaceutical containing said precursor. activating a source of .sup.3 He.sup.++ ions to produce a low energy beam of .sup.3 He.sup.++ ions; 2. The system of claim 1 wherein said desired radionuclide belongs to the group comprising .sup.13 F, .sup.13 N, .sup.15 O, and .sup.11 C. 3. The system of claim 1 wherein said ion source, beam transport means, RFQ accelerator, and target system collectively weigh no more than one ton. 4. The system of claim 1 wherein said ion source, beam transport means, RFQ accelerator, and target system are mounted for operation within a movable compartment, such as a trailer, whereby said entire system is transportable. 5. The system of claim 1 further including: 6. The system of claim 5 further including beam dump means selectively coupled to said high energy transport means, whereby the accelerated .sup.3 He.sup.++ beam can be selectively dumped away from said target system. 7. The system of claim 1 further including cooling means for removing heat from said source of ions and said RFQ accelerator. 8. The system of claim 7 wherein said cooling means maintains the temperature of said RFQ accelerator to within one degree Centigrade of a specified operating temperature. 9. The system of claim 1 further including vacuum means coupled to said RFQ accelerator means for maintaining a vacuum around said RFQ of up to 10.sup.-6 Torr. 10. The system of claim 1 further including operator means for controlling the operation of said system, said operator means providing a push-button operator interface that selects one of three operating states for the system: a standby state, a ready state, and a run state. 11. The system of claim 1 wherein said target system comprises a windowless target system, said windowless target system including a long, narrow tube connecting the high energy end of said RFQ accelerator means to said selected target compound and a vacuum system means for continuously pumping said tube with a vacuum pump. 12. The system of claim 11 wherein said windowless target system further includes pulsed aperture means near the target end of said tube for opening and closing said tube in phase with the delivery of said high energy beam from said RFQ accelerator means. 13. A method for producing a radiopharmaceutical suitable for use with a positron emission tomography (PET) system, said method comprising the steps of: 14. The method of claim 13 wherein step (a) comprises:
051695928	claims	1. In a method for protecting a nuclear reactor in the event of an increase in its load, said method comprising the steps of: (a) monitoring an operating temperature of said reactor; (b) setting an emergency stop limit for nuclear power of said reactor; (c) monitoring said nuclear power; (d) comparing said monitored nuclear power to said emergency stop limit; and (e) stopping said reactor when said monitored nuclear power exceeds said emergency stop limit; (f) setting a reference temperature for said operating temperature; (g) comparing said monitored operating temperature to said reference temperature; and (h) lowering said emergency stop limit when said monitored operating temperature becomes less than said reference temperature. a core (2) containing fuel rods in which a nuclear reaction takes place, giving off nuclear power which is spread between a top and a bottom of the core and which is transformed into heat; a heat exchange circuit (4, 6, 8) for causing a heat exchange fluid to penetrate into the core via an inlet duct (4), for causing it to flow through the core, and for causing it to leave the core via an outlet duct (6), thereby removing said heat, said circuit delivering the heat to a heat receiver (10) having varying needs; and control clusters (12) penetrating in controlled manner into said core in order to control said nuclear reaction; said method comprising the steps of: the improvement wherein said method further comprises the steps of: 2. In a method for protecting a nuclear reactor in the event of an increase in its load, said reactor comprising: 3. A method according to claim 2, comprising the step of further using said function generator for further lowering said emergency stop limit when said operating temperature decreases from a value less than said reference temperature. 4. A method according to claim 2, comprising the step of further using said function generator for further lowering said emergency stop limit by a predetermined limit-lowering amount each time said operating temperature decreases by a predetermined value from a value less than said reference temperature. 5. A method according to claim 2, wherein said reference temperature (TR) lies in the range of 270.degree. C. to 320.degree. C. 6. A method according to claim 5, wherein said method is applied to a pressurized water reactor and said reference temperature (TR) lies in the range of 290.degree. C. to 300.degree. C. 7. A method according to claim 5, wherein said function generator gives to said emergency stop limit, when said operating temperature (ST) is 20.degree. C. less than said reference temperature (TR), a value which is less than one-half the value that said function generator gives to it when said operating temperature is close to but greater than said reference temperature.
056174659	summary	FIELD OF THE INVENTION This invention relates to an X-ray imaging system and method, and, more particularly, relates to a scan-type X-ray imaging system and method having a fixed converter screen. BACKGROUND OF THE INVENTION The use of X-ray imaging systems is well known for use in diverse fields, including utilization in connection with medical diagnosis and/or procedures. Such systems have included fixed-type imaging systems wherein the X-ray source and sensor are maintained in fixed positions to image a body portion within a field of view (FOV) at a scan area (see, for example, U.S. Pat. No. 5,142,557 to Toker et al.) and scan-type imaging systems wherein the X-ray source and/or sensor are moved to image a body portion within a field of view (FOV) at a scan area (see, for example, U.S. Pat. Nos. 4,709,382 to Sones and 4,998,270 to Scheid et al.). In addition, X-ray imaging systems have also included full field film-type readout units therein an image is recorded on a film cassette or the like (see, for example, U.S. Pat. No. 4,998,270 to Scheid et al.), as well as electronic readout units wherein electrical signals indicative of an image are normally converted to digital signals and the digital signals are then used to display and/or electronically store the image (see, for example, U.S. Pat. Nos. 5,142,557 to Toker et al. and 5,289,520 to Pellegrino et al.). Such systems normally require a converter, such as a phosphor converter screen, to form and provide light signals responsive, and proportional, to received X-rays passed through the body portion then subjected to X-rays, and electronic readout systems require the converted signals (i.e., the light signals converted from the X-rays) to be coupled, normally through a coupler, such as a fiber optic (OF) coupler, to a sensor, such as a charge coupled device (CCD) or preferably a time delay integrated (TDI) CCD, providing electrical signal outputs responsive to received light signals. In electronic diagnostic X-ray imaging applications, it has been found to be impractical to attempt to instantaneously image large fields of view since large FOV systems require one or both of very large CCDs or very large fiber optic (OF) reducers, making such sensors impossible, or at least quite expensive, to produce. While the problem of obtaining a large FOV might be overcome by using lens based systems with large magnification, such systems would be subject to being excessively lossy, requiring an increase in patient dosage of X-rays in order to obtain a satisfactory signal-to-noise ratio (SNR) for the system. Optically coupled system shortcomings might also be solved, at least in part, by the use of a slit scanner using either one or a multiple number of CCDs working in the time delay integrated (TDI) mode. In general, these TDI-CCDs are bonded to a OF-Reducer on whose front surface an X-ray phosphor is mounted, and this single, or multistage, TDI-CCD-FO-Phosphor assembly is then mechanically scanned while the charge accumulated in the TDI-sensor is manipulated by vertical transport phases synchronous to the mechanical scan. The use of a layer of phosphor over the entirety of a photodiode array without relative movement therebetween is shown, for example, in U.S. Pat. Nos. 4,709,382 to Sones and 4,845,731 to Vidmar et al. A difficulty arises with respect to the above approach, however, if the phosphor moving under the object, or body portion, to be imaged has an appreciable decay time with respect to the time of motion (a short decay time is required of the X-ray phosphor in order to avoid smear to obtain high modulation within the image). If the decay time is appreciable, then smear, and therefore a significant loss of modulation of the signal (i.e., loss of resolution) is experienced. Since diagnostic X-ray imaging, for example, is of low contrast, any loss of modulation is also a loss of contrast and therefore is unacceptable. Also, the scanning speed that can be obtained is limited by the X-ray to visible light conversion efficiency of the phosphor and the phosphor converter output decay time. In general, short decay time phosphors have a poor conversion efficiency and poor resolution. Some of these shortcomings, however, might be at least partially overcome by using exotic phosphor systems. Thus, the reason that high efficiency short decay time X-ray phosphors are needed for TDI-CCD applications is the necessity to move the phosphor with the sensor. If only the sensor is moved and the X-ray phosphor remains stationary, the decay time of the phosphor is immaterial. Obviously, an X-ray imaging system that does not require movement of the phosphor along with the sensor, thus removing the necessity for short decay time X-ray phosphors (since the decay time of the phosphor would then be immaterial), would be advantageous. SUMMARY OF THE INVENTION A scan-type X-ray imaging system and method are provided with the system including a fixed, or stationary, converter screen, preferably a phosphor screen, and a movable sensor, preferably including at least one charge coupled device (CCD) sensor, with signal coupling from the converter to the sensor being through a coupler, preferably a fiber optic (FO) coupler, having an input portion, or face, that movably engages the converter screen. Positive engagement of the input face of the coupler with the fixed converter screen is maintained, throughout the entire scanning movement of the sensor and coupler, by a force, such as use of a cushion, preferably an air cushion, between the object, or body portion, positioner and the converter screen, with alternate (or additional) positive engagement being effected by a force, such as by use of a vacuum between the input face of the coupler and the converter screen, and/or by a force, such as by use of springs to bias the input face of the coupler toward engagement with the converter screen. It is therefore an object of this invention to provide a scan-type X-ray imaging system with a fixed converter. It is another object of this invention to provide an X-ray imaging system and method having a fixed converter screen and a movable sensor/coupler unit. It is still another object of this invention to provide a scan-type imaging system and method having a fixed converter screen and a coupler that movably engages the fixed converter screen. It is still another object of this invention to provide a scan-type imaging system and method having a sensor connected with a coupler having an input portion maintained in positive engagement with a fixed converter screen during the entire scanning movement of the sensor and coupler. It is still another object of this invention to provide an X-ray imaging system and method having a movable sensor/coupler with the coupler having an input face that is maintained in positive engagement with a fixed converter screen through the use of a force, such as provided by one or more of an air cushion, a vacuum, and springs. With these and other objects in view, which will become apparent to one skilled in the art as the description proceeds, this invention resides in the novel construction, combination, arrangement of parts and method substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that changes in the precise embodiments of the herein disclosed invention are meant to be included as come within the scope of the claims.
	description	This invention was made with government support under W911NF-15-2-0061 awarded by the ARMY/ARL and 1720220 awarded by the National Science Foundation. The government has certain rights in the invention. The field of the disclosure is related to systems and methods for controlling particles. More particularly, the disclosure relates to systems and methods for trapping particles using projected light. The ability to confine and manipulate particles using optical techniques has paved the way for a number of scientific advancements. For instance, defect-free artificial crystals have been created using trapped particles, and used to investigate various fundamental principles governing interactions and material properties. Neutral atoms have been particularly attractive because of their well-defined quantum structure and charge neutrality. Charge neutrality isolates atoms from charge-related perturbations, and helps to retain quantum information for longer times. In addition, neutral atoms can be controlled individually, and scaled to large systems. An atom becomes trapped by the coherent interactions between the electromagnetic fields of applied light, and oscillating electric dipole moment induced in the atom. Specifically, the electromagnetic fields induce internal atomic energy shifts that generate effective potentials from which confinement forces arise. To trap the atom, the frequencies of the light are typically shifted, or detuned, with respect to the atomic resonance frequencies. In particular, when the frequency of the light is below an atomic transition frequency, or “red detuned,” the induced atomic dipole moment is in-phase, and the atom becomes attracted to the intensity maxima of the light. The attraction strength is dependent upon the magnitude of detuning. By contrast, when the frequency is “blue detuned,” the induced moment is out of phase, and the atom is repelled from the maxima. In addition, the strength of attraction/repulsion can be modified by controlling the intensity or power of the applied light. Optical techniques have also been widely used for trapping arrays of atoms for quantum computing and atomic clock applications. Arrays have been prepared in 1-, 2-, or 3-dimensional configurations or optical lattices. Bright, red detuned, arrays localize atoms at the local maxima, while dark, blue detuned, arrays localize the atoms at local minima. In general, dark arrays require more complicated optical systems, but offer the important advantage that by localizing atoms where the intensity is low, there is less perturbation. This is significant for extending the coherence time of atomic qubits and for minimizing disturbance to atoms in optical clocks. Optical lattices are commonly formed by the interference of light from different sources. For example, a 1D lattice can be created using a standing wave generated by superposing two counter-propagating laser beams. Higher dimensional optical lattices require additional optical sources. For example, a 3D simple-cubic lattice structure can be produced by overlapping three orthogonal standing waves formed using 3 pairs of counter-propagating optical sources. However, atomic positions in a lattice generated by the interference of counter-propagating beams are very sensitive to optical path-length. Slight drifts can cause differential phase shifts between beams, and significantly affect the atomic positions. Although phase shifts can be, in principle, compensated by using active stabilization, such techniques are commonly applied to single atoms. This is because of the increased system complexity required for performing active stabilization on multiple atoms. The position of the interference fringes is sensitive to the relative phase of the interfering light beams, and is thus sensitive to optical path lengths. Such sensitivity may be removed by projecting intensity patterns that do not require interferometric stability. However, projected light forms more than one plane of optical traps due to the Talbot effect, which arises from the periodic nature of phase coherent light repeating in free space. This can lead to unwanted atom trapping in multiple spatial planes. In attempting to suppress this effect, some prior techniques have utilized different frequencies of light for each optical trap, or spatial light modulators to impart random phases to each trap. However, such approaches require a number of components (e.g. acousto-optic deflectors, spatial light modulators, diffractive, polarization sensitive optical components, and so on) that add significant system complexity and cost. Given the above, there is a need for systems and methods for particle confinement that are simple to implement and avoid undesired effects, such as position drifts due to optical phase fluctuations, crosstalk, and the Talbot effect. The present disclosure overcomes the drawbacks of previous technologies by providing a system and method for controlling particles using projected light. In one aspect of the present disclosure, a system for controlling particles using projected light is provided. The system includes a particle system configured to provide a plurality of particles, and an optical source configured to generate a beam of light with a frequency shifted from an atomic resonance of the plurality of particles. The system also includes a beam filter positioned between the particle system and plurality of particles, and comprising a first mask, a first lens, a second mask, and a second lens, wherein the optical source, beam filter, and particle system are arranged such that the beam of light from the optical source passes through the beam filter, and is projected on the plurality of particles to form an optical pattern that controls the positions of the particles in space. In another aspect of the present disclosure, a method for controlling particles using projected light is provided. In some aspects, the method includes generating a beam of light using an optical source, and directing the beam of light to a beam filter comprising a first mask, a first lens, a second mask and a second lens. The method also includes forming an optical pattern using the beam filter, and projecting the optical pattern on a plurality of particles to control their locations in space. The foregoing and other aspects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention. Conventional particle trapping technologies generally rely on interference between mutually coherent light beams. These approaches suffer from a number of drawbacks, including sensitivity to beam misalignments, source phase drift and phase noise. By contrast, the inventors have discovered that projected light fields can be used to trap particles. As detailed in U.S. Pat. No. 9,355,750, which is incorporated herein by reference in its entirety, projected light fields can be used to overcome shortcomings of conventional technologies, and provide a number of advantages. For example, particle traps created using projected light fields are scalable, can provide deeper trap depths, and will not change position or depth in response to a source phase drift or noise. In addition, less energy is required per trapping site, thereby allowing more sites for a given energy. In recognizing practical considerations, such as ease of implementation and cost, the present disclosure introduces a novel approach for trapping particles using light fields. In particular, the present disclosure provides a simple, low-cost, solution that enhances performance compared with previous techniques by improving trapping strength and particle localization. In addition, the present approach increases robustness and makes efficient use of light. As appreciated from description below, the present invention can be used to improve a variety of technical fields. For example, an atomic particle array, generated in accordance with the present disclosure, can be part of a hardware configuration for a quantum computer or a quantum computation system. Additionally, atoms trapped using methods herein can also be used as atomic clocks or atomic sensors, as well as in quantum simulation applications. Other improved technical fields may include optomechanics, and small-sphere applications. For example, trapped particles (e.g. microspheres, nanospheres) may be used as probes for measuring physical quantities, or as lasers sources for optical frequency combs. Turning now to FIG. 1, a schematic of an example system 100, in accordance with aspects of the present disclosure, is shown. In general, the system 100 may include an optical source 102, a beam filter 104, and a particle system 106. The system 100 may optionally include a controller 108 in communication with, and configured to control, the optical source 102, the light filter 104, and/or the particle system 106. The optical source 102 may include various hardware for generating light. In particular, the optical source 102 may be configured to generate light with various frequencies, wavelengths, power levels, spatial profiles, temporal modulations (e.g. periodic or aperiodic), and so on. In some aspects, the optical source 102 may be configured to generate light fields using frequencies shifted from at least one atomic resonance. For example, the optical source 102 may be configured to generate blue-detuned or red-detuned light, where the amount of detuning may depend upon the species of particles (e.g. atomic species) to be trapped. As an example, the detuning may be in a range between approximately 10 and approximately 100 nanometers. In one embodiment, the optical source 102 includes a laser that produces light with wavelengths in a range between approximately 500 nm and approximately 1500 nm, although other wavelengths are possible. In another embodiment, the optical source 102 includes multiple lasers operated at multiple frequencies, where the frequency separation between the lasers is configured to achieve a target coherence. The frequencies may be selected to achieve a full coherence, a partial coherence, or an incoherence between various light regions of an optical pattern. In one non-limiting example, two frequencies can be utilized, where the difference in wavelength can vary up to approximately 100 nanometers, although other values are possible. In this manner, different components forming particular light fields can be configured to be mutually incoherent. The beam filter 104, positioned downstream from the optical source 102, is configured to control the beam(s) of light generated by the optical source 102. In particular, the beam filter 104 is configured to form an optical pattern using the generated light, which when projected upon various particles (e.g. neutral atoms), will trap the particles in space. Referring specifically to FIG. 2A, in general, the beam filter 104 may include a first mask 202, a first lens 204, a second mask 206 and a second lens 208, configured such that incident light 200 passes sequentially through the first mask 202, the first lens 204, the second mask 206, and second lens 208, thereafter exiting the beam filter 104 to form an optical pattern 210. In another variation, as shown in FIG. 2B, the beam filter 104 may further include a third mask 212 positioned between the first mask 202 and the first lens 202, where the third mask 212 may include a phase scrambling mask. The phase scrambling mask may include a number of scrambling regions, each transmitting and imparting a phase shift to light passing therethrough. In some embodiments, phase shifts provided by different phase scrambling regions are different, and distributed randomly across the phase scrambling mask over 2π. To this end, the different phase scrambling regions may include different dielectric properties or layers. In some aspects, the first mask 202 may have a variety of transmitting regions (e.g. apertures) and reflecting regions configured to generate an optical pattern that includes bright and dark regions. The bright and dark regions are configured to confine the positions of one or more particles in a desired pattern due to optically-induced trapping forces. As used herein, “bright” refers to regions of light intensity maxima, while “dark” refers to regions of light intensity minima. In some non-limiting examples, the optical pattern may include an arrangement of one or more bright spots or dark spots, respectively. For instance, the optical pattern may include an array of bright, or dark, spots arranged in a one-dimensional (1D) or a two-dimensional (2D) array. Other 1D and 2D arrangements may also be possible. For example, non-rectilinear grids, such as parallelogram, triangular, or hexagonal grids, and as well as configurations of bright and dark regions may be produced. In addition, in some embodiments, the optical pattern may include a 3D configuration that includes multiple 1D or 2D arrays of bright and/or dark regions having various desirable spatial separations between them. In some embodiments, the first mask 202 of the beam filter 104 may be formed using a reflecting plane 300, as shown in FIGS. 3A-3B. The reflecting plane 300 may include a substrate 302 (e.g. glass or other transparent substrate) coated with a reflective layer 304, having a predetermined reflectivity, r. As shown in FIG. 3A, the reflective layer 304 may cover a portion of the substrate 302 to form at least one aperture 306 through which light can be transmitted. In this manner, one or more bright spots may be formed when the reflecting plane 300 is exposed to light. In some variations, the aperture 306 may also extend through the substrate 302. Alternatively, the reflective layer 304 may form a reflecting region 308 on the substrate 302 so as to form at least one dark spot, as shown in FIG. 3B. Although the aperture 306 in FIG. 3A, and reflecting region 308 in FIG. 3B are shown as circular, they may have various other shapes (e.g. linear, rectangular, square, oval, and other regular or irregular shapes), numbers, dimensions, and spatial arrangements/separations, depending on the optical pattern desired. Referring again to FIG. 1, the particle system 106 may be configured to provide and control a number of particles. Specifically, the particle system 106 may include various materials, gases and hardware configured to generate, transfer, manipulate and generally confine the particles. For example, the particle system 106 can include a vacuum system, and capabilities for generating, transferring and confining particles in the vacuum system. In some non-limiting examples, the particles may include any species of neutral atoms, such as Rb, Cs, Ho, Sr, Tb, Ca, and so on, or combinations thereof. However, systems and methods of the present invention are not limited to alkalis or atomic particles, and can be applied to any particles or molecules suitable for optical confinement. In some aspects, the particle system 106 can be configured with capabilities for cooling the particles to any desired temperatures, in order to facilitate trapping. For instance, the particle system 106 may include a laser for cooling the particles to temperatures in a range between 1 and 100 microKelvins, although other values are also possible. Alternatively, the optical source 102 may be used for this purpose. Additionally, the particle system 106 may also include various optical elements to facilitate projection of generated light fields onto the particles therein. In some embodiments, the system 100 may also include a variety of other hardware and optical elements for directing, transmitting, modifying, focusing, dividing, modulating, and amplifying generated light fields to achieve various shapes, sizes, profiles, orientations, polarizations, and intensities, as well as any other desirable light properties. For instance, in one non-limiting example, the system 100 may include top-hat beam shaper configured to transform a Gaussian-shaped beam emitted by a laser, for example, into a uniform-intensity beam of light with sharp edges. The system 100 may also include other optical elements, such as various beam splitters, beam shapers, shapers, diffractive elements, refractive elements, gratings, mirrors, polarizers, modulators and so forth. These optical elements may be positioned between the optical source 102 and beam filter 104, and/or after the beam filter 104. In addition, the system 100 can optionally include other capabilities, including hardware controlling or interrogating quantum states of particles configured and arranged in accordance with the present disclosure. Such capabilities facilitate applications including quantum computation, and so forth. These, along with other tasks, may optionally be performed by the controller 108 shown in FIG. 1. For instance, the controller 108 may be configured to trigger the optical source 102 to generate light. Additionally, or alternatively, the controller 108 may also be configured to control operation of the particle system 106, and its various components there. In some embodiments, the beam filter 104 of the system 100 may be configured to generate an optical pattern using a Fourier filtering or “4f” optical arrangement. Referring specifically to FIG. 4A, the beam filter 104 may include a first mask 402 having a circular aperture with radius a, a first lens 404 with focal length f1, a second mask 406 having a circular aperture with radius b, and a second lens 408 with focal length f2. As shown, the first mask 402 and the second mask 406 are positioned at the focal length f1 of the first lens 404. In addition, the second mask 406 is positioned at the focal length f2 of the second lens. 408. When the beam filter 104 is uniformly illuminated, a portion of the input light 400 traverses through the first aperture 402, located at the input plane, and the first lens 404 produces an Airy light pattern at its back focal plane where the second mask 406 is positioned. The second mask 406 then filters the Airy light pattern, and the filtered Airy pattern is Fourier transformed by the second lens 408 to produce the optical pattern 410 at the output plane. Using standard optical diffraction theory the field at the output plane is given by: A 2 ⁡ ( ρ 2 ) = - A 0 ⁢ α ⁢ ⁢ k f 2 ⁢ ∫ 0 b ⁢ d ⁢ ⁢ ρ 1 ⁢ J 0 ⁡ ( ρ 2 ⁢ k f 2 ⁢ ρ 1 ) ⁢ J 1 ⁡ ( α ⁢ ⁢ k f 1 ⁢ ρ 1 ) ⁢ ; ( 1 ) where A0 is the amplitude of the input light 400. The finite integral of Bessel functions in Eqn. 1 can be expressed as a power series in b using ∫ 0 b ⁢ dzJ 0 ⁡ ( cz ) ⁢ J 1 ⁡ ( dz ) = ∑ j = 0 ∞ ⁢ ⁢ ( - 1 ) j j ! ⁢ ( j + 1 ) ! ⁢ ( 2 ⁢ j + 2 ) 2 ⁢ F 1 ⁡ ( - j , - 1 - j ; 1 ; c 2 / d 2 ) ⁢ b 2 + 2 ⁢ j ⁡ ( d / 2 ) 1 + 2 ⁢ j . ⁢ ( 2 ) Here, 2F1 is the hypergeometric function. In some aspects, the focal lengths and aperture of the second mask 406 may be selected as f1=f2=f, and b=(f/ak)x1, where x1 is 3.8317 is the first zero of J1. This selection corresponds to blocking the Airy rings outside of the central lobe, resulting in only a small power loss since the integrated power in the central lobe is 0.84 of the total power I0πa2, with I0 being the input intensity. With these selections, the output field can be expressed as a power series in ρ2/a. The leading terms are I 2 ⁡ ( ρ 2 ) I 0 = 1.978 - 4.147 ⁢ ( ρ 2 α ) 2 + 3.918 ⁢ ( ρ 2 α ) 4 - … ⁢ . ( 3 ) The resulting optical pattern is referred to as an Airy-Gauss (AG) beam because the beam filter 104 filters an Airy light pattern and the intensity has a near Gaussian form. As shown in FIG. 5, the AG beam is a quadratic function of ρ2 near the origin. Matching the quadratic term with that of a Gaussian intensity profile gives I G = e - 2 ⁢ ρ 2 2 / w 2 , w = 0.974 ⁢ a . Thus, to a good approximation, Fourier filtering of a uniformly illuminated circular aperture produces a Gaussian profile with waist parameter slightly less than the aperture radius a. Although the AG beam is not a pure Gaussian, and has secondary lobes as seen in the inset of FIG. 5, the lobes are sufficiently weak that the profile remains close to that of a Gaussian after diffractive propagation. To note, time reversal symmetry implies that by propagating a Gaussian or near-Gaussian beam through a similar double aperture setup it is possible to efficiently prepare a uniform or near-uniform beam. Therefore, in some implementations, the beam filter 104 shown in FIG. 4A may also be used to prepare a uniform beam. To do so, a Gaussian or near-Gaussian beam may be propagated in reverse through the beam filter 104 (i.e. sequentially through the second lens 408, the second mask 406, the first lens 404 and first mask 402), and thereby transforming the incident beam into a beam with a uniform intensity profile and sharp edges (e.g. a top-hat beam). The above-described Fourier filtering approach to beam shaping can be readily extended to create an array of Gaussian like beams. Referring specifically to FIG. 4B, in some embodiments, the first mask 402 of the beam filter 104 may include an array of apertures arranged on a two-dimensional grid with spacing d. The light field transmitted through each aperture of the first mask 402 have the form given by Eqn. 1, and appear at position −ρij in the output plane, where ρij is the position of the ijth aperture relative to axis 412 of the first mask 402. Provided that the spacing satisfies the relation d≥3a, the interference between adjacent beams can be negligible. In some aspects, the array of bright spots at the output plane can be reimaged with any desired magnification to create an array of beams with spacing given by dout=(df2/f1)×M, where M the magnification of the reimaging optics. The efficiency of the array creation can be defined as ε=It/Id where It is the peak intensity of an output beam and Id=P/d2 is the input intensity with power P per d×d unit cell. The peak intensity may then be written as: I t = .84 ⁢ P ⁢ πα 2 d 2 πα 2 × 1.978 = 1.66 ⁢ I d ; ( 4 ) so ε=1.66, independent of the value of a. In some applications, such as quantum computation, an array of dark spots having Gaussian profiles may be desired for trapping particles at local minima of the optical intensity. As such, dark spots can be created by combining a broad input beam, or plane wave, and bright Gaussian beams having equal amplitudes and n phase difference to create a field zero from destructive interference. To do so, the first mask 402 of the beam filter 104 shown in FIG. 4B may be replaced with a modified first mask 402′ having an array of reflecting spots with radius a, and which is otherwise fully transmitting, as shown in FIG. 4C. In some embodiments, the modified first mask 402′ may be formed using a transparent substrate, and an array of partially or fully reflecting regions (e.g. circular spots), as described with reference to FIG. 3B. Particularly with reference to FIG. 4B, the light field transmitted through the modified first mask 402′ may be written as: E = E d - r ⁢ ∑ ij ⁢ ⁢ E ij ; ( 5 ) where Ed is the amplitude of the plane wave incident on the modified first mask 402′, Eij is the light field transmitted by ijth aperture, and r is the reflectivity of each spot. The plane wave, which may be much broader than the field of a single aperture, will be fully transmitted through the modified first mask 402′, and beam filter 104. Therefore the field at the output plane will be: E 2 = - E d - r ⁢ ∑ ij ⁢ ⁢ E 2 , ij ; ( 6 ) where E2,ij is the field of Eq. (1) centered at position −ρij in the output plane. Choosing r=1/√1.66=0.78 there will be a zero in the field at −ρij surrounded by an intensity pattern with a Gaussian profile. The efficiency may then be given by: ɛ = I t I d = I d I d = 1. ( 7 ) . This efficiency is somewhat lower than the one obtained for an array of bright spots, as described above. Nevertheless, both efficiencies compare favorably with conventional methods. Specifically, darks spots created previously with a Gaussian beam array using diffractive optical elements have ε≤0.51, and a line array has ε≤0.97. By contrast, the present Fourier filtering approach provides substantially better efficiency than a line array since the diffractive multi-spot gratings used to prepare such arrays have efficiencies ˜0.75. In part, this is because beam shapers providing uniform illumination (e.g. top hat beam shaper) can have near 100% efficiency. In particle or atom trapping, important parameters are the depth of the trap, which is proportional to It, and the spatial localization. When the trapped particles have motional energy that is small compared to the depth of the trapping potential, the degree of localization is governed by the quadratic variation of the intensity near the trap center. For a bright trap, which localizes a particle near the intensity maxima, the trapping potential can be written asU=U0(1−α⊥ρ2−α∥z2+ . . . ). (8). Here ρ is the radial coordinate and z is the axial coordinate along the trap axis. For a particle with motional temperature T, the virial theorem gives:2U0α⊥ρ2=2kBT 2U0α∥z2=kBT (9); where kB is the Boltzmann constant. The standard deviations of the particle position are therefore, σ ρ ⁢ 〈 ρ 2 〉 = 1 α ⊥ 1 / 2 ⁢ ( k B ⁢ T U 0 ) 1 / 2 , ⁢ σ z ⁢ 〈 z 2 〉 = 1 ( 2 ⁢ α ❘ ❘ ) 1 / 2 ⁢ ( k B ⁢ T U 0 ) 1 / 2 . ( 10 ) . For an ideal Gaussian beam with waist parameter wG, and optical wavelength λ, one can have α ⊥ = 2 / ω G 2 ⁢ ⁢ α ❘ ❘ = λ 2 π 2 ⁢ ω G 4 . ( 11 ) Equation 10 may then be written as σ ρ ( k B ⁢ T U 0 ) 1 / 2 ≡ σ ~ ρ = ω G 2 , ⁢ σ z ( k B ⁢ T U 0 ) 1 / 2 ≡ σ ~ z = πω G 2 2 ⁢ λ . ( 12 ) . For Airy-Gauss beam, wG=0.974a, giving position deviations σ ~ ρ = 0.69 ⁢ α , ⁢ σ ~ z = 2.1 ⁢ α 2 λ . ( 13 ) . Using a=d/3, the position factors can be written as σ ~ ρ = 0.23 ⁢ d , ⁢ σ ~ z = 0.233 ⁢ d 2 λ . ( 14 ) . Equations 12 and 14 give the position spreads for bright optical traps. For a dark optical trap created by interfering a Gaussian beam with a plane wave, the axial profile far from the origin is different than that of a bright trap due to the variation of the field phase with z, given byϕ(z)=tan−1[z/(πωG2/λ)]. (15). This is illustrated in FIG. 5. Note that the axial profiles are somewhat different for Airy-Gauss and Gaussian beams. Nevertheless the leading quadratic terms are unchanged so the localization parameters are still given by Eqs. 12 and 14. These results can be compared with prior approaches for the Gaussian line array. There the optimum localization is obtained for {tilde over (σ)}ρ=0.42d and {tilde over (σ)}z=0.30d2/λ. By contrast, the present approach has a 45% better transverse localization and 22% better axial localization. Specifically, as shown in FIG. 6, the localization obtained is {tilde over (σ)}ρ=0.69 μm and {tilde over (σ)}z=2.6 μm. Parameters used for numerical calculations included a=b=1.0 μm, λ=0.825 μm, f=2 μm and wG=0.974a. With a temperature to trap depth ratio of less than a factor of 9, which is standard for atoms in optical traps, this implies sub-micron localization in all dimensions. The Fourier filtering approach described herein, whether used to create an array of bright or dark traps, may lead to formation of multiple trapping planes due to the Talbot effect. Should such planes be undesired, a variation to the configuration of FIG. 4B may be utilized, as shown in FIG. 7. Specifically, a phase scrambling mask 414 may be positioned between the first mask 402 and first lens 404. As shown, the phase scrambling mask 414 may include an array of scrambling regions 416 positioned at ρij, each providing full transmission of light passing therethrough, along with a phase shift φij. In some aspects, the phase shift φij for each scrambling region 416 may vary between 0 and 2π, and be randomly distributed across the phase scrambling mask 414. Turning now to FIG. 8, steps of a process 800 for controlling particles using projected light, in accordance with the present disclosure, are provided. In some implementations, steps of the process 800 may be carried out using systems described herein, as well as other suitable systems or devices. The process 800 may begin at process block 802 with generating a beam of light using an optical source. As described, the light beam generated by the optical source may have a variety of properties, including various frequencies, wavelengths, power levels, spatial profiles, temporal modulations, and so on. In some aspects, the light beam may have frequencies shifted from at least one atomic resonance of particles to be trapped. The beam of light may then be directed to a beam filter, as indicated by process block 804. In accordance with aspects of the present disclosure, the beam filter may include a first mask, a first lens, a second mask and a second lens. In some variations, the beam filter may further include a third mask positioned between the first mask and the first lens, where the third mask may include a phase scrambling mask. The beam filter may be configured such that the beam of light passes sequentially through the first mask, optionally the third mask, the first lens, the second mask, and second lens, and thereafter exists the beam filter to form an optical pattern, as indicated by process block 806. As described, the optical pattern may have a variety of configurations depending on the particular application. The optical pattern may then be projected on a plurality of particles (e.g. atomic particles) to control their locations in space, as indicated by process block 808. To this end, the particles may be provided by a particle system that is configured to generate and confine them to a particular volume or a general location in space. As described, the provided particles can be held in a vacuum and cooled to temperatures suitable for optical trapping. The present invention has been described in terms of one or more preferred embodiments, and it should be appreciated that many equivalents, alternatives, variations, and modifications, aside from those expressly stated, are possible and within the scope of the invention.
