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043404430	claims	1. A method for determining the gold content of an auriferous material, comprising the operations of irradiating a body of the material with neutrons and determining the intensity of .gamma.-rays having an energy of 279 keV arising from the reaction .sup.197 Au (nn') .sup.197.sbsp.m Au.fwdarw.279 keV. 2. A method according to claim 1, wherein there is used a neutron source which does not produce neutrons which have an energy sufficient to excite fast neutron reactions in non-auriferous constituents of the auriferous material. 3. A method according to claim 2, wherein there is used a neutron source which produces neutrons by means of the deuteron-deuteron or deuteron-beryllium reaction. 4. Apparatus for determining the gold content of an auriferous material, comprising means for passing discrete samples of auriferous material past a source of neutrons, and means for determining the intensity of .gamma.-rays having an energy of 279 keV arising from the reaction .sup.197 Au (nn') .sup.197.sbsp.m Au.fwdarw.279 keV. 5. Apparatus according to claim 4, wherein there is included means responsive to the means for determining the intensity of .gamma.-rays arising from the reaction .sup.197 Au (nn') .sup.197.sbsp.m Au .fwdarw.279 keV to separate those samples of auriferous material having a gold content above a predetermined value from those which do not. 6. Apparatus according to claim 4, wherein the neutrons are provided by a tube source utilising the deuteron-deuteron or deuteron-beryllium reaction to generate the neutrons. 7. Apparatus according to claim 4, wherein the means for passing discrete sources of auriferous materials past a source of neutrons comprises a plurality of tubes regularly disposed parallel to one another around the periphery of a central tube adapted to contain a source of neutrons having energies which are insufficient to excite fast neutron reactions in non-auriferous constituents of the samples of auriferous material, and means for directing the samples of auriferous material into the said tubes. 8. Apparatus according to claim 7, wherein there is a separate .gamma.-ray detector channel and responsive sorter associated with each of the said tubes.
	claims	1. A target supply device comprising:a tank, formed of a metal, configured to hold a target material;a nozzle including a hole that communicates with the interior of the tank;an insulating member configured to make contact with at least part of the periphery of the tank; anda heater that is separated from the tank and is configured to heat the tank via the insulating member. 2. The target supply device according to claim 1,wherein the insulating member is formed of at least two insulating members disposed so that a gap is defined therebetween;the target supply device further includes a jacket configured to hold the at least two insulating members in contact with the tank; andthe heater is disposed on the jacket. 3. The target supply device according to claim 2,wherein the jacket is configured of at least two members, andthe target supply device further includes:a fastening member configured to fasten the at least two members together; andan elastic member disposed between the jacket and the fastening member. 4. The target supply device according to claim 2,wherein thermal expansion coefficients of the tank, the insulating member, and the jacket fulfill a relationship βT<βI<βJ, where βT represents the thermal expansion coefficient of the tank, βI represents the thermal expansion coefficient of the insulating member, and βJ represents the thermal expansion coefficient of the jacket. 5. The target supply device according to claim 2,wherein the insulating member includes:a contact portion that makes contact with the tank; anda protruding portion that protrudes from an end area of the contact portion. 6. The target supply device according to claim 1, further comprising:an insulating sheet disposed around the outer circumference of the heater. 7. An extreme ultraviolet light generation apparatus that generates extreme ultraviolet light by irradiating a target material with a laser beam introduced from the exterior, the apparatus comprising:a chamber into which the laser beam is introduced; anda target supply device configured to supply the target material to the interior of the chamber,the target supply device including:a tank, formed of a metal, configured to hold a target material;a nozzle including a hole that communicates with the interior of the tank;an insulating member configured to make contact with at least part of the periphery of the tank; anda heater that is separated from the tank and is configured to heat the tank via the insulating member.
	abstract	A method for manufacturing a high melting point metal based object includes providing pure high melting point metal based powder, fabricating a green object from the powder, by way of a laser sintering technique, providing infiltration treatment to the green object, and providing heating pressure treatment to the green object. The temperature to the green object is controlled to the re-sintering point of the green object.
063255383	abstract	A shield apparatus is disclosed that encloses the human torso (or part of a human torso) during X-ray procedures. The shield protects medical personnel from scatter radiation, is adjustable to fit different size torsos, and will move with the X-ray equipment as the position of the equipment is adjusted to examine different areas of the body.
052326560	abstract	A fast-acting nuclear reactor control device for moving and positioning a fety control rod to desired positions within the core of the reactor between a run position in which the safety control rod is outside the reactor core, and a shutdown position in which the rod is fully inserted in the reactor core. The device employs a hydraulic pump/motor, an electric gear motor, and solenoid valve to drive the safety control rod into the reactor core through the entire stroke of the safety control rod. An overrunning clutch allows the safety control rod to freely travel toward a safe position in the event of a partial drive system failure.
	description	This application: is a continuation-in-part (CIP) of U.S. non-provisional patent application Ser. No. 16/361,825, titled “METHODS FOR ENHANCED ELECTROLYTIC LOADING OF HYDROGEN,” filed Mar. 22, 2019, which issued as U.S. Pat. No. 10,767,273 on Sep. 8, 2020; and, by continuity via the '825 application, claims the benefit of priority of U.S. provisional patent application No. 62/804,989, titled “METHODS FOR ENHANCED ELECTROLYTIC LOADING OF HYDROGEN,” filed on Feb. 13, 2019. Each above-referenced application is incorporated herein in its entirety by this reference. The present disclosure relates to methods of producing heat through electrochemical means. Specifically, the present disclosure relates to the production of heat through electrolytic loading of hydrogen into a cathode. Some electrochemical applications involve the loading of hydrogen or similar species into one or more electrodes. There are three primary competing technologies for the loading of hydrogen into an electrode: “Low High” DC voltage application by Takahashi, the “q wave” method of Brillouin, and the “superwave” forms of Dardik. Most current methods of electrolytic loading of hydrogen into metals involve slow, steady loading with constant current DC or with a constant voltage. Some systems use pulsed high-low series of DC pulses to aid the process. Shaped AC waves are known in the art, however these still require long, slow loading and do not achieve internal compression of the hydrogen within the metal electrodes. Some experimental and engineering designs require regions of very high hydrogen concentrations to be reached before the desired effects can be achieved or studied. For example, United States Patent Application No. 20070280398 describes a fractal based superwaves technique for hydrogen loading involving the addition of many AC waveforms without DC bias. The problem with known methods of electrochemical hydrogen loading is that the production of the capacitive double layer around the electrode often limits the loading rates and levels reached in the electrode. Therefore, a protocol that can achieve high regions of hydrogen loading within or upon the surface of electrodes in a shorter time and can continue to produce or maintain high loading levels for extended times is needed. The present invention uses the synergistic addition of both Low-High DC stepped switching with a shaped AC superimposed to the DC in the hydrogen loading process. This allows the DC to increase loading during the lower (i.e., less negative) voltage, high current step by taking advantage of the in and out flushing of the hydrogen at the surface utilizing the capacitance nature of the well-known electrochemical double layer formed by the electrolyte near the surface. Additionally, during the higher voltage and lower current DC step, the AC can cause added egress of the hydrogen from the metal and keep diffusion channels open. (For cathode loading the cathode is at a negative potential.) By altering the duty cycle of the DC stepping between the high and low stages, the loading rate during the high voltage step can add more hydrogen than is lost during the low voltage stage. The in and out migration of the hydrogen tends to open up more transport routes and other features that allow much higher levels of loading and faster loading than either DC or AC alone or one following the other in succession independently. The advantage of this synergistic effect is greatly desired in some application. One of ordinary skill in the art will appreciate that references to hydrogen throughout the specification may refer to all stable isotopes of hydrogen including protium, deuterium, and/or tritium. Likewise, the term water includes its various isotopic forms. In one embodiment, an electrolytic method of loading hydrogen into a cathode may include placing the cathode and an anode in an electrochemical reaction vessel filled with a solvent, mixing a DC component and an AC component to produce an electrolytic current, and applying the electrolytic current to the cathode. The DC component may include cycling between: a first voltage applied to the cathode for a first period of time, a second voltage applied to the cathode for a second period of time, wherein the second voltage is higher than the first voltage, and wherein the second period of time is shorter than the first period of time. The AC component may have a frequency between about 1 Hz and about 100 kHz. The peak sum of the voltages supplied by the DC component and AC component may be higher than the dissociation voltage of the solvent. In yet another embodiment, the method may further include performing an initial loading. The initial loading may include mixing an initial DC component and an initial AC component to produce an initial electrolytic current and applying the initial electrolytic current to the cathode. The initial DC component may include cycling between: a third voltage applied to the cathode for a third period of time, a fourth voltage applied to the cathode for a fourth period of time, wherein the fourth voltage is higher than the third voltage, wherein the third period of time and the fourth period of time are approximately the same, and wherein the third voltage is lower than the first voltage and the fourth voltage is lower than the second voltage. The initial AC component may have a frequency between about 1 Hz and about 100 kHz. In another embodiment, a system for electrolytic loading of hydrogen into a cathode may include an electrochemical reaction vessel filled with a solvent, a cathode and an anode disposed within the electrochemical reaction vessel, and an electrolytic current source connected to the cathode. The electrolytic current may include a DC component, wherein the DC component may cycle between a first voltage applied to the cathode for a first period of time, and a second voltage applied to the cathode for a second period of time, wherein the second voltage may be higher than the first voltage, and wherein the second period of time may be shorter than the first period of time. The electrolytic current may further include an AC component with a frequency between about 1 Hz and about 100 kHz. The peak sum of the voltages supplied by the DC component and AC component may be higher than the dissociation voltage of the solvent. In yet another embodiment, the method may further comprise sealing the electrochemical reaction vessel. In yet another embodiment, the method may further include flushing the electrochemical reaction vessel with a reductive gas prior to sealing the electrochemical reaction vessel. In yet another embodiment, the method may further include applying a magnetic field to the electrochemical reaction vessel. In yet another embodiment, the frequency of the AC component may be dynamically adjusted. In yet another embodiment, the DC component and the AC component of the electrolytic current may be mixed with a DC bias. In yet another embodiment, the cathode may be comprised of at least one of palladium or a palladium alloy. In yet another embodiment, the cathode may have a hydrogen diffusion rate greater than about 0.1 cm3/cm2/s. In yet another embodiment, the cathode may have a hydrogen diffusion rate greater than about 1.4 cm3/cm2/s. In yet another embodiment, the solvent may be solutions containing LiOH. In yet another embodiment, the solvent may be solutions containing LiOD. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. One skilled in the art will recognize that the embodiments of the invention may be practiced without these specific details or with an equivalent arrangement. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the embodiments of the invention. The presently disclosed subject matter is presented with sufficient details to provide an understanding of one or more particular embodiments of broader inventive subject matters. The descriptions expound upon and exemplify particular features of those particular embodiments without limiting the inventive subject matters to the explicitly described embodiments and features. Considerations in view of these descriptions will likely give rise to additional and similar embodiments and features without departing from the scope of the presently disclosed subject matter. Referring now to FIG. 1, in one embodiment of the present invention, an electrolytic method of loading hydrogen into a cathode may comprise placing the cathode and an anode in an electrochemical reaction vessel filled with a solvent 10, mixing a DC component and an AC component to produce an electrolytic current 30, and applying an electrolytic current to the cathode 40. The DC component may include cycling between: a first voltage applied to the cathode for a first period of time, a second voltage applied to the cathode for a second period of time, wherein the second voltage is higher than the first voltage, and wherein the second period of time is shorter than the first period of time. The AC component may have a frequency between about 1 Hz and about 100 kHz. The peak sum of the voltages supplied by the DC component and AC component may be higher than the dissociation voltage of the solvent. DC currents and voltages used here may be switched in time but have a specific polarity above 0 volts as measured by traditional electrochemical methods, i.e. related to uncharged unbounded hydrogen. For clarity, the term DC includes switched DC where the desired voltage remains stable over an extended time. The term AC currents and voltages are used to describe currents which pass through the 0 voltage levels or through the value set by the DC voltages. That is we are using the term relative to the anode of the electrochemical system and AC is meant to be current that alternates between positive and negative charge on the cathode. It should be clear to those skilled in the art of electrochemistry, that the desired DC biased AC wave forms are applied to electrodes within an electrochemical cell. Specifically, at least the primary current of the DC applied to the cell is polarized so that the electrode (cathode) to receive the hydrogen is negatively charged compared to one of the other electrodes so that hydrogen species are moved toward the cathode. When the frequency of the AC waveform is discussed it is meant to refer to the Fourier component of that waveform which has the greatest amplitude. It should be realized that the waveform can take a variety of forms. Waveforms having a component with rise-times shorter than 250 ns are preferred. To avoid confusion, it should be noticed in electrochemical system one electrode is taken as a reference. For this electrolysis system, the anode is taken as the reference and set to ground. The cathode is negatively charge with respect to the anode and to ground. It is preferred that the DC component's duty cycle be such to have a greater on time for the high voltage or high currents than for the lower ones after the initial loading protocol. This is for the purpose of giving a net ingress of the hydrogen into the electrode. In one embodiment, the cycle timing was 5 minutes with 90% on time for the lower voltage and 10% on time for the higher voltage. (Note: the cathode being loaded is at a negative potential.) In that embodiment, the high voltage was set at 10 VDC and the low voltage at 1 VDC. In the preferred embodiment, the time between the DC Lo-High cycles (period) should be less than 20 minutes for electrodes with maximum thicknesses of 1 mm. Longer times do not seem to be beneficial for such commonly used materials. The AC waveform component to the electrolytic current can be of many different functional forms such as sine, square, pulsed, or triangular as commonly available from function generators. Sine waves are used in the description herein but others waveforms can be envisioned by those skilled in the art of electrical engineering. The AC component is added to the stepped cycle DC component for the purpose of causing dynamic movement of the hydrogen into, though, and out of the electrochemical double layer and the surface of the electrode. The sum of the DC and AC components is applied between the electrode to be loaded with hydrogen and another electrode in a manor customary to electrolysis and known within the art of electrochemistry. In the preferred embodiment the addition of the AC and DC components should allow the voltage at the cathode to rise above zero voltage to release hydrogen from the electrode but not, however, to strip the hydrogen completely. Thus, the greatest rise of the voltage should be slightly above zero volts but not significantly above zero nor remain at such levels for extended times. It is desired that the cathode be at a negative potential compared to the anode electrode (taken as ground) for longer total times than the positive times. In one embodiment the DC volts where chosen at −10V (90% of the time) and −1.5V (10% of the time) volts and the AC sine amplitude was chosen as 2.5 volts with a frequency of 100 Hz. This results in short-term peak voltages at the cathode to rise to 1 volt. However, the majority of the time the cathode experiences voltages above the dissociation voltage of the water solvent of about 1.5 volts and thus loads hydrogen into the electrode. Referring now to FIG. 2, deloading can occur when the AC component adds to the DC in such a way to raise it above zero potential. The anode potential is taken as ground or 0 potential. The primary loading occurs during the time the DC component is at a more negative potential. There is a greater current flow when the cathode is at its more negative potentials. In the embodiment illustrated in FIG. 2, the two DC supplies are two DC-DC Adjustable Power Supply Output Step-down Module 6.5V-60V to 1.25-30V 10A UPC 741870439544. Their purpose is to supply a DC bias to the cathode for loading of hydrogen into the electrode. To that end, it is important that voltages in excess of the dissociation of the solvent (i.e. water) be developed between the two electrodes. For water-basedsolvents, this is around 1.2 to 1.5 V dependent on pressures, electrolyte concentration, isotopic makeup, and temperatures. The two currents are wired to a double pole double throw relay (in one embodiment this was an Enclosed Power Relay, 8 Pin, 24 VDC, DPDT SCHNEIDER ELECTRIC 92S11D22D-24D). The relay was cycled by a repeating unit 12V DC Multifunction Self-lock Relay PLC Cycle Timer Module Delay Time Switch UPC 714046658482. Its function is to activate the relay to cycle between the two DC power supplies. One of ordinary skill in the art would appreciate that any suitable DC supply, controller, and relay may be used in the present invention. Referring now to FIG. 3, a general conception of the AC/-DC mixing according to an embodiment of the present invention is shown. It is shown as component units with discrete purposes. The parts' purpose is to supply a cycled DC voltage in a repetitive low-high cycle. It should be obvious by those skilled in the art of electrical engineering that many circuit designs can be employed for the same purpose. For example, a single programmable DC supply could replace the unit or a computer-controlled DC supply. Alternatively, a dedicated AC generator which can provide DC Fourier components could be used. However, the separate components of the figure illustrates one embodiment the desired DC part of the input power can be obtained. As mentioned elsewhere, one supply should be set so that there is net hydrogen-mediated current into the electrode and it should also have a voltage setting so the hydrogen can be dissociated in the solvent. The output of the stepped DC part of the system 303 is then directed to an AC/DC mixing unit 304 for the purpose of adding the two components for supply to the electrodes within the electrochemical system. Referring now to FIG. 4, a voltage vs. time output from the stepped DC portion of the system is shown. The duty cycle provides for the greater potential difference, and hence greater electrochemical current, for longer times than the lesser potential difference between electrodes. Thus, greater time is spent at the larger negative values for the purpose of providing hydrogen to the cathode. The AC may be supplied by any suitable AC supply 305, for example, a HIGH PRECISION Audio Signal Generator 1 Hz-1 MHz with Sine Triangle Square outputs, UPC 0713893274877 or the like. It should be noted that other frequencies may be used, however, frequencies between 1 Hz and 100 kHz have been observed to be adequate for most applications. The primary factor in setting frequencies is the electrochemical double layer capacitance at the cathode. It is preferred that the expected frequencies range of the specific cell be determined by a method common within the art of electrochemical impedance spectroscopy. That is the primary AC frequency applied should allow for the greatest current flow into the cathode. The output of the AC or functional form device is fed via a current sensor into the AC/DC mixer 304. In yet another embodiment, the frequency of the AC component 305 may be dynamically adjusted. A current sensor may indicate the absorption of the AC by the electrochemical cell. This, in turn, may signal the transport of the ionic species into, through, and out of the electrochemical double layer and eventually the movement of the hydrogen at the surface or near the surface of the cathode. The AC current sensor may relay the information to a frequency controller whose role is to keep the AC frequency center near the area of maximum AC absorption. Thus, it assures a large movement of the hydrogen at the surface and near the surface of the cathode. It is conjectured that this keeps the surface clean and diffusion pathways open. It also shuttles ions through the double layer from the solvent. However, since the cathode experiences outflow of some hydrogen for only short limited times there is net loading of the cathode. It is envisioned that the entire AC part of the system could comprise a single electronic unit. Referring now to FIG. 5, a typical AC output using a simple sine form is shown. Other functional forms are contemplated in the present invention. In yet another embodiment, the DC component and the AC component of the electrolytic current may be mixed with a DC bias. For enhanced loading of the electrode, the AC or other functional form and the stepped DC current need to be mixed while retaining the DC bias of the output. The goal is to enhance loading by allowing the AC to assist transport through the double layer while fluxing into and out of the metal surface. The DC bias gives a net influx of ions and other species into the cathode. Thus the combination has greater utility than either method alone and greater utility than one following later in time by the other. This synergistic combination is important for the performance of the method and device described herein. A large number of DC bias AC mixing circuits are known within the art. A typical embodiment is a simple bias Tee circuit designed to pass the AC through a capacitor and the DC through an inductor while blocking the reflection back into the supplies. Such circuits are well known and component sizes should be selected based on the expected frequency ranges. In one embodiment, the bias tee mixer was constructed using a series of 10 mH inductors and a parallel circuit of Metallized Polyester Film 22 mF Capacitors. Referring again to FIG. 1, in yet another embodiment, the method may further comprise performing an initial loading 20. The initial loading may comprise applying an initial electrolytic current to the cathode, the initial electrolytic current may include an initial DC component, wherein the initial DC component may include cycling between: a third voltage applied to the cathode for a third period of time, a fourth voltage applied to the cathode for a fourth period of time, wherein the fourth voltage is higher than the third voltage, wherein the third period of time and the fourth period of time are approximately the same, and wherein the third voltage is lower than the first voltage and the fourth voltage is lower than the second voltage. The initial electrolytic current may further include an AC component with a frequency between about 1 Hz and about 100 kHz. It is preferred that the initial loading of the electrode is conducted at lower temperatures such as below room temperature and that the initial loading is first to be done with low currents and voltages and with the high low DC component duty cycle be near 50%. After 1 hour, the currents can be raised and the duty cycle reduced. This is thought to provide a more gradual loading and avoid some volume expansion distortions due to unequal loading. Once the electrode has been initial loaded and conditioned above 0.6 H/Pd atomic ratios, it can be later be loaded more quickly. Additionally, the duty cycle may be set to 0% after the initial loading protocols and a simple flat DC voltage biased AC can be used with care taken so that the average potential is favorable to retaining loading. In yet another embodiment, the method may further comprise sealing the electrochemical reaction vessel. In yet another embodiment, the method may further include flushing the electrochemical reaction vessel with a reductive gas prior to sealing the electrochemical reaction vessel. In most electrochemical systems, gases are released during operation. Such cells are termed “open” when the system is open for gas exchange to and from the environment and termed “closed” when sealed against such exchanges or have methods to control such exchanges. In systems designed for hydrogen loading into electrodes, the gas is retained by the electrode and a companion gas such as oxygen from electrolysis is released into the system. This often results in the accumulation of so-called “orphaned oxygen” since there is not enough free hydrogen or reductive species to react with the free oxygen. This is usually detrimental to most thermal energy studies and devices. To that end, it is preferred to first run the system be conducted open or vented to the atmosphere so the orphaned oxygen can leave during the initial loading stages and then be closed later to limit contamination and conserve the electrolyte. In one embodiment this is accomplished by first loading a Pd based cathode run with amp-secs in excess of the time calculated amount that would be required from an estimate based on Faraday's laws of electrolysis of hydrogen needed to fully load the amount of Pd used in said system. In many embodiments, runs were run open longer than ten times the estimated time calculated by Faraday's law. After such time, the cell was sealed or pressure monitored for controlled release or for overpressures leading to higher operating pressures and temperatures. In one embodiment, Pd on Al2O3 recombination catalyst was used with a cell that was first run open for 4 days and then closed. The initial running systems open before closing also allows for volatiles to be removed from the solution. This is especially important when trying to load with deuterium from heavy water solutions. Since deuterium oxide (i.e. heavy water) is hygroscopic, solutions often are supplied or become contaminated with the lighter isotope of hydrogen. Light hydrogen is more quickly evolved than the deuterium isotope of hydrogen in electrolytic systems due to its lower voltage required for dissociation. Running open at low voltages and currents preferentially remove the lighter isotope. One alternative is to flush the gas out of the cell with a reductive species such as hydrogen and then sealed so that any orphaned oxygen will have enough hydrogen to react and be