	claims	1. A method to reduce friction and physical contact between an outer surface of a fuel rod and a support grid in a fuel rod assembly of a nuclear reactor during loading of the fuel rod into the support grid, comprising:applying to the outer surface of the fuel rod a lubricant composition to form a film thereon, said lubricant composition comprising polyalkylene glycol; andloading the fuel rod having said film applied thereon into the support grid of the fuel rod assembly,wherein the friction and physical contact between the outer surface of the fuel rod and the support rid loading is reduced as a result of the film formed on the outer surface of the fuel rod. 2. The method of claim 1, wherein the lubricant composition further comprises a solvent. 3. The method of claim 2, wherein the solvent is water. 4. The method of claim 3, wherein the lubricant composition and the water are combined to form a lubricant-water mixture and the lubricant-water mixture is maintained at a temperature of less than 140° F. for the applying to the outer surface of the fuel rod. 5. The method of claim 1, wherein the lubricant composition has a viscosity of greater than about 1050 cSt at 40° C. and 178 cSt at 100° C. 6. The method of claim 1, wherein the film has a thickness of from 0.0005 inch to 0.0015 inch. 7. The method of claim 1, further comprising:washing the fuel rod having said film applied thereon and loaded into the support grid of the fuel rod assembly to substantially remove the lubricant composition; andinserting the fuel rod having said lubricant composition substantially removed therefrom into the nuclear reactor. 8. A method for loading a coated fuel rod into a support grid of a fuel rod assembly for a nuclear reactor to reduce friction and physical contact between an outer surface of the fuel rod and the support grid, and for inserting the fuel rod into the nuclear reactor so as to substantially reduce an amount of coating composition from contacting reactor coolant in the nuclear reactor, comprising:applying to the outer surface of the fuel rod a lubricant composition to form a film thereon, said lubricant composition comprising polyalkylene glycol;loading the fuel rod having said film applied thereon into the support grid of the fuel rod assembly;washing the fuel rod having said film applied thereon and loaded into the support grid of the fuel rod assembly to substantially remove the lubricant composition; andinserting the fuel rod having said lubricant composition substantially removed therefrom into the nuclear reactor.
	description	The current application is a U.S. national stage application of International Application No. PCT/US07/62315, which claims priority to U.S. Utility application Ser. No. 11/355,719, which was filed on 16 Feb. 2006, and which has issued as U.S. Pat. No. 7,266,475, both of which are hereby incorporated by reference. The invention relates generally to trust evaluation, and more particularly, to a solution for evaluating trust between a plurality of computing devices in a computer infrastructure. It is becoming increasingly important that a computer that seeks to communicate with another computer be able to ensure that the other computer can be trusted. For example, information for financial transactions and other sensitive information are increasingly being transferred between computers over public networks such as the Internet. In order to ensure the authenticity and security of this data, it is important that a level of trust be established between the sending and receiving computers. To meet this need various solutions have been proposed. For example, the Trusted Computing Group (TCG) has defined a set of specifications for establishing trust between two or more computing devices, which are hereby incorporated herein by reference. The specifications define a set of information (e.g., measurements) that are maintained by a computing device and a solution for maintaining and communicating these measurements in a secure manner. The measurements represent the components of the computing device and the configuration thereof. For example, the measurements typically reflect the various pieces of a basic input output system (BIOS) and firmware that are implemented on the computing device as well as the configuration information that controls the behavior of these pieces (e.g., “BIOS settings”). The measurements also reflect the hardware itself, such as a type and version of a processor, a size of the main memory, types of peripheral controllers present in input/output (I/O) bus slots, and/or the like. The measurements are kept in a “log” that is secured by a set of Program Configuration Registers (PCRs). The PCRs serve as cryptographic proof that the log is intact and has not been tampered. FIG. 1 shows a prior art computing infrastructure 100 for evaluating trust between computing devices 102 and 104. Using the TCG architecture as an exemplary solution, validation system 106 on computing device 102 (e.g., “the challenger”) requests an attestation from another computing device 104. The attestation comprises the measurements and the corresponding PCR values (e.g., device measurements 110) combined and cryptographically signed by an attestation system 108 of the computing device 104. In the TCG architecture, attestation system 108 is referred to as a Trusted Platform Module (TPM), and comprises a chip built into a motherboard for computing device 104. Subsequently, validation system 106 evaluates the attestation using a set of reference measurements 112, which represent all approved results. If the evaluation indicates that the computing device 104 may have been tampered with, a transaction can be aborted before any sensitive information is exchanged. Otherwise, the transaction can proceed with computing device 102 having established a certain level of trust with computing device 104. In another application, the TCG architecture can be used to ensure that various computing devices 104 conform to an appropriate policy. To this extent, computing device 102 can be used by a system administrator or the like, and can query multiple computing devices 104 in a network and compare the device measurements 110 received for each computing device 104 to a “golden master” set of reference measurements 112. In this case, if device measurements 110 match reference measurements 112, the corresponding computing device 104 is considered conformant and/or trustworthy. However, when device measurements 110 do not match reference measurements 112, the corresponding computing device 104 can be isolated from the remaining computing devices 104 and/or repaired. Since the process of validating measurements must account for variability in the measurements received from various computing devices 104, e.g., different ordering of entries in a log, the validation process can be very complex. As a result, current solutions provide a centralized approach, in which a single computing device 102, often with the direct interaction of a system administrator, evaluates numerous other computing devices 104 and/or provides any required fixes. However, these solutions do not scale well and are subject to failures and/or delays that create security lapses. To this extent, a need exists for a solution for evaluating trust in a computer infrastructure that addresses the problems discussed herein and/or other problems recognizable by one in the art. The invention provides a solution for evaluating trust in a computer infrastructure. In particular, a plurality of computing devices in the computer infrastructure evaluate one or more other computing devices in the computer infrastructure based on a set of device measurements for the other computing device(s) and a set of reference measurements. To this extent, each of the plurality of computing devices also provides a set of device measurements for processing by the other computing device(s) in the computer infrastructure. The evaluations can be performed using a small amount/excess computing capacity of each computing device. When the number of computing devices in the computer infrastructure becomes too great, a plurality of sub-groups can be created in which computing devices only evaluate other computing devices in the same sub-group(s). In this manner, a distributed, efficient and scalable solution is provided for evaluating trust in a computer infrastructure. A first aspect of the invention provides a system for evaluating trust in a computer infrastructure, the system comprising: on each of a plurality of computing devices in the computer infrastructure: a system for providing device measurements for the computing device for processing by another computing device in the computer infrastructure; and a system for evaluating another computing device in the computer infrastructure based on a set of device measurements for the another computing device and a set of reference measurements. A second aspect of the invention provides a method of evaluating trust in a computer infrastructure, the method comprising: on each of a plurality of computing devices in the computer infrastructure: periodically providing device measurements for the computing device for processing by another computing device in the computer infrastructure; and periodically evaluating another computing device in the computer infrastructure based on a set of device measurements for the another computing device and a set of reference measurements. A third aspect of the invention provides a computer infrastructure comprising: a plurality of computing devices, each of the plurality of computing devices including: a system for providing device measurements for the computing device for processing by another computing device in the computer infrastructure; and a system for evaluating another computing device in the computer infrastructure based on a set of device measurements for the another computing device and a set of reference measurements. A fourth aspect of the invention provides a program product stored on a computer-readable medium, which when executed, enables a computer infrastructure to evaluate trust, the program product comprising computer program code for enabling a computing device in the computer infrastructure to: periodically provide device measurements for the computing device for processing by another computing device in the computer infrastructure; and periodically evaluate another computing device in the computer infrastructure based on a set of device measurements for the another computing device and a set of reference measurements. A fifth aspect of the invention provides a method of deploying a system for evaluating trust in a computer infrastructure, the method comprising: providing a computer infrastructure that comprises: a plurality of computing devices, each of the plurality of computing devices operable to: provide device measurements for the computing device for processing by another computing device in the computer infrastructure; and evaluate another computing device in the computer infrastructure based on a set of device measurements for the another computing device and a set of reference measurements. A sixth aspect of the invention provides a business method for evaluating trust in a computer infrastructure, the business method comprising managing a computer infrastructure that performs the process described herein; and receiving payment based on the managing. A seventh aspect of the invention provides a business method for managing trust evaluation reporting in a computer infrastructure, the business method comprising managing a computer infrastructure that performs the process described herein; and receiving payment based on the managing. The illustrative aspects of the present invention are designed to solve the problems herein described and other problems not discussed, which are discoverable by one in the art. It is noted that the drawings are not to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings. As indicated above, the invention provides a solution for evaluating trust in a computer infrastructure. In particular, a plurality of computing devices in the computer infrastructure evaluate one or more other computing devices in the computer infrastructure based on a set of device measurements for the other computing device(s) and a set of reference measurements. To this extent, each of the plurality of computing devices also provides a set of device measurements for processing by the other computing device(s) in the computer infrastructure. The evaluations can be performed using a small amount/excess computing capacity of each computing device. When the number of computing devices in the computer infrastructure becomes too great, a plurality of sub-groups can be created in which computing devices only evaluate other computing devices in the same sub-group(s). In this manner, a distributed, efficient and scalable solution is provided for evaluating trust in a computer infrastructure. Turning to the drawings, FIG. 2 shows an illustrative computer infrastructure 12A for evaluating trust according to an embodiment of the invention. Computer infrastructure 12A includes a plurality of computing devices 14A-C, each of which includes an attestation system 40 and a validation system 30, which make computing devices 14A-C operable to evaluate trust by performing the process described herein. In general, validation system 30 periodically evaluates the other computing devices 14A-C in computer infrastructure 12A. To this extent, validation system 30 can request and/or receive a set of device measurements 50 from attestation system 40 on the other computing devices 14A-C and compare the device measurements 50 to reference measurements 52. Based on this comparison, validation system 30 can evaluate the trustworthiness of the other computing devices 14A-C. Computer infrastructure 12A can comprise any type of computing infrastructure 12A that includes a group of two or more computing devices 14A-C. To this extent, computing devices 14A-C can communicate over any combination of one or more types of communications links, such as a network, a shared memory, or the like, to perform the process described herein. The communications link(s) can comprise any combination of various types of wired and/or wireless links; comprise any combination of one or more types of networks (e.g., the Internet, a wide area network, a local area network, a virtual private network, etc.); and/or utilize any combination of various types of transmission techniques and protocols. In one embodiment, computer infrastructure 12A comprises a grid, and each computing device 14A-C comprises a server in the grid. However, it is understood that this is only illustrative of many possible embodiments. FIG. 3 shows a more detailed view of one of the computing devices 14A according to an embodiment of the invention. Computing device 14A is shown including a processor 20, a memory 22A, an input/output (I/O) interface 24, and a bus 26. Further, computing device 14A is shown in communication with an external I/O device/resource 28 and a storage system 22B. As is known in the art, in general, processor 20 executes computer program code, such as validation system 30, which is stored in memory 22A and/or storage system 22B. While executing computer program code, processor 20 can read and/or write data, such as device measurements 50, to/from memory 22A, storage system 22B, and/or I/O interface 24. Bus 26 provides a communications link between each of the components in computing device 14A. I/O device 28 can comprise any device that enables an individual to interact with computing device 14A or any device that enables computing device 14A to communicate with one or more other computing devices using any type of communications link. In any event, computing device 14A can comprise any general purpose computing article of manufacture capable of executing computer program code installed thereon (e.g., a personal computer, server, handheld device, etc.). However, it is understood that computing device 14A, validation system 30 and attestation system 40 are only representative of various possible equivalent computing devices that may perform the process described herein. To this extent, in other embodiments, the functionality provided by computing device 14A, validation system 30 and attestation system 40 can be implemented by a computing article of manufacture that includes any combination of general and/or specific purpose hardware and/or computer program code. In each embodiment, the program code and hardware can be created using standard programming and engineering techniques, respectively. Regardless, it is understood that computing devices 14B-C (FIG. 2) can comprise the same components (processor, memory, I/O interface, etc.) as shown for computing device 14A. These components have not been separately shown and discussed for brevity. As discussed further herein, validation system 30 and attestation system 40 enable each computing device 14A-B in computer infrastructure 12A to evaluate trust. To this extent, validation system 30 is shown including a challenge system 32, an evaluation system 34 and a management system 36. Operation of each of these systems is discussed further herein. However, it is understood that some of the various systems shown in FIG. 3 can be implemented independently, combined, and/or stored in memory for one or more separate computing devices that are included in computer infrastructure 12A. Further, it is understood that some of the systems and/or functionality may not be implemented, or additional systems and/or functionality may be included as part of computer infrastructure 12A. Regardless, the invention provides a solution for evaluating trust in a computer infrastructure 12A. For example, computing device 14B can evaluate a level of trust for computing device 14A. To perform such an evaluation, computing device 14A is shown including an attestation system 40. Attestation system 40 provides a set of device measurements 50 for the corresponding computing device 14A for processing (e.g., evaluation) by another computing device 14B in computer infrastructure 12A. To this extent, attestation system 40 can comprise a Trusted Platform Module (TPM) and device measurements 50 can comprise the set of measurements and Program Configuration Registers (PCRs) as defined and described in the Trusted Computing Group's specifications. However, it is understood that this is only an illustrative embodiment, and numerous alternative embodiments are possible under the invention. Similarly, computing device 14A can evaluate a level of trust for computing device 14B. In this case, validation system 30 can include a challenge system 32 that periodically requests device measurements 50 for other computing device(s) 14B in computer infrastructure 12A. In response, an attestation system 40 or the like in computing device 14B can provide the device measurements 50 for processing by the requesting computing device 14A. Challenge system 32 can request device measurements 50 from the other computing device(s) 14B using any type of event-based and/or timing-based solution. For example, a user, such as a system administrator, or another system can instruct challenge system 32 to request device measurements 50 for one or more computing devices 14B. Alternatively, challenge system 32 can request device measurements 50 after expiration of a period of time (e.g., once an hour), prior to providing sensitive data to the computing device 14B, upon detection of an abnormal event, and/or the like. When challenge system 32 receives device measurements 50, evaluation system 34 can evaluate the corresponding computing device 14B based on the device measurements 50 to determine whether it can be trusted. In particular, evaluation system 34 can compare the device measurements 50 to a set of reference measurements 52. The set of reference measurements 52 can define a set of measurements and their corresponding trust level. The set of reference measurements 52 can be specific to a particular computing device 14B, e.g., reference measurements 52 can comprise device measurements 50 for each computing device 14B in computer infrastructure 12A, and/or reference measurements 52 can comprise a set of standard measurements that computing device(s) 14B in computer infrastructure 12A must meet in order to obtain a particular trust level. In one embodiment, evaluation system 34 can assign computing device 14B one of a plurality of trust levels. For each increasing trust level, evaluation system 34 can perform a more exacting comparison of device measurements 50 with reference measurements 52. To this extent, another system can request that validation system 30 determine whether computing device 14B meets a particular trust level. In this case, challenge system 32 can obtain a corresponding amount and/or type of device measurements 50 based on the particular trust level and/or evaluation system 34 can perform a varying amount and/or type of evaluations of device measurements 50 with respect to reference measurements 52 based on the particular trust level. Regardless, evaluation system 34 can detect a failure of the other computing device 14B to obtain a trust level. In this case, evaluation system 34 can respond to the failure. For example, evaluation system 34 can provide an indication of the failure to a requesting system and/or user, can generate a notification to a user of the failure, and/or can communicate the failure to the evaluated computing device 14B and/or one or more other computing devices 14C (FIG. 2) in computer infrastructure 12A. When computer infrastructure 12A includes three or more computing devices 14A-C as shown in FIG. 2, evaluation system 34 can compare the evaluation of a particular computing device 14B with the other computing device(s) 14C in computer infrastructure 12A. For example, when evaluation system 34 detects a failure of a particular computing device 14B, evaluation system 34 can respond by comparing the evaluation with the evaluation result(s) for the particular computing device 14B that were obtained by the remaining computing device(s) 14C. Subsequently, any additional action can be determined using any voting algorithm or the like between the other computing devices 14A, 14C in computer infrastructure 12A. In one embodiment, validation system 30 includes a management system 36 that manages a set (one or more) of computing devices 14B that are evaluated by validation system 30. To this extent, in response to a failure of a particular computing device 14B, management system 36 can isolate the computing device 14B from communicating with the rest of the computing devices 14C (FIG. 2) in computer infrastructure 12A and/or communicating with any other computing devices outside of computer infrastructure 12A. Further, management system 36 can add and/or remove computing device(s) 14B that are evaluated by validation system 30. For example, management system 36 can receive a communications address or the like for computing device 14B and an instruction to add/remove computing device 14B from a system administrator and/or another system. Alternatively, management system 36 can automatically detect the presence of a new computing device 14B in computer infrastructure 12A and begin evaluating it. For example, a new computing device 14B can petition to join computer infrastructure 12A. As part of this process, the new computing device 14B can provide various information on its system, such as device measurements 50, which can be evaluated versus a known standard, and a particular trust level can be assigned. Further, when challenge system 32 does not receive a response to a request for device measurements 50 of a particular computing device 14B, management system 36 can remove the computing device 14B from the set of evaluated computing devices and/or isolate the computing device 14B as no longer being trusted. When adding computing devices 14B to the set of computing devices being monitored, management system 36 can detect that a threshold number of computing devices being monitored has been exceeded. In this case, management system 36 can divide computer infrastructure 12A into a plurality of sub-groups of computing devices 14A-B for evaluating trust. To this extent, computer infrastructure 12A can comprise a sub-group of computing devices 14A-B. For example, FIG. 4 shows an illustrative computer infrastructure 12B that includes a plurality of sub-groups 60A-C. In this case, each computing device 14A-F only evaluates trust for the other computing devices 14A-F in the same sub-group 60A-C. Management system 36 can use any threshold number to divide computer infrastructure 12B into a multiple sub-groups 60A-C. In general, each computing device 14A-F should be able to readily monitor the other computing devices in the same sub-group without substantially impacting a primary function of the computing device 14A-F. Consequently, the threshold number can be selected to ensure that the impact on the overall performance of computing devices 14A-F remains at an acceptable level. Similarly, management system 36 can detect when a number of computing devices in a sub-group 60A-C falls below a threshold number (e.g., three). In this case, management system 36 can combine two sub-groups 60A-C or independently assign each computing device 14A-F to another sub-group 60A-C. In any event, management system 36 can implement any solution for assigning computing devices 14A-F in computer infrastructure 12B to a corresponding sub-group 60A-C. For example, management system 36 can assign computing devices 14A-F to different sub-groups 60A-C based on the communications addresses, physical proximity, primary function(s), and/or the like. Further, a user, such as a system administrator, can use management system 36 to designate membership in sub-groups 60A-C, add and/or remove computing devices 14A-F from sub-groups 60A-C, create and/or delete sub-groups 60A-C, and/or the like. Sub-groups 60A-C can comprise disjoint membership, e.g., no computing device 14A-F is included in more than one sub-group 60A-C. However, as shown, one or more computing devices 14A-F can be included in multiple sub-groups 60A-C. For example, computing device 14A is shown included in both sub-group 60A-B and computing device 14C is shown included in both sub-groups 60A, C. By including computing devices 14A-F in multiple sub-groups 60A-C, redundancy is provided for computer infrastructure 12B and sub-groups 60A-C may need to be created/removed less frequently. To this extent, each computing device 14A-F can be included in two sub-groups 60A-C. In this case, each sub-group 60A-C can comprise a single computing device 14A-F that comprises a “trusted authority” from which other computing devices 14A-F in the sub-group 60A-C can obtain reference measurements 52 (FIG. 2). Should a trusted authority in one sub-group 60A-C become corrupted, the corruption can be detected by the other partially overlapping sub-groups 60A-C and trust evaluation can continue for the other computing devices 14A-F in the corrupted sub-group 60A-C. While each computing device 14A-F is shown and described as including both validation system 30 (FIG. 2) and attestation system 40 (FIG. 2), it is understood that one or more computing devices 16 in computer infrastructure 12B can comprise only attestation system 40 or neither system 30, 40. For example, computing device 16 could comprise a computing device that includes a TPM. In this case, computing device 14C can evaluate the trust level of computing device 16 as described herein. However, computing device 16 would not evaluate the trust of computing device 14C or any other computing device in computer infrastructure 12B. Alternatively, computing device 16 may not include either system 30, 40. In this case, computing device 14C can use other solutions for evaluating computing device 16, limit the sensitivity of data communicated to computing device 16, and/or limit the types of transactions in which computing device 16 can participate. Returning to FIG. 2, reference measurements 52 are critical to effectively evaluating other computing devices 14A-C in computer infrastructure 12A. In particular, any corruption or misrepresentation of reference measurements 52 could cause wide-spread disruption in computer infrastructure 12A. For example, insertion of a “bad” measurement into reference measurements 52 could allow unapproved software, such as a virus or other security attack, to execute on a computing device 14A-C, thereby defeating the evaluation process. As shown, each computing device 14A-C can include its own copy of reference measurements 52. This provides protection against a compromise of one copy of reference measurements 52 at one of computing devices 14A-C. Further, when voting, or the like, is used to determine a trust level for a computing device 14A-C that fails an evaluation, a compromised set of reference measurements 52 may be detected. In this case, validation system 30 can stop evaluating other computing devices 14A-C until an accurate set of reference measurements 52 is obtained. One problem with each computing device 14A-C comprising its own copy of reference measurements 52 is the need to distribute reference measurements 52 to each computing device 14A-C. In an alternative embodiment, a single computing device, e.g., computing device 14A, could comprise a copy of reference measurements 52 and validation systems 30 on the other computing devices 14B-C could request and obtain data from reference measurements 52 using secure communications on an as needed basis. Regardless, reference measurements 52 should be generated and/or distributed in a trusted manner, e.g., using a “clean room” solution. To this extent, a single computing device 14A in computer infrastructure 12A can enable a user to add, delete, and/or modify reference measurements 52 using, for example, management system 36 (FIG. 3), and subsequently, management system 36 can communicate an updated reference measurements 52 to the other computing devices 14B-C in computer infrastructure 12A. Management system 36 on each of the other computing devices 14B-C can receive the updated reference measurements 52 and ensure that they are valid. In one embodiment, reference measurements 52 and validation system 30 are cryptographically signed by the creator and are only replaceable/updateable by trustworthy procedures that protect the integrity of the signed data and/or program code. Validation system 30 and/or attestation system 40 can maintain a set of trust evaluation reports 54. Trust evaluation report 54 can comprise various data on the computing device(s) 14B that are evaluated by evaluation system 34, the results of the evaluation (s), response(s) to request(s) for device measurements 50, and/or the like. For example, in one embodiment, trust evaluation report 54 can comprise a change log that is updated each time the trust level of an evaluated computing device 14B changes. Similarly, trust evaluation report 54 can comprise an audit report that logs all evaluations, updates of device measurements 50 and/or reference measurements 52, requests for evaluation data and/or device measurements 50, and/or the like, that are processed by validation system 30 and/or attestation system 40. In any event, validation system 30 and/or attestation system 40 can provide some or all of a trust evaluation report 54 for processing by another system and/or display to a user. While shown and described herein as a method and system for evaluating trust in a computer infrastructure, it is understood that the invention further provides various alternative embodiments. For example, in one embodiment, the invention provides a program product stored on a computer-readable medium, which when executed, enables a computer infrastructure to evaluate trust as described herein. To this extent, the computer-readable medium includes program code, such as validation system 30 (FIG. 3) and attestation system 40 (FIG. 3), which implements the process described herein. It is understood that the term “computer-readable medium” comprises one or more of any type of physical embodiment of the program code. In particular, the computer-readable medium can comprise program code embodied on one or more portable storage articles of manufacture (e.g., a compact disc, a magnetic disk, a tape, etc.), on one or more data storage portions of a computing device, such as memory 22A (FIG. 3) and/or storage system 22B (FIG. 3) (e.g., a fixed disk, a read-only memory, a random access memory, a cache memory, etc.), and/or as a data signal traveling over a network (e.g., during a wired/wireless electronic distribution of the program product). In another embodiment, the invention provides a method of generating a system for evaluating trust in a computer infrastructure. In this case, a computer infrastructure, such as computer infrastructure 12A (FIG. 2), can be obtained (e.g., created, maintained, having made available to, etc.) and one or more systems for performing the process described herein can be obtained (e.g., created, purchased, used, modified, etc.) and deployed to the computer infrastructure. To this extent, the deployment of each system can comprise one or more of: (1) installing program code on a computing device, such as computing device 14A (FIG. 3), from a computer-readable medium; (2) adding one or more computing devices to the computer infrastructure; and (3) incorporating and/or modifying one or more existing systems of the computer infrastructure, to enable the computer infrastructure to perform the process steps of the invention. In still another embodiment, the invention provides a business method that performs the process described herein on a subscription, advertising, and/or fee basis. That is, a service provider, such as a network security service provider, could offer to evaluate trust in a computer infrastructure as described herein. Similarly, a service provider could offer to manage trust evaluation reporting in a computer infrastructure. In the latter case, the service provider can manage trust evaluation report(s) 54 for computer infrastructure 12A. Trust evaluation report(s) 54 can be used to ensure compliance with one or more laws and/or regulations. In either case, the service provider can manage (e.g., create, maintain, support, etc.) a computer infrastructure, such as computer infrastructure 12A (FIG. 2), that performs the process described herein for one or more customers. In return, the service provider can receive payment from the customer(s) under a subscription and/or fee agreement and/or the service provider can receive payment from the sale of advertising to one or more third parties. As used herein, it is understood that the terms “program code” and “computer program code” are synonymous and mean any expression, in any language, code or notation, of a set of instructions that cause a computing device having an information processing capability to perform a particular function either directly or after any combination of the following: (a) conversion to another language, code or notation; (b) reproduction in a different material form; and/or (c) decompression. To this extent, program code can be embodied as one or more types of program products, such as an application/software program, component software/a library of functions, an operating system, a basic I/O system/driver for a particular computing and/or I/O device, and the like. The foregoing description of various aspects 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. Such modifications and variations that may be apparent to an individual in the art are included within the scope of the invention as defined by the accompanying claims.