sequestered in the form of water. In yet another embodiment, the method may further include applying a magnetic field to the electrochemical reaction vessel. In many thermally active electrochemical systems, the magnetic fields are applied for either study of the processes or for adjusting internal spin-based reactions. This is especially useful when paramagnetic or ferromagnetic materials are used for one or more electrodes. Hence, in one embodiment, a disc magnet (N42 2×½ Inch Rare Earth Neodymium Disc Magnet from Magnets4Less) was placed beneath the reactive chamber and a second ring magnet (3 OD×2 ID×½ Inch Rare Earth Neodymium Ring Magnet Grade N42 from Magnets4Less). This supplied a field of 300 gauss in the region occupied by the central electrode. In yet another embodiment, the cathode may be comprised of at least one of palladium or a palladium alloy. In yet another embodiment, the cathode may have a hydrogen diffusion rate greater than about 0.1 cm3/cm2/s. In yet another embodiment, the cathode may have a hydrogen diffusion rate greater than about 1.4 cm3/cm2/s. It is recommended that care is performed in selecting metal electrodes for loading of hydrogen. The material should have a hydrogen diffusion rate greater than 0.1 cm3/cm2/s and with rates greater than 1.4 cm3/cm2/s. The function of the reaction vessel is to provide a relatively inert and structurally stable container for the electrochemical reaction. Such vessels are known to those skilled in the art of chemistry. In one embodiment a Glass Proglass 250 mL Flask fitted with 24/40, 14/20 Two Necks lid and sealed with an Easy Open PTFE Clamp. The central 24/40 neck of the lid is suited to mount a Graham condenser for returning steam from the system back into the vessel. The 14/20 side neck is suited for passing the electrical connections to the electrodes and sensors. One of ordinary skill in the art would understand any other suitable reaction vessel known in the art may be used in the present invention. In one embodiment, the electrochemical reaction vessel was partially filled with 100 ml of an LiOD 0.1M heavy water based solution. A Pt coated Ti mesh electrode was used as the anode and the cathode was selected as discussed below. The chemical reflux condenser assembly was insulated with vermiculite and cooling water at 30 C was passed down through the condenser (common counter-flow systems in chemistry). This allowed the system to run at boiling temperatures for extended times. This was slightly above 92 C due to the altitude of the inventor's laboratory. In yet another embodiment, the solvent may be LiOH. In yet another embodiment, the solvent may be LiOD. Referring now to FIG. 6, in another embodiment, a system for electrolytic loading of hydrogen 600 into a cathode 604 may comprise an electrochemical reaction vessel 606 filled with a solvent, a cathode 604 and an anode 605 disposed within the electrochemical reaction vessel 606, and an electrolytic current source 603 connected to the cathode 604. The electrolytic current may comprise a DC component 602, wherein the DC component 602 may cycle between a first voltage applied to the cathode 604 for a first period of time, and a second voltage applied to the cathode 604 for a second period of time, wherein the second voltage may be higher than the first voltage, and wherein the second period of time may be shorter than the first period of time. The electrolytic current may further comprise an AC component 601 with a frequency between about 1 Hz and about 100 kHz. The peak sum of the voltages supplied by the DC component 602 and AC component 601 may be higher than the dissociation voltage of the solvent. One of ordinary skill in the art will appreciate the system may be used in a manner consistent with the electrolytic methods of loading hydrogen into a cathode as described above and in the example herein. The increase loading rate and maximum loading ratios of Hydrogen species into metals is useful in a wide range of utilities. For example, in studies of hydrogen storage materials, hydrogen embrittlement studies, measurements of circuit's resistance and inductance, and even in areas where isotopic hydrogen is studied for thermal release or for tritium storage. To verify the utility of the method, a series of experiments were conducted to compare loading rates by the electrochemical method described herein and with traditional loading for simple DC electrolysis. Resistance versus time measurements of a palladium wire were made to judge loading rates. Such resistance changes need to be well studied for the case of hydrogen being loading electrochemically into Palladium. The relative resistance, R/R0 (i.e. loaded resistance divided by preloaded resistance), increases by a factor of approximately 1.8 as the H to Pd atomic ratio reaches 0.65 at room temperatures and standard atmospheric pressures. Thus, the rate of change of resistance upon loading can be used to evaluate the loading rate and levels. Also, when both samples are from the same original wire length, operated under the same environmental conditions, and same amp-seconds of electrolysis, a comparison can be made. In one embodiment, two 1 foot 95% Pd 5% Ru 28-gauge (AGW) wires were cut from a single piece and were loaded by the two methods described herein for comparison. This was done simply by lowering a loop of each wire into a 0.1M LiOH solution which also contained a platinized Ti mesh electrode commonly used for Pd and Rh electroplating. The resistance of each wire was monitored with respect to time. The resistance was measured by an EXTECH 380560 PRECISION MILLIOHM METER via conventional four wire Kelvin clips placed on the wire ends just above the surface of the solution. The clips were adjusted so the two wires had the same initial resistance of 0.971 ohms. The two wires were run at the same RMS average power levels as measured with a Valhalla Scientific 2100 Digital Power Analyzer. One was run at constant DC current and one at a high DC voltage of 5 volts and a low of 1.75 volts and an AC sine wave at 100 Hz with an amplitude of 3.5 volts peak to peak. The switching between the DC values was set at 5 minutes with a 20% duty cycle. The resistance maximum was reached at 14.5 hours and indicates a loading of about 0.75 D/Pd ratio. The turn down in the resistance past that time shows continued loading as the phase of the Pd begins to change. The average rate over the 18-hour run of the competing loading ratios shows that the method described herein is 1.47 higher than DC current alone for the first 18 hours. It is also worth noting that the ultimate loading ratio achieved by this method is higher than the DC alone. For example, after 10 hours, the DC alone loading only achieved a R/R0 level of 1.3 while the method of this invention achieved a level of over 1.5. FIG. 7 is a Nyquist Plot of an electrolytic cell during hydrogen loading into a metal. It illustrates the complex impedance of the cell and plots the imaginary part of the electrical impedance against the real part of the impedance. A Nyquist Plot can be obtained, for example, by scanning the frequency of a sine wave current applied to a cell and observing phase shifts between voltage and current values. FIG. 8 is a Nyquist Plot obtained using a mathematical model of a cell. FIG. 9 is a Nyquist plot with captioned interpretations of the major physical events thereof. FIG. 10 is a circuit diagram 700 representing a simplified electronic model of an electrolytic cell. In FIG. 10, CPE 702 is the double layer capacitance due to the electrolysis events near the surface of the metal. The Warburg term 704 is the mass transfer effect. Ract 706 is the due to the oxygen evolution reaction at the anode. The ohmic resistance, Rohm 708, describes the ohmic losses of the whole cell. The inductance of the conductors is presented by Ind 710. It should be noted that the oxygen evolution is slower than the hydrogen production due to numbers of atoms with water molecules and mass diffusion rates. With such a model, as in FIG. 10, the complex Nernst impedance is given by the Equation below:Z(w)={Qanode□WNanode[cos((pi/2)□Nanode)+j sin((pi/2)□Nanode)]+[Rctanode+s□w−0.5−j□s□e−0.5]−1}−1+j□w□L+Rel+{Qcathode□wNcathode[cos((pi/2)□Ncathode)+j□ sin((pi/2)□Ncathode)]+[Rctcathode]}−1 (Equation) Where: Nanode=factor of the phase shift at the anode Rctanode=charge transfer resistances associated with the anode w=frequency s refers to the value of the mass transport effect. L=inductance of the conductors Rel=electrolyte resistance Ncathode=factor of the phase shift at the cathode Rctcathode=charge transfer resistances associated with the cathode In FIG. 9, the intercept of the high frequency arc with the real axis indicates the ohmic resistance. The low frequency region of a Nyquist plot can differ extremely depending on the operating current density. The Q value is the value of the phase shift at 90 degrees due to the couple layer of the various electrodes. It should be noted that the Q effects the depth of the local minimum at the preferred operating region with smaller Q values giving greater “depth” to the minimum. In an advantageous method according to these descriptions, hydrogen loading is conducted in the “preferred operating region” as shown in FIG. 9. A Nyquist plot as shown can be obtained by the use of such instruments as the galvanistat like the BioLogic SP240 as used in, for example, chemical impedance spectroscopy. The indicated operating region is preferred because it represents the area of operation where mass transport (i.e. Hydrogen movement) is taking place but at frequencies lower than those resulting in significant loss at the anode or due to electrolyte resistance. The preferred operating region can be found by locating the local minimum of the Nyquist plot with the lowest frequency, which may be found at values in the hundreds of Hz. In at least one embodiment, the AC frequency is selected to be in the preferred operating region. In one example, using Pt anode, Pd cathode and a 0.1M LiOD solution, this is in the range of 100 to 600 Hz. The more specific frequency depends on temperatures, concentration variations, anode and cathode relative surface areas. Some such items can be predetermined by the formula above. In at least one embodiment, the value is selected by conducting a scan of frequencies and locating the local minimum of the Nyquist plot. The above description and drawings are illustrative and are not to be construed as limiting the invention to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure. Numerous specific details are described to provide a thorough understanding of the disclosure. However, in certain instances, well-known or conventional details are not described in order to avoid obscuring the description. Reference in this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but not other embodiments. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” As used herein, the terms “connected,” “coupled,” or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; the coupling of connection between the elements can be physical, logical, or any combination thereof. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or,” in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. The teachings of the disclosure provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the disclosure in light of the above Detailed Description. While the above description describes certain embodiments of the disclosure, and describes the best mode contemplated, no matter how detailed the above appears in text, the teachings can be practiced in many ways. Details of the system may vary considerably in its implementation details, while still being encompassed by the subject matter disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the disclosure should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the disclosure with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the disclosure to the specific embodiments disclosed in the specification, unless the above Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the disclosure encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the disclosure under the claims. The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Certain terms that are used to describe the disclosure are discussed above, or elsewhere in the specification, to provide additional guidance to the practitioner regarding the description of the disclosure. For convenience, certain terms may be highlighted, for example using capitalization, italics and/or quotation marks. The use of highlighting has no influence on the scope and meaning of a term; the scope and meaning of a term is the same, in the same context, whether or not it is highlighted. It will be appreciated that same element can be described in more than one way. Consequently, alternative language and synonyms may be used for any one or more of the terms discussed herein, nor is any special significance to be placed upon whether or not a term is elaborated or discussed herein. Synonyms for certain terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and is not intended to further limit the scope and meaning of the disclosure or of any exemplified term. Likewise, the disclosure is not limited to various embodiments given in this specification. Without intent to further limit the scope of the disclosure, examples of instruments, apparatus, methods and their related results according to the embodiments of the present disclosure are given below. Note that titles or subtitles may be used in the examples for convenience of a reader, which in no way should limit the scope of the disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In the case of conflict, the present document, including definitions will control. Some portions of this description describe the embodiments of the invention in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof. Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter pertains. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described. Following long-standing patent law convention, the terms “a,” “an,” and “the” refer to “one or more” when used in the subject specification, including the claims. Thus, for example reference to “an additive” can include a plurality of such additives, and so forth. Unless otherwise indicated, all numbers expressing quantities of components, conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the instant specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter. As used herein, the term “about,” when referring to a value or to an amount of mass, weight, time, volume, concentration, and/or percentage can encompass variations of, in some embodiments +/−20%, in some embodiments, +/−10%, in some embodiments +/−5%, in some embodiments +/−1%, in some embodiments +/−0.5%, and in some embodiments, +/−0.1%, from the specified amount, as such variations are appropriate in the disclosed products and methods.