	summary
041586816	abstract	Sintering nuclear fuel pellets of nuclear fuel oxides having oxygen in stoichiometric excess of the dioxides by passing the nuclear fuel pellets through a reduction furnace having a reducing atmosphere under regulated exposure time or residence time to produce reduced nuclear fuel oxides of desired oxygen content. The reduced pellets are cooled and sent to an intermediate station for checking or holding. The cooled pellets from the intermediate station are sent through a sintering furnace with means for independently regulating the exposure time or residence time in the sintering furnace. Additional features are the independent control of the atmospheres and temperature as well as the humidity concentration in each furnace. Less expensive nitrogen gas may efficiently be used in the process.
050733354	description	MODES(S) FOR CARRYING OUT THE INVENTION Illustrated in FIG. 1 is an exemplary natural circulation boiling water reactor 100 comprising a pressure vessel 102, a core 104, a chimney 106, a steam separator 108, and a steam dryer 110. Control rod drive housings 112 extend through the bottom of the vessel 102 and support control rod guide tubes 113. The control rod guide tubes 113 extend to the bottom of the core 104 so that conventional control blades therein can be inserted into and retracted from the core 104 to control its power output. Water flows, as indicated by arrows 114, into the core 104 from below. This subcooled water is boiled within the core 104 to yield a water/steam mixture which rises through the chimney 106. The steam separator 108 helps separate steam from water, and the released steam exits through a steam exit 116 near the top of the vessel 102. Before exiting, any remaining water entrained in the steam is removed by the dryer 110. The separated water is returned down a peripheral downcomer 118 by the gravity forces due to the difference in water density between the downcomer 118 and the chimney 106. The feedwater enters vessel 102 through a feedwater inlet nozzle 120 and feedwater sparger 122 to replenish and help cool the recirculating water in the downcomer 118. The core 104 comprises a lower fuel matrix 124 and an upper fuel matrix 126. The upper fuel matrix 126 is filled with upwardly oriented fuel bundles 130, and the lower fuel matrix 124 is filled with downwardly oriented fuel bundles 128. The water 114 may be additionally recirculated through the downcomer 118 by conventional pumps as described above. For example, conventional axial or centrifugal motor-driven pumps could be used, or, alternatively, a steam-driven jet pump could be used, requiring an auxiliary steam source but having no moving parts. However, such pumps have one or more of the disadvantages described above. Another embodiment, in accordance with the present invention as described below, uses a turbine-driven internal pump. A water-driven turbine is coupled to a centrifugal pump and provides the recirculation flow. The motive fluid for the turbine would be the feedwater. This device is more efficient than the steam-driven jet pump, and eliminates the above mentioned disadvantages. More specifically, illustrated schematically in FIG. 2 is a recirculation system 10 in accordance with one embodiment of the present invention for driving the reactor coolant water 114 in the downcomer 118 inside the pressure vessel 102. The downcomer 118 is an annular flow channel defined between the nuclear reactor vessel 102 and a conventional annular core shroud 12 spaced radially inwardly therefrom, which surrounds the core 104. Means 14 for supplying feedwater 16 to the vessel 102 are shown schematically. A plurality of turbopumps 18 in accordance with one embodiment of the present invention are disposed inside the downcomer 118 and below the top or level 114a of the coolant water 114 for driving the coolant water 114 downwardly through the downcomer 118 for increasing the recirculation thereof. As illustrated in FIG. 3, each of the turbopumps 18 is axisymmetrical about a longitudinal centerline 20, and includes a stationary elongate axle 22 disposed coaxially with the centerline 20. A plurality of circumferentially spaced inlet guide vanes (IGV's) or struts 24 are fixedly joined to an upstream end 22a of the axle 22 for receiving therebetween the coolant water 114 from the downcomer 118. A centrifugal pump impeller 26 is rotatably joined to the axle 22 and has an inlet end 26a for receiving the coolant 114 from the IGV's 24. The impeller 26 also includes an outlet end 26a or charging the coolant 114 at an increased pressure. A plurality of circumferentially spaced outlet guide vanes (OGV's) or struts 28 are fixedly joined to a downstream end 22b of the axle 22 for channeling the discharged coolant 114 back into the downcomer 118 for continuing its passage through the downcomer 118 to the bottom of the vessel 102 wherein it turns radially upwardly around the downstream end of the core shroud 12 to flow into the core 104. The turbopump 18 also includes an annular plenum 30 surrounding the impeller 26 and joined to the feedwater supplying means 14 for receiving the feedwater 16. More specifically, the turbopump 18 includes an annular casing 32 which surrounds the impeller 26, and which has an upstream end 32a to which the IGV's 24 are fixedly connected and a downstream end 32b to which the OGV's 28 are fixedly connected for supporting the upstream end 22a and the downstream end 22b of the axle 22, respectively. The casing 32 is generally toroidal-shaped to define the annular plenum 30 therein and includes an annular feedwater inlet 34 disposed in flow communication with the feedwater supplying means 14. The turbopump 18 also includes a plurality of circumferentially spaced conventional water, or hydraulic, turbine blades 36 fixedly joined to the outlet end 26b of the impeller 26 at radially outer ends thereof, and disposed in flow communication with the plenum 30 for receiving the feedwater 16 for rotating the impeller 26 for driving the coolant 114 through the turbopump 18. A plurality of conventional circumferentially spaced, stationary nozzle vanes 38 are fixedly joined to the casing 32 in flow communication between the plenum 30 and the blades 36 for channeling the feedwater 16 to the blades 36 for rotating the impeller 26. In this exemplary embodiment of the present invention, the blades 36 are also disposed in flow communication with the OGV's 28 for discharging the feedwater 16 from the blades 36 to mix with the discharged coolant 114 from the outlet end 26b of the impeller 26. The turbopumps 18 are disposed entirely inside the pressure vessel 102 and are, therefore, subject to the harsh reactor environment therein. More specifically, the turbopumps 18 are preferably conventionally supported by and bolted to an annular pump deck 40 which extends radially outwardly from a longitudinal centerline axis 42 of the vessel 102, as shown in FIG. 2, and between the reactor vessel 102 and the core shroud 12 for fixedly supporting the turbopumps 18 within the downcomer 118. The deck 40 and the turbopumps 18 are preferably disposed axially above the reactor core 104 for reducing radiation received thereby. The turbopumps 18 are also preferably disposed longitudinally in line with the downcomer 118 for assisting in driving the coolant 114 in the downward direction parallel with the natural gravity flow of the coolant 114. Preferably, the turbopump longitudinal axis 20 is disposed parallel to the vessel longitudinal axis 42, and the IGV's 24 and the OGV's 28 are longitudinally, or axially, spaced from each other for driving the coolant 114 by the impeller 26 generally parallel to the vessel centerline axis 42 within the downcomer 118. Referring again to FIG. 2, since the turbopumps 18 are disposed in the downcomer 118, they are exposed to the relatively high temperature and high pressure of the coolant 114, which in an exemplary embodiment of the reactor 100 is about 520.degree. F. (271.degree. C.) and about 1,000 psi (6.89 MPa). Also in the preferred embodiment of the present invention, the feedwater 16 is provided to the plenum 30 by the supplying means 14 at a pressure of about 1,200 psi (8.27 MPa). The differential pressure between the feedwater 16 in the plenum 30 and the coolant 114 at the IGV's 24 and the impeller end 26a is used effectively in accordance with the present invention for rotating the turbine blades 36 and in turn the impeller 26 connected thereto for driving the coolant 114 through the turbopump 18. The feedwater 16 from the blades 36 and the coolant 114 from the impeller 26 are discharged to the common OGV's 28 at about the same pressure. In view of the high temperature, high pressure, and radiation environment inside the vessel 102, conventional lubrication of the turbopumps 18 using, for example, hydrocarbon lubricants such as oil cannot be used. The coolant 114 cannot be contaminated from oil which might leak from a conventional pump. And, conventional pump and electrical motors which might alternatively be used would not be suitable for this environment since radiation is known to degrade hydrocarbon lubricants such as oil, and electrical insulation used around motor windings. The high temperature environment also is known to shorten service life and degrade conventional pumps and electrical motors. Furthermore, the high pressure environment within the vessel 102 would also require suitable high pressure seals for the conventional pumps and electrical motors. The turbopump 18 disclosed above in accordance with the present invention is effective for eliminating all of these problems associated with conventional pumps and electrical motors driving such pumps. More specifically, since the turbopump 18 is hydraulically or water-driven by the feedwater 16 within the high pressure coolant 114 in the downcomer 118, only the differential pressure therebetween must be accommodated. And, this differential pressure is effectively used for driving the turbine blades 36, with the feedwater 16 being discharged between the OGV's 28 at a common outlet pressure with the coolant 114 discharged from the impeller 26. Furthermore, the impeller 26 may be suitably rotatably supported and lubricated by the high pressure feedwater 16 channeled to the plenum 30. More specifically, means 44, as shown in FIG. 3, for lubricating the impeller 26 solely by the feedwater 16, and not by conventional lubricants such as oil, are provided which both lubricates the rotating impeller 26 and provides a water bearing interface between the impeller 26 and the axle 20 upon rotation of the impeller 26 about the axle 22. Referring again to FIG. 3, the impeller 26 further includes a radially inner, axially extending, cylindrical surface 46 defining with a complementary radially outer, cylindrical surface 48 of the axle 28 a hydrodynamic radial bearing 50. The impeller 26 also includes a radially extending aft surface 52 which defines with a radially extending flange 54 of the axle 22 a hydrodynamic axial thrust bearing 56. The lubricating means 44 preferably include a conduit 58 having a first portion 58a which extends through at least one of the IGV's 24 in flow communication with the plenum 30 for receiving a portion of the high pressure feedwater 16 therefrom and channeling the feedwater 16 through the conduit 58 to a second portion 58b which is disposed in flow communication between the inner surface 46 and the outer surface 48 of the radial bearing 50 for providing the feedwater 16 thereto for both hydrodynamically supporting the impeller 26 and providing lubrication between the impeller 26 and the axle 22. The conduit 58 also includes a third portion 58c which channels a portion of the feedwater 16 from the conduit 58 between the aft surface 52 and the radial flange 54 of the thrust bearing 56 for hydrodynamically axially supporting the impeller 26 and providing lubrication therebetween. The feedwater 16 is suitably discharged from the radial bearing 50 and the thrust bearing 56 through gaps between the impeller 26 and the axle 22 to join with the coolant 114 being channeled through the turbopump 18. In this way, the differential pressure between the feedwater 16 in the plenum 30 and the coolant 114 channeled into the turbopump 18 is effectively used for not only driving the impeller 26 but for hydrodynamically supporting the rotating impeller 26 on the stationary axle 22 and providing lubrication therebetween utilizing solely the feedwater 16 without any conventional hydrocarbon-type lubricants. In one exemplary embodiment of the turbopump 18 for the boiling water reactor 100 and for the exemplary pressures of the feedwater 16 in the plenum 30 and of the coolant 114 channeled to the turbopump 18, the impeller 26 preferably includes a plurality of circumferentially spaced conventional mixed flow impeller blades 60. Mixed flow for a hydraulic turbine is a conventional term meaning that the blades 60 are sized and configured for channeling the coolant 114 both axially and radially as it passes through the impeller 26. For the exemplary embodiment illustrated, the impeller 26 has a specific speed of about 5,000 in english units, and 197 in metric units. As illustrated in FIG. 3, the turbine blades 36 are preferably fixedly joined to the impeller blades 60 at the impeller outlet end 26b. In this way, the turbine blades 36 are disposed radially outwardly from the centerline axis 20 at the largest outer diameter of the impeller 26 for providing more effective rotation of the impeller 26. In the exemplary embodiment of the turbopump 18, as illustrated in FIG. 4, an annular impeller shroud 62 is fixedly joined to the tips of the impeller blades 60 for providing an outer flow boundary for the coolant 114 being channeled through the impeller 26. The turbine blades 36 are conventionally fixedly joined to the impeller blades 60 at the impeller shroud 62, and may also include an annular turbine shroud 64 surrounding the tips of the turbine blades 36 for providing an outer flow boundary for the feedwater 16 channeled through the turbine blades 36. Illustrated in FIG. 5 is a schematic representation of the flowpath for the feedwater 16 from the plenum 30 and through the nozzle vanes 38, the turbine blades 36, and the OGV's 28. Illustrated in FIG. 6 is a schematic representation of the flowpath of the coolant 114 from the downcomer 118 and through the turbopump 18 between the IGV's 24, the impeller blades 60, and the OGV's 28. The camber and twist of the various vanes and blades for these two flowpaths may be conventionally designed for obtaining suitable work from the feedwater 16 for rotating the impeller 26 at suitable velocities for pumping the coolant 114 in the downcomer 118. Referring again to FIG. 2, the recirculation system 10 further includes a conventional steam turbine 66 conventionally joined in flow communication with the steam exit 116 of the reactor vessel 102 for receiving steam 68 for driving the steam turbine 66. The steam turbine 66 is conventionally joined to a conventional electrical generator 70 which is rotated by the turbine 66 for generating electrical power provided to a conventional power grid. The feedwater supplying means 14 include a conventional feedwater pump 72 conventionally disposed in flow communication with the steam turbine 66 for receiving condensed steam therefrom for forming the feedwater 16 under pressure at about 1,000 psi (6.89 MPa). A conventional variable first control valve 74 is conventionally disposed in flow communication through a conduit 76 between the feedwater pump 72 and the turbopumps 18 for selectively regulating the feedwater 16 channeled from the pump 72 to the turbopumps 18 for controlling recirculation of the coolant 114 being pumped by the turbopumps 18. A conventional controller 78 is provided in conventional electrical communication with the first control valve 74 for selectively controlling the valve 74 for regulating the amount of the feedwater 16 passing therethrough. A conventional variable second control valve 80 is disposed in conventional flow communication between the feedwater pump 72 and the feedwater sparger 122 for selectively regulating the feedwater 16 channeled from the pump 72 to the sparger 122. The second control valve 80 is disposed in parallel flow with the first control valve 74 so that the feedwater 16 from the pump 72 is split between the sparger 122 and the turbopumps 18. The controller 78 is also conventionally electrically connected to the second control valve 80 for controlling the amount of feedwater 16 channeled through the second valve 80 to the sparger 122. The controller is effective for controlling both the first and second control valves 74 and 80 inversely relative to each other so that each of the valves 74 and 80 further closes as the other valve further opens. Since the recirculation system 10 is substantially a closed loop system having a finite volume of water therein i.e. the feedwater 16 and the coolant 114, the returning feedwater 16 channeled from the pump 72 is preferably split between the sparger 122 and the turbopumps 18. Since the feedwater 16 returned to the vessel 102 through the turbopumps 18 is discharged from the turbopumps 18 and mixes with the coolant 114 in the downcomer 118, that amount of the feedwater 16 need not be channeled to the sparger 122 for reintroduction into the vessel 102. While there has been described herein what is considered to be a preferred embodiment of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein, and it is, therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention.
	abstract	An apparatus arranged to control the temperature of uranium material in a uranium material storage container, comprising a thermal guide which wraps around an external surface of the uranium material storage container to cause the uranium material storage container to exchange heat energy with a heat transfer medium inside the thermal guide and a heat exchanger to heat or cool the heat transfer medium outside the thermal guide. A method of controlling the temperature of uranium material in a uranium material storage container is also described.
	claims	1. A neutron monitoring method comprising the steps of: counting negative pulse signals output from a neutron detector that outputs negative pulse signals upon detecting neutron flux; counting positive pulse signals from the neutron detector; and measuring the neutrons based on said negative pulse signals and said positive pulse signals so as to reduce influence by noise pulses. 2. A neutron monitoring system comprising: a neutron detector that outputs negative pulse signals upon detecting neutron flux; a first pulse count rate measurement means provided with the pulse signals output from said neutron detector for counting the negative pulses per unit time; a second pulse count rate measurement means provided with the output pulse signals from said neutron detector for counting positive pulses per unit time; and a pulse count correction means for obtaining a corrected count rate excluding the fluctuation of the pulse count rate caused by the influence of the electric noises, by computing a pulse count of first pulse count rate measurement means and a pulse count of said second pulse count rate measurement means.
048805599	description	EXAMPLE 1 Samples of tubes from the steam generator of a pressurized water nuclear reactor about 1% inches long and 3/4 inches in diameter were cut in half longitudinally. The samples were placed in beakers containing various decontamination solutions (except in some experiments the solutions were circulated over the samples in the beakers). After each sample was treated with a decontamination solution, the decontamination factor was determined. (The decontamination factor (DF) is the radioactivity in microcuries before treatment divided by the radioactivity in microcuries after treatment.) The following table gives the sequence of treatment of eleven different samples treated with various decontamination solutions for different times and temperatures. In the table, "CM" is a commercial decontaminating solution believed to be 30% citric acid, 30% oxalic acid, 40% ethylenediaminetetraacetic acid, and containing an inhibitor believed to be thiourea. "CAS" is ceric ammonium sulphate, "CAN" is ceric ammonium nitrate, and "TSCA" is tetrasulfato ceric acid. __________________________________________________________________________ Treatment Sequence Step DF Final 1 2 3 4 5 1 2 3 4 5 DF __________________________________________________________________________ .5% CM .1% K.sub.2 FeO.sub.4 4 hrs .5% CM, .5% TSCA, 1% H.sub.2 SO.sub.4 .5% CM 1.06 1.00 1.10 143.06 1.81 300.40 4 hrs, 100C 40C, pH10 4 hrs, 100.degree. C. 6 hrs, 100C 4 hrs, 100C .5% CM .1% K.sub.2 FeO.sub.4, .5% CM .1% CAS, 4 hrs, .5% CM -- -- 1.05 -- 1.00 1.05 24 hrs, 100C 4 hrs, 48C 23 hrs, 95.degree. C. 100C, pH 2.6 10 hrs, 100C " " " .1% CAS, 6 hrs, .5% CM -- -- 1.05 -- 1.00 1.05 100C, pH 2.6 12 hrs, 100C .5% CM .5% CAS, .5% CM 1.10 .94 1.01 1.05 4 hrs, 100C 6 hrs, 100C 4 hrs, 100C " " .5% CM 1.01 1.08 .89 .97 4 hrs, 121.degree. C. " .1% CAS, .1% CAN, .5% CM 1.11 .95 1.34 .88 1.24 6 hrs, 100C .4% HNO.sub.3 4 hrs, 100C 7.5 hrs, 100C " .1% TSCA, .5% C 1.03 1.03 1.03 1.09 .3% H.sub.2 SO.sub.4 4 hrs, 100.degree. C. 7.5 hrs, 100.degree. C. " .25% TSCA .5% C .5% TSCA .5% CM 1.05 1.22 1.03 60.60 .97 77.83 .75% H.sub.2 SO.sub.4 4 hrs, 100.degree. C. 1% H.sub.2 SO.sub.4 4 hrs, 100C 6 hrs, 100C 6 hrs, 100C " .25% CAN, " 1.03 1.02 1.00 1.05 " .75% HNO.sub.3 6 hrs, 100C " .5% CAN, " 1.07 1.11 .94 1.11 1% HNO.sub.3 6 hrs, 100C " .5% CAN, " 1.06 1.13 1.02 1.23 1% HNO.sub.3 6 hrs, 70C __________________________________________________________________________ The above table shows that ceric ammonium nitrate is not effective in decontaminating the samples. It also shows that tetrasulfato ceric acid is very effective at higher concentrations, but is ineffective at concentrations of 0.25% or less. EXAMPLE 2 Example 1 was repeated. The following table gives the results: __________________________________________________________________________ Treatment Sequence Step DF Final Step 1 Step 2 1 2 DF Comments __________________________________________________________________________ 1% H.sub.2 SO.sub.4 .5% CM -- 1.04 1.04 Ineffective 6 hrs, 95C 6 hrs, 95C .5% TSCA, 1% H.sub.2 SO.sub.4 .5% CM 33.81 1.10 37.17 ID still covered 6 hrs, 100C 4 hrs, 100C by oxide layer, effective .5% CAN, " 1.03 1.26 1.29 Ineffective 1% HNO.sub.3, 6 hrs, 100C 5% H.sub.2 SO.sub.4 1.01 1.01 Ineffective 6 hrs, 22C 1% TSCA, 5% H.sub.2 SO.sub.4 1% TSCA, 5% H.sub.2 SO.sub.4 1.01 326.6 329.5 ID still covered 6 hrs, 20C 6 hrs, 100C by oxide no mixing no mixing very effective 5% H.sub.2 SO.sub.4 49.47 49.47 Oxide layer still 6 hrs, 100C present many no mixing cracks __________________________________________________________________________ The above table shows that 1% sulfuric acid by itself was ineffective and 5% sulfuric acid was ineffective at 22.degree. C., but effective at 100.degree. C., albeit with considerable corrosion. (The "100.degree. C." temperature was actually the highest possible temperature that could be obtained without boiling the solution.) The table also shows that the ceric ammonium nitrate-nitric acid solution did not effectively decontaminate the samples. The tetrasulfato ceric acid in combination with sulfuric acid was also ineffective at 20.degree. C., but was extremely successful at 100.degree. C., and much more effective at a concentration of 5 to 6% than was sulfuric acid alone.