	claims	1. A spot scanning (SS) ion therapy system, comprising:a. an ion therapy source comprising at least one scanning magnet, the ion therapy source configured to sequentially direct a particle pencil beam to a number of spot positions in a target;b. a dynamic trimming collimator configured to be mounted downstream of the at least one scanning magnet of the ion therapy source, the dynamic trimming collimator comprising:i. at least one trimmer located downstream of the at least one scanning magnet and configured to intercept a portion of said pencil beam; andii. at least one driving mechanism configured for moving said at least one trimmer; andc. a controller configured to control the ion therapy source to execute the sequence of spot irradiations by sequentially directing and delivering the particle pencil beam to the number of spot positions in the target and control the position of said at least one trimmer as a function of each of said number of spot positions. 2. The spot scanning ion therapy system according to claim 1, wherein said at least one driving mechanism is configured for moving said at least one trimmer along a first axis of motion. 3. The spot scanning ion therapy system according to claim 2, wherein said first axis is substantially perpendicular to said pencil beam. 4. The spot scanning ion therapy system of claim 3, wherein the at least one trimmer is further configured to move in a second axis of motion, wherein the second axis of motion is substantially parallel to said pencil beam. 5. The spot scanning ion therapy system according to claim 1 wherein said at least one driving mechanism comprises a first axis of motion and a second axis of motion for moving said at least one trimmer. 6. The spot scanning ion therapy system according to claim 5, wherein said first axis and said second axis are substantially perpendicular to said pencil beam. 7. The spot scanning ion therapy system according to claim 5 wherein said first and second axes of motion are translation axes for translating said at least one trimmer, said translation axis are non-parallel axes. 8. The spot scanning ion therapy system according to claim 5 wherein first axis of motion is a translation axis and second axis of motion is a rotation axis. 9. The spot scanning ion therapy system according to claim 5, wherein the said at least one trimmer is further configured to move in a third axis of motion, wherein the third axis of motion is substantially parallel to said pencil beam. 10. The spot scanning ion therapy system of claim 1, wherein said at least one trimmer has a thickness and shape adapted to modify the phase space of said pencil beam. 11. The spot scanning ion therapy system of claim 1, wherein said controller is further configured for receiving a signal indicating a beam on/off status information to allow motion of said at least one trimmer only when the beam is in an off status. 12. The spot scanning ion therapy system of claim 1, wherein said controller is configured for dynamically moving said at least one trimmer in synchrony with the execution of said sequence of spot irradiations. 13. The spot scanning ion therapy system of claim 1, further comprising a position planning controller configured for defining one or more of said spot irradiations, corresponding to pre-defined positions for positioning said at least one trimmer. 14. The spot scanning ion therapy system of claim 1, wherein said at least one trimmer further comprises a plurality of trimmers and wherein said at least one driving mechanism comprises a plurality of driving mechanisms that correspond to the plurality of trimmers, wherein said controller is configured for independently controlling the position of each of said plurality of trimmers as a function of said spot position. 15. The spot scanning ion therapy system of claim 1, further configured for two-dimensional delivery. 16. The spot scanning ion therapy system according to claim 1, wherein the controller is configured to receive data defining the trimmer position for each of the number of spot positions. 17. A dynamic trimming collimator comprising:a. at least one trimmer configured to limit spillage of radiation from a two-dimensional scanning ion beam; andb. at least one driving mechanism configured for moving the at least one trimmer;wherein the dynamic trimming collimator is capable of being mounted downstream an ion therapy source configured to produce the two-dimensional scanning ion beam in a sequence to a number of spot positions in a target, and wherein the dynamic trimming collimator is capable of controlling the position of said at least one trimmer to limit spillage of radiation of the two-dimensional scanning ion beam at said target as a function for each of the number of spot positions. 18. The dynamic trimming collimator of claim 17, wherein the at least one trimmer is configured to limit spillage of radiation by partially blocking the two dimensional scanning ion beam. 19. The dynamic trimming collimator of claim 17, wherein the at least one trimmer is configured to move along a first path substantially perpendicular to an axis of the two dimensional scanning ion beam. 20. The dynamic trimming collimator of claim 19, wherein the at least one trimmer is further configured to move along a second path substantially parallel to the axis of the two dimensional scanning ion beam. 21. The dynamic trimming collimator of claim 20, wherein the first axis and the second axis are non-parallel to each other. 22. The dynamic trimming collimator of claim 17, wherein the at least one trimmer is further configured to move along a third path substantially parallel to the axis of the two dimensional scanning ion beam. 23. The dynamic trimming collimator of claim 19, wherein the at least one driving mechanism comprises a linear motor. 24. The dynamic trimming collimator of claim 19, wherein the at least one trimmer is configured to move in a substantially pendulous arc. 25. The dynamic trimming collimator of claim 19, wherein the at least one trimmer comprises a rectangular shape. 26. The dynamic trimming collimator of claim 19, wherein the at least one trimmer is configured to have a radiological thickness that is greater than the range of the two dimensional scanning ion beam. 27. The dynamic trimming collimator of claim 19, wherein the apparatus is configured to position the at least one trimmer approximate the skin of a patient. 28. The dynamic trimming collimator of claim 19, wherein the at least one trimmer is configured to move in synchrony with the two dimensional scanning ion beam. 29. The dynamic trimming collimator of claim 19, wherein the at least one trimmer comprises a plurality of trimmers and the at least one driving mechanism comprises a plurality of driving mechanisms, wherein at least each of the plurality of trimmers is associated with at least one of the plurality of driving mechanisms. 30. The dynamic trimming collimator of claim 29, wherein at least one of the plurality of trimmers is associated with at least two driving mechanisms. 31. The dynamic trimming collimator of claim 17, further comprising a range shifter. 32. The dynamic trimming collimator of claim 17, further comprising a ridge filter. 33. The dynamic trimming collimator of claim 17, wherein the dynamic trimming collimator is further configured to attach to a nozzle of the ion therapy source.
	claims	1. An apparatus comprising:a control rod guide frame having a central passage of constant cross-section as a function of position along a central axis that passes through the central passage, the central passage sized and shaped to guide a traveling assembly including at least one control rod as the traveling assembly moves along the central axis,wherein the control rod guide frame comprises at least two radial guide frame sections that are secured to each other in alternating up and down orientations and configured to surround and define the central passage. 2. The apparatus as set forth in claim 1, wherein each radial guide frame section comprises an extruded radial guide frame section. 3. The apparatus as set forth in claim 2, wherein the central passage includes control rod guidance channels parallel to the central axis and machined into the extruded radial guide frame sections. 4. The apparatus as set forth in claim 2, wherein the extruded radial guide frame sections are made of extruded steel. 5. The apparatus as set forth in claim 1, wherein the at least two radial guide frame sections consist of between four and eight radial guide frame sections. 6. The apparatus as set forth in claim 1, wherein the central passage includes control rod guidance channels parallel to the central axis. 7. The apparatus as set forth in claim 1, wherein the control rod guide frame further comprises:bands wrapped around the outside of the at least two radial guide frame sections to secure the at least two radial guide frame sections together to define a control rod guide frame body of the control rod guide frame. 8. The apparatus as set forth in claim 1, wherein the control rod guide frame further comprises:welds at interfaces between the at least two radial guide frame sections that secure the at least two guide frame sections together to define a control rod guide frame body of the control rod guide frame. 9. The apparatus as set forth in claim 1, wherein the at least two radial guide frame sections secured around and defining the central passage define a guide frame body, and the control rod guide frame further comprises:a lower plate connected to a lower end of the guide frame body; andan upper plate connected to an upper end of the guide frame body. 10. The apparatus as set forth in claim 9, wherein each radial guide frame section is a single element that extends the entire length along the central axis between the lower and upper plates. 11. The apparatus as set forth in claim 1, wherein the at least two radial guide frame sections secured around and defining the central passage define a guide frame body having a constant outer perimeter as a function of position along a center axis. 12. The apparatus as set forth in claim 1, wherein the at least two radial guide frame sections secured around and defining the central passage define a guide frame body, and the radial guide frame sections include flow slot passages providing fluid communication between the central passage and the exterior of the guide frame body. 13. The apparatus as set forth in claim 1, wherein the control rod guide frame further comprises:keys disposed in alignment features of the at least two radial guide frame sections. 14. The apparatus as set forth in claim 1, further comprising:a nuclear reactor core comprising a fissile material; anda control rod drive mechanism (CRDM) arranged to control movement of the traveling assembly as the traveling assembly moves along the central axis. 15. The apparatus as set forth in claim 14, further comprising a reactor pressure vessel that contains the nuclear reactor core, the CRDM, and the control rod guide frame.
	abstract	A controlled fusion process is provided that can produce a sustained series of fusion reactions: a process that (i) uses a substantially higher reactant density of the deuterium and tritium gases by converging cationic reactants into the higher reaction density at a target cathode rather than relying on random collisions, the converging producing a substantially higher rate of fusion and energy production; (ii) uses a substantially lower input of energy to initiate the fusion; (iii) can be cycled at a substantially higher cycle frequency; (iv) has a practical heat exchange method; (v) is substantially less costly to manufacture, operate, and maintain; and, (vi) has a substantially improved reaction efficiency as a result of not mixing reactants with products.
	abstract	A flow tripping device according to a non-limiting embodiment of the present invention may include a peripheral band surrounding a central space. A plurality of flow tabs may extend from an upper portion of the peripheral band toward the central space. A plurality of finger structures may extend from a lower portion of the peripheral band. When installed in a fuel channel of a boiling water reactor (BWR), the critical power ratio (CPR) performance of the periphery rods may be increased, thereby also increasing overall performance. Consequently, the increased power translates to lower fuel cycle costs.
	summary
	abstract	A gantry applies particle beams to a subject. An ultrasonic diagnostic apparatus scans the subject with ultrasonic waves via an ultrasonic probe, and acquires an ultrasonic image concerning a radiotherapy target region of the subject. A processing circuitry specifies a first planned point of a Bragg peak in the ultrasonic image, which anatomically coincides approximately with a second planned point of the Bragg peak decided in radiotherapy planning. The processing circuitry estimates a sighting point of the Bragg peak of a particle beam based on a body surface position of the subject and an actual range of the particle beam. The display displays the ultrasonic image to indicate the first planned point and the sighting point.
	description	The present application claims the benefit of U.S. Patent Provisional Patent Application Ser. No. 61/016,446, filed Dec. 22, 2007, the entirety of which is hereby incorporated by reference. The present invention relates generally to systems and methods of storing of high level radioactive waste, and specifically to systems and methods of storing high level radioactive waste that emits a heat load, such as spent nuclear fuel, in a clustered arrangement wherein such systems utilize natural convective cooling for ventilation. Concerns regarding the viability of oil as a practical energy source continue to mount throughout the world whether brought on by resource scarcity, economic climate, or strained relations with entities in possession of oil reserves. Additionally, environmental issues associated with burning oil, such as air pollution and global warming, have further put the long-term viability of oil-based energy at question. As a result, alternative energies, such as nuclear power, solar power and wind power, have become the focus of increased use and evaluation by a multitude of governments and private entities throughout the world. It is believed by many that nuclear power provides the only energy source that can realistically meet the energy needs of industrialized nations. The fundamental concern with the use of nuclear power has been related to the disposal of the spent nuclear fuel rods after they have been depleted in the nuclear reactor. As a result, the industry continues to search for new and improved methods and systems for storing, transporting and transferring spent nuclear fuels rods. These systems must be meet carefully regulated government safety mandates regarding radiation containment, structural integrity, adequate ventilation, etc. An example of an existing ventilated storage system (and its associated method of storage and transfer) are disclosed in U.S. Pat. No. 7,330,526 (the '526 patent), issued Feb. 12, 2008 to Krishna P. Singh, one of the present inventors of the present application. Another suitable existing ventilated storage system (and its associated methods of storage and transfer) are disclosed in U.S. Pat. No. 7,068,748 (the '748 patent), issued Jun. 27, 2006 to Krishna P. Singh. The entireties of these applications are incorporated by reference herein. The systems and methods disclosed in the '526 and '748 patent are extremely useful and effective as they are designed to utilize the naturally existing radiation shielding properties of the ground to increase the radiation containment abilities of the systems while still affording adequate ventilation. While these designs are adequate, and even optimal, in many circumstances, these systems can not be universally used at all existing spent nuclear fuel storage sites, whether temporary or long-term, for a number of factors. Such factors may include existing capital equipment at the site, geographic layout, climate, space limitations, etc. For obvious reasons, storage space at any storage site, whether temporary or long-term, is at a premium. Thus, one of the major considerations in any storage system is the maximization of storage capacity per area (or volume). To this extent, storage systems that provide storage cavities in an arrayed configuration have been developed. An example of an arrayed underground storage system is disclosed in United States Patent Application Publication 2006/0251201, published Nov. 9, 2006, to Krishna P. Singh. Another above-grade arrayed storage system is also disclosed in UK Patent Application Publication GB2337772A, published Jan. 12, 2999, to Blackbourn et al. The Blackbourn system for storing canisters containing hot spent nuclear fuel or waste. The Blackbourn system stores the canister in respective chambers of a vault and are air-cooled by natural convection. The vault is constructed from pre-cast concrete sections, assembled on-site and secured together by poured concrete. Each chamber has a stainless steel liner defining inner and outer annular spaces between the hot wall of