	summary
	description	The invention relates generally to optics, and more particularly to multilayer optic devices and methods of making the same. In X-ray based imaging and analysis applications, such as but not limited to computed tomography (CT) or X-ray diffraction, conventional X-ray sources generate a sufficient amount of X rays for imaging and analysis; however, more than 99% of the generated X rays travel in directions where these X rays are not utilized for the intended purpose. The unused X rays are absorbed by the source housing or primary X-ray beam collimator. Due to a large portion of generated X rays not being utilized for the intended purpose, existing X-ray imaging and analysis applications suffer from insufficiently low X-ray flux at the patient or sample being imaged or analyzed. Currently, commercially-available optic devices capture and redirect typically 1% or less of the unused X rays from the source in desirable directions. Hence, these X rays remain unused even after employing commercially-available optic devices in the X-ray system. Prior and currently available approaches for increasing the X-ray flux on the patient or sample rely on increasing the number of X-rays generated in the source. The X-ray flux is typically increased by increasing the electron beam density impacting a target. Although this approach provides enhanced flux values, there is a physical limit to maximum number that can be produced this way that is imposed by the target materials. For example, when electrons impact the target and create X rays, if the heat generated is not dissipated quickly enough, the target will evaporate or melt. Moreover, by using this approach of increased electron beam density, the X-ray flux may be increased only by about 50 percent over current state of the art before target integrity is compromised. In applications such as medical CT or X-ray diffraction (e.g., baggage scanning for explosives detection), the X-ray beam shape is not circularly symmetric. In such cases, the X-ray flux on a patient or sample may be increased by using multilayer total internal reflection (TIR) optics to redirect some of the “unused” X rays into one of the useful directions, such as a cone direction of the X-ray beam. Such collection and redirection of the X-ray beam in one direction is referred to as a one-dimensional compression and can result in intensity gains of more than several hundred times over the gains achieved by other optic devices. In several instances, for example cardiac CT imaging for reducing cardiac motion effects or fast baggage scanning using X-ray diffraction, it may be desirable to have even higher intensity X-ray fluxes. It would thus be desirable to provide an optic device that can collect and redirect X rays in directions other than the cone direction and increase the intensity of the X-ray flux on the patient or the object. In one embodiment, a multilayer optic device having an input face and an output face is provided. The optic device includes a high-index material layer having a first real refractive index 1−δ1 and a first absorption coefficient β1, wherein the core comprises a first surface and a second surface, a low-index material layer having a second real refractive index 1−δ2 and a second absorption coefficient β2, and a grading zone disposed between the high-index material layer and low-index material layer, the grading zone comprising a grading layer having a third real refractive index 1−δ3 and a third absorption coefficient β3, such that 1−δ1>1−δ3>1−δ2, where at least a portion of one or more of the high-index material layer, the grading zone and the low-index layer comprises one or more corrugations along a first direction. In another embodiment, a method of making an optic device is provided. The method includes providing a first multilayer section having a high-index layer, a grading zone and low-index layer conformally disposed, wherein the high-index layer, the grading zone and the low-index layer comprises one or more corrugations along a first axis, and wherein at least one corrugation is curved along a second axis, providing a second multilayer section having a high-index layer, a grading zone and low-index layer conformally disposed, wherein the high-index layer, the grading zone and the low-index layer comprises one or more corrugations along the first axis, and wherein at least one corrugation is curved along the second axis, and disposing the first multilayer section on the second multilayer section such that the high-index layer of the first and the high-index layer of the second multilayer sections are disposed adjacent each other. In yet another embodiment, a method of making an optic device is provided. The method includes providing a multilayer optic device. The multilayer optic device comprising a high-index material layer having a first real refractive index 1−δ1 and a first absorption coefficient β1, wherein the core comprises a first surface and a second surface, a low-index material layer having a second real refractive index 1−2 and a second absorption coefficient β2, and a grading zone disposed between the high-index material layer and low-index material layer, the grading zone comprising a grading layer having a third real refractive index 1−3 and a third absorption coefficient β3, such that 1−δ1>1−δ3>1−δ2, where at least a portion of one or more of the high-index material layer, the grading zone and the low-index layer comprises one or more corrugations along a first direction. The method further includes removing at least a portion of the low-index layer, and at least a portion of the grading zone along a plane to form grooves in the multilayers, and depositing a material in the grooves to form the corrugations. Embodiments of the invention describe a multilayer total internal reflection (TIR) optic device suitable for collecting and redirecting incident X rays in more than one direction. In certain embodiments, the multilayer optic device may be configured to redirect the incident X rays in two directions. In one example, as described in detail with regard to FIGS. 1-4, the multilayer optic device may be configured to redirect the incident X rays in a cone direction and a fan-beam direction. In this example, the amount of X-ray flux collected in the fan direction of the X-ray beam, in addition to the X-ray flux collected in the cone direction, results in increased X-ray flux on the patient or the object. In certain embodiments, the TIR multilayer optic device includes an input face and output face. The input face of the optic device may be defined as the face of the optic device that is closest to the radiation source. The X-rays produced by the target enter the optic device through the input face. The output face may be defined as the face through which the redirected X-ray beams exit the optic device. The optic device includes a high-index material layer, a low-index material layer and a grading zone disposed between the high-index material layer and the low-index material layer. At least a portion of one or more of the high-index material layer, the grading zone and the low-index layer includes one or more corrugations along a first direction. In one embodiment, at least one of the corrugations may be curved along a second direction. The second direction may be about perpendicular to the first direction. The second direction may be a fan-beam direction, and perpendicular to the first direction and a direction of the cone of the X-ray beam exiting the output face of the optic device. The corrugations may be curved outward with respect to a central axis of the optic device. The curvature of the curved corrugations may be decided based upon X-ray energy levels, size of the optic device, distance between the optic device and an X-ray source. As used herein, the term “first direction” refers to a direction along the input face of the optic device. Although directional orientation is relative, as is the convention employed by those skilled in the art and used herein, the term, “fan-beam direction” refers to a horizontal direction. As described below with regard to FIG. 1, the fan-beam direction is a direction parallel to a direction generally represented by reference numeral 26 of FIG. 1. As used herein, the term “cone direction” refers to a direction perpendicular to the fan-beam direction. As described below with regard to FIG. 1, the fan-beam direction is a vertical direction that is parallel to a direction generally represented by reference numeral direction 30 in FIG. 1. In some embodiments, the multilayer optic device may include alternating lower and higher refractive index materials with concurrent high and low X-ray absorption properties, respectively, in contiguous layers. By using the alternating lower and higher refractive index materials with concurrent high and low X-ray absorption properties, respectively, in contiguous layers, the multilayer optic device can utilize the principle of total internal reflection of electromagnetic radiation. In one embodiment, at least a portion of the high-index material layer may form a core. The core may be formed of a higher index of refraction material such as beryllium, lithium hydride, magnesium, or any other suitable elements or compounds having similarly higher refractive indices and high X-ray transmission properties. The core may be less than a micrometer to greater than one centimeter in diameter. The core may include a first surface and a second surface. Layers of the multilayer optic device may be disposed on the first and second surface of the core. The layers may be disposed radially exterior to the core. In other embodiments, a minimum of three different materials including a high-index material layer, a grading zone and a low-index material layer, are used in a multilayer section to obtain increased total internal reflection by maximizing the difference in real refractive indices between successive layers, with the real refractive index decreasing in successive layers traversing from the high-index material layer to the low-index layer. In an embodiment that provides even greater total internal reflection, the ratio of the change in imaginary parts to the change in real refractive index between successive layers is minimized by simultaneously minimizing the change in the imaginary part and maximizing the change in the real refractive index between successive layers. The imaginary part of the refractive index is related to the mass-energy absorption coefficient of the material in which the X rays are traveling. Additionally, each successive layer has higher X-ray mass-energy absorption properties, while the real refractive index decreases monotonically from layer to layer. These criteria provide for relatively optimal changes in real refractive index and X-ray absorption properties than in current materials used for X-ray optics that redirect X rays by total internal reflection. In one embodiment, the multilayers in the grading zone are arranged according to refractive indices such that the real parts of the refractive indices of the materials of the multilayer are graded generally from a high value to a low value within the grading zone. For improved reflectivity, X-ray absorption differences also are generally minimized between adjacent multilayer materials. For the purpose of this disclosure, a first layer is considered adjacent to a second layer when there are no other materials interposed between the first and second layers that have a real refractive index or a coefficient of absorption that are different from the respective real refractive indices or coefficients of absorption of the first and second layers. Generally, the complex refractive index ‘n’ of a material at X-ray energies can be expressed as n=1−δ+iβ, where the term (1−δ) is the real part of the complex refractive index of the material and the parameter β is the imaginary part of the complex refractive index and is related to the mass-energy absorption coefficient in the material. At X-ray energies, the real part of the refractive index is very close to unity and is therefore usually expressed in terms of its decrement δ from unity, with δ typically on the order of 10−6 or smaller. The high-index material layer may be made of a high-index material having a first complex refractive index n1 with a real part Re (n1) and an imaginary part β1. The real part Re(n1) of the first complex refractive index may also be represented as (1−δ1). A low-index material layer having a second complex refractive index n2 having a real part Re (n2) and an imaginary part δ2. The real part Re(n2) of the second complex refractive index may also be represented as (1−δ2). A grading zone may be disposed between the high-index material layer and low-index material layer. The grading zone may include a plurality of grading layers. The grading layers may have a third complex real refractive index n3 having a real part Re (n3) and an imaginary part β3 such that Re(n1)>Re(n3)>Re(n2). The real part Re(n3) of the third complex refractive index may also be represented as (1−δ3). As used herein, the term “imaginary part of the complex refractive index” corresponds to the mass-energy absorption coefficient. For improved reflectivity, in one embodiment, the ratio of the change in β to the change in δ between adjacent multilayer materials is generally minimized. For the purpose of this disclosure, a first layer is considered adjacent to a second layer when there are no other materials interposed between the first and second layers that have a real refractive index or a coefficient of absorption that are different from the respective real refractive indices or coefficients of absorption of the first and second layers. The multilayer optic may be adapted for use in redirecting an incident X-ray beam through total internal reflection as a reflected X-ray beam. The optic device may be configured to produce circularly symmetric beams, or a stack of fan-shaped beams. The multilayer stack may comprise a plurality of multilayer zones. The multilayer optic device may be made by employing the techniques disclosed in the commonly assigned application titled “OPTIMIZING TOTAL INTERNAL REFLECTION MULTILAYER OPTICS THROUGH MATERIAL SELECTION” having application Ser. No. 12/469,121. In certain embodiments, the individual layers of the multilayer optic device may be conformally disposed on one another. The conformation of the corrugated layers enables the multilayer optic device to be utilized in a vacuum environment. The multilayer optic device may be employed in applications that require the optic device to operate at energy levels above 60 keV, such as but not limited to, medical imaging, explosive detection, industrial X-ray, and cargo inspection using X-ray diffraction. In one embodiment, the multilayer TIR optic device may operate at energy levels of about 450 keV. A plurality of TIR optic devices may be stacked to collect a majority of the available X rays (e.g., about 2 percent to about 40 percent) from the target. In one embodiment, such a stack of optic devices may produce a set of parallel fan beams in a direction perpendicular to the plane of the fan. In another embodiment, the multilayer optic device may be circularly symmetric to generate a highly collimated beam in each spatial direction. The number of multilayer zones comprising the multilayer material stack is not limited in any way but is rather a function of the particular application for which the multilayer material stack is configured. The multilayer material stack may comprise tens or thousands of multilayer sections. For example, in the case of high-resolution industrial computed tomography (CT) where the resolution is on the order of micrometers, the number of multilayers in the stack may be less than ten layers. In other types of CT, where large optic collection angles are desired, the number of layers may be in the thousands. In addition to a high-index layer, a low-index layer, and a grading zone with one or more grading layers disposed between the high-index layer and the low-index layer, the multilayer optic device may also comprise an X-ray opaque cladding layer at the outermost surface of the optic device to prevent the emission of X-ray radiation from the interior of the optic device through the edges of the non-emitting face of the device. The X-ray opaque cladding layer may be disposed on the optic device such that X-rays enter the optic device through the input face and exit the optic device substantially through the optic output face. In one embodiment, at least a portion of one or more of the high-index material layers, the grading zone and the low-index layer may include one or more non-corrugation portions along a first direction. The corrugation and the non-corrugation portions may be disposed alternately to form a layer of the optic device. The non-corrugation portions may be relatively free of corrugations. In one embodiment, at least one corrugation and a non-corrugation section of a layer of the optic device may be made of the same material. In another embodiment, the corrugation and the non-corrugation portions may be made of different materials. In this embodiment, the corrugation may include a high refractive index material. The high refractive index material may be same as the high refractive index material used in the high-index material layers of the optic device. Hence, in some layers of the optic device, the corrugation and non-corrugation portions may have the same material, while in the other layers, the corrugation and non-corrugation portions may have different materials. For example, for high-index material layers, the corrugation and non-corrugation portions may have the same material, while for the low-index material layer the corrugations and non-corrugation portions may have different materials with the corrugations having a high refractive index material and the non-corrugations having a low refractive index material In one embodiment, the high refractive index material of the corrugations may have relatively higher refractive index compared to the high refractive index material of the high-index material layers of the optic device. Typically, high refractive index materials transmit X rays with minimal losses. The higher refractive index material may be used to modify the properties of the output beam by providing a low-loss path for transmission of the X-ray beams through the higher refractive index corrugations. The different corrugations within a layer of the optic device may have the same or different materials. In one embodiment, the material of the corrugations may be used to block X-ray beams from outputting from certain portions of the optic device. In this embodiment, the corrugations which are configured to block the X-ray beams may be made of low refractive index material. The length of the portions of the multilayers of the optic device in which the corrugations are present may be decided based upon the desired X-ray flux, or intensity. The composition of materials making up the multilayer optic device, the macroscopic geometry of the multilayer optic device, the thickness of the multilayer optic device, the curvature of the corrugations, and the number of individual layers determine the angular acceptance ranges of the multilayer optic device. The maximum solid angular acceptance range may be from about 0 steradians up to about 2π steradians of a solid angle of a source of the photons. For example, the curved corrugations in the fan-beam direction enable the optic device to collect X rays from a much wider incident fan beam than the existing optics. The curved corrugations also enable compression of an input X-ray fan beam to produce a compressed fan beam. In some embodiments, the fan beam may be compressed to an extent such that the output beam does not diverge. In these embodiments, the output beam may be parallel or converging. In one embodiment, the corrugated multilayers may act as X-ray reflecting coatings that facilitate collection and redirection of X rays by satisfying the total internal reflection condition along the corrugations. Shaping the layers with the appropriate curvature and fabricating them with the appropriate thicknesses produces output X-ray beams having desired properties. The optic device may have an exterior surface sloping between an input and an output face. In certain embodiments, each layer at the optic input (side closest to the source) may be curved at the same or different radius of curvature enabling the combined layers in the optic device to capture a large source solid angle. The various layers of the optic device may be curved or sloped in a cone direction as described in detail in the commonly assigned application titled “Multilayer optic device and system and method for making same” having U.S. Pat. No. 7,412,131, to provide redirection regions. In addition to a redirection region of the core and other multilayers in the cone direction, another redirection region is provided by curving the one or more corrugations in a second direction, such as the fan-beam direction. In these embodiments, the ridges of the corrugated layers may be curved in the fan-beam direction. In certain embodiments, curving the grooves in a particular direction enables the optic device to collect X rays from a much wider angle than is currently used and redirects the extra X rays in useful imaging directions. The multilayer optic devices having layers that are curved in the cone direction collect source X rays from a large cone angle and redirects the X rays into useful imaging directions in the cone portion of the beam. Similarly, the curved corrugations in the fan beam direction collect source X rays from a large fan beam and redirect the X rays into useful imaging directions in the fan beam direction. The curved corrugations enable the X rays in the fan beam direction entering the input face to be redirected to form a relatively less divergent (more focused) fan beam, thereby increasing the X-ray flux density at the output face. Depending upon the number of layers in the multilayer optic, there may be an X-ray density gain of 100 keV X rays of as much as 5000 times in the electromagnetic radiation output from the multilayer optic device over the output of conventional pinhole collimators. These two curvatures in the fan-beam and cone directions therefore collect and redirect X rays from the input X-ray beam resulting in maximal two-dimensional source-beam compression by the optic device. Such compression of the X-ray beam provides one of the highest possible X-ray flux gain from TIR multilayer X-ray optic devices. Suitably shaping the input face of the optic device and selecting suitable materials within the optic device may eliminate undesired energy levels from the output X-ray beam and provide an output X-ray beam having desired spectral properties. In one example, a monochromatic X-ray beam may be produced by shaping the input face (curving or sloping the layers of the optic device at the input face of the optic device) and selecting suitable materials for the layers of the optic device to prevent transmission of undesired low or high energy X rays, respectively, through the optic. Further, the undesired energy regions may be minimized or eliminated using the total internal reflection within the optic device. In another example, a polychromatic X-ray beam may be produced by proper selection of material for the layers of the optic device. As described in detail with regard to FIGS. 6-7, in one embodiment, a filtering region may be disposed on the input face of the optic device. In one example, the filtering region may be configured to filter out low-energy X rays from the incident X rays. FIGS. 1 and 2 illustrate an example of a multilayer optic device 10. For ease of illustration, only a few layers have been illustrated with reference to the illustrated multilayer optic devices of various figures. However, it should be appreciated that any number of layers, including into the hundreds, thousands, or millions of layers, can be fabricated to utilize total internal reflection principles to form desirable beam shapes. In the illustrated embodiment, the optic device 10 includes an input face 12 and an output face 14. The optic device 10 includes a core 16 that is a high-index material layer. The core 16 has a first surface 15 and a second surface 17. A grading zone 18 is disposed on the first surface 15 of the optic device 10. A low-index material layer 20 is disposed on the grading zone 18. A grading zone 22 is disposed on the second surface 17 of the optic device 10. A low-index material layer 24 is disposed on the grading zone 22. The layers disposed on the two surfaces 15 and 17 may or may not have same composition. For example, the grading zone 18 may have a different composition of grading layers than the grading zone 22. The grading zones 18 and 22, and the low-index material layers 20 and 24 are positioned exterior to and contiguous with the core 16. The core 16 may be formed of a high refractive index material such as beryllium, lithium hydride, magnesium, or any other suitable elements or compounds having similarly high refractive indices and high X-ray transmission properties. The core 16 may be less than a micrometer to greater than one centimeter in diameter. At least a portion of the core 16 may have corrugations 25 in a first direction represented by the reference numeral 26. The corrugations 25 may be curved in a second direction represented by the reference numeral 28. The second direction 28 may be the direction in which the X-rays exit the optic device in a fan-beam shape. The curved corrugations 25 facilitate additional X-ray collection and redirection of the X rays in the fan-beam direction 26 of the beam. The corrugations 25 may be curved outwardly in the second direction with respect to a central axis 29 of the optic device 10. The multilayers of the optic device 10 are curved in a cone direction 30 to define a redirection region 32 and a transmission region 34. The redirection section 32 functions to substantially collimate and redirect an incident divergent X-ray beam 48 as a substantially collimated beam to a desired region of space via the transmission section 34, which provides further collimation. In one example, an X-ray beamlet may undergo hundreds or thousands of reflections along a curved surface of a corresponding multilayer in the redirection section 32 before passing out of the optic device through the output face 14. As will be appreciated, the desired trajectories of the collimated X-ray beamlets 36 (FIG. 2) are achieved when the reflected beamlets pass from the redirection section 32 into the transmission section 34, that is, when the tangent to the curved portion of a layer is substantially parallel to the continuing linear portion. The physical length of the transmission section 34 may be largely arbitrary and can be specified so as to provide a convenient physical size for handling or integrating the optic device 10 into a source subsystem. The design shown allows diverging electromagnetic radiation to be input into the input face 12, and redirected by the multilayers, and output from the output face 14 into a stack of parallel fan beams. Depending upon where the output face 14 is located relative to the photon redirection regions, the shape of the curved corrugations, and the position of the corrugations in the multilayers, the fan beams may be parallel or near parallel or may be somewhat divergent but still concentrated relative to the input of electromagnetic radiation. In conventional medical and industrial CT applications, the X-ray beam shape is formed as a cone of X rays in a direction substantially perpendicular to the X-ray travel direction (represented by reference numeral 30) and a fan beam shape in the plane formed by directions 26 and 28. The fan beam direction is perpendicular to the central symmetry axis of the fan beam and in FIGS. 1 and 2 is shown by direction 26. X rays entering the optic device follow a three-dimensional path. In optic devices, X-rays in the cone beam direction are compressed, and the X-rays in the fan-beam direction 26 are not compressed by the optic device. By redirecting X rays from beyond the boundaries of a standard fan beam used in the CT imaging to within the fan-beam boundaries, the X-ray beam intensity may be increased. The curvature in the optic device 10 along the cone direction 30 and the fan beam direction 26 (curved corrugations) collect and redirect X rays from the input X-ray beam in two directions. This results in two-dimensional source-beam compression by the optic device. Such compression of the X-ray beam provides higher X-ray flux gain from the optic device than with compression in only one direction. FIG. 3 is an enlarged perspective view of a portion 40 of the optic device 10 of FIG. 1. The curved-line portions 42 of the corrugations in the first direction 26 represent physical surfaces of positive and negative curvature such as, for example, grooves and ridges. One or more corrugations have ridges with curved shapes. The curved ridges are concave looking from a central axis or optic axis 46 of the optic device 10. A divergent photon beam 48 may be provided by a photon source 50 to irradiate an input face of the multilayer optic device 10. The photon beam 48 is physically a continuous beam distributed over a specified solid angle (Ω) of emission, and the representation of the photon beam 48 as discrete beamlets is made only to facilitate the presentation of the various exemplary embodiments herein. FIG. 4 illustrates a top view of FIG. 3. In the illustrated embodiment, compression of the incident beam 48 in the fan-beam direction is illustrated. The outwardly curved corrugations 44 facilitate compression of the incident beam 48 in the fan beam direction 26. FIG. 5 illustrates a multilayer optic device 60 having an input face 66. Further, the multilayer optic device includes corrugations 62 in determined portions of the multilayers of the optic device 60. The corrugations 62 and non-corrugation sections 63 may be adjacently disposed to form a layer of the multilayer optic device. Although shown as disposed in three discrete portions 68, 70 and 72, the corrugations 62 may be disposed in less or more number of portions in the optic device 60. As illustrated by dotted lines 74, the corrugations 62 are curved in the fan direction 26 to re-direct the beams in the fan direction. As described in detail below with regard to FIG. 12, an existing optic device like the ones described in U.S. Pat. No. 7,412,131 may be modified to form the optic device 60. It should be appreciated, however, that only some of the multilayers may include corrugations. In some embodiments, a multilayer optic device may be coated with a TIR reflecting multilayer on the fan edges of the optic. In other embodiments, as described in detail with regard to FIGS. 5 and 12 the corrugations may be formed in one or more multilayers of an optic device, the corrugations may be coated with one or more materials. FIGS. 6-7 illustrate a multilayer optic device 80 having a filtering region 82. The filtering region 82 enables selective filtration of determined X-ray energy levels. In the illustrated embodiment, the filtering region 82 may filter out low energy X-rays 98. The optic device 80 may comprise a multilayer stack 84. The multilayer optic device 80 includes a high-index core 86, grading zones 88, and low-index layers 90. In the illustrated embodiment, the filtering region 82, disposed adjacent to the input face 92 of the optic device 80, is pointed and spatially limited, making the electric potential higher than any surrounding support structure. The optic device 80 further includes an output face 94. In the illustrated embodiment, the source 96 emits X-rays 98 that are directed towards the optic device 80. The filtering region may be concave in a direction of the X-rays 98. The filtering region may be made of a material having lower refractive index than the medium through which the X rays travel after leaving the source 96. The slopes 104 of lines 100 and 102, which are tangent to the surface of the filtering region 82, may be selected so as to cause total internal reflection of incident X-rays of specific energies, preventing these X rays from entering the optic device 80. In this manner, the output X-ray spectrum of the optic device 80 may be tailored. The curvature of the surface of filtering region 82 is such that that the angle between the tangent line 100 and 102 to the surface and the orientation of the incident X ray 98 is constant, wherein the angle facilitates total internal reflection of low-energy X-ray beams. The low-energy X rays 106 reflected by the surfaces of the filtering region 82 may be absorbed using low-energy X-ray absorbers. The surfaces of filtering region 82 may be made of a single layer or multilayers to provide sufficient reflection of low-energy X-ray beams 106. The slopes 104 of the lines 100 and 102, which are tangent to the surface of the filtering region 82, may have determined angles relative to incident X-ray beams 98. The slopes 104 of the tangent lines 100 and 102 may be designed such that the angle between these lines and the incident X-rays 98 may be kept constant. By keeping constant the angle between the slope 104 of the lines 100 and 102 relative to the incident X-ray beams 98, reflections of X-rays with a determined energy level may be ensured. In one embodiment, the slopes 104 of lines 100 and 102 may have the same angle relative to the incident X ray 98 to enable X-rays of particular energy levels to be filtered out before the rest of the X-ray beam enters the optic device 80. FIG. 8 illustrates a flow chart for a method of making the multilayer optic device. At step 110, a template having a corrugated pattern along a first direction is provided. The corrugated patterns in the template may be curved along the fan direction. The template may be made of any suitable materials, such as but not limited to, a ceramic, polymer, metal, cermet, composite materials, or combinations thereof. The dimensions of the corrugations correspond to corrugations desirable in the layers of the optic device. At step 112, a high-index layer is conformally deposited on the template. Details for deposition of the layers of the multilayer optic device are provided in U.S. patent application Ser. No. 11/869,337. At step 114, a grading zone is conformally deposited on the high-index layer. At step 116, a low-index layer of material is conformally deposited on the grading zone to form a first multilayer section of a multilayer optic device. Although only a single multi-layer section is mentioned in reference to the steps identified in the flow chart in FIG. 8, any number of multi-layer sections may be fabricated and disposed adjacent to one another to form the multilayer optic device. Steps 112-116 may be repeated based on the number of multilayer sections desirable in the multilayer optic device. In one embodiment, the template may be made of the material of the high-index material layer. In this embodiment, the template may form part of the multilayer optic device and serve as a high-index material later. In this embodiment, the method may begin by depositing a grading zone (step 114) on the template (high-index material layer). Optionally, at step 118, a layer of low-index material having a high X-ray absorption may be disposed on the high-index layer. The low-index material layer may be used to reduce the X-rays leaking out of the multilayer optic device at least from the side of the high-index material layer. Optionally, at step 120, the edges of the multilayer optic device may be coated with a TIR reflecting coating. For example, the fan edges of the multilayer optic device may be coated with a TIR reflecting coating. In one example, the TIR reflecting coating may include lead. FIG. 9 illustrates an example of a template 128 that may be used in the method of FIG. 8. The template includes a base 129 and curved corrugations 130. The corrugations 130 may be representative of corrugations that are to be formed in the multilayers of the optic device. The template 128 may be made of a polymer, a ceramic, a metal, a polymer, or combinations thereof. In one embodiment, the template 128 may be made of a sacrificial material. In this embodiment, after the formation of the multilayer section, the sacrificial material may be decoupled from the multilayer section by disintegrating the template. The template may be disintegrated using techniques, such as but not limited to, etching or laser ablating. In another embodiment, the template 128 may be a reusable template. In this embodiment, the template 128 may be used to deposit the first and second multilayer sections. The first multilayer section may be decoupled from the template 128 before depositing the second multilayer section. FIG. 10 illustrates a method of making the multilayer optic device. In the illustrated embodiment, the core may be used as the template. At step 131, a core having corrugations that are curved in a fan beam direction is provided. The core includes first and second surfaces. The core may be formed of a higher refractive index material such as beryllium, lithium hydride, magnesium, or any other suitable elements or compounds having similarly higher refractive indices and high X-ray transmission properties. The core may be less than a micrometer to greater than one centimeter in diameter. In an alternate embodiment, a layer formed of a core material suitable for transmitting X rays may be provided. Next, curved corrugations may be formed on portions of the first and second surfaces of the core layer. The corrugations may be formed by photolithography and etching, which provides channels on a small enough scale to minimally affect image resolution. Individual layers of the optic device may be conformally formed on the patterned core. At step 132, layers of a multilayer zone may be conformally deposited on the core to form a first multilayer zone on the core. At step 134, subsequent layers, such as the low-index material layer may be deposited on the first multilayer zone to form the first multilayer section. At step 136, the partially formed multilayer optic can be turned over and the layers of the second grading zone may be deposited on the second surface of the core. At step 138, the second low-index layer may be deposited on the second grading zone to form the multilayer optic device. FIG. 11 illustrates a core 140 having a base 141 and two opposite surface 142 and 144. Corrugations 146 and 148 are formed in the surfaces 142 and 144, respectively. The pattern of corrugations 146 and 148 may be same or different. The corrugations 146 and 148 may be continuous or discrete. FIG. 12 provides a method of making a multilayer optic device like the one illustrated in FIG. 5. The method enables modifying an existing multilayer optic device into a corrugated multilayer optic device. The method begins by providing a multilayer optic device 150. The multilayer optic device 150 includes a core 152 having two opposite surfaces 154 and 156. Multilayer zones 158 and 160 are disposed on the surfaces 154 and 156, respectively. Low refractive index layers 162 and 164 are disposed on the multilayer zones 158 and 160, respectively. Portions of the optic device where it is desirable to have corrugations to redirect the X-rays in the fan-beam direction may be removed to form corrugations. For example, the portions of the optic device closer to the two edges in the fan-beam direction may be etched out to form corrugations. As illustrated, one or more portions of the multilayer optic device 150 may be etched out. Also, the etched portions may be on either sides of the outer surfaces 154 and 156 of the core 152. The body of the core may not have any etched portions; accordingly, the body of the core may not have corrugations within it. In one embodiment, one third of the depth from the outer surfaces 165 and 167 of the optic device 150 may be removed. In another embodiment, from the outer surface 165 to the surface 154 of the core may be removed, and from the outer surface 167 to the surface 156 of the core may be removed. In the illustrated embodiment, the multilayer optic device 150 may be etched in portions 162, 164 and 166 disposed between the surfaces 165 and 167 of the optic device 150. The surfaces 154 and 156 may or may not be etched. The etching may be done to provide curved regions in the etched layers. Next, a high or a low refractive index material, or graded region, may be deposited in the etched out regions. The material may include materials used to fabricate the original optic device 150. The material may be deposited using vapor deposition techniques, such as but not limited to, chemical vapor deposition and physical vapor deposition. In one example, the device 150 may be etched on one side of the core 152, and the material of the corrugation may be deposited in the etched portions before etching on the other side of the core 152. Advantageously, the invention enables a substantial increase in the X-ray flux intensity in a fan-beam direction for a fan-shaped X-ray beam. The fan-shaped beam may be employed in medical CT imaging and X-ray diffraction explosives detection. This written description uses examples to disclose the invention and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. For example, although only two grading zones are shown in FIGS. 1, 3, 5, 7, and 12, the scope of the invention covers any number of such zones that are necessary to provide a specific optic device design for a particular application. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
	abstract	An apparatus for inspecting and testing a startup range neutron monitoring system for a nuclear reactor. The apparatus includes: a neutron-flux detector; a preamplifier that amplifies an electric signal output from the neutron-flux detector; a pulse measurement unit that counts times when electric signal output from the preamplifier exceeds a discrimination voltage; a discrimination-voltage setting unit that applies the discrimination voltage to the pulse measurement unit; a voltage-setting unit that applies a voltage to the neutron-flux detector; an arithmetic processing unit that calculates an output power of the reactor based upon an output signal of the pulse measurement unit; an output unit that outputs data representing the output power of the reactor, calculated by the arithmetic processing unit; and an inspecting/testing unit that sets the discrimination voltage and the voltage to be applied by the voltage-setting unit.