the canister and the concrete wall of the chamber through which cooling air flows by convection. Air from the outer space discharges via exit vents cast into the concrete, air from the inner space via gap between metal lid and flanges. The liner shields the concrete from direct thermal radiation from the hot canister wall and provides additional surfaces from which heat can be lost by convection. The inner metal-lined air path prevents very hot air from coming into direct contact with concrete. Slots allow hot air to discharge via one of the exit vents in the event of blockage of the other. The concrete walls themselves are cooled by further ducts formed as an integral part of the pre-cast structure. While the Blackbourn system is a suitable structure, it suffers from a number drawbacks. For example, the concrete structures between the separated and isolated storage chambers is susceptible to being subjected to overheating and eventual degradation. Moreover, by surrounding each chamber with a concrete structure, additional space is occupied per chamber, thereby increasing the overall size of the vault without achieving increased storage capacity. Additionally, by designing the Blackbourn vault so that each storage chamber acts as its own independent ventilated system, the proper ventilation of any single chamber can be easily choked off by the blocking of only a few inlet ducts. Finally, the Blackbourn system does not accommodate thermal expansion of its metal parts adequately, thereby exposing certain components to great stresses and increasing the possibility of eventual fatigue and failure. It is therefore an object of the present invention to provide an improved system and method of storing and/or transferring high level radioactive waste. Another object of the present invention is to provide a system and method of storing high level radioactive waste that utilizes natural convection cooling (i.e., the chimney effect). Still another object of the present invention is to provide a system and method of storing high level radioactive waste that utilizes natural convection cooling (i.e., the chimney effect) that can store containers in an array of tightly clustered storage chambers. Yet another object of the present invention is to provide a system and method of storing high level radioactive waste that utilizes natural convection cooling (i.e., the chimney effect) wherein the storage shells provide additional structural integrity to the system. A further object of the present invention is to provide a system and method of storing high level radioactive waste wherein the storage shells act as load bearing columns for the roof a radiation containment enclosure. In one aspect, the invention can be a system for receiving and storing high level radioactive waste comprising: a concrete enclosure comprising walls, a roof and a floor, the concrete enclosure forming an internal space; the roof comprising an array of holes; an array of metal shells, each metal shell having a cavity for accommodating one or more containers holding high level radioactive waste, the array of metal shells arranged in a substantially vertical and spaced apart manner within the internal space of the enclosure, the array of the metal shells being co-axial with the array of holes in the roof so that containers holding high level radioactive waste can be lowered through the array of holes in the roof and into the cavities of the array of metal shells; the array of metal shells fastened to the floor and to the roof of the concrete enclosure, the array of metal shells acting as load bearing columns for the roof; each of the metal shells comprising (i) an expansion joint for accommodating thermal expansion and/or contraction of the metal shells; and (ii) one or more holes at a bottom portion of the metal shell that create a passageway between the internal space of the concrete enclosure and the cavity of the metal shell; and the walls of the concrete enclosure comprising one or more inlet ventilations ducts forming passageways from outside of the concrete enclosure to the internal space of the concrete enclosure. In another aspect, the invention is a system for receiving and storing high level radioactive waste comprising: an enclosure comprising walls having inlet ventilation ducts, a roof comprising an array of holes, and a floor; an array of metal shells located in an internal space of the enclosure, the array of metal shells being co-axial with the array of holes in the roof so that containers holding high level radioactive waste can be lowered through the array of holes in the roof and into the array of metal shells; the array of metal shells acting as load bearing columns for the roof; and each of the metal shells comprising (i) an expansion joint for accommodating thermal expansion and/or contraction of the metal shells; and (ii) one or more holes at a bottom portion of the metal shell. Referring first to FIG. 1, a clustered storage system 1000 is illustrated according to an embodiment of the present invention. The clustered storage system 1000 is specifically designed to achieve the dry storage of multiple hermetically sealed containers containing spent nuclear fuel in an above-grade environment. However, it should be understood that many of the inventive concepts can be applied to a below grade environment with a simple re-configuration of the inlet vents. Generally speaking, the clustered storage system 1000 is designed to facilitate the receipt, transfer and ventilated storage of containers storing spent nuclear fuel or other high level radioactive waste. The clustered storage system 1000 is a vertical, ventilated dry spent fuel storage system that is fully compatible with 100 ton and 125 ton transfer casks for spent fuel multi-purpose canister transfer operations. The clustered storage system 1000 can, however, be modified/designed to be compatible with any size or style transfer cask. The clustered storage system 1000 is designed to accept multiple spent fuel multi-purpose canisters for storage at an Independent Spent Fuel Storage Installation (“ISFSI”) in a compact, ventilated and structurally sound enclosure. All container types engineered for the dry storage of spent fuel can be stored in the clustered storage system 1000. Suitable containers include multi-purpose canisters and thermally conductive casks that are hermetically sealed for the dry storage of high level wastes, such as spent nuclear fuel. Typically, containers comprise a honeycomb grid-work/basket, or other structure, built directly therein to accommodate a plurality of spent fuel rods in spaced relation. An example of a multi-purpose canister that is particularly suitable for use in the present invention is disclosed in U.S. Pat. No. 5,898,747 to Krishna P. Singh, issued Apr. 27, 1999, the entirety of which is hereby incorporated by reference in its entirety. An example of a thermally conductive cask that is suitable for use in the present invention is disclosed in U.S. Patent Application Publication No. 2008/0031396, to Krishna P. Singh, published Feb. 7, 2008, the entirety of which is hereby incorporated by reference in its entirety. The clustered storage system 1000 is a storage system that facilitates the passive cooling of stored containers through natural convention/ventilation. The clustered storage system 1000 is free of forced cooling equipment, such as blowers and closed-loop cooling systems. Instead, the clustered storage system 1000 utilizes the natural phenomena of rising warmed air, i.e., the chimney effect, to effectuate the necessary circulation of air throughout the system. Referring still to FIG. 1, the clustered storage system 1000 generally comprises a container receiving area 10, a gantry crane 20 a frame crane support structure 30 and a concrete enclosure 100. The container receiving area 10 can take on variety of embodiments and include a variety of infrastructure and capital equipment depending on the desired method of container delivery to the clustered storage system 1000. For example, the container receiving area 10 can comprise one or more sets of tracks for rail cars or the like so that rails cars carrying transfer containers (such as transfer casks holding a loaded multipurpose container or a thermally conductive cask) can be stopped in a position within reach of the gantry crane 20 for unloading and positioning above the concrete enclosure 100. In other embodiments, the container receiving area 10 may be designed as a dock to accommodate trucks for loading and/or unloading. The frame structure 30 extends from the concrete enclosure 100 and into the container receiving area 10. The frame structure 30 along with the top surface of the roof 101 of the concrete enclosure 100 are adapted so that the gantry crane 20 can translate between a position above the container receiving area 10 where it can engage and lift containers from a transport vehicle (such as a rail car, truck, crane, etc.) and a position above the roof 101 of the concrete enclosure 100. The gantry crane generally comprises a vertical lifting mechanism 21, an upright frame 23 and a set of rails 22 upon which the lifting mechanism 21 can translate. The lifting mechanism 21 is of the type well known in the art for multi-purpose canister transfer procedures, including a lift yoke, a hoist and the necessary motors. Both the lift yoke and handling hoist are single-failure proof. In the illustrated embodiment, a set of rails 31 are incorporated into (or onto) the roof 101 of the concrete enclosure 100 and the frame structure 30 along which the gantry crane 20 rides. The sections of the rails 31 built into the enclosure 100 are positioned on the roof 101 so as to be vertically aligned with the walls 102 of the enclosure 100, thereby ensuring that the load imparted by the gantry crane 20 and its load are borne by the walls 102, which in turn transfer the load to the foundation 103. The rear section of the frame structure 30 also rests atop the foundation 103 via its rear load bearing columns. The front section of the frame structure 30 (which extends into the canister loading area 10) also comprises load bearing columns that are adequately founded. In an alternative embodiments of the invention, the gantry crane 20 can be supported and translated upon rails that are not built into the enclosure 100 itself. In such an embodiment, the rails for the gantry crane 20 could run adjacent the enclosure 100 atop a frame structure or other load bearing assembly. The height of the gantry crane 20 is sized so that it can vertically lift a container to a sufficient height so that the bottom of the container clears the roof of the concrete enclosure 100. The gantry crane 20 can translate the container in a first horizontal direction by moving along the rails 31 and in a second horizontal direction by sliding the lifting mechanism 21 along the crane's rails 22. As a result, the gantry crane 20 can position a container above the roof of the concrete enclosure 100 and in precise axial alignment with any of the storage chambers (discussed in detail below) within the concrete enclosure 100 to facilitate the transfer procedure of the spent nuclear fuel into the desired storage chambers. Referring now to FIGS. 2-3 concurrently, the details of the concrete enclosure 100 will now be discussed. In the illustrated embodiment, the concrete enclosure 100 is a rectangular box-like structure that is designed to provide the necessary neutron and gamma radiation shielding. However, it is to be understood that the shape of the concrete enclosure 100 can take on other shapes and still incorporate the various principles of the present invention. For example, the enclosure 100 can be cylindrical, a truncated pyramid, dome-like, irregularly shaped or combinations thereof. The concrete enclosure 100 is a building-like structure that forms an internal space 110 that houses a plurality of metal storage shells 200. The concrete enclosure 100 is formed by the structural cooperation of the side walls 102, the end walls 104, the roof slab 101, and the foundation 103. The components 101-104 of the enclosure 100 are preferably formed of reinforced concrete. Of course, other materials or combinations of materials can be used so long as the necessary radiation containment requirements are met. Additionally, in some embodiments of the concrete enclosure 100, one or more of the inner surfaces of the components 101-104 that form the internal space 110 may be lined with a metal, such as steel, to protect against degradation from the heat and radiation loads emanating from the high level radioactive waste stored in the storage shells 200. Referring now to FIGS. 2-4 concurrently, the side walls 102 and the end walls 104 together form a wall assembly. The side walls 102 and the end walls 104 are constructed of two overlapping wall structures 105A, 105B, that can be formed as inter-fitting monolithic structures. The wall structures 105A, 105B are keyed to mate with vertical reinforced columns that stand on the foundation 103. Thus, the wall structures 105A, 105B can expand and contract without loading the columns. The wall structures 105A, 105B are specifically shaped so that when they are fitted together to form the wall assembly 105, air inlet ventilation ducts 106, 107 are formed in the side walls 102 and the end walls 104 respectively. The details of these air inlet ventilation ducts 106, 107 will be discussed in greater detail below. Referring now to FIGS. 1-2 concurrently, the foundation 103 of the enclosure 100 is a monolithic reinforced concrete slab, designed to support the necessary loading and to provide additional radiation shielding for the ground. The foundation also serves to prevent below-grade liquids from seeping into the internal space 110. Referring now to FIGS. 5A-5C, the roof 101 of the concrete enclosure 100 is formed as a monolithic reinforced concrete structure that is designed to matingly engage with the wall assembly 105 when lowered thereon (i.e., as assembled in FIGS. 1-3). To this extent, the roof 101 has flange portions 111 that rest atop the top edges of the end walls 104. The roof 101 comprises an array of holes 120 that extend through the slab, thereby forming passageways through the roof 101 from the bottom surface 121 to the top surface 122 of the roof 101. As used herein, the term “array” is not intended to be limited to elements arranged in a row and column format but is intended to include, without limitation, any arrangement of a plurality of spaced apart elements. A gridwork of intersecting beams 123 are formed into and protruding from the bottom surface 121 of the roof slab 101. The gridwork of beams 123 are formed as part of the concrete monolithic roof structure 101 but can also be formed as a separate structure that is later connected to the main slab. The gridwork of beams 123 are designed to form a concrete wall extending from the bottom surface 121 that surrounds the perimeter of each hole 120, thereby separating the holes 120 for a short distance. The gridwork of beams 23 is provided to shield the exterior environment (and personnel) during the loading of a particular storage shell 200 from radiation shine emanating from an adjacent loaded storage shell 200. Stated simply, the gridwork of beams 23 eliminates the possibility of radiation shine through an open hole 120 from spent nuclear fuel already within the enclosure 100 by shielding any angled escape. It should be noted that the structure surrounding the perimeter of the holes 120 is not limited to a gridwork arrangement. For example, in an alternative embodiment, a collar of concrete (or another material) can be formed or fastened to the bottom surface 121 of the roof slab 101 around each hole 120. In still other embodiment, the portion of the slab comprising the array of holes 120 may simply be made thicker and bored out (our molded accordingly). As best illustrated in FIG. 5C, each of the holes 120 is formed/delineated by a stepped surface comprising a first riser surface 124, a tread surface 125 and a second riser surface 126. As will be discussed in detail below, the stepped surface of the holes 120 are designed to correspond to the top portion of the storage shells 200 in size and shape. The holes 120 accommodate the top portion of the storage shells 200. There is no limitation on the shape of the holes 120 however in other embodiments. When the enclosure 100 is assembled, the axis A-A of the holes 120 are substantially vertical, and as discussed below, when the storage shells 200 are inserted, are also in alignment with the axis of the storage shells 200. Referring back to FIGS. 2-3 concurrently, the side walls 102 and end walls 104 respectively comprise inlet ventilation ducts 106, 107. The inlet ventilation ducts 106, 107 provide passageways from the external environment to the internal space 110 of the concrete structure 100 so that cool air can enter and fill the internal space 110 (and eventually be drawn into the shells 200 for cooling of the loaded containers). The air flow is indicated in FIG. 3 by the black arrows. While both the inlet ventilation ducts 106, 107 form serpentine and tortuous passageways, the inlet ventilation ducts 