	claims	1. A system for attenuating seismic forces in a nuclear reactor assembly comprising:a containment vessel configured located above a support surface;a reactor pressure vessel mounted within the containment vessel to house a nuclear reactor core; andan attenuation device integrally operatively coupled to the containment vessel and located along a longitudinal centerline of the reactor pressure vessel to attenuate seismic forces transmitted from the support surface to the reactor pressure vessel via the containment vessel in a substantially transverse direction to the longitudinal centerline;wherein the attenuation device includes an integrated vertical key portion and an integrated lateral support portion, the integrated vertical key portion extending upwardly in a substantially vertical direction from an inner surface of the containment vessel and the integrated lateral support portion extending downwardly in a substantially vertical direction from an outer surface of the containment vessel;wherein the integrated vertical key portion is to engage a recess of the reactor pressure vessel to provide lateral support to the reactor pressure vessel; andwherein the integrated lateral support portion is to engage between at least a pair of stops extending upwardly from the support surface to receive the seismic forces transmitted from the support surface. 2. The system of claim 1, wherein the attenuation device is configured to provide for a thermal expansion of the reactor pressure vessel within the containment vessel. 3. The system of claim 2,wherein the integrated vertical key comprises a substantially vertical protrusion; andwherein the recess comprises a vertical clearance to account for a thermal expansion of the reactor pressure vessel along the longitudinal centerline. 4. The system of claim 3,wherein the vertical protrusion comprises a diameter; andwherein the vessel recess further comprises an annular-shaped clearance to account for the thermal expansion of the diameter of the vertical protrusion. 5. The system of claim 1,further comprising a support structure located in an upper half of the containment vessel and configured to support the reactor pressure vessel within the containment vessel;wherein the attenuation device is located in the bottom half of the containment vessel. 6. The system of claim 5,wherein a majority of a weight of the reactor pressure vessel is supported by the support structure; andwherein substantially none of the weight of the reactor pressure vessel is supported by the attenuation device. 7. The system of claim 1,wherein the containment vessel comprises a cylindrical-shaped support skirt that contacts the support surface;wherein a bottom head of the containment vessel is located some distance above the support surface; andwherein the support skirt comprises through-holes configured to allow coolant to flow through the support skirt and contact the bottom head. 8. The system of claim 1,wherein the integrated vertical key comprises a vertical post located along the longitudinal centerline of the containment vessel; andwherein the vertical post is inserted into the recess of the reactor pressure vessel. 9. The system of claim 8,wherein the containment vessel comprises a bottom head; andwherein the vertical post extends upward from the bottom head of the containment vessel into the recess associated with the reactor pressure vessel. 10. The system of claim 9,wherein the integrated lateral support may be configured to contact the at least the pair of stops without directly contacting the support surface.
	abstract	System and method for EMI shielding for a CD-SEM are described. One embodiment is a scanning electron microscope (“SEM”) comprising an electron gun for producing an electron beam directed toward a sample; a secondary electron (“SE”) detector for detecting secondary electrons reflected from the sample in response to the electron beam; and a dual-layer shield disposed around and enclosing the SE detector. The shield comprises a magnetic shielding lamina layer and a metallic foil layer.
051907216	abstract	A corrosion resistant zirconium alloy is comprised of, in weight percent, about 0.1 to less than 0.5 percent bismuth, about 0.1 to less than 0.5 percent niobium, and the balance substantially zirconium. Preferably, niobium is about 0.1 to 3 weight percent. The alloys have improved corrosion resistance as compared to the moderate-purity sponge zirconium while maintaining a ductility comparable to sponge zirconium.
053435060	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is seen a reactor building R shown in section, which includes a safety vessel 1 that is also referred to as a containment and is formed by a spherical steel sealing skin 3, a reinforced concrete foundation 2 having an appropriate spherical receiver 2.1, and a nuclear reactor installation KA being disposed inside the safety vessel 1 and including installation components and connecting lines of tubes, electrical lines and building structures which are enclosed in a gas-tight manner by the steel sealing skin 3. The latter is enclosed, including a gap, by a non-illustrated concrete containment shell connected with the reinforced concrete foundation 2 and protects the safety vessel 1 from effects from the outside ("Eva"). A concrete structure 4 of the safety vessel 1 is adapted by means of a downwardly oriented convex receiver 4.1 thereof to the convex steel sealing skin 3 and the correspondingly concave receiving surface 2.1 of the concrete foundation 2. At connecting points 5.1 and 5.2 thereof, the concrete structure 4 is connected with the reinforced concrete foundation 2 by means of anchor bolts sealingly penetrating the steel sealing skin 3. A reactor pressure vessel of the pressurized water type, which is identified as a whole by reference numeral 6, is surrounded at a distance in the lateral and vertical direction by a supporting and protective structure 7. This supporting and protective structure 7, with a bottom or bottom region 7.1 and a circumferential wall 7.2 thereof is a component of the concrete structure 4 within the containment 1. A reactor cavern 8 is formed by the bottom region 7.1 and the circumferential wall 7.2, within which the reactor pressure vessel 6 is disposed. A central, recessed bottom part 7.10 of a preferably central inlet chamber 33 which will be described below, is also part of the bottom region 7.1. The essentially hollow-cylindrical reactor pressure vessel 6, having a vertical axis z and being formed of a lower part 6a with a bottom cup 6.1 and an upper part 6b with a top receiver 6.2, is suspended by its lower part 6a in a support ring structure 9. The support ring structure 9 is seated and secured against lifting and twisting, in an annular recess in the circumferential wall 7.2 of the supporting and protective structure 7. The reactor pressure vessel 6 is seated on the support ring structure 9 and is secured against twisting and lifting, within a circular recess with a flange of its lower part 6a and/or suitable lug supports, in a manner which is not shown in FIG. 1. A reactor core 10 is indicated by dashed lines. A steam generator DE of the primary circuit components of the nuclear reactor installation KA which is also shown, is connected to the reactor pressure vessel 6 through a so-called hot leg 11 of main coolant channels HL. The respective hot leg 11 (this is a multi-loop installation) guides hot coolant to a primary chamber 12 of the steam generator DE. The primary chamber 12 is separated from a secondary chamber 13 of the steam generator DE by a tube sheet 14 and U-shaped heat exchanger tubes indicated at reference numeral 15. In addition, the primary chamber 12 is divided by a separating wall 16 into two chamber halves. Thus, the primary coolant flows from the hot leg 11 over one half of the primary chamber 12 into the heat exchanger tubes 15, transfers its heat there to the secondary medium which turns into steam, and is fed back into the interior of the reactor pressure vessel 6 in a circuit through the other half of the primary chamber 12, a so-called cold leg 17 connected therewith, a non-illustrated primary coolant pump disposed in this cold leg 17, and the remainder of the cold leg 17. This can be a so-called two-loop installation, i.e. a pressurized water reactor with two steam generators and a pair of main coolant lines each. This would be the case in the exemplary embodiment of FIG. 1 if a cold leg 17 (only one is shown) were assigned to each of the two hot legs 11. However, it can also be a three-loop or four-loop installation, if it is contemplated that further pairs of legs are added in FIG. 1, or as can be seen from the illustrations in FIGS. 2 and 3. The steam generators DE are seated on the concrete structure 4 by means of support rings 18 in their tube sheet area. A bottom wall 20 of a coolable collecting basin 19 of a core catcher device CC is disposed inside the reactor cavern 8 and below the reactor pressure vessel 6 and a jacket wall 21 of the collecting basin 19 extends upward from the bottom wall 20. The circumferential wall 7.2 of the supporting and protective structure 7 which is vertical or is slightly inwardly inclined as is illustrated, is also referred to as a biological shield, because it constitutes a protective shield against neutrons and gamma radiation. The circumferential wall 7.2 is clad on its inner periphery with a steel liner 22, as are inside surfaces of the bottom region 7.1. Thus, the bottom region 7.1 and the circumferential wall 7.2 are outside of this liner 22 and at a vertical and lateral distance from the collecting basin 19 and are connected with the remainder of the concrete structure 4. The latter is built as a chambered structure, and a reactor sump in the form of a cooling water reservoir 24 with a normal level P1 is disposed in a chamber 23, which should be imagined to be in the approximate shape of a rotational solid and which surrounds the circumferential wall 7.2 (biological shield). A ceiling 25 of this chamber 23 is supported by steel walls 26. A separating wall 27, together with a U-shaped ascending pipe 30, constitutes an inlet structure of an inlet channel configuration 31. The main coolant lines (hot legs) 11 extend through appropriate wall openings 7.3 in the circumferential wall 7.2, and the cold legs 17 extend through similar openings which cannot be seen in FIG. 1. Preferably, the jacket wall 21 of the collecting basin 19 extends approximately at least as far as the lower edge of the reactor core 10, as is illustrated. In this case, a spacing gap 28 is defined between the bottom wall 20 and the jacket wall 21 of the collecting basin 19 relative to the bottom 7.1 and the circumferential wall 7.2 of the supporting and protective structure 7. A cooling system 29 on the outside of the collecting basin 19 which has cooling channels 29.1, 29.2 at bottom and jacket sides is provided inside the spacing gap 28 for the purpose of exterior cooling of the collecting basin 19. The invention is not limited to the spherical containment 1 of FIGS. 1 to 3, but instead it can also be employed with a cylindrical containment, wherein the transition from the concrete structure 4 of the safety vessel 1 to the foundation 2 does not take place through spherical surfaces (as in the embodiment according to FIG. 1), but instead through level transition surfaces. Reference is made below to the detailed illustration in accordance with FIGS. 2 to 6 for further explanation. Parts which are the same as in FIG. 1 have the same reference numerals. The cooling channels 29.1 at the bottom of the exterior cooling system 29 are connected through the inlet channel configuration 31, and the cooling channels 29.2 on the jacket are connected through an outlet channel configuration 32, to the cooling water reservoir 24 which is provided outside of the supporting and protective structure 7 and which forms a reactor housing sump or is connected therewith with such a lifting height that, with a hot collecting basin 19 and a water-filled cooling system 29, a naturally circulating flow in the cooling system 29 through the cooling channels 29.1 and 29.2 is generated. The inlet channel configuration 31 flows into the exterior cooling system 29 of the spacing gap 28 in the central area of the bottom wall 20 of the collecting basin 19 through the inlet chamber 33. The cooling channels 29.1, which are delimited by turbulence bodies 34 and the bottom wall 20 as well as the bottom region 7.1 of the supporting and protective structure 7, extend outward from the inlet chamber 33 as far as a rounded-off edge area 19.1 of the collecting basin 19. Following this, the upwardly leading cooling channel 29.2 on the jacket side extends from the edge area 19.1 as far as the outlet channel configuration 32. As can be seen from FIGS. 2 to 4, the inlet channel configuration 31 extends through the bottom region 7.1 of the supporting and protective structure 7. Inlet channels 31a extend in a star pattern or radially-horizontally from a short vertical inlet channel piece 31b to the inlet chamber 33. A vertical inlet channel piece is constructed as a pump sump chamber 31c of a non-illustrated pump, as is seen in the lower left part of FIGS. 2 and 3. An inlet chamber 35 is placed upstream of the inlet channel piece 31b and in normal operation is separated by the separating wall 27 from the chamber 23 of the cooling water reservoir 24. It is only when the normal level P1 of the cooling water rises, namely to a high water or minimum water level P2, that cooling water reaches the inlet chamber 35 and the remainder of the inlet channel configuration 31 through the ascending pipe 30, as will be described further below. The outlet channel configuration 32 penetrates the circumferential wall 7.2 of the supporting and protective structure 7, forms a continuation of the cooling channel 29.2 on the jacket side and empties into the cooling water reservoir 24 in the area of the upper level P2 of the reservoir 24, which can only be seen in FIG. 1. FIG. 4 shows that outlet channels 32a of the outlet channel configuration 32 are distributed over the circumferential wall 7.2. Six of the outlet channels 32a are shown. Four of the outlet channels 32a are in an axial crossing configuration and two additional outlet channels are in first and third quadrants of parts of the circumferential wall 7.2. As can be seen in FIGS. 2 and 3 (as well as FIG. 1), the collecting basin 19 is constructed in the shape of a crucible, and in order to achieve this, its bottom wall 20 is curved downwardly or toward the exterior. The bottom wall 20 makes a transition into the jacket wall 21 through the rounded-off edge area 19.1. A base body 19a of the collecting basin 19 is formed as a crucible which is preferably formed of a temperature-resistant steel alloy. Interior bottom and jacket surfaces of the crucible 19a are clad with a protective shell 19b, which is used to protect the crucible material against an attack by the melt. Preferably, this protective shell 19b is formed of one of the following alloys: MgO, UO.sub.2 or ThO.sub.2. A sacrificial material deposit 19c follows the protective shell 19b as a second protective layer for the crucible 19a. This sacrificial material deposit 19c is preferably formed of shielding concrete blocks 36, which are connected with each other and the protective shell 19b for forming a masonry facing. A distance between the sacrificial material deposit 19c in the form of the masonry facing and the bottom cup 6.1 of the reactor pressure vessel, is sufficiently great to enable the surfaces of the masonry facing oriented toward the bottom cup to be clad with a heat-insulating shell W1. This heat-insulating shell W1 is the lower portion of a heat insulation which is indicated as a whole by reference symbol W, for the reactor pressure vessel 6. The lower insulating portion W1 has an approximately cup-shaped form. This lower insulating portion W1, as well as a central insulating portion W2 at the interior periphery of a shielding ring 37 and an upper insulating portion W3 extending from the shielding ring 37 to the region of a cover portion gap 38 of the reaction pressure vessel 6, all enclose the reactor pressure vessel 6 with a sufficient gap, so that an air chamber 39 is formed. The collecting basin 19 therefore is a cup or crucible-like multi-layered structure, with the base body 19a in the shape of a crucible which can have a wall thickness of 50 mm, for example, and the protective shell 19b lining the interior surface of the crucible with a wall thickness three times that of the crucible. The wall thickness of this protective shell 19b is preferably increased in a central area 19.0 of the collecting vessel 19, because the greatest temperature stresses can occur in this area in the case of a possible core melt. As mentioned above, the sacrificial material deposit 19c, which is adapted to the contour of the crucible, follows the protective shell and the appropriately adapted lower insulation portion W1. Preferably, the jacket wall 21 of the crucible 19a, that is of the collecting vessel 19, extends from the rounded-off edge area 19.1 to an upper edge 21.1 seen in FIG. 1, in a conically tapering manner. Due to this structure, the contour of the crucible 19a or of the collecting vessel 19 is adapted to the contour of the outer periphery of the circumferential wall 7.2 of the supporting and protective structure 7, and a desired cross section for a spacing gap 28 or the cooling channels 29.2 of cooling system 29 on the jacket side is attained. The bottom wall portion 20 of the crucible 19a of the collecting basin 19 widens in the shape of a flat envelope of a cone from the lowest central area 19.0 to the edge area 19.1, and intersecting surfaces thereof that are located in axial-radial intersecting planes, extend with a slight angle of slope .alpha. relative to the horizontal. This slight inclination of the bottom wall 20 which is present from the central area 19.0 to the edge area 19.1 results in defined flows of cooling water in the channel system 29, in which no air bubbles are formed or maintained (leading to an avoidance of so-called dead cooling zones). Instead, this slight inclination aids the natural circulation. Thus, there is a slight slope in the interior of the collecting basin 19 from the edge area 19.1 to the central area 19.0, so that a possible core melt will always collect in a centered manner in the collecting basin 19 (provided it is in the liquid state). In accordance with a preferred embodiment, the collecting basin 19 is seated in the bottom region 7.1 of the supporting and protective structure 7 by means of the turbulence bodies 34. This does not preclude an additional support, where needed, by means of non-illustrated support bodies. It is also possible to provide turbulence bodies 34d which are only used for turbulence generation (and not for support), as will be described below by means of FIG. 5. The turbulence bodies 34 are inserted in the exterior cooling system 29 between the bottom wall 20 of the collecting basin 19 or the base body or crucible 19a and the bottom region 7.1 and are used for supporting the collecting basin 19 on the bottom region 7.1 and for generating a turbulent flow of the cooling liquid. In FIGS. 2 and 3, only turbulence bodies 34 are shown in the cooling channel 29.1 on the bottom which are not only used for flow guidance and turbulence generation, but also for support. This is also true for central turbulence bodies 34a disposed in the central area 19.0. These turbulence bodies 34a are supported on the central, recessed bottom part 7.10 which is part of the bottom region 7.1 and is located at the level of the lower wall 4.2 of the inlet channels 31. The turbulence bodies 34a are longer than the turbulence bodies 34, because they have to bridge a greater channel height of the inlet chamber 33. The turbulence bodies 34, 34a are distributed within the cooling channels 29.1 on the bottom and inside the inlet chamber 33, in such a way that an even weight transfer into the bottom region 7.1 of the supporting and protective structure 7 is assured, and cooling flow paths 40 seen in FIG. 5 can be formed along a path from the inside, i.e. from the central inlet chamber 33, radially outward to the edge area 19.1 and directed from there into the cooling channel 29.1. The latter is an annular channel. The cooling flow paths 40 can extend in their main direction along radii, i.e. they can be star-shaped or in the form of involutes, for example, in the course of which the turbulence bodies 34, 34a create a turbulence flow, particularly within the cooling channels 29.1 on the bottom when the naturally circulating flow is started in the cooling system. FIGS. 5 and 6 show closer details of the structure and disposition of the turbulence bodies 34 (the same is correspondingly true for the turbulence bodies 34a). Flow arrows for cooling liquid, particularly cooling water, are generally indicated by reference symbol fl and shown in dashed lines. Flow arrows for cooling air are generally indicated by reference symbol f2 and are shown in solid lines (also see FIGS. 1 to 3). Either only cooling air (solid arrows f2) or cooling water (dashed arrows fl) can flow in the cooling channels 29.1 and 29.2, which will be explained below. Heat flow arrows in FIG. 5 for the heat flow emanating from the reactor pressure vessel 6 or a possible core melt and penetrating the collecting basin 19, in particular its base body or crucible 19a and the bottom wall 20 of the crucible, are generally indicated by reference symbol f3 and shown in heavy solid lines. The arrows fl therefore symbolize an emergency cooling water flow in the cooling system 29. FIG. 5 is a diagrammatic, perspective view which shows a section of the cooling system 29, namely in the area of the bottom wall portion 20 of the collecting basin 19 and of the bottom 7.1 with the liner 22 of the supporting and protective structure 7 located opposite a cooling gap al. The turbulence body 34 illustrated therein is constructed as a pipe socket (this embodiment preferably applies to all of the turbulence bodies 34 in FIGS. 1 to 3). In order to distinguish the pipe sockets from the other general turbulence bodies 34, these pipe sockets are designated by reference symbol 34r and in order to distinguish delta wings which generate turbulence and are still to be explained from the other general turbulence bodies 34, the delta wings are indicated by reference symbol 34d. The pipe sockets 34r are provided with channel recesses 41 on ends thereof facing the bottom wall portion 20 of the cooling basin 19. In particular, two U-shaped recesses 41 per pipe socket 34r are provided which are in alignment in the flow direction (main direction of the flow arrow fl) and have edges 41.1 thereof which are made angular to increase turbulence. Partial cooling water flows f11 are generated by the channel recesses 41 with their edges 41.1, which in the area of the turbulence bodies 34 in general and in the area of the pipe sockets 34r in particular are forced into contact with the cooling surfaces of the bottom wall portion 20. It is important to generate a sufficiently large turbulence of the flow within the cooling water flow paths 40 and the cooling paths 40a of the partial cooling water flows f11, to ensure that intimate mixing of the partial cooling water flows is achieved and the formation of a steam film on downwardly pointing cooling surfaces 20.0 of the bottom wall portion 20 is prevented. The so-called delta wings 34d which are in the shape of prisms with triangular surfaces F1 to F4 and which have the shape of tetrahedons, are provided for this purpose. These are fastened at least on the bottom 7.2 located opposite the cooling surface 20.0 within the cooling gap al, or on the liner 22 of the bottom 7.2. The delta wings 34d or flow guidance bodies in general are preferably manufactured of corrosion-resistant steel which in composition is the same as the steel alloy of the liner 22 or is similar to it, so that they can be attached by welding, as is seen by weld beads that are indicated at reference numeral 42. For the sake of clarity, only two delta wings 34d are shown in FIG. 5, and the effect that these flow guidance bodies in the form of the delta wings 34d have on the otherwise mostly laminar flow is schematically indicated by spiraling flow lines f12. Strong turbulence is generated, which increases a safety distance against film boiling on the cooling surfaces 20.0. It can be seen in FIG. 6, that the collecting basin 19 is supported on the bottom 7.1 through its pipe sockets 34r and in a spring-elastic manner with the interposition of a spring element 43. The pipe socket 34r is welded on the bottom wall 20 of the base body or crucible 19a of the collecting container 19 by weld beads 44, in which case again the steel alloys of the pipe sockets 34r and the crucible 19a are adapted to each other in such a way that a compatibility in relation to welding is assured. The spring elements 43 can be helical pressure springs, which are supported by a lower spring plate 43a on the bottom parts 7.1 and through another non-illustrated spring plate at the upper end thereof on the pipe socket 34r. In place of helical pressure springs it is also possible to employ non-illustrated plate springs or plate spring packets, wherein helical pressure or plate springs are appropriately pre-stressed because of the heavy weight to be supported. The underside of the lower spring plate 43a is preferably finely worked, i.e. smoothed, so that the coefficients of friction relative to the adjoining surface of the steel liner 22 becomes as low as possible. By making a sliding movement possible, even if only over small distances, it is possible to prevent constraining forces during heating in the course of a hypothetical case of a core melt. The spring elements 43 can also be constructed as non-illustrated spring rods permitting spring-elastic yielding in the lateral direction to a limited extent. The delta wings 34d shown in FIG. 5 can be used with advantage for the generation of a turbulent flow within a cooling channel, not only within the purview of the exemplary embodiment shown, but also in all places where a liquid coolant flows through the cooling channel and is delimited in the vertical direction by two channel walls disposed above each other and at a distance from each other, namely by an upper first channel wall heated by the heat to be dissipated, and a lower second channel wall provided on the inside with the delta wings 34r. Referring again to FIGS. 1 to 3, it is noted that it would be possible in principle to suspend the collecting basin 19 with its crucible 19a from the supporting and protective structure 7. In this case the jacket wall 21, for example, could be upwardly extended and seated by means of a support flange on its upper end on a support ring inserted into an annular recess in the wall portions 7.2 in the supporting and protective structure 7, in a non-illustrated manner. In such an embodiment too, the turbulence bodies 34, 34a can be used, at least in part, as support bodies, i.e. not only as flow guidance bodies, or they can be disposed in a narrow gap below the bottom wall 20 as a safety measure against a crash. However, the embodiment shown with the seating of the collecting basin 19 on the channel bodies 34, 34a is more advantageous, because in this case the circumferential wall 7.2 (biological shield) is not additionally loaded. Instead, the transmission of the seating forces takes place over the considerably larger surface area of the concrete structure 4 and the bottom region 7.1. Preferably, the collecting basin 19 extends at least as far as about the lower edge of the reactor core 10 seen in FIG. 1 and, as explained at the start, the required lifting height of at least approximately 3 m needed for the natural circulation of the cooling liquid through the cooling system 29 is therefore achieved. In this way, the collecting basin 19 encloses the entire bottom cup 6.1. With the extent in height of the collecting basin 19 as shown, it is a preferred feature of the embodiment to provide the shielding ring 37 seen in FIGS. 2 to 4, which is installed above the collecting basin 19 and adjoins it in an annular chamber 45 seen in FIGS. 2A and 3A between the circumferential wall 7.2 of the supporting and protective structure 7 and the outer periphery of the reactor pressure vessel 6. The shielding ring 37 assumes the function of the biological shield in the area of the core 10 seen in FIG. 1 in the places where the circumferential wall 7.2 (biological shield) is penetrated by outlet channels 32. The shielding ring 37 is preferably made of shielding concrete. Suitable compositions for such shielding concrete can be found in Table XXIV on page 701 of the book entitled: "Nutzenergie aus Atomkernen" [Useful Energy from Atomic Cores] by Dr. K. R. Schmidt, Vol. II, Walter D. Gruyter & Co., publishers, Berlin 1960, so that a detailed description thereof can be omitted herein. The shielding ring 37 is anchored on the circumferential wall 7.2 of the supporting and protective structure 7. Wedge-shaped bars 46 that are evenly distributed over the outer periphery of the shielding ring 37 can be provided for this purpose, as is shown in FIG. 4. It is also possible, such as is indicated by dashed lines in FIG. 3, to provide wedge-shaped support surfaces 47 on the circumferential wall 7.2, in which the shielding ring 37 is interlocked by means of wedge-shaped counter-surfaces 37a. It is advantageous for installing the shielding ring 37 if it is composed of non-illustrated individual ring segments. The ring segments then must be interlocked with each other and the circumferential wall 7.2 of the supporting and protective structure 7 as is seen in FIG. 3, or wedged against it as is seen in FIG. 4. According to another advantageous embodiment, the shielding ring 37 is made of shielding, prestressed concrete, and its steel reinforcement is combined into a uniform steel reinforcement system with the steel reinforcement of the supporting and protective structure 7 also being formed of prestressed concrete. Reinforcing steel cables 48' for such an embodiment are indicated by dashed lines in FIG. 2A. It is possible to provide additional ring clamping cables inside the shielding ring 37, by means of which the individual ring segments, which are interlocked with each other, are clamped together in the circumferential direction in a non-illustrated manner. In order to minimize heat losses of the reactor pressure vessel 6 during normal operation, its heat insulation W seen in FIGS. 2 and 3, is of great importance. Of equal importance is the ventilation of this heat insulation on its exterior by the cooling air flows, which are symbolized in their totality by flow arrows f2. The heat insulation W includes the heat insulating portions W1 to W3 for the lower part 6a of the reactor pressure vessel 6, a movable or removable heat insulating hood W4 extending over the upper part 6b of the reactor pressure vessel 6, and additional heat insulating portions W5 for the main coolant lines HL. Essentially, three insulating portions that merge into each other are provided for the lower part 6a, namely: the lower insulating portion W1 which lines the sacrificial layer of the collecting basin 19 and encloses the bottom cup 6.1 of the reactor pressure vessel 6, the central insulating portion W2 lining the interior periphery of the shielding ring 37, and a ring-shaped connecting piece W21, which extends around the bottom of the shielding ring 37 and provides a connection between the lower insulating portion W1 and the upper insulating portion W3 extending from the shielding ring 37 to the area of the cover portion gaps 38 of the reactor pressure vessel 6 and which is penetrated by a main coolant connection 48. The main coolant connection 48, as well as the adjoining main coolant lines HL are enclosed by the additional insulating portions W5, as was mentioned above. The heat insulation W is preferably constructed of all-metal cassettes which are made of austenitic, i.e. corrosion-resistant steel. Appropriate fastening structures made of lightweight materials for securing these individual cassettes, which can be aligned to form a complete heat insulating shell, are not shown. The exterior cooling system 29 of the collecting basin 19 is constructed as a dual air and water cooling system which, in the normal operation of the nuclear reactor installation KA, i.e. with the exterior cooling system 29 dry, is used for air-cooling of the reactor pressure vessel 6, or for air-cooling of the exterior of the heat insulation W in general and the individual insulating portions W1 to W3 and W5 in particular. For this purpose, the inlet channel configuration 31 is connected to at least one cooling air source. In FIGS. 2A and 3A this source is schematically indicated as a cooling air blower 49. This blower represents a plurality of blowers which convey the cooling air in accordance with the arrow f2 into the inlet channel configuration 31 in the area of the pump sump chamber 31c. FIG. 2 shows the cooling air paths of the cooling air, which are superimposed on one another as is seen by the solid flow arrows f2, and the paths of the cooling water as is seen by the dashed flow arrows f1. In case of a hypothetical accident, the air cooling in the cooling system 29 smoothly transitions into water cooling of the collecting basin 19, which is still to be described. The outlet channel configuration 32 terminates in the containment and in this way provides a cooling air sink for the cooling air coming out of the cooling system 29, which therefore is used for indirect cooling of the outside of the lower insulating portion W1. A further air cooling system which is superimposed on the dual cooling system indicated by the flow arrows f1 and f2 seen in FIG. 2, is indicated by flow arrows having reference symbols f21 to f23 in FIGS. 2 and 3. The entirety of the first air cooling system in accordance with the flow arrows f2 is identified by reference symbol ZL1, and the additional air cooling system in accordance with the flow arrows f21 to f23 is identified by reference symbol ZL2. In order to provide