106 are purposely made to have a different design/layout than that of the inlet ventilation ducts 107. Specifically, each of the inlet ventilation ducts 106 extend from an opening 112 located near the top of the outer surface of the side wall 102 to an opening 113 located near the bottom of the inner surface of the side wall 102. To the contrary, each of the inlet ventilation ducts 107 extend from an opening 114 located near the bottom of the outer surface of the end wall 104 to an opening 115 located near the top of the inner surface of the end wall 104. The different openings 112-115 are illustrated well in FIG. 4. As a result of the different designs of the inlet ventilation ducts 106, 107, the internal space 110 of the enclosure 100 is provided with incoming cool air at different heights within the space 110, thereby effectively circulating the cool air throughout the entirety of the internal space and against the height of the shells 120 which will assist in cooling. Furthermore, by providing a plurality of spaced-apart inlet ventilation ducts 106, 107 which circumferentially surround the internal space 110 which houses the entire cluster of storage tubes 200, adequate and continuous ventilation of the internal space 110 (and thus all storage shells 200) is ensured and the danger of any one storage chamber being choked off is eliminated. Of course, in other embodiments, only one type of inlet ventilation duct may be used. As mentioned in passing above, the inlet ventilation ducts 106, 107 form serpentine and tortuous passageways from the external of the enclosure 100 to the internal space 110. In all embodiments, however, the passageways may not be serpentine or tortuous, so long as direct line of sight does not exist through the passageways formed by the inlet ventilation ducts 106, 107 from exterior of the enclosure 100 to the storage shells 200 within the internal space 110. For example, the inlet ducts could be sufficiently angled or V-shaped The openings 114, 112 in the outer surface of walls 102, 104 are equipped with grates, which can be constructed of heavy metal, that permit air inflow but protects against intrusion by a vehicle, animal or man. Screens may also be used to prevent inset ingress. Referring still to FIGS. 2-3 concurrently, the clustered storage system 1000 further comprises an array of prismatic storage shells 200 arranged within the internal space 110 formed by the concrete enclosure 100. The array of storage shells 200 are arranged within the internal space 110 in a tightly spaced and substantially vertical orientation. The storage shells 200 extend from the foundation 103 (which acts as the floor of the internal space 110) to the roof 101 of the enclosure 101. The storage shells 200 are integrally fastened to both the floor 103 and the roof 101, thereby providing load bearing support to the roof 101. Stated simply, the storage shells 200 act as load bearing columns. The additional structural support added by the storage shells 200 to the roof slab 101 assists in ensuring that the roof slab 101 does not fail when subjected to repeated load cycling experienced during container transfer procedures. For example, when the clustered storage system 1000 is used to store multi-purpose canisters (“MPCs”) holding spent nuclear fuel, the MPCs will be brought to the clustered storage system 1000 in transfer casks which can typically weight as much 100-125 tons. During the transfer procedure according to the present invention, a transfer cask (which houses the MPC) is positioned atop the roof 101 and operably coupled to one of the open storage shells 200 with a mating device. One suitable example of a mating device and the corresponding MPC transfer procedure is disclosed in U.S. Pat. No. 6,625,246, issued Sep. 23, 2003, to Krishna P. Singh, the entirety of which is hereby incorporated by reference. During this transfer procedure, the roof 101 experience substantial loading, which is repeated during every loading/unloading sequence. If the roof 101 were to fail or crack, such a failure would be catastrophic for the whole system as the integrity of the entire enclosure 100 would be compromised, allowing radiation from previously loaded storage shells 200 to leak out. Thus, the structural integrity of the roof 101 must be preserved. Utilizing the storage shells 200 as load bearing columns for the roof 101 allows for the maximization of storage capacity per area/volume of the system 1000 and eliminates the need for additional structural supports, which occupy valuable potential storage space. As a result, the storage shells 200 can be tightly clustered in manner unprecedented in previous systems. The array of storage shells 200 are co-axially aligned with the array of holes 120 in the roof 101 so that containers loaded with high level radioactive can be lowered through the holes 120 in the roof 101 and into the cavities 201 (FIG. 6) of the storage shells 200. The storage shells 200 are located within the internal space 110 so as to be located within a single uninterrupted volume wherein the cool air inflow is fed by the same set of inlet vents 106, 107. Stated another way, the internal space 110 of the concrete enclosure 100 is not divided into spatially isolated sections and all of the storage shells 200 are located within that uninterrupted volume. With the exception of stringers or struts that may be added to connect adjacent storage shells 200 for horizontal structural integrity in earthquake vulnerable regions, the spaces between adjacent storage shells 200 are left empty within the internal space 110 of the concrete enclosure 100. Referring now to FIGS. 6-9 concurrently, the structural details of one of the storage shells 200 will be described with the understanding that all shells 200 in the array are constructed in an identical manner. The storage shell 200 is a generally elongated tubular structure extending from a top portion 201 to a bottom portion 202 and having an axis B-B. The storage shell 200 is preferably constructed of a metal, such as steel. Of course, other materials and metals can be used if desired. The storage shell 200 defines an internal storage cavity 203 for receiving and accommodating one or more containers 300 holding spent nuclear fuel. The length of the shell 200 can be sized to accommodate a single container 300 or a plurality of containers 300 stacked atop one another inside of the cavity 203. The width of the shell (i.e., the cavity 203) is preferably sized and shaped so as to have a horizontal cross-section that accommodates only a single container 300, such as a single MPC or a single thermally conductive cask, so that an annular clearance 204 (i.e., a gap) exists between the outer surface 301 of the container 300 and the inner surface 205 of the storage shell 200. In one embodiment, the cavity 203 of the storage shell 200 has a diameter that is in the range of 6 to 10 inches larger than the diameter of the container 300 it is used to store. Of course, other dimensional ranges are possible. By designing the shell 200 so that only a small clearance 205 exists between the inner surface 205 of the shell 200 and the outer surface of the container 300, the shell 200 provides lateral support to the container 300 under earthquake and other hazardous loadings. The clearance 204 is maintained by spacer plates 206, which are tapered at their top and bottom edges to facilitate in guiding the container 300 during loading and unloading procedures. Sets of the spacer plates 206 are located circumferentially about the inner surface 205 of the shell 200 and at different axial positions along the length. The shell 200 generally comprises a first tubular section 207, a flange plate 208, and a second tubular section 209. The first tubular section 207 forms the storage cavity 203. The flange plate 208 surrounding the top of the first tubular section 207 and extends radially outward therefrom. The second tubular section 209 extends upward from an outer edge of the flange plate 208. This portion of the shell 200 is designed to correspond to the stepped surface of the holes 120 of the roof 101 of the enclosure 100. A plurality lid support brackets 210 are connected atop the flange plate 208 and to the inner surface of the second tubular member 209. The lid support brackets 210 are circumferentially spaced about the flange plate 208 so as to provide nesting and support structure for the lid 250. In the illustrated embodiment, the lid support brackets 210 are generally L-shaped brackets having a tapered upper edge to guide the lid 250 into position so that it nests within the second tubular section 208. The lid support brackets 210 not only provide support but also provide lateral confinement of the lid 250 within the second tubular section 208 in the event of horizontal loading during earthquakes or other events. As can be seen best in FIG. 8, the lid support brackets 210 supports the lid 250 in a spaced apart manner from both the flange plate 208 and the second tubular section 209, thereby creating air outflow passageways 211 between the cavity 203 (or the clearance gap 204 when loaded) and the external atmosphere of the enclosure 100. Thus, air heated by the container 300 is allowed to escape the system 1000. It should be noted that other ventilated lid structures can be used in conjunction with this system 1000, including those of the type disclosed in U.S. Pat. No. 7,330,526, issued Feb. 12, 2008 to Krishna P. Singh. Referring now to FIGS. 6-7 concurrently, a floor plate 212 is connected to the bottom edge of the first tubular section 207. The floor plate 212 provides a bottom flange 213 so that the shell 200 can be fastened secure to the foundation 203 when installed. A plurality of openings 214 are provided in the bottom of the first tubular section 207. These opening 214 can be preformed or cutout. The openings 214 create a passageway from exterior of the shell 200 to the internal cavity 203. When installed in the enclosure 100, the openings 214 form cool air inflow passageways between the internal space 110 of the enclosure and the cavity 203 of the shell, thereby allowing cool air to come into contact with the containers 300, become heated thereby, rise within the gap 204 as warmed air, and exit the system 100 via the outflow passageways 211 around the lid 250. The shells 200 also comprise an expansion joint 220. Because the top and bottom of the shells 200 are integrally fastened to the foundation 103 and roof 101 respectively, and because the shells 200 undergo thermal cycling and thus will need to expand and contract, the expansion joint 220 allows the thermally induced stresses within the shells 200 to release while affording the shells 200 the ability to act as load bearing columns for the roof 101. The expansion joint 220 is preferably a collar style expansion joint that is built into the shell 200. One type of expansion joint 220 that is suitable for the present invention is a flanged and flued expansion joint, the type which are commonly utilized in heat exchangers and pressure vessels. Examples of such flanged and flued expansion joints, along with design principles, are disclosed in Mechanical Heat &changers and Pressure Vessels, Chapter 15, by Singh, Krishna P. & Soler, A. I., Arcturus Publishers, 1984. Referring now to FIG. 9, the lid 250 is a concrete disc with a steel liner. The lid 250 performs the required gamma and neutron radiation shielding for the open top end of the cavity 203 when in place. The lid comprises lifting appurtenances. Referring now to FIGS. 2 and 10 concurrently, the installation of the shells 200 within the concrete enclosure 100 will be described. To begin, each shell 200 is inserted through the desired hole 120 of the roof 101 until the flange plate 208 of the shell 200 contacts and rests atop the tread surface 125 of the stepped surface of the hole 120. The shells 200 are constructed to accord with the height of the enclosure 100 so that the floor plates 212 of the shells 200 also rest atop the foundation 103. When installed the shells 200 form a fit with the roof 101 so that no air leakage occurs at the interface between the shells 200 and the roof 101. The second tubular member 109 is designed to have a height so that when the flange plate 208 is resting the tread surface 125, the second tubular member 109 protrudes above the top surface 122 of the roof 101 so as to prevent precipitation ingress that may collect and flow off the top surface 122 of the enclosure 100. Further protection against the ingress of water from rain or other precipitation into the cavity 203 is further provided by a weather cover 275 (shown in FIG. 12). Referring to FIGS. 10 and 12 concurrently, once a container 300 is loaded into the storage shell 200, the lid 250 is positioned atop the brackets 110 as discussed above. Once the lid 250 is in place, the weather cover 275 is positioned over the hole 120 so as to surround the protruding portion of the second tubular member 109. The weather cover 275 comprises a side wall 276 and a sloped roof 277 that overhangs the side wall 276. The side walls 276 comprise a plurality of openings 278 that allow heated air that has escaped through the passageways 211 around the lid 225 to exit the system 1000. The openings 278 have screens for keeping birds and bugs out. The lid also comprises lifting lugs 279 and tie down brackets 180. Referring back to FIG. 2, once the shells 200 are in place, the shells 200 are fastened to the foundation 103 and the roof slab 101. More specifically, the bottom of the shells 200 are rigidly fastened to the foundation 103 by anchoring the flange portion 113 of the floor plates 112 to the foundation 103 with concrete anchors. Similarly, the top section of the shells 200 are fastened to the roof 101. This fastening can be achieved by anchors protruding from the outside surface of the shell 200. Alternatively, the shells 200 can also be fastened to the roof 101 via collars surrounding the outer surfaces of the shells 200 that act as an upper flange that can either be pressed against a bottom surface of the roof, anchored thereto, or embedded therein. The height of the enclosure 100 is designed to accord with the height of the container stack within the shells 200. Referring now to FIGS. 1, 3 and 11, a loading procedure and subsequent ventilation of an MPC 300 into the clustered system 1000 will be described. Beginning with FIG. 1, a transfer cask containing a loaded MPC arrives in the container loading area 10 via a rail car or other delivery vehicle. The gantry crane 20 is moved into position above the transfer cask via the rails 31. The lift mechanism 21 is then coupled to the transfer cask and MPC via the yoke and hoist receptively. The transfer cask and MPC 300 are then lifted to a height above thro of 101 of the enclosure by the gantry crane 20. The gantry crane 20 is then translated along the rails 31 to the desired position. If necessary the lifting mechanism 21 is translated along rails 22 until the transfer cask and MPC 300 are in proper alignment axial alignment with the desired hole 120 of the roof slab 101. At this time, the weather cover 275 and lid 250 are removed from that hole 120. A mating device is used to operably connect the transfer cask and the roof 101. The MPC 300 is then lowered through the hole 120 and into the cavity 203 of the shell 200 until the MPC rests atop the floor plate 212 (or on supports that create a bottom plenum) in a substantially vertical orientation. The MPC 300 is released and the mating device removed. The lid 250 and the weather cover 275 are then installed as described above. It is preferred that MPCs 300 with low heat and radiation loads be arranged in the perimeter storage shells 200 of the clustered system 1000. In the clustered arrangement, the outer storage shells 200 and their loads provide radiation shielding for the radioactive loads in the inner shells 200. Referring now to FIGS. 3 and 11 concurrently, once the MPCs 300 are loaded in the shells 200, they give off heat. This heat warms the air in the annular gaps 204. The warmed air within the gaps 204 rise within the gap 204, passes through passageways 211 around the lid 250 and exits the system 100 via the holes 278 in the cover 275. As a result of this chimney effect, additional cool air is drawn from the internal space 110 of the enclosure 100 into bottom of the annular gap 204 via the openings 214. This results in additional cool air being drawn into the internal space 110 of the enclosure 100 via the inlet ducts 106, 107. Cool air within the internal space is free to ventilate around the room as needed. In certain embodiments, additional small holes may be added at strategic locations along the height of the shells to draw air in via the Venturi effect. Preferably, the enclosure 100 and shells 200 are assembled so that the only way air within the internal space 110 can exit the enclosure is by passing through the shells 200 as described above. While a number of embodiments of the current invention have been described and illustrated in detail, various alternatives and modifications will become readily apparent to those skilled in the art without departing from the spirit and scope of the invention.