the air supply for this additional air cooling system ZL2, inlet channels 50 which penetrate the circumferential wall 7.2 of the supporting and protective structure 7 and the shielding ring 37 terminate in the upper air cooling annular chamber 45. This annular chamber 45 extends outside of the upper insulating portion W3 as far as a support ring structure 51 of the reactor pressure vessel 6 and is delimited on the exterior by the inner periphery of the circumferential wall 7.2. The upward-flowing cooling air is guided in a plurality of partial flows along the following cooling surfaces: at the outer periphery of the upper insulating portion W3 and the inner periphery of the circumferential wall 7.2. In this case the flow of cooling air f22 comes from the inlet channels 50. The inlet channels 50 are formed of two channel parts: a first channel part 50a which penetrates the circumferential wall 7.2 and extends at a slight incline in the flow direction, and a second channel part 50b which penetrates the shielding ring obliquely upward at an angle of inclination of approximately 45.degree.. The channel parts 50a, 50b, or the entire inlet channel 50, can be formed by brickwork channels 52, seen FIG. 4. In a mouth opening region of the inlet channels 50, the shielding ring 37 is provided with an inclined surface 37a, and a flow guidance sheet 53 covers each of the mouths of the inlet channel 50 and permits the cooling air to exit while being distributed over the cross section of the cooling air chamber 45 through non-illustrated outlet openings; the cooling air flow f21 comes from the first cooling air system ZL1. The flow f21 is upwardly guided on the inner periphery of the circumferential wall 7.2 and forms a cooling air veil distributed over the circumference of the biological shield, which unites with the cooling air flows f22 above the cooling air chamber 45, forming the cooling air flow f23 that is also seen in FIG. 2, and flows along the exterior surfaces of a support ring structure 51, particularly along support arms 51a which support lug supports 54 of the reactor pressure vessel and along a seat or support 55 of the support ring structure 51; furthermore, in accordance with FIG. 2A, outlet ring channels 7.4. are provided for the cooling air flows f23, in which case these outlet ring channels are formed between the main coolant lines HL and the inner periphery of wall openings 7.3 of the supporting and protective structure 7. From there the cooling air reaches the containment or the interior of the safety vessel 1 and from there it travels into a non-illustrated exhaust air filter installation. An additional water cooling system for the surface of a possible core melt, which is suitably integrated into the air cooling systems ZL1 and ZL2 and the exterior cooling system 29 for water cooling, is located in the collecting basin 19 and has at least one melt cooling tube 56 shown in FIG. 2. For this purpose, the collecting basin 19 is penetrated in the upper half of its jacket wall by the at least one melt cooling tube 56 which, in the multi-layer construction of the collecting basin 19 as shown, extends through its crucible wall 19a, the protective layer 19b, the sacrificial material deposit 19c and the lower thermal insulation W1. An inner end of this melt cooling tube 56 is sealed by means of a melting plug 56a. As is shown, the melt cooling tube 56 extends with a gradient (for example, an angle of inclination of 20.degree.) from the outside to the inside and is attached on the inlet side to a cooling liquid reservoir, which can be identical to the cooling water reservoir 24 of FIG. 1. With a core melt present in the collecting basin 19, the melting plug 56a is heated to its melting temperature (the melting temperature lies above the temperature reached in the air chamber 39, but far below the melting temperature of the core melt, for example at 600.degree.). The melting plug 56a is caused to melt and in this way opens a flow channel for cooling liquid to the surface of the hypothetical core melt, so that it is additionally shielded upwardly by a water film and is cooled, and the evaporating coolant, particularly water vapor, can escape upwards through the cooling channels provided for air cooling. An inlet end 56.1 of the melt cooling tube 56 is located outside of the circumferential wall 7.2. It may be connected with the separately ascending pipe 30 shown in FIG. 2B or FIG. 1, so that when the cooling water enters the inlet channel configuration 31 and thus the cooling system 29 through the normal ascending pipe 30 in the course of a rising level, the melt cooling tube 56 is also correspondingly supplied with cooling water. Therefore, the illustrated embodiment is particularly advantageous, since the inlet 56.1 of the melt cooling tube 56 is located outside of the supporting and protective structure 7 and accordingly the melt cooling tube 56 penetrates the circumferential wall 7.2 of the supporting and protective structure 7 and the spacing gap 28 of the exterior cooling system 29. Anchors 57 are used for anchoring the liner 22 and the entire supporting and protective structure 7 in the concrete structure 4. Although only two anchor points are shown, the anchors 57 connect the supporting and protective structure 7 with the concrete structure 4 at such a large number of anchor points that all forces and moments which are transmitted by the reactor pressure vessel 6 through the support structure or ring 51 shown in FIG. 3 on the supporting and protective structure 7 and vice versa are assuredly controlled. Besides the weight forces, these can also be lifting forces, tangential forces, tilting moments or lateral forces which may occur in case of an earthquake or structure disrupting event. In order to provide a more rapid reduction of overpressure which might build up in the collecting basin 19 during steam and gas generation, it can be practical to provide the shielding ring 37 with additional non-illustrated relief openings or overflow openings. It is furthermore recommended to fasten the heat insulation W or W1 to W3 on a relatively thin-walled insulation support container of stainless steel and to suspend this insulation support container on the support arms 51a of the support ring 51 through suitable protrusions or annular flanges and to fix it in place. In this way a particularly earthquake-proof and accident-proof fastening of the heat insulation W is assured. Such a non-illustrated insulation support container is advantageously provided with one or more inspection ports which can be closed by covers. In this way, installation of the insulation support container is made easier. The support ring or the support ring structure 51 is connected to the liner 22 and therefore additionally to the circumferential wall 7.2 by clamping elements 66 for the liner. The support ring structure 51 can be welded or screwed together from forged ring segments with a sufficient number of sturdy lug support segments, for example eight, on which the support arms 51a are formed. Additional non-illustrated anchors are provided for the steel sealing skin 3 of the safety vessel 1. A base plate 59 is fastened by means of an anchor device 58 on the lower wall or channel bottom surface 4.2 which supports the turbulence bodies 34a and on which further flow guidance bodies 60 are fastened. An upper region of FIG. 3B shows a so-called cover compensator 61 between the concrete structure of the circumferential wall 7.2 and the support ring 51. The latter is upwardly fixed by an upper counter seat 62, namely against a cover 63a for an annular recess 63 in the circumferential wall 7.2. A plug for a repeat test opening 64a in the support ring structure 51 is indicated by reference numeral 64. As was mentioned above, it is possible by means of the invention to provide a method for initiating and maintaining an exterior emergency cooling of the collecting basin 19 of the nuclear reactor installation KA. Referring to FIGS. 1 and 2, the individual method steps are as follows: during normal operation of the nuclear reactor installation KA, the cooling water level of the cooling water reservoir 24 is at the low water level P1, at which no cooling water but rather only cooling air in accordance with the flow arrow f2 can enter the inlet channel configuration 31 of the collecting basin cooling system 29, as was already explained; for the continued course of the method it is assumed that an event exceeding the structural limitations is imminent or has already occurred. Such an event can be the result of an LOCA, for example, which will first be described below. In case of an LOCA (loss of coolant accident) it is postulated that a crack in one of the main coolant lines HL or a detachment of such a line has occurred. When such a leakage occurs in the primary circuit, emergency cooling water is pumped from the pressure reservoirs which can be activated as a function of the primary circuit pressure into the main coolant lines HL of the reactor pressure container 6, such as has been described in German Patent DE-PS 23 57 893. This is accomplished due to the fact that check valves react to the pressure decrease in the primary system (normally the pressure in the pressure reservoirs is lower than in the primary system). If this pressure reduction occurs as a result of a leak, the check valves open and the pressure reservoirs supply their contents to the main coolant lines HL on the cold as well as on the hot side. Through the use of this step the reactor core 10 is supplied with a sufficient amount of cooling water. Emergency cooling water then exits from the leak into the reactor sump or the cooling water reservoir 24, which has a level that slowly rises as a result. During this emergency cooling situation in the form of an LOCA, naturally all control rods have been inserted into the core ("scram"), i.e. the normal output operation of the nuclear reactor has been shut off, and only the so-called post-decay heat is generated in the core 10, which amounts to approximately 5% of the rated output of the nuclear reactor. Then, if the emergency cooling systems function satisfactorily, it is possible to sufficiently cool down the primary circuit and the secondary circuit after some time, so that a repair of the ripped or damaged main coolant line becomes possible. The non-illustrated volume of water in the pressure reservoirs is sufficient to raise the cooling water level of the cooling water reservoir 24 to the high water level P2 shown in dashed lines. Once this high water level P2 has been reached, cooling water is conveyed through the ascending pipe 30 (a plurality of such ascending pipes 30 can be distributed over the circumference of the separating wall 27) into the inlet chamber 35, and the cooling water flows from this inlet chamber 35 through the inlet channels 31b, 31a to the inlet chamber 33 and from there into the exterior cooling system 29. In accordance with the principle of communicating pipes, the exterior cooling system is filled with cooling water. However, there is no natural circulation yet, because the effect of heat on the collecting basin 19 due to a core melt is lacking. If the water rises in the ascending pipe 30 (which can also be described as a syphon), a check valve 65 opens. If the water should fall from the water level P2 to the water level P1 or lower, in accordance with the syphon principle water would still be conveyed through the ascending pipe 30 into the inlet chamber 35, because the check valve 65 is closed. The exterior cooling system 29 has been filled with cooling water because of the above-described course of the events as a preventive measure. Then, if the emergency cooling system which supplies emergency cooling water to the reactor pressure vessel through its main coolant lines HL should break down for any reason, so that the water level in the reactor pressure vessel 6 begins to fall, finally the core 10 seen in FIG. 1 will no longer be covered by cooling water and the remaining cooling water in the reactor pressure vessel 6 will also evaporate without a replacement being possible, if the hypothetical event of a core melt occurs. The collecting basin 19 with its external cooling system then is ready for such an event on its own and without any control commands, as described above. In other words, a core melt which following melting of the bottom cup or receiver 6.1 would at first drip and then flow into the collecting basin 19, would mix with the sacrificial material deposit 19c (after having melted through the heat insulation W1) and would be distributed inside the collecting basin 19. The heat flow would heat the crucible 19a correspondingly, along with the cooling water (that is still stationary) contained in the exterior cooling channels 29.1, 29.2. Due to the supply of heat to this cooling water column, a natural circulation could then develop, i.e. the heated cooling water could rise in accordance with the flow arrow f1 and leave the cooling system 29 through the outlet channel configuration 32. A portion of the cooling water would evaporate and condense on recoolers disposed inside the containment or on containment walls. The condensate would drip or flow back into the cooling water reservoir 24 and be available again for the circuit or the natural circulation cooling. After a defined amount of core melt has penetrated into the collecting basin 19, the radiation heat is so great that the melting plug 56a melts away. Then cooling water can flow through the melt cooling tube 56 to the surface of the core melt and can cool it also from above. In this way the core melt is intensely cooled from below through the crucible 19a and from above by means of the cooling water film. Since the protective material 19b also mixes with the core melt and forms an alloy with it, the melting point of which has been preferably lowered so that a liquifying effect is exerted on the melt, the heat dissipation from the core melt and its internal rolling cell flow is also favored by this process. Since the cooling water is available in sufficient amounts, the core melt is caused to set after some time, which can take several days. Some time will elapse after solidification until the core melt is completely cooled, and in this state the repair of the nuclear reactor installation can be begun. It is required for this purpose to decontaminate the nuclear reactor installation and to replace the damaged nuclear reactor pressure vessel 6, together with the collecting basin 19 containing the solidified core melt, with corresponding new components.
062263552	claims	1. An X-ray examination apparatus for forming X-ray images of an object, including an X-ray source for generating an X-ray beam, an X-ray filter which includes tubes containing an X-ray absorbing liquid, the quantity of X-ray absorbing liquid being adjustable in order to adjust an intensity profile on the object, and an X-ray detector for detecting an X-ray image of the object, characterized in that the tubes of the X-ray filter are arranged such that lines through all longitudinal axes of the tubes are intersecting lines extending through the X-ray source via the X-ray filter to the X-ray detector. a plurality of tubes containing an X-ray absorbing liquid, a quantity of the X-ray absorbing liquid being adjustable in order to adjust an intensity profile on an object, wherein the tubes of the X-ray filter are arranged such that lines through all longitudinal axes of the tubes are intersecting lines extending through an X-ray source via the X-ray filter to an X-ray detector of the X-ray examination apparatus. 2. An X-ray examination apparatus as claimed in claim 1, in which the tubes of the X-ray filter are oriented towards a center, a distance from the center to a first normal to an image plane of the X-ray detector through a midpoint of a focus of the X-ray source being at least equal to a focus radius of the focus. 3. An X-ray examination apparatus as claimed in claim 2, in which a first cross-section of the X-ray filter in a first direction comprises a first segment of a first circle having a first radius and in which a second cross-section of the X-ray filter comprises, in a second direction which is perpendicular to the first direction, a second segment of a second circle having a second radius. 4. An X-ray examination apparatus as claimed in claim 1, in which the tubes of the X-ray filter are arranged in parallel, an angle enclosed by a longitudinal direction of a tube relative to a second normal to an image plane of the X-ray detector being dependent on a first distance from a center of the X-ray filter to a tube near an edge of the X-ray filter and on a second distance from the center to the X-ray source. 5. An X-ray examination apparatus as claimed in claim 1, in which the tubes are of capillary dimensions, the capillary tubes being provided with electrically conductive walls. 6. An X-ray examination apparatus as claimed in claim 1, in which the X-ray examination apparatus includes a first plate and a second plate, both plates being positioned transverse to the tubes, between which plates the tubes are arranged, and that a means for connecting various tubes to the first plate contains an adhesive. 7. An X-ray examination apparatus as claimed in claim 6, in which the adhesive contains X-ray absorbing particles. 8. An X-ray filter for use in an X-ray examination apparatus comprising: 9. An X-ray filter as claimed in claim 8, in which the tubes of the X-ray filter are oriented towards a center, a distance from the center to a first normal to an image plane of the X-ray detector through a midpoint of a focus of the X-ray source being at least equal to a focus radius of the focus.
	abstract	A reactor control interface includes a home screen video display unit (VDU) displaying blocks representing functional components of a nuclear power plant and connecting arrows that connect blocks that are providing the current heat sinking path for the nuclear power plant. Directions of the connecting arrows represent the direction of heat flow along the current heat sinking path. If the current heat flow path of the plant changes, the connecting arrows are updated accordingly. Additional VDUs include: a mimic VDU displaying a mimic of a plant component; a procedures VDU displaying a stored procedure executable by the plant; a multi-trend VDU trending various plant data; and an alarms VDU displaying side-by-side alarms registries sorted by time and priority respectively. If a VDU fails, the displays are shifted to free up one VDU to present the display of the failed VDU, and one display is shifted to an additional VDU.
	summary
	description	The present application is a continuation application of U.S. patent application Ser. No. 13/047,657, filed on Mar. 14, 2011 and entitled “Beam Forming Apparatus”, which relies on U.S. Provisional Patent Application No. 61/313,772, filed on Mar. 14, 2010, for priority, both of which are herein incorporated by reference in their entirety. The specification relates generally to security systems for screening threats contained on persons, and specifically, to a helical shutter for an electron beam system, and more specifically, to a system and method for modifying the shape of a travelling radiation scan beam, using helical apertures on a cylindrical surface. Security systems are presently limited in their ability to detect contraband, weapons, explosives, and other dangerous objects concealed under clothing. Metal detectors and chemical sniffers are commonly used for the detection of large metal objects and certain types of explosives; however, a wide range of dangerous objects exist that cannot be detected using these devices. Plastic and ceramic weapons increase the types of non-metallic objects that security personnel are required to detect. Manual searching of subjects is slow, is inconvenient, and would not be well tolerated by the general public, especially as a standard procedure in high traffic centers, such as airports. It is known in the art that images of various types of material can be generated using X-ray scattering. The intensity of scattered X-rays is related to the atomic number (Z) of the material scattering the X-rays. In general, for atomic numbers less than 25, the intensity of X-ray backscatter, or X-ray reflectance, decreases with increasing atomic number. Images are primarily modulated by variations in the atomic number of the subject's body. Low-Z materials present a special problem in personnel inspection because of the difficulty in distinguishing the low-Z object from the background of the subject's body which also has low-Z. Known prior art X-ray systems for detecting objects concealed on persons have limitations in their design and method that prohibit them from achieving low radiation doses, which is a health requirement, or prevent the generation of high image quality, which are prerequisites for commercial acceptance. An inspection system that operates at a low level of radiation exposure is limited in its precision by the small amount of radiation that can be directed against a person being searched. X-ray absorption and scattering further reduces the amount of X-rays available to form an image of the person and any concealed objects. In prior art systems this low number of detected X-rays has resulted in unacceptably poor image quality. This problem is even more significant if an X-ray inspection system is being used in open venues such as stadiums, shopping malls, open-air exhibitions and fairs, etc. This is because that in such venues, people can be located both proximate to and/or at a distance from the machine. If a person being scanned is not very close to the X-ray machine, the obtained image may not be clear enough since the amount of radiation reaching the person is very low. This limits the range of scanning of the system to a few feet from the front of the machine. If, however, a person being scanned is too close to the X-ray machine, the amount of radiation impinging on the person may not be safe. The amount of radiation exposure caused by known X-ray screening systems is commonly limited by the beam chopping apparatus employed in the systems. Conventional beam chopping mechanisms generally consist of a disc wheel with collimator slits embedded therein at fixed distances from one another. The disc wheel is spun at a particular velocity and an X-ray beam of a particular energy is directed into more focused beams when passing through slits of the chopper wheel. The conventional chopper wheel is described in greater detail below throughout the specification in reference to the present disclosure. It should be understood by persons having ordinary skill in the art that radiation sources are typically very heavy. In order to accommodate for the weight of the X-ray source, a chopper wheel configuration, as employed in the prior art, would need to be rather large. This substantially increases the weight of the system and makes it less portable. In addition, the chopper wheel, as employed in the prior art, is fraught with balance and gyroscopic effects. For example, the gyroscopic effect can be likened to a gyroscope toy where a string is pulled (such as a spinning top). As the top is spun fast, fluctuations in motion are not discernable, but, once it slows down, the top will start to wobble and vibrate. Thus, there is a certain RPM that must be kept to maintain balance. In addition, with increasing weight there are issues of humming noises at higher RPMs. In order to overcome the challenges in using conventional chopper wheel configurations, mechanical manipulation of the speed and size of the chopper wheel is necessary. Therefore, what is needed is a beam chopping apparatus, and more specifically, a helical shutter for an electron beam system, that allows for variability in both velocity and beam spot size by modifying the physical characteristics or geometry of the beam chopper apparatus. There is also need for a beam chopper apparatus, and more specifically, a helical shutter for an electron beam system, which provides a vertically moving beam spot with constant size and velocity to allow for equal illumination of the target. Further, there is need for a beam chopping apparatus, and more specifically, a helical shutter for an electron beam system, which creates a wider field of view during operation. Also, there is need for a beam chopping apparatus, and more specifically, a helical shutter for an electron beam system, that is lightweight and does not cause an X-ray source assembly employing the beam chopper to become heavy and difficult to deploy. The present specification discloses an X-ray apparatus comprising: a) an X-ray source for emitting X-ray radiation; and b) a beam chopping (or beam forming) apparatus coupled to said X-ray source, wherein said beam chopping apparatus is adapted to receive said X-ray radiation and form a moving beam spot having a frequency, wherein said beam frequency is substantially constant. Optionally, the beam chopping apparatus comprises a hollow cylinder having at least one helical aperture. The beam chopping apparatus comprises a hollow cylinder having at least two helical apertures. The beam has a linear scan velocity and wherein said linear scan velocity is varied by modifying a pitch and roll of at least one of said helical apertures. The beam has a linear scan velocity and wherein said linear scan velocity is kept constant by modifying a pitch and roll of at least one of said helical apertures. The beam has a spot size and wherein said spot size is varied by modifying an aperture width of at least one of said helical apertures. The beam has a spot size and wherein said spot size is kept constant by modifying an aperture width of at least one of said helical apertures. The X-ray apparatus further comprises a motor for rotating said cylinder. The X-ray apparatus further comprises a controller for dynamically modifying a rotation speed of said cylinder to achieve a predetermined scan velocity. The rotation speed is equal to or less than 80,000 rpm. The beam has a scan velocity and a spot size and wherein scan velocity and spot size can be modified without varying a speed of said motor. The beam chopping apparatus comprises a hollow cylinder having at least two helical apertures, each having a length and an aperture width along said length and wherein said aperture width narrows along length. The beam chopping apparatus comprises a hollow cylinder having at least two helical apertures, each having a length and an aperture width along said length and wherein said aperture width increases along length. In another embodiment, the X-ray apparatus comprises: a) an X-ray source for emitting X-ray radiation; and b) a beam chopping (or beam forming) apparatus coupled to said X-ray source, wherein said beam chopping apparatus is adapted to receive said X-ray radiation and form a moving beam spot having a velocity, wherein said beam velocity is substantially constant. In another embodiment, the X-ray apparatus comprises: a) an X-ray source for emitting X-ray radiation; and b) a beam chopping (or beam forming) apparatus coupled to said X-ray source, wherein said beam chopping apparatus comprises a hollow cylinder with a first end and a second end defining a length of said cylinder and at least one helical aperture extending substantially along said length, wherein said cylinder is adapted to receive said X-ray radiation and emit said X-ray radiation through said helical aperture. Optionally, the X-ray radiation passes through the helical aperture to produce a beam spot projection pattern, wherein said beam spot projection pattern comprises a beam spot moving vertically with a substantially constant velocity in a plane perpendicular to a plane of the X-ray source. The beam spot projection pattern comprises a beam spot moving vertically with a substantially constant velocity in a plane parallel to a plane of the beam chopping apparatus. The beam spot provides substantially equal illumination of a target object. The beam spot is trapezoidal. The helical aperture has a width that is more narrow at the second end relative to said first end. The present invention provides a spin-roll beam chopper apparatus, or a helical shutter for an electron beam system, which when implemented in a system for threat detection provides an improved method of screening individuals at security locations without exposing the individuals to high radiation while retaining the efficiency of the screening process. The beam chopper of the present invention allows for maximum threat detection performance and image clarity irrespective of the individual's distance from the screening system. In addition, the spin-roll chopper of the present invention is advantageous in that it can be spun at relatively high speeds, and therefore will effectively reduce the scan time required per person. Further, the spin-roll chopper of the present invention allows for variable velocity and beam spot size with modification of the physical characteristics or geometry of the spin-roll chopper. In one embodiment of the present invention, the spin-roll chopper is used in conjunction with a threat detection system in which a radiographic image is formed using any available radiation imaging technique for “body imaging” such as, but not limited to X-ray scattering, infrared imaging, millimeter wave imaging, RF imaging, radar imaging, holographic imaging, CT imaging, and MRI. Any “body imaging” system that has the potential for displaying body detail may be employed. In one embodiment, any photodetectable radiation or any radiation source with a light beam may be employed with the spin-roll chopper of the present invention. The following disclosure is provided in order to enable a person having ordinary skill in the art to practice the invention. Language used in this specification should not be interpreted as a general disavowal of any one specific embodiment or used to limit the claims beyond the meaning of the terms used therein. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention. In various embodiments, the present invention provides a unique beam chopping mechanism that is designed to present a helical profile shutter (aperture), formed on a cylinder, for X-ray beam scanners. FIG. 1 illustrates an exemplary design for one embodiment of the spin-roll chopper, as used in various embodiments of the present invention. Beam chopper 102 is, in one embodiment, fabricated in the form of a hollow cylinder having helical chopper slits 104. The cylindrical shape enables the beam chopper 102 to rotate about the Z-axis and along with the helical apertures 104, create a spin-roll motion, which provides effective scanning and therefore good image resolution, as described below, while at the same time keeping the chopper lightweight and having less moment of inertia as the spin-roll mass is proximate to the axis of rotation. Stated differently, the radius of the spin-roll chopper is small compared to prior art beam chopping mechanisms, and in particular, the disc chopper. In one embodiment, the hollow cylinder has a height 120 of 7.23 inches at the half-way point along its vertical axis. Therefore, in one embodiment, the full height of the cylinder is 14.46 inches. The helical slits 104, in one embodiment, have a helical twist angle 125 of 112.5 degrees, a pitch of 23.1250 degrees and a roll of 0.3125 degrees. It should be noted that the helical twist angle 125 represents the angle of motion of the helical aperture from the y-axis (center line) when the cylinder is spun about the Z-axis a total of 90 degrees. Thus, an X-ray beam scanner employing the spin-roll chopper of the present invention effectuates beam chopping by rotating the hollow cylinder 102 machined with at least two helical slits 104, which enables X-ray beam scanning with both constant and variable linear scan beam velocity and scan beam spot size. The spin-roll chopper of the present invention enables both constant and variable linear scan beam velocity by manipulating the geometry of the helical apertures. In one embodiment, the velocity is varied or kept constant by manipulating the pitch and roll of the helical apertures along the length of the spin-roll chopper. Thus, it is possible to have a constant speed or to slow the scan down towards areas where more resolution is desired. The spin-roll chopper of the present invention also enables variable and constant beam spot size by manipulating the geometry of the helical apertures, thus varying the resultant beam power. In one embodiment, it is possible to manipulate the actual width of the aperture to alter the beam spot size. In one embodiment, the width of the helical aperture varies along the length of the spin-roll chopper cylinder to compensate for the varying distance of the aperture from the center of the source and allow for uniform beam spot projection along the scan line. Thus, in one embodiment, the farther the aperture is away from the source, the narrower the width of the helical aperture to create a smaller beam spot size. In one embodiment, the closer the aperture is to the source, the wider the helical aperture to create a larger beam spot size. This structure is described in greater detail below. When employed in a body scanning system, it is possible to vary the pitch and roll and width of the helical apertures such that more beam scanning power is directed towards areas of the body (hair, feet, etc) that require more detail and resolution and less power is directed towards areas of the body (midsection, etc.) that are more sensitive to radiation. Helical slits 104 also ensure that the projection of the X-ray beam is not limited by the dual collimation of the two slits. As described in greater detail below, dual collimation refers to the concept whereby the X-ray beam will pass through two helical slits at any given point in time. The resultant X-ray beam trajectory 130 is also shown in FIG. 1 and described in greater detail with respect to FIG. 10 below. In one embodiment, a pair of helices will produce one travelling beam. In another embodiment, additional pairs of helices may optionally be added to produce additional travelling beams depending upon scanning requirements. It should be noted that the chopper wheel of the prior art is only capable of producing one scanning beam. In an embodiment of the present invention a plurality of viewing angles ranging from sixty degrees to ninety degrees can be obtained through the helical slits in the spin-roll chopper. In one embodiment, the scan angle is a function of the distance between the spin-roll chopper and both the source and the target. In addition, the overall height and diameter of the spin-roll chopper affects the viewing angle. The closer the spin-roll is placed to the source, the smaller the spin-roll chopper will need to be and similarly, the farther the spin-roll chopper is placed from the source, the larger the spin-roll chopper would need to be. FIG. 2 illustrates a beam chopping mechanism using the spin-roll chopper described with respect to FIG. 1. Referring to FIG. 2, the cylindrical spin-roll chopper 202 is placed in front of a radiation source 204, which, in one embodiment, comprises an X-ray tube. In one embodiment, rotation of the chopper 202 is facilitated by including a suitable motor 208, such as an electromagnetic motor. In another embodiment, as described in greater detail below, magnetic bearings are employed to facilitate rotational movement of the spin-roll chopper of the present invention. The speed or RPM of rotation of the spin-roll chopper system is dynamically controlled to optimize the scan velocity. In one embodiment, the spin-roll chopper system is capable of achieving speeds up to 80K RPM. In one embodiment, a radiation shield (not shown) is provided on radiation source 204 such that only a fan beam of radiation is produced from the source. The fan beam of radiation emits X-rays and then passes through the spin-roll chopper, which acts as an active shutter. Thus, there is only a small opening when the spin-roll chopper, and therefore helical apertures are rotating, which provides the moving flying spot beam. FIG. 2 also shows a conventional, prior art disc chopper wheel 210 superimposed upon the source along with the spin-roll chopper. It can be seen from FIG. 2 that chopper wheel 210 is substantially larger than spin-roll chopper 202. For prior art chopper wheels, because of the round nature of the chopper wheel itself, the resultant flying spot beam has different acceleration and deceleration coming in right on the axis. Also, the chopper wheel itself has only one opening at each point that the ray passes through. Since the geometrical characteristics of the singular aperture cannot be changed, the farther the slit is from the center, the bigger the beam, and the closer the slit is from the center, the smaller the beam. Further, the velocity and spot size can only be mechanically manipulated using the prior art chopper wheel, by varying the speed of the motor attached to the chopper wheel. It should be noted, however, that since there are multiple apertures in the disc chopper wheel, there will always be a variance in the frequency and the scanning line because it is difficult to create each aperture such that they behaves in the exact same manner, as is known to those of skill in the art. The spin-roll chopper of the present invention overcomes these disadvantages because it is designed such that the frequency is continuous throughout. FIGS. 3A to 3D illustrate a geometrical rendering of a flying X-ray spot beam projection obtained by using the spin-roll chopper of the present invention, described in FIG. 1, showing empirical data captured at five degree increments of a total scanning beam traversal of +45 degrees and spin-roll chopper rotation of −90 to +90 degrees. Thus, to generate empirical data, the scan is frozen in time at 5 degree increments of a total scanning beam traversal of 45 degrees. It should be understood, however, that the movement of the spin-roll and traversal of the scanning beam are continuous in application. Referring to FIGS. 3A through 3D simultaneously, radiation emitted by a radiation source 302, such as an X-ray source, is modulated by the spin-roll chopper 304. The radiation beam, at each rotation, passes through two helical slits 315 of the chopper 304 to produce the resultant beam spot projection pattern (target) 306, in the “target” plane 308 which, in one embodiment, is perpendicular to the plane 310 of the X-ray source and parallel to the plane 312 of the chopper 304. In one embodiment, “target” plane 308 is located 18 inches from the source 302. It should be noted herein that these scan points, while empirical data points, are representative of real motion of the beam and chopping mechanisms, and are presented to show the advantages of the present invention. Thus, it should be understood that the true movement of the traversing radiation beam and rotation of the spin-roll chopper are continuous. FIG. 3B is a diagram showing the linear displacement values between flying spots and the relative shape and size of the flying spots that result from using the spin-roll chopper of the present invention, where the empirical data represents five degree increments of a total scanning beam traversal of 45 degrees and spin-roll chopper rotation of −90 to +90 degrees. As shown more clearly in FIG. 3B, in one embodiment, the beam spot pattern 306 produced exhibits characteristics consistent or superior to that of detection systems using prior art wheel chopping mechanisms. As mentioned above, the spin-roll chopper 304 allows for customization of the size and position of the beam spot 306 by modifying the helical aperture width and helical pitch and roll along the cylinder. FIG. 3B illustrates exemplary values of the linear displacements 320, at scan plane 308, along with projected target widths 325 and projected target heights 330 for angular rotations of the cylinder varying from −90 to +90 degrees. The resultant beam spot 306 is trapezoidal in shape, in one embodiment. The greater the height of the trapezoidal spot and the narrower the width of the trapezoidal spot, the higher the resolution. Since the flying spot beam travels vertically, having a height that is longer in the flying direction yields better scan performance. This is because in “aggregating” the flying beam spot projections, taller adjacent beam spots will be closer to one another and overlap, thus creating a continuous scan line at a higher energy, with better resolution, resulting in a higher resolution image. In addition, the smaller the resultant flying spot, the greater the power, because it is more focused. FIG. 3C illustrates a view of the X-ray beam projection at the center line of the vertical spin-roll chopper plane 312, showing the X-ray beam 313 passing through two helical apertures 315 on spin-roll chopper 304 when the X-ray beam traverses from source 302 is at the 45 degree position. FIG. 3D illustrates the X-ray beam projection at the center line of the vertical spin roll chopper plane as the radiation beam passes through the two helical slits of the spin-roll chopper, illustrating empirical data at five degree increments of a total scanning beam traversal of +45 degrees and spin-roll chopper rotation of −90 to +90 degrees. As shown in FIG. 3D, the beam 340 will pass through a first aperture point 342 on the spin-roll chopper helical aperture 315a and then propagate through a second aperture point 344 on the spin-roll chopper helical aperture 315b. The spin-roll chopper of the present invention provides a vertically moving beam spot with substantially constant velocity to allow for equal illumination of the target, unlike the prior art spinning disc chopper wheel. Thus, the spin roll chopper of the present invention moves and projects the beam spot substantially precisely and at a substantially constant speed. Also, the spin roll allows for the beam to be substantially equal in size at all points on the object. Thus, the radiation is a function of power and distance and using the spin roll the speed of the beam can be controlled precisely for even power distribution of the flying beam (such that power and distance are equal at all points). Again, using the spin roll chopper of the present invention attenuation to the shape of the scanning beam can be provided such that it will change the shape with the axis of the scanning beam itself. The distinctions between a conventional chopper wheel and the spin roll chopper of the present invention are described with respect to FIGS. 4A, 4B, 4C, 5A, 5B, 6A, 6B, 7A, 7B, 8A, 8B, 9A, and 9B. FIG. 4A is a table providing empirical data for a plurality of beam spot/target parameters obtained using a prior art disc wheel chopper, where data is provided at five degree increments of a total scanning beam traversal of −45 to +45 degrees. FIG. 4A, comprising parts 4A-1 and 4A-2, shows variations of a plurality of parameters for various angular displacements 405 of the source and thus, beam, such as but not limited to linear displacement 410 in the scan plane (representing a slice somewhere along the length of the distance from source to target); scan displacement 415 between points (where the points are flying spots arbitrarily chosen to provide empirical data); projected width 420; projected target height 425; and projected target size 430, all of which are described in greater detail below. FIG. 4B illustrates the resultant beam projection from using a prior art chopper wheel 440, showing that the width of the beam 442 and size of the resultant spot 444 vary across the scan. Persons of ordinary skill in the art would appreciate that a conventional chopper wheel comprises four slits, each one at 90 degrees from the other on the periphery of the flange. It is not realistic, however, to assume that these slits will be manufactured and cut at exactly 90 degrees. Thus, when the chopper wheel is rotated, not only is there a skew due to the inexact nature of these slits, but a skew due to the beam size depending on the distance of the slit and thus beam from the center of the chopper wheel as described above. In addition, on the prior art chopper wheel, the size of the slit cannot be easily manipulated as there is only one opening at each point and not a continuous slit. This results in the flying spot to be at distinct and uneven distances from each point on the chopper wheel. FIG. 4C is a table providing empirical data for a plurality of beam spot/target parameters obtained using the spin-roll chopper of the present invention, where data is provided at five degree increments of a total scanning beam traversal of −45 to +45 degrees and a spin-roll chopper rotation of −90 to +90 degrees. Thus, FIG. 4C, comprising parts 4C-1 and 4C-2, shows variations of a plurality of parameters for various angular rotations 450 of the spin-roll chopper of the present invention and various angular displacements 452 of the source and thus, resultant beam, such as, but not limited to linear displacement 454 in the scan plane (representing a slice somewhere along the length of the distance from source to target, and in this case 18 inches); scan displacement 456 between points (where the points are flying spots arbitrarily chosen to provide empirical data); spot size width 458 at the vertical plane located at the center line of the spin-roll chopper and along the z-axis; spot size height 460 at the vertical plane located at the center line of the spin-roll chopper and along the z-axis; spot size area 462 (in square inches) at the vertical plane of the center line of the spin-roll chopper and along the z-axis; projected target width 464 across the x-axis vertical plane of the center line of the spin-roll chopper and along the z-axis; projected target height 466 along the z-axis at the vertical plane of the center line of the spin-roll chopper and along the z-axis; and projected target size 468, vertical plane of the center line of the spin-roll chopper and along the z-axis, all of which are described in greater detail below. FIG. 5A is a graphical illustration of the variation of the linear displacement of the beam spot, in the scan plane, using the prior art disc wheel chopper, where data is provided for a total scanning beam traversal of −45 to +45 degrees. It has been found that these spots track in patterns of four, representing the four slits in the wheel. FIG. 5A shows a graph wherein the beam spots have variable linear displacement 505a of spots in the scan plane for the chopper wheel as compared to linear displacement 505b for the spin-roll chopper shown in FIG. 5B. FIG. 5B is a graphical illustration of the variation of the linear displacement of the beam spot, in the scan plane, using the spin-roll chopper of the present invention, where data is provided for a total scanning beam traversal of −45 to +45 degrees and a spin-roll chopper rotation of −90 to +90 degrees. The resolution depends on how the chopper wheel is spun and at what velocity, as described in detail above. The faster the chopping mechanism is spun, the smaller the variance in frequency. The spin-roll chopper of the present invention can be spun at RPMs up to 80K. FIG. 6A is a graphical illustration of the variation of scan displacement of the beam spot using the prior art disc wheel chopper, where data is provided for a total scanning beam traversal of −45 to +45 degrees, showing that the scan displacement 610a between points is skewed for the chopper wheel. FIG. 6B is a graphical illustration of the variation of scan displacement of the beam spot using the spin-roll chopper of the present invention, where data is provided for a total scanning beam traversal of −45 to +45 degrees and a spin-roll chopper rotation of −90 to +90 degrees, showing, however, that the scan displacement 610b is substantially straight for the spin roll chopper as shown in FIG. 6B. This is because in the spin-roll chopper of the present invention there are two helical slits that overlap at every 180 degrees. Thus, the radiation beam has two slits to run through such that at one point in time, the X-rays will pass through both slits to create the beam spot. This is referred to as dual collimation and also prevents frequency deviation thereby keeping the frequency substantially constant. Since the slits in the spin roll are continuous, there is less error in the “distance between slits”, while with the chopper wheel it is, in practice, quite difficult to get the slits at exactly 90 degrees from one another. In accordance with an embodiment of the present invention, at certain distances from the center of the beam, the helical slit (of the spin roll chopper) is kept wider than others. FIG. 10 shows a mathematical expression of the trajectory 1005 of the beam using a single source, in accordance with one embodiment. In order to get the dimensions of the helical cuts in the spin-roll cylinder, one dimension of this trajectory was removed. More specifically, the slit is narrower at the top 1010 because there is a greater distance for the beam to travel. Note that when an X-ray beam travels through any opening, the beam is collimated. The farther the beam travels, the wider the resultant “spot” (fan beam) is at the end of the beam. By making the slit narrower at the top 1010, this greater distance and beam widening is accounted for. In addition, the slit is made wider where the distance to the object is shorter, such as at point 1015. Also, persons of ordinary skill in the art should appreciate that by controlling the size of the slit one can control the density of the beam that is projected straight through. FIG. 7A shows a graphical illustration of the variation of projected target/beam spot width using the prior art disc wheel chopper, where data is provided for a total scanning beam traversal of −45 to +45 degrees, while FIG. 7B is a graphical illustration of the variation of projected target/beam spot width using the spin-roll chopper of the present invention, where data is provided for a total scanning beam traversal of −45 to +45 degrees and a spin-roll chopper rotation of −90 to +90 degrees. FIG. 7B shows that, for the spin-roll, there is equal resultant beam/spot width 715b throughout, because the slit is wider at shorter distances from the object (under inspection) and narrower at longer distances from the object to compensate for this distance (−90 degrees to +90 degrees)—as compared to the relatively varying beam/spot width 715a for the chopper wheel as shown in FIG. 7A. FIG. 8A is a graphical illustration of the variation of the projected target/beam spot height using the prior art disc wheel chopper, where data is provided for a total scanning beam traversal of −45 to +45 degrees, while FIG. 8B is a graphical illustration of the variation of projected target/beam spot height using the spin-roll chopper of the present invention, where data is provided for a total scanning beam traversal of −45 to +45 degrees and a spin-roll chopper rotation of −90 to +90 degrees. Thus, FIG. 8A shows that for the chopper wheel the projected target height 820a varies significantly when compared to the projected target height 820b, in FIG. 8B, for the spin-roll. FIG. 9A is a graphical illustration of the variation of projected target/beam spot size using the prior art disc wheel chopper, where data is provided for a total scanning beam traversal of −45 to +45 degrees, while FIG. 9B is a graphical illustration of the variation of projected target/beam spot size using the spin-roll chopper of the present invention, where data is provided for a total scanning beam traversal of −45 to +45 degrees and a spin-roll chopper rotation of −90 to +90 degrees. Again, as shown in FIG. 9A the projected target size 925a for the chopper wheel varies significantly as compared to the projected target size 925b of the spin-roll as shown in FIG. 9B. FIG. 11 illustrates the design and fabrication of the spin-roll chopper, in accordance with an embodiment of the present invention. As illustrated, a hollow tungsten cylinder 1102 machined with helical slits 1104 forms the inner layer of spin-roll chopper assembly 1100. The cylinder 1102 is formed from one or two pieces of tungsten formed together. Since tungsten is opaque to ionizing radiation, an X-ray beam will not pass through it. A carbon fiber fabric 1106 (such as, but not limited to Kevlar) is wrapped around the tungsten cylinder 1102. The carbon fiber is transparent to the X-ray beams and thus, creates a window (moving aperture) through which the beam passes in the shape of the helical slits cut out of the tungsten cylinder 1102. Further, in one embodiment, an epoxy shield 1108, such as a polyethylene epoxy shield is used to bind the carbon fiber 1106 to the tungsten cylinder 1102. The epoxy shield also creates a window (moving aperture) through which the beams pass in the shape of the helical slits cut out of the tungsten. The epoxy shield prevents unraveling of the carbon fiber cover. In a first embodiment, the cylinder is machine spun and fabricated from brass. In one embodiment, in order to form the epoxy shield around the carbon fiber coated tungsten cylinder, a chemical setting technique is employed whereby at least two liquid components are mixed together and upon mixing, the chemical components form a solid epoxy coating. In one embodiment, the solid epoxy coating formed is a polyethylene epoxy. In one embodiment, in order to form the epoxy shield around the carbon fiber coated tungsten cylinder, a thermal setting technique is employed whereby the cylinder is placed into a spinning and heated epoxy powder mold (at say, 400 degrees C.) which is heated to the melting point to create a light structure with tungsten and Kevlar inside. In one embodiment, the epoxy shield 1108 has sufficient hardness, strength, and durability to withstand centrifugal forces of up to 80K RPM. In one embodiment, the spin roll chopper assembly 1100 is dynamically controlled for rotation using an electromagnetic motor drive. In one embodiment, the light-weight chopper assembly 1100 is spun using a magnetic bearing assembly 1110, which eliminates the need for a motor to spin the chopper, thereby contributing to keeping the chopper assembly further lightweight. The magnetic bearing assembly 1110 comprises a magnetic rotor 1110a, and a magnetic bearing stator 1110b. Besides a spinning motion, the magnetic bearing assembly 1110 is also used to provide magnetic levitation for the chopper during power-up (ON state) and power-down (OFF state), as well as during accidental power-failure. Depending upon the material of the cylinder 1102 and the bearings used to support the rolling movement of the chopper, various ranges of RPMs are achievable. For example, a bare cylinder 1102 fabricated from brass with diamond bearings can be spun to achieve up to 1K RPMs; a bare cylinder 1102 fabricated from tungsten with diamond bearings can achieve up to 4K RPM; while a bare cylinder 1102 fabricated from tungsten and coated with Kevlar and epoxy and spun using diamond bearings can achieve up to 80 K RPM. FIG. 12 illustrates the assembled spin roll chopper cylinder 1200, along with the magnetic bearing assembly 1210. Persons of ordinary skill in the art would appreciate that magnetic bearings support the rolling motion of the spin-roll chopper without physical contact and permit relative motion with very low friction and no mechanical wear. In one embodiment, referring back to FIG. 11, the space between the rotor 1110a and the stator 1110b is filled with an inert gas, such as Argon, to suspend the spin roll in space and enable higher RPMs. A magnetic bearing works on the principle of electromagnetic suspension and in one embodiment comprises an electromagnet assembly, a set of power amplifiers which supply current to the electromagnets, a controller, and gap sensors with associated electronics to provide the feedback required to control the position of the rotor within the gap. The power amplifiers supply equal bias current to two pairs of electromagnets on opposite sides of a rotor. This constant tug-of-war is mediated by the controller which offsets the bias current by equal but opposite perturbations of current as the rotor deviates by a small amount from its center position. The gap sensors are usually inductive in nature and sense in a differential mode. The power amplifiers in one embodiment are solid state devices which operate in a pulse width modulation (PWM) configuration. The controller is a microprocessor or DSP. It should be appreciated that since the spin-roll chopper of the present invention can be spun very fast, it is possible to use the chopper with multiple X-ray beams. In one embodiment, four beams are used, with four separate corresponding detector panels to determine which beam is active. The present invention provides that the distance of the spin-roll chopper is directly correlated with a minimum scan height. This allows for longer distance from source to the target, thereby extending the depth of field with respect to dose rate. Therefore, for a given depth of imaging, a smaller radiation dose is required in a threat detection system employing the spin-roll chopper of the present invention, as compared to other systems known in the art. In one embodiment, due to the kinematics and resultant moment of inertia of the spin-roll chopper of the present invention, it is insensitive to orientation. In an exemplary embodiment, the spin-roll chopper is employed in a detection system which is implemented as a walk-through detection system. The novel design of the spin-roll chopper enables utilization of low-level radiation doses to detect weapons and dangerous materials, regardless of whether they consist of metal or low Z materials. Besides being employed for screening of passengers at airports and railway stations, at open and crowded venues such as stadiums and shopping malls, applications of the spin-roll chopper of present invention may be extended detection systems for inspecting the contents of vehicles and containers at transit points such as ports, border crossings and customs checkpoints, and other secure locations. The above examples are merely illustrative of the many applications of the system of present invention. Although only a few embodiments of the present invention have been described herein, it should be understood that the present invention might be embodied in many other specific forms without departing from the spirit or scope of the invention. Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive.
042591554	description	DETAILED DESCRIPTION OF THE INVENTION In the above drawings, FIG. 1 is provided mainly to show the problem solved by the present invention. In this figure a fuel assembly supporting structure is shown as having the top and bottom end pieces 4 connected together in interspaced relationship by control rod guide tubes 2 and with a plurality of the interspaced fuel rod spacer grids 3 positioned between the end pieces and forming the openings 3' through which the fuel rods are to be inserted. The spacer grids form a pattern of these openings designed to interspace fuel rods inserted in the openings, in accordance with the nuclear physics involved by the particular reactor for which the ultimate fuel assembly is intended. The structure shown by FIG. 1 is generally of the type used by a pressurized-water reactor fuel assembly, but with the fuel rods inserted in the openings, the assembly could also be used in the case of a reactor involving the higher operating temperatures, and particularly in a gas-cooled reactor operating at temperatures within the range from about 300.degree. to 600.degree. C., for example. It is to be appreciated that FIG. 1 is provided largely to show that in any reactor core fuel assembly, a plurality of interspaced fuel rod spacer grids are required to properly position the fuel rods in their mutually parallel and laterally interspaced relationship. In all modern reactors using metal clad fuel rods, comparable fuel assemblies are involved because the number of fuel rods required to form a core is so great that for manipulating convenience during refueling, for example, the fuel rods are integrated into assemblies involving the use of fuel rod spacer grids of one type or another. In all cases, the spacer grids have fuel rod openings or passages of substantially greater cross-sectional extent than that of the fuel rods themselves, therefore, requiring contact or supporting elements to maintain the fuel rods properly centered within the openings of these spacer grids. A possibly more common type of fuel assembly, as used in the case of gas-cooled reactors with which the present invention is concerned, comprises a tubular metal duct within which the fuel rod spacer grids are mounted, the configuration in that case generally being hexagonal in cross section, an example of such a spacer grid being shown by FIG. 5. However, regardless of the cross-sectional contour of the fuel assembly, when used in the core of a gas-cooled reactor, the fuel rod centering elements must be rigidly made of solid metal and effect rigid and solid contact with the metal clad fuel rods engaged by the elements, because the high operating temperatures prohibit the use of contact elements functionally relying on any kind of metal resilient, elastic or spring elements. FIGS. 2 and 3 show the square meshes 3 of spacer grids of the type shown by FIG. 1, these grids forming the openings by criss-cross flat web members. In both figures, the metal claddings 2a of the fuel rods have radially projecting and axially extending fins 22 transversely engaged in FIG. 2 on both opposite sides by flanges 32 projecting inwardly from the surfaces of the grid 3 defining the fuel rod opening, while in FIG. 3 the grid 3 has flange 33 projecting inwardly and engaging only one side of the axially extending fins 22. In both cases, the flanges which extend inwardly from the spacer grid surfaces forming the fuel rod's opening, are designed to lock the fuel rod against both rotative and transverse motions, the locking action being effected by interengaging, rigidly positioned, metal elements having intercontacting surfaces which must rub on one another, possibly under substantial pressure in the circumferential direction of the fuel rod, when working under the operating conditions of a gas-cooled reactor. Heretofore, due to conventional manufacturing practices, such rubbing metal surfaces have been smoothly finished. Furthermore, because it is desired that the fuel rods be able to freely move, both axially and radially, while thermally expanding and contracting, and relative to the spacer grids, normal engineering technology clearly suggested the use of smooth bearing surfaces rubbing on one another. However, as previously noted, in spite of such an assumption based on the prior art knowledge, in the case of a fuel assembly operating within the temperature ranges encountered in a case of a gas-cooled reactor, instead of sliding smoothly relative to each other, it has been found that the surfaces stick relative to each other, resulting in the spacer grids locking or partially locking, the metal clad fuel rods against movement in any direction relative to the spacer grids. Incidentally, it is to be noted that as shown by FIGS. 2 and 3, the rigid, inflexible metal contact elements, although locking the fuel rods against transverse displacement, do permit the fuel rod metal claddings to thermally expand and contract both axially and radially, the fins 22 having free ends and being restrained only in directions transversely with respect to the fins or, in other words, circumferentially with respect to the fuel rods. FIG. 4 represents an attempt to in the best possible way illustrate the side surfaces of, in this instance, the projections 33 shown by FIGS. 2 and 3. As illustrated, the surfaces 33a of the projections 33 are roughened as by being grooved at right angles to the axial direction of the fuel rods. In the case of FIG. 5, showing a spacer grid perhaps more typical of the fuel assembly of a gas-cooled reactor, the spacer grid 3a, in this case, provides solid inwardly extending projections or axially extending posts 31' having inner ends which directly in abutting relationship engage the cladding of the fuel rods, 2a, this metal cladding enclosing the nuclear fuel 25. With such a simple arrangement of rigid strutting or centering metal elements 31', radial expansion of the fuel rod results in very high rubbing pressures between the inner ends of the elements or posts 31' and the outsides of the metal cladding 2a, but at the same time, the fuel rods must move axially relative to the spacer grids having the elements 31'. With the above in mind, FIG. 7 in vertical cross section shows that the end face of each of the rigid metal parts 31', and which is the face engaging the metal cladding 2a of the fuel rod, is formed with transversely extending grooves 35. In the case of the spacer grid of FIG. 5, specially designed for use in the tubular gas duct of a gas-cooled reactor fuel assembly, a piece of solid metal is drilled to form the beginnings of the fuel rod openings 3b shown by FIG. 5, the inside diameters of the holes coinciding substantially with the outside diameters of the metal clad fuel rods involved, as exemplified by a diameter of about 9 mm, for example. Then by a screw threading machine, these holes are internally screw-threaded to form valleys having a depth of about 0.6 mm. Thereafter, by, for example, the spark-erosion process, the metal is worked off in such a manner that the hexagonal plate of FIG. 5 is produced, leaving the projections 31' of FIG. 6, now having their inner end faces screw-threaded as shown at 35 in FIG. 7. Alternately, the roughening of the inner ends of the projections 31' might be effected also by the spark erosion technique. The method which is more advantageous depends on the design of the spacer grid involved as well as on its material, spacer grids normally being made of stainless steels, although other materials, exemplified by nickel and zirconium alloys, might also be used. The fuel rod claddings are normally tubes of corresponding materials, although the metal alloy of the cladding and that from which the spacer grids are made, need not be the same. The same kind of grooved surface can also be applied to the fins shown by FIGS. 2 and 3 which, in such cases, are normally soldered or welded to the normal cladding 2 of the fuel rods. In such cases, the surface roughening can be given to the surfaces of the fins 22 prior to their attachment to the fuel rod cladding tubes. The principles of the present invention are particularly applicable in the case of the appropriate components of the fuel assemblies used in gas-cooled reactors which use helium, or possibly carbon dioxide, as the gas coolant. In general, the principles are applicable to any fuel rod assembly using metal clad fuel rods and spacer grids having fuel rod centering or contact elements, of course, also made of metal, which operate at temperatures high enough to introduce the problem of the fuel rod and spacer grid contact elements stocking together. It is assumed that such sticking phenomena is caused in the case of smooth, unroughened rubbing surfaces producing by abrasion, particles of fine particle size which, therefore, are capable of welding the parts together with the temperatures involved. With adequately roughened surfaces, these particles pass off from the tips or peaks of the roughening and into the valleys, preventing the interwelding action. Particularly considering that the fuel rod assembly of all coolant reactor designs operate in vertical positions, the use of a roughening having the characteristics of screw threads, or in other words, which are made as helical cuts in one or both of the interrubbing parts, is of particular importance because the helical valleys thus formed provide paths down through which abrasion products, possibly in the form of very fine particles of metal, can pass gradually downwardly so as to work off from the bottom ends of the grooves or threads and fall free from the locations where they might otherwise cause undesired interwelding action. In FIG. 6 the rod's cladding directly forms a metal surface contacted by the spacer grid elements; in FIGS. 2 and 3 the rod also forms metal surfaces, in this case via the fins secured to and, in effect, forming parts of the rod. In all cases the spacer elements contact a metal surface formed by the rod.