	summary
	claims	1. A beam filter for insertion between a radiation source and a detection area, comprising at least one absorbing body that masks, in its working position, different fractions of a radiation emitting area of the radiation source at different points of the detection area, where the at least one absorbing body is comprised of a plurality of absorbing sheets, and where at least one of the plurality of absorbing sheets has a varying width as measured in radial directions with respect to a given point. 2. The beam filter according to claim 1, wherein the absorbing body comprises a material that is highly absorbing over the whole spectrum of radiation emitted by the radiation source preferable a material with a high atomic number, most preferably a material selected from the group consisting of Mo, W, Au, Pb, Pt, Ta and Re. 3. The beam filter according to claim 1, where the plurality of absorbing sheets are arranged with intermediate spaces in a stack. 4. The beam filter according to claim 3, wherein the intermediate spaces are filled with a spacer material which has a significantly lower attenuation coefficient for the radiation of the radiation source that the material of the absorbing sheets, particularly a polymer. 5. The beam filter according to claim 3, wherein the absorbing sheets lie in planes that intersect in a least one common point. 6. The beam filter according to claim 1, wherein the width assumes a minimal value in a central region of the absorbing sheet. 7. The beam filter according to claim 3, wherein the absorbing sheets have varying thicknesses. 8. The beam filter according to claim 1, wherein it comprises a second body that is movable relative to the first absorbing body and arranged in line with it as seen in a direction from the radiation source to the detection area. 9. An X-ray device, particularly a CT scanner, comprising a radiation source and a beam filter according to claim 1. 10. The beam filter of claim 3, where the stack is configured to be tiltable. 11. The beam filter of claim 1, comprising:a second body that is movable relative to the first absorbing body and arranged out of line with the first body as seen in a direction from the radiation source to the detection area. 12. A beam filter for insertion between a radiation source and a detection area, comprising:at least one absorbing body that masks, in its working position, different fractions of a radiation emitting area of the radiation source at different points of the detection area, where the at least one absorbing body is shaped as at least two absorbing sheets, where the at least two absorbing sheets are arranged with spaces in a stack, and where at least two of the at least two absorbing sheets vary in thickness relative to one another. 13. The beam filter of claim 12, comprising:a second absorbing body that is movable relative to the first absorbing body and arranged in line with the first body as seen in a direction from the radiation source to the detection area. 14. The beam filter of claim 12, comprising:a second absorbing body that is movable relative to the first absorbing body and arranged out of line with the first body as seen in a direction from the radiation source to the detection area. 15. The beam filter of claim 12, wherein the absorbing body comprises a material selected from the group consisting of Au, Pb, Pt, Ta and Re. 16. The beam filter of claim 12, comprising:at least two absorbing bodies that are adjustable relative to one another to adjust an absorption property of the beam filter. 17. The beam filter of claim 12, where at least one absorbing sheet has a varying width as measured in radial directions with respect to a given point. 18. A system, comprising:at least one absorbing body that masks, in its working position, different fractions of a radiation emitting area of a radiation source at different points of a detection area, where the at least one absorbing body causes a first point on the detection area to experience a first intensity level, where the at least one absorbing body causes a second point on the detection area to experience a second intensity level, where the first intensity level and the second intensity level are different, where the first point and the second point are on a line perpendicular to the radiation emitting area, where the radiation emitting area causes a non-zero intensity across a continuous portion of the detection area that includes the first point and the second point, and where the at least one absorbing body comprises:a plurality of relatively high absorbing material sheets; anda plurality of relatively low absorbing material sheets; where the relatively high absorbing material sheets are stacked, are spaced apart from one another, and are separated by at least one sheet of the plurality of relatively low absorbing material sheets. 19. The system of claim 18, where at least one of the relatively high absorbing material sheets has a varying thickness among points on the relatively high absorbing material sheet. 20. The system of claim 18, where at least two of the relatively high absorbing material sheets have a varying thickness relative to one another.
045487847	claims	1. A nuclear reactor power control system comprising: a plurality of fuel rods; a control rod for flattening a fuel power distribution; a control rod for controlling a power level; a safety rod for reducing the power in case of emergency; a plurality of neutron detectors for detecting the power; a sampling adjuster for receiving power signals from said neutron detectors and comparing them with a preset power level signal to produce a difference signal therebetween; control rod drive means responsive to the difference signal from said sampling adjuster to drive said control rods for controlling the power level; means for detecting the drop of said control rod for flattening the fuel power distribution or said safety rod for reducing the power in case of emergency; and means responsive to the detection of the drop to stop the drive by said control rod drive means for controlling the power level. means disposed in said reactor core for controlling the power of said nuclear reactor; a plurality of neutron detectors disposed in said reactor core; means responsive to the outputs of said neutron detectors for providing a power signal representative of the power of said reactor; means for comparing said power signal with a reactor power preset value to provide a difference signal therebetween; means responsive to said difference signal for adjusting the controlling ability of said power controlling means so that said power signal is equal to said reactor power preset value; means responsive to said difference signal to produce a detection signal when said power signal is reduced to less than a threshold value identical with said reactor power preset value minus a predetermined value; and means responsive to said detection signal for disabling said adjusting means. a plurality of control rods disposed in said reactor core for controlling the power of said nuclear reactor; a plurality of neutron detectors disposed in said reactor core; means responsive to the outputs of said neutron detectors for providing a power signal representative of the power of said reactor; means for comparing said power signal with a reactor power preset value to provide a difference signal therebetween; means responsive to said difference signal for driving said control rods to adjust the lengths of those portions of said control rods which are within said reactor core so that said power signal is equal to said reactor power preset value; means responsive to said difference signal to produce a detection signal when said power signal is reduced to less than a threshold value identical with said reactor power preset value minus a predetermined value; and means responsive to said detection signal for preventing said driving means from driving said control rods. 2. A nuclear reactor power control system according to claim 1 wherein said sampling adjuster comprises a combination of a summing and averaging circuit and a comparator. 3. A system for controlling the power of a nuclear reactor having a reactor core, the system comprising: 4. A system according to claim 3, wherein said means for controlling the power of said nuclear reactor includes control rods. 5. A system according to claim 3 or 4, wherein said threshold value identical with said reactor power preset value minus a predetermined value is representative of 95% of the reactor power corresponding to said reactor power preset value. 6. A system according to claim 3, wherein said means for controlling the power of said nuclear reactor includes liquid poison. 7. A system for controlling the power of a nuclear reactor having a reactor core, the system comprising: 8. A system according to claim 7, wherein said threshold value identical with said reactor power preset value minus a predetermined value is representative of 95% of the reactor power corresponding to said reactor power preset value.
044366949	summary	TECHNICAL FIELD This invention pertains to nuclear reactors and, more particularly, to apparatus for decontaminating the walls of boiling water reactor cavities and storage pits. BACKGROUND ART One of the operations which is normally performed during the outage of a nuclear boiling water reactor is the decontamination of the reactor cavity. This is considered to be a "critical path" operation as opposed to a "collateral" operation. In other words, it is an operation which must be performed before the succeeding operation can be undertaken and, thus, adds directly to the length of the shutdown period. Decontamination of boiling water reactor cavity and storage pit walls is achieved by the spraying of high pressure water on the walls. The manner in which this is conventionally achieved is by lowering a man into the cavity or pit in a container suspended from a crane. He then proceeds to wash down the wall with a high pressure hose. It is desirable to use very high pressure water for this purpose, for example, up to 10,000 psi. However, the high reaction forces acting upon a container at the end of a relatively long cable cause the container and workman to be bounced from side to side. The man, even though wearing protective gear, is exposed to highly contaminated water droplets in a highly radioactive environment. The radioactivity, coupled with the sheer physical stress, makes this a very difficult and undesirable job. Because of the reaction forces, it is usually necessary to reduce the water pressure below its optimum value. As a result, the decontamination period is substantially increased and may be, for example, on the order of 8 hours. As reactor shutdowns are very costly, it would be highly desirable to shorten the time for decontamination. It would also, of course, be desirable to reduce or eliminate the exposure of personnel to the dangers and stress-inducing features of the conventional decontamination washdown. DISCLOSURE OF INVENTION In accordance with the invention, apparatus is provided for decontaminating the inside walls of a nuclear reactor cavity or storage pit in a refueling floor having a raised curb around its periphery. The apparatus comprises a chassis which has wheels in rolling contact with the floor and first and second curb wheels mounted on the chassis in rolling contact with the curb. A support member includes a vertical portion which extends upwardly from the chassis, and a horizontal arm which extends laterally from the top of the vertical portion to overhang the edge of the cavity or pit. An elongated mast depends from the horizontal arm and into the reactor cavity and carries at least one stabilizing wheel for horizontal rolling engagement with the cavity or pit wall. A spray carriage is selectively, vertically positionable along the elongated mast and carries means for spraying decontaminating fluid on the wall.