048428051	claims	1. A method of detecting the fall of an anti-reactive element into the reactor of a nuclear power station, said method being characterized by the fact that variations are monitored firstly in the nuclear power of the reactor under the control of a loop for regulating said power and secondly of at least one external parameter related to events outside the reactor and used in calculating the power reference value which is supplied to said regulation loop in order to control the reactor, said fall being detected by the fact that a rapid drop in said power is detected while no large external parameter variation is detected with a predetermined time relationship to said rapid drop. 2. A nuclear power station having a reactor protected against the fall of an anti-reactive element, said reactor comprising: a core containing fissile fuel elements for maintaining a nuclear reaction providing nuclear power; a cooling fluid circuit having a branch passing through said core to remove said power in the form of heat and to enable said heat to be utilized outside the reactor; measurement means for continuously measuring the current nuclear power of the reactor; anti-reactive regulation elements suitable for reversibly reducing said power; and regulation drive means controlled by said power measurement means in order to cause said regulation elements to penetrate to a greater or lesser extent into said core depending on whether the current nuclear power is greater than or less than a power reference value, in such a manner as to constitute a nuclear power regulation loop and to enable the reactor to be controlled by varying said reference value, with any reaction of said loop giving rise to transient power variations before settling if possible; at least one anti-reactive element being suspended above a passage into said core such that an accidental fall of said element causes it to penetrate into the core, thereby initiating a rapid decrease in nuclear power, followed by a reaction from said regulation loop, which reaction is accompanied by transient variations in said power prior to said power settling back on its value prior to said fall; said reactor further including stop means under the control of a reactor stop signal; and accident detection means for providing such a reactor stop signal after an accident in the core, in particular such a fall of an anti-reactive element, and thus for protecting the reactor against the damage which would result if said reaction were to continue without the accident being repaired; said power station further including: a power outlet member receiving inlet thermal power from another branch of said cooling fluid circuit and providing variable and/or interruptible outlet power to a load; and at least one nuclear power regulating system receiving the values of parameters external to the reactor such as parameters relating to the operation of said power outlet member, and generating said power reference value in response thereto in order to continuously match the current nuclear power to variations in said parameters so that if such a variation is large it is capable of causing a rapid variation in nuclear power; said power station being characterized by the fact that said accident detection means comprise a circuit specifically for detecting the fall of an anti-reactive element, said circuit being suitable for detecting firstly rapid drops in nuclear power and secondly said large variations in at least one said external parameter, and for providing a said reactor stop signal (15) when such a drop in nuclear power is detected with no such external parameter variation in a predetermined time relationship with said drop. a nuclear power monitoring circuit comprising differentiating means (4c) receiving a measurement signal representative of said power (3) and delivering a derivative signal (11) which is differentiated with respect to time; and threshold means (6j) receiving said derivative signal and delivering a signal (12j) representative of a rapid drop in nuclear power when said power drops at a rate greater than a predetermined rate; at least one external parameter monitoring circuit, each such circuit including differentiator means (4a, 4b) receiving a measurement signal (1, 2) representative of such a parameter and delivering a derivative signal (9, 10); and threshold means (6e, 6f, 6g, 6h) receiving the, or each, said derivative signal and providing a signal (12e, 12f, 12g, 12h) representative of large variation in an external parameter when any such derivative signal leaves a predetermined range; and a logic circuit (13, 14) having its inputs connected to said monitoring circuits in order to provide said reactor stop signal (15) on receiving a signal representative of a rapid drop in nuclear power (optionally after a delay) without receiving a signal representative of a large variation in an external parameter (optionally after a delay). said logic circuit (13, 14) comprising means (13) for logically adding the output signals from said monitoring circuits. said logic circuit (13, 14) providing said reactor stop signal (15) when said signal representative of a rapid drop in the current nuclear power (12j) is present and none of said delayed and non-delayed signals representative of a large variation in an external parameter is simultaneously present. said cooling fluid circuit includes cooling loops each of which comprises a primary pressurized water circuit and a secondary water and steam circuit, the primary circuit cooling said core, the secondary circuit including at condenser and a steam generator heated by said primary circuit, each of said circuits including a pump for circulating water; said means for measuring nuclear power are chambers sensitive to return flux and disposed in said core; said anti-reactive regulation elements are control clusters each comprising a plurality of vertically-suspended rods that penetrate to a greater or lesser extent into passages in said core, each of said cluster simultaneously constituting one of said anti-reactive elements capable of suffering an accidental fall; said power outlet member comprising at least one steam turbine driven by the steam from at least one of said secondary cooling fluid circuits and driving an alternator; said load being an electricity supply grid fed from said alternator; control means being provided on said cooling fluid secondary circuit to control the steam pressure at the inlet to the turbine as a function of the turbine speed and/or the electrical conditions at the alternator outlet, in such a manner as to constitute a regulation loop for the turbine-alternator assembly; and circuit breaking means are provided to isolate the alternator from the grid in the event of a grid fault or when necessary for power station operation. said power station being characterized by the fact that said circuit for detecting a fall includes two of said circuits for monitoring large variations in external parameter, one of said circuits (4b, 6g, 6h) detecting variations in steam pressure at the inlet to the turbine, and the other (4a, 6e, 6f) detecting variations in the speed of the pump in said primary circuit. 3. A power station according to claim 2, characterized by the fact that said circuit for detecting a fall comprises: 4. A power station according to claim 3, characterized by the fact that said circuit for detecting a fall comprises a plurality of said circuits for monitoring external parameters (4a, 4b, 6e, 6f, 6g, 6h) each detecting variations in a corresponding external parameter. 5. A power station according to claim 3 characterized by the fact that said circuit for detecting a fall comprises at least one delay means (5a, 5b) for delaying the measurement signal or a signal (9, 10) derived from the measurement signal (1, 2) of at least one of said external parameters in order to provide at least one signal (12a, 12b, 12c, 12d) representative of a large variation in an external parameter which signal is delayed relative to another non-delayed signal (12e, 12f12g, 12h) representative of a large variation in the same parameter; 6. A power station according to claim 4, wherein: 7. A power station according to claim 6, wherein said pump for the primary cooling fluid circuit is driven by a motor fed with electricity from said alternator such that the speed of said pump varies with the speed of said alternator and said turbine;
	summary
047284846	summary	BACKGROUND OF THE INVENTION The present invention relates to an apparatus for handling a control rod driving mechanism of a nuclear reactor. More particularly, the invention is concerned with an improvement in an apparatus for mounting and demounting, at the time of periodical inspection of a nuclear reactor, the control rod driving mechanism on and from a housing attached to the pressure vessel of a nuclear reactor, as well as for transporting the control rod driving mechanism to and from a place suitable for inspection and maintenance. The control rod driving mechanism (referred to as "CRD", hereinunder) has to be demounted and then mounted at the time of periodical inspection of the nuclear reactor. The handling of CRD essentially requires a suitable countermeasure for reducing the radioactive dosage, because the work for handling CRD has to be done in an atmosphere of a high rate of radioactive dosage. The specification of U.S. Pat. No. 4,292,133 discloses an apparatus for replacement of CRD. This apparatus has a CRD mounting/demounting means and a CRD transporting means which are constructed separately, such that the replacement of the CRD is conducted by cooperation between these two means. These two means are equipped with respective trucks for carrying the CRD. In order that the cooperation between these two means can be conducted satisfactorily, it is essential that the trucks of both means are aligned with each other at a high precision. In the replacement of CRD, it is necessary to operate a mast driving mechanism such as to horizontally lay down the mast in advance to the transportation of the CRD to and from the mounting position. This in turn requires the CRD mounting/demounting means to clear the mast because the mast has a large length. The replacement of the CRD which is disposed in the peripheral region of the reactor and, hence, closest to a pedestal, requires the greatest care in order to avoid any risk of interference between various equipments and pipes on the pedestal wall and the CRD mounting/demounting means of the apparatus when this means is retracted in advance of the horizontal laying down of the mast. To avoid this risk, hitherto, a visual check or observation of the clearance between the pedestals and the CRD mounting/demounting sections by the operator has been necessary. SUMMARY OF THE INVENTION Accordingly, an object of the invention is to provide an apparatus for handling a CRD which is improved such that the positioning of this apparatus is remarkably facilitated. Another object of the invention is to provide an apparatus which can eliminate the necessity for the visual check or observation of the space in which the pedestals are disposed. Still another object is to obtain a compact CRD handling apparatus. To these ends, according to the invention, there is provided an apparatus for handling a control rod driving mechanism (CRD) comprising: a turn carriage provided in a space within a reactor container where a pedestal is provided; a truck adapted to run along the turn carriage; a mast provided on the truck; a mast driving means for driving the mast between an upright position and a horizontal position; a CRD cart accommodated by the mast; and a CRD mounting/demounting means secured to the mast and adapted to be moved up and down by the CRD cart such as to mount and demount the CRD in and from a CRD housing. The above and other objects, features and advantages of the invention will become clear from the following description of the preferred embodiments when the same is read in conjunction with the accompanying drawings.
	description	This application claims the benefit of U.S. Provisional Patent Application No. 62/672,688 filed on May 17, 2018, which is incorporated in its entirety by reference herein. The present invention relates to a radiation scatter protection system, and more particularly to protection system designed to limit exposure to radiation for both medical staff and patients. In the medical field, personnel are often required to work in close proximity to patients undergoing imaging procedures involving x-rays, commonly referred to as fluoroscopy. The hazard to the worker arises from x-rays scattered by the patient's body toward the worker. Although such scattered radiation has a lower energy level than the direct x-ray beam, it does maintain its ionizing potential. Exposure to this scattered radiation has the potential to produce a significant radiation hazard over the working lifetime of the worker. For this reason, workers traditionally wear a radiation shielding garment that places a protective barrier between the scattering tissues of the patient and the body of the worker. Traditionally such garments are made from a flexible rubber or polymer material within which is embedded powdered lead, a good absorber of x-rays. Unfortunately, lead garments are heavy and can cause significant injury to the wearer with daily use over a working lifetime. There has thus begun a search for lighter weight materials which can provide equivalent protection under the conditions of this job. An underlying principle of such reduced weight garments is that for a large portion of the x-ray energy levels commonly used in medical procedures, certain elements, provide greater attenuation per unit weight than lead. Until now, most workers have assumed that the testing of the effectiveness of such elements other than lead requires meeting the requirements of shielding from the effects of the direct x-ray beam from the x-ray source. It is now realized, however, that the danger to the worker is primarily caused by radiation reflected from the patient's body, so-called “scattered radiation”. An additional problem, however, arises from the fact that many of these lower atomic number heavy metals reradiate the x-rays they absorb, albeit at lower energy levels. This can lead to a problem where the exposure to the wearer is greater than that evident from the attenuation tests. According to an embodiment of the present invention, there is disclosed a radiation scatter protection system designed to attach to an X-ray table to limit exposure to radiation for both medical staff and patient. The radiation scatter protection system includes an arm board adapted to be disposed around an arm of the patient; an arm board shielding including one large sheet of shielding extending downward from the X-ray table and a plurality of additional sheets of shielding, removably mounted to the arm board; a sand bag shield including a plurality of sheets of top shielding and a plurality of sheets of bottom shielding which connect to an elongated, cylindrical sandbag; a side curtain shield hanging from the X-ray table; and a throw shield. According to an embodiment of the present invention, there is disclosed a method for attaching a radiation scatter protection system to an X-ray table to limit exposure to radiation for both medical staff and patient. The method includes disposing an arm board around an arm of the patient; removably mounting an arm board shielding including one large sheet of shielding and a plurality of additional sheets of shielding to the arm board; placing atop the patient a sand bag shield including a plurality of sheets of top shielding and a plurality of sheets of bottom shielding which connect to an elongated, cylindrical sandbag; hanging a side curtain shield from the X-ray table; and placing a throw shield atop the patient. In the description that follows, numerous details are set forth in order to provide a thorough understanding of the present invention. It will be appreciated by those skilled in the art that variations of these specific details are possible while still achieving the results of the present invention. Well-known processing steps are generally not described in detail in order to avoid unnecessarily obfuscating the description of the present invention. In the description that follows, exemplary dimensions may be presented for an illustrative embodiment of the invention. The dimensions should not be interpreted as limiting. They are included to provide a sense of proportion. Generally speaking, it is the relationship between various elements, where they are located, their contrasting compositions, and sometimes their relative sizes that is of significance. In the drawings accompanying the description that follows, often both reference numerals and legends (labels, text descriptions) will be used to identify elements. If legends are provided, they are intended merely as an aid to the reader, and should not in any way be interpreted as limiting. Physicians and allied clinical personnel, collectively referred to as medical staff, are commonly involved in medical procedures involving patients in which fluoroscopic and other types of radiation systems (such as computer tomography, or CT systems) are used for purposes of diagnostic detection or guidance procedures. These radiation systems allow the medical staff to peer into the body systems of a patient with minimal invasiveness. The images generated may be in the form of a single image, or a video feed, both of which may be live. For example, the anatomy of a patient may be illuminated using x-rays so that the medical staff can carry out medical procedures using a fluoroscopic viewing screen. In one case, x-ray fluoroscopy may be used to indirectly guide the placement of a surgical device within the patient during a surgical procedure. When working with a patient on an x-ray table, doctors and other medical personnel can be exposed to primary radiation that emanates directly from the source and/or exposed to secondary radiation that is scattered by an object such as the x-ray detector, the x-ray table, and even the patient. Traditionally, there have been apparatuses and methods for protecting and shielding against radiation in x-ray laboratories. Though there are numerous shapes and designs for protective shields, and although they may be constructed of various materials, they do not sufficiently protect against radiation exposure, and thus medical personnel must still wear heavy and encumbering leaded protective clothing. The radiation scatter protection system 10 (hereafter “protection system 10”) is designed to limit exposure to radiation for both medical staff and patients. It is also desirable to protect medical staff members from radiation in a way that does not interfere or limit them from conducting their medical procedures. FIGS. 1-8 illustrate the various components that collectively form the protection system 10. In general terms, the protection system 10 includes one or more plastic arm boards 12, arm board shielding 16, a sandbag shield 18 as shown in FIG. 7, a side curtain shield 20, and a throw shield 21. The plastic arm boards and the various shields described hereinafter are designed to minimize the risk of radiation exposure to both the medical staff, and the patient 22 during a medical procedure requiring the use of X-ray. An aluminum hanger to mount on the wall may be provided to store the elements of the protection system 10. As illustrated in FIGS. 2, 3, and 4, the plastic arm board 12 is disposed on the side of an X-ray table 23. The plastic arm board 12 is preferably manufactured from PETG (Polyethylene Terephthalate Glycol), also known as DACRON. DACRON is a condensation polymer obtained from ethylene glycol and terephthalic acid. Its properties include high tensile strength, high resistance to stretching, both wet and dry, and good resistance to degradation by chemical bleaches and to abrasion. The use of DACRON is advantageous for the present invention, since it is allows more X-rays to pass through arm board thickness than other plastics. The draw back to the use of PETG to form the plastic arm board is that the material is very har to work with and to form the radius bends 24 and 25, described herein after, is extremely difficult and tedious. Preferably, the plastic arm board 12 is formed of an approximately ¼″ thick PETG plastic sheet molded into a “C” shape with first and second ¾″ radius longitudinal bends 24 and 25, as seen in FIG. 4. It must be noted that the plastic arm board 12 may also be constructed with an “L” shape, with only one ¾″ radius longitudinal bend. Further, it must be noted that more than one plastic arm board 12 may be utilized to offer a greater amount of protection with additional shields. The plastic arm board 12 has exemplary overall dimensions of a width W of about 28″ of a lower horizontal leg 28. A vertical leg 32 has a height h of about 11″ between a first longitudinal bend 24 having a radius of about ¾″ radius and a second longitudinal bend 25 having a radius of about ¾″. The vertical leg 32 is preferably canted inward an angle x of about 5 and 15 degrees, and preferably about 10 degrees, off the perpendicular from the lower horizontal leg 28 to the vertical leg 32. An upper horizontal leg 29 extends inward from the vertical leg 32 and parallel to the lower horizontal leg 28.4. The first longitudinal bend 24 extends along the intersection of the upper horizontal leg and the vertical leg, and the second longitudinal bend 25 extending along the intersection of the lower horizontal leg and the vertical leg. The arm board 12 has a plurality of notches 34 cut into the curvature 26 formed along the length of the board along the first longitudinal bend 24. The notches 34 have exemplary dimensions of 1″ in wide by 1″ in length, although any desired dimensions may be utilized. In use, the notches 34 disposed through the arm board 12 accept corresponding knobs protruding from the arm board shielding 16, to hold the arm board shielding in place. As shown in FIGS. 2 and 3, with a patient 22 laying on an X-ray table 23, the bottom horizontal leg 28 of the arm board 12 is inserted under the X-ray table mattress 27, and the vertical leg 32 secures the patient's arm to the patient's side preventing the arm from swinging down and away from the table. The patient's weight holds the arm board 12 in place. The plastic arm board 12 blocks less X-rays from the emitter disposed under the X-ray table 23 (not shown), so that the emitter in use can generate less X-rays then previously required. If the Image Intensifier disposed above the patient (not shown) senses that not enough X-ray light is coming through the patient, the Image Intensifier will cause the emitter to generate more X-rays. It's understood that more the more X-rays the patient is subjected to, the more dangerous the procedure. Being that the plastic arm board 12 is constructed of DACRON, both the technician and the patient are less at risk of radiation exposure because less X-rays are being generated, than if a protection device similar to the plastic arm board 12 is used that is not made of composite materials including DACRON. FIGS. 5 and 6 illustrates the arm board shielding 16, which includes one larger sheet of shielding 36, extending downward from the top of table 23 to the floor. Three additional sheets of shielding 38a, 38b, and 38c overlap each other and are placed on the patient 22 and extend across the patient and above the table 23. The three sheets of shielding 38a, 38b, and 38c have one end that drapes over the arm board 12. All the shielding described herein is preferably constructed of a sheet of lead-impregnated rubber covered on both the back and the front sides with two sheets of 500 denier nylon cloth covering and sewn together around circumference of the shielding. The nylon cloth has a urethane coating on the inside surfaces against the sheet of lead-impregnated rubber for water proofing. The shielding 36, 38a, 38b, and 38c are fastened together, such as with bolts 40 and all attach to a sheet of durable plastic sandwiched in between the bottom of the shields 38a-38c, and the top of the shield 36. The durable plastic sheet is typically approximately ¼″ thick by 2″ wide by 28″ long and is provided to give lateral support to the shields. There are three knobs 16a, as seen in FIG. 4, bolted through the durable plastic sheet which correspond to the notches 34 of the plastic arm board 12. The shielding 36 protects against radiation emitted from between the table 23 and the floor. The shielding 36 has exemplary dimensions of 30″ wide by 24″ high. The sheets of shielding 38a, 38b, and 38c drape over the patient's body, and move independently from each other to allow medical personnel to move each piece of shielding independently when necessary to access a specific area of the patient's body. In an exemplary embodiment, the sheet of shielding 38a will be 10″ wide by 16″ long, the sheet of shielding 38b will be 12″ wide by 16″ long, and sheet of shielding 38c will be 10″ wide by 16″ long. The arm board shielding 16 will typically be positioned across the top of the patient's body, and hang down below the top part of the X-ray table 23. The sand bag shield 18, as illustrated in FIGS. 1 and 7, includes three sheets of top shielding 42a, 42b, 42c, (42a-42c) and three sheets of bottom shielding 44a, 44b, 44c, (44a-44c) all of which connect to an elongated, cylindrical sandbag 46, to hold the shielding in place across the patient. The top sheets of shielding (42a-42c) are rectangular in shape whereby the following exemplary dimensions may be utilized, although any appropriate dimensions may be used: shield 42a will be 10″ wide by 16″ long, shielding 42b will be 12″ wide by 16″ long, and shielding 42c will be 10″ wide by 16″ long. The bottom sheets of shielding (44a-44c) include shielding 44a being 10″ wide by 10″ long, shielding 44b being 12″ wide by 10″ long, and shielding 44c being 10″ wide by 10″ long. The sandbag 46 is preferably approximately 2″ in diameter and extends the width of top shielding 42a, 42b, 42c. The shielding 42a-42c and 44a-44c move independently from each other to allow medical personnel to move each piece of shielding when needed to access a specific area of the patient's body. The top shielding 42a-42c will typically be positioned across the top of the patient's body, while the bottom shielding 44a-44c will lay across the portion of the table where technician is located and will also hang down several inches below the top of the table 23. FIG. 8 illustrates the side curtain shield 20, which is one panel with exemplary dimensions of 30″ by 28″. First and second stainless steel rods 48 and 49 extend along the top 20a of the side curtain shield 20 and are secured thereto. The shield 20 hangs from the X-ray table 23 and can be secured to it with first and second “S” hooks 50 and 51, which attach to a stainless steel elongated hanger strip 52 that attached to the X-ray table 23. A throw shield 21, as seen in FIG. 1, may be included, having exemplary dimensions of a 20″ inch square. The throw shield 21 that may be used anywhere, generally to cover areas that may be exposed to radiation due to gaps in the shielding, usually caused by the relative size of the patient. An aluminum hanger (not shown) may be included, and formed of a long solid aluminum bar. The hanger includes one or more holes, and one or more pins looped over the top edge of the aluminum bar. Typical dimensions of the hanger is ½″ thick by 3″ wide by 20″ long. The hanger is utilized to neatly hang the various lead shielding components, described herein, so that they are not draped over other equipment in the room or hung over devices which take up further space in the procedure room. Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, certain equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, etc.) the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiments of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several embodiments, such feature may be combined with one or more features of the other embodiments as may be desired and advantageous for any given or particular application.
	summary
	claims	1. A tight connection device for tight connection between a system for feeding with powdery or granular materials and a container fitted with a filling orifice, where the said device includes:a stationary connection portion intended to be connected to the feed system,a moving connection portion which moves relative to the stationary connection portion along a vertical direction, said moving connection portion being intended to be connected to the filling orifice of the container, the moving connection portion including:a first part forming a support which is configured to move relative to the stationary connection portiona second part forming a downstream end of the moving connection portion and supporting at least one seal to accomplish a tight connection by contact with the contour of the filling orifice, said first part and said second part being connected by flexible sealing system such that the downstream end of the moving connection portion and the stationary connection portion can be mechanically disengaged,a device for limiting the movement of the second part away from the first part, said device being active when the second part is not in contact with the contour of the filling orifice, and being inactive when the second part is in contact with the contour of the filling orifice. 2. A tight connection device according to claim 1, in which the limitation device includes radial pins and a shoulder upstream from the pins such that, when the second part comes into contact with the contour of the filling orifice the shoulder and the pins separate. 3. A tight connection device according to claim 1, in which the stationary connection portion forms a hopper collecting the materials, and in which the first part of the moving connection portion includes a supporting ring assembled in sliding and tight fashion around the collecting hopper and in which the second part forms a seal ring, the seal ring and the supporting ring being connected by a tight bellows providing the mechanical disengagement between the stationary connection portion and the downstream end of the moving connection portion. 4. A tight connection device according to claim 3, in which the seal supported by the seal ring is formed by a lip seal assembled in a groove. 5. A connection device according to claim 3, in which the supporting ring is extended by a pipe conveying in the direction of the seal ring. 6. A tight connection device according to claim 5, comprising a seal between the conveyance pipe and the collecting hopper to provide tight sliding. 7. A tight connection device according to claim 3, including a device to cause the supporting ring to slide axially relative to the stationary connection portion. 8. A tight connection according to claim 3, in which the bellows is assembled on the supporting ring by means of a mounting flange, and the upstream and downstream ends of the bellows are attached on the mounting flange and on the seal ring, respectively, by means of clamp connections. 9. A tight connection device according to claim 8, in which the mounting flange is secured axially to the supporting ring by a bayonet system. 10. A tight connection device according to claim 5, including a ventilating aperture in the supporting ring, and communicating with the interior of the jar through a passage demarcated between the bellows and the conveyance pipe. 11. A filling system including a tight connection device according to claim 1, pipes for feeding with powdery or granular materials upstream to the tight connection device, and a weighing device supporting the container, the feed pipes being connected to the stationary connection portion. 12. A filling system according to claim 11, in which the feed pipes are of the vibrating chute type. 13. A filling system according to claim 12, in which the vibrating chutes are operated so as to deliver the materials at high speed at the start of the filling, and then to deliver the materials at slower speeds when the delivered quantity is close to the desired quantity. 14. A filling system according to claim 11, in which the weighing system is able to bring the filling orifice of the container close to the tight connection device. 15. A jar-filling system according to claim 11, with a mixture of powdery materials including uranium oxide and/or plutonium oxide or a mixture of these, and intended for the production of nuclear fuel. 16. A method of filling a container by means of the system for filling a container according to claim 11, including the following steps:positioning of the container beneath the tight connection device,weighing of the container,bringing the tight connection device close to the container's filling orifice,bringing the seal ring into contact with the contour of the filling orifice in order to make a tight connection,weighing of the assembly formed by the container and the seal ring,arrival of the material or materials. 17. A filling method according to claim 16 in which, between each filling by a material, the seal ring is separated from the contour of the filling orifice and the container with its content is weighed.

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