050842374	summary	INTRODUCTION This invention relates to a side insertable spacer designed to permit rapid repair of irradiated fuel assemblies. Fuel assemblies for nuclear reactors are formed of a large number of long, parallel fuel rods. At each end of the assembly, there is a tie plate to which, in some designs, the fuel rods are attached. In other designs the fuel rods terminate short of the tie plates and the tie plates are connected to tie rods so as to form the framework for the assembly. Intermediate the tie plates there are a number of grid spacers formed of "egg crate" strips which serve to space the fuel rods and restrain them from vibration. At times there may be fretting of fuel rods at or adjacent to the tie plates so that it is desirable to insert additional grid spacers. In other cases, the grid spacers may be damaged in handling so that the replacement becomes necessary. In previous designs, it has been necessary to essentially disassemble the fuel bundle if new spacers are to be inserted. This is, of course, a difficult procedure, particularly since it will ordinarily be carried out on assemblies which have been irradiated in the nuclear reactor and have therefore become radioactive. BRIEF DESCRIPTION OF THE INVENTION Our invention provides a spacer which can be inserted into a finished fuel assembly without disassembling the latter. It is formed of two superposed "combs." Each comb includes an end strip corresponding in length to one side of the fuel assembly. Perpendicular to this end strip are a plurality of grid strips which engage the fuel rod. The grid strips are so constructed as to have spring members which press against the fuel rods. When the spacer is completely assembled, the superposed combs will extend at right angles or some other angle, depending on the shape of the assembly, to each other. Together they form a complete grid spacer which will hold the rods in position. The combs are of such structure that they can be remotely inserted into the assembly even under water by the use of long-handled tools.
	abstract	A rear door system for transferring hot cell equipment into or out of a hot cell is disclosed. The rear door system of the present invention includes a rear door, which is provided to a rear wall of the hot cell so as to be movable to open or close the rear wall of the hot cell, and a vertical moving table, which is provided at a predetermined position on the lower portion of the front surface of the rear door so as to be movable upwards or downwards. The rear door system further includes a drive unit, which is provided at a predetermined position in the lower end of the rear door to move the rear door, and a stationary working table, which is disposed above the vertical moving table and is fixed in the hot cell in a horizontal orientation. The rear door system further includes a removable table, which is removably coupled at a predetermined position to the stationary working table, and a hot cell crane hook and a service area crane hook, which are respectively provided inside and outside the hot cell.
	summary
	abstract	The invention is for a system and method to reduce neutron production from a deuterium-helium-3 (D-3He) fueled, steady-state, small nuclear fusion reactor. The reactor employs a field-reversed configuration (FRC) magnetic confinement scheme and an odd-parity rotating magnetic field (RMFo) that produces periodic, co-streaming, energetic ion beams which heat the plasma. This is accomplished through radio-frequency (RF) heating, which can effectively heat and maintain the plasma. Use of this method will lessen damage to and activation of reactor components and, in doing so, can advance the development of fusion reactors for electrical, power and propulsion applications by alleviating the need for both nuclear-materials and tritium-breeding-technology testing programs.
	claims	1. A scintillator panel comprising:a substrate portion having a first main surface and a first rear surface intersecting a first direction on sides opposite to each other, and a first side surface extending such that the first main surface and the first rear surface are joined to each other;a scintillator layer portion having a second rear surface formed of a plurality of columnar crystals extending in the first direction and formed to include a base portion being on one end side of the columnar crystals and facing the first main surface, a second main surface formed to include a tip portion on the other end side of the columnar crystals, and a second side surface extending such that the second main surface and the second rear surface are joined to each other; anda barrier layer formed to come into contact with each of the first main surface in the substrate portion and the second rear surface in the scintillator layer portion,wherein the first side surface and the second side surface are substantially flush with each other,wherein in the substrate portion, an angle between the first rear surface and the first side surface is smaller than 90 degrees,wherein the barrier layer is formed fo thallium iodide, andwherein the scintillator portion is made of a material having cesium iodide as a main component. 2. The scintillator panel according to claim 1,wherein the scintillator layer portion generates scintillation light, andwherein the substrate portion absorbs the scintillation light. 3. The scintillator panel according to claim 1,wherein the scintillator layer portion generates scintillation light, andwherein the substrate portion reflects the scintillation light. 4. The scintillator panel according to claim 1,wherein the substrate portion is formed of polyethylene terephthalate. 5. The scintillator panel according to claim 1,wherein the second rear surface of the scintillator layer portion comes into contact with the first main surface of the substrate portion. 6. A radiation detector comprising:a scintillator panel according to claim 1 emitting scintillation light in response to incident radiation; anda photo-detection substrate facing the scintillator panel and detecting the scintillation light.
	summary
	summary
	abstract	This invention relates to a device for switching and controlling an electron dose emitted by a micro-emitter comprising a sensor module (30) that receives the output current from the micro-emitter and a voltage to adjust the polarization point of the said device, a comparator module that receives a threshold voltage to adjust the quantity of charges to be emitted, a logical module to initialize the electron emission, and to define whether or not the micro-emitter should emit, a control module that generates the voltages necessary for initialization and extinction of the micro-emitter current pulse, means of varying the threshold voltage.
	abstract	An apparatus for treating metal which is capable of selectively monitoring and controlling various aspects of a multi-staged metal treatment process to more accurately and reliably administer treatment. The apparatus comprises a first stage for cleaning a metal workpiece with a alkaline solution, a second stage for applying an ionic conditioner to the workpiece, a third stage for applying a phosphate solution to the workpiece, a fourth stage for applying a finishing overcoat in an ionic aqueous sealing agent to the workpiece, a plurality of sensors for monitoring temperature and conductivity of the alkaline solution in the first stage, conductivity and pH of the conditioner in the second stage, temperature, conductivity and pH of the third stage, and conductivity and pH of the fourth stage, a controller for selectively monitoring the sensors and controlling output actuators to maintain desired parameters of the metal treatment process, and capable of controlling the metal treatment process in a first and second mode of control, wherein the first mode comprises automatic controlling of the treatment process, and the second mode comprises timed controlling of the treatment process, and a plurality of output actuators for responding to the controller to maintain the desired parameters of the treatment process.
	summary
	abstract	A radiation detection apparatus comprising a sensor panel and a scintillator panel is provided. The scintillator panel including a substrate, a scintillator disposed on the substrate, and a scintillator protective film that has a first organic protective layer and an inorganic protective layer, and covers the scintillator. The scintillator protective film is located between the sensor panel and the scintillator. The first organic protective layer is located on a scintillator side from the inorganic protective layer. A surface on a sensor panel side of the scintillator is partially in contact with the inorganic protective layer.
	description	The United States Government may have certain rights to this invention under Management and Operating Contract No. DE-AC05-06OR23177 from the Department of Energy. The present invention relates to the production of radioactive isotopes, and, more specifically, methods of producing radioactive isotopes using an electron accelerator. The use of radioactive isotopes in research and medicine is a multi-billion dollar industry that serves nearly twenty million Americans each year in nuclear medical procedures. It also serves an essential function in the nation's nuclear security and nuclear research. Numerous reports extensively document the national need for research radioisotopes, especially for both beta/gamma particle emitters and alpha particle emitters. 67Cu is a valuable isotope with both beta and gamma emissions which are extremely useful for image-guided radiopharmaceutical therapy. Among other valued characteristics, it emits both therapeutic and imaging radiation and has been approved for trials with human patients. Even though the use of this isotope in radiopharmaceutical therapy is highly advantageous, research with 67Cu has been hampered by the limited availability of the isotope. The limited supply of certain 67 radioisotopes, including Cu, is a fundamental limiting factor in many biomedical research programs that are exploring targeted treatment with radioisotopes. The nation's supply of such isotopes is reliant upon a scant number of production facilities utilizing very few production processes. Radioactive nuclides can be produced through radio-activation of a target using any radiation that carries sufficient energy to induce nuclear breakup. The vast majority of isotopes used in research are produced by research nuclear reactors. Aside from a paucity of such facilities, more than half of the research reactors involved in isotope production are forty years old or older. Accordingly, no robust sources of these isotopes exist in the Unites States today. Novel ways of producing research isotopes for medical and other purposes are necessary to address the issues of (i) the inability of reactors to produce certain isotopes, e.g., proton-rich isotopes, and (ii) the production of isotopes currently in short supply, and (iii) the potentially impending shortage of isotopes as ageing reactors are shut down. One potential solution is to focus upon electron accelerators. When coupled to sub-critical assemblies, electron accelerators are capable of producing large quantities of both neutron-rich and proton-rich radioisotopes. High power electron accelerators are well suited for the production of some important isotopes for medical and industrial applications. Accordingly, new methods of isotope production suitable for electron accelerators and corresponding new processing technologies are necessary in order to make more isotopes available for research and other applications. The present invention comprises a system and process for the photo-nuclear production of 67Cu using mainly the 71Ga (γ, α)67Cu reaction. The system and process uses a high energy electron beam, with or without a radiator, to generate photons in order to isotopically convert at least a portion of a liquid gallium-71 target to copper-67. The system and method may be used to create a supply of certain radioisotopes, including 67Cu, at a reasonable cost and on a larger scale than is currently in practice. A preferred embodiment of this method uses a radiator, which is physically isolated from the isotope production target, to generate photons. More specifically, in the preferred embodiment, a radiator, composed of a high Z material such as tungsten, is struck with a beam from a high power electron linac. Bremsstrahlung photon emissions are then focused on a target downstream of the radiator. A thick liquid gallium target is used when producing 67Cu via the 71Ga (γ, α)67Cu reaction. Unlike the 67Cu production methods by zinc activation, this method permits higher power irradiation, easier separation of the resulting copper from the target or other converted products within the target using the chemical differences of the materials, and results in a radiologically pure final product. The present invention is a method of photo-nuclear production using a source of high energy photons emitted from a bremsstrahlung source powered by an electron linear accelerator. The principal embodiment operates at nuclear excitation energies in the 20-100 MeV region and results in the production of 67Cu via the 71Ga (γ, α)67Cu photo-nuclear reaction. The fundamental production mechanism set forth herein involves photo-nuclear reactions at giant dipole resonance energies (nuclear excitation energies in the 30-50 MeV region). Historically, this production mechanism has been discounted because of the difficulties in separating chemically-identical species that are produced from the prevalent (γ, n) reactions in the original target, which results in a low specific activity of the final product. High power (˜100 kW) electron accelerators are well suited for the production of various isotopes. One method of producing isotopes at electron accelerators is using a high Z radiator to generate bremsstrahlung photons, which in turn irradiate the target. A large fraction of the electron energy in such setup is converted into the photon flux, thus making the irradiation of the lower Z targets significantly more efficient, as compared with the case when a lower Z target is irradiated directly by the electron beam. In addition to that advantage, the use of such radiator generates photons in a material that is physically isolated from the isotope production target and makes the heat management simpler. In general, photo-nuclear resonant cross sections have large widths. This feature, in conjunction with the large flux of photons that can be produced at high power electron accelerators, enables substantial yields of desired isotopes by photo-production because the yields are proportional to the integral of the flux and the cross section. In addition, the high penetrating power of photons enables much thicker targets than can be used with proton beams of comparable energy, which further boosts photo-nuclear yields, and alleviates some of the heating and corrosion issues encountered when using high power density proton beams. Higher activity yields may be obtained by raising the average current of the photon-producing beam as high as achievable. Electron beam energies over the range of 20 MeV to 100 MeV are suitable for photonuclear production of various isotopes. The output energy of the accelerator produced electron radiation should be optimized such that it is sufficiently high to produce the desired activity but low enough to limit the production of undesired radionuclides through other competing reactions. The energy range for 67Cu production with a 71Ga target is optimal at 30-50 MeV. The exposure time necessary would be based upon the other process parameters, e.g. beam energy and target thickness, and the desired quantity of the selected isotope. In a preferred embodiment, the electron beam would first strike and interact with a high-Z radiator. This produces the flux of the energetic photons in the radiator which then strike the target. The bremsstrahlung converter or radiator is composed of a material such as tungsten or tantalum which has the necessary properties of a high conversion rate of electrons to photons and such other properties as to be able to withstand high power densities and accompanying temperature excursions. The parameters and optimization of the radiator are critical as they directly affect the dissipation of the electron energy, the cooling of the radiator, and the attenuation of the appropriate energy photons intended for the target. Among such parameters are the composition of the radiator, the thickness of the radiator, and the distance between the radiator and the target. In a second embodiment, the electron beam would directly impinge upon the target and go through it, without first striking a radiator/convertor. A portion of the beam would be converted to energetic photons which would continue to go through the target and produce the desired isotope. When producing 67Cu, a thick liquid gallium (Ga) target is used. Gallium has a high boiling point (2200 deg. C.) and a low melting point (30 deg. C.). The high boiling point makes it an attractive target which can handle high beam power for an extended period of time. The target design must be optimized as well. The target is subject to irradiation by photons of energies sufficient to cause nuclear conversions and, also, irradiation by photons and electrons of insufficient energy to cause conversions. The target must accommodate all of this incident energy. Therefore, the characteristics of the target must be managed to avoid boiling the target material or inducing unwanted chemical or radiolytic reactions in the material. Since Gallium does not boil nor tungsten melt at any reasonably achievable temperature during this process, the target can be directly exposed to the electron beam during irradiation, simplifying the design. The target must be thick enough to have a noticeable probability for the energetic photons to interact in it and produce the desired isotope. Ideally, a gallium target would be maintained between 30° and 2000° C. with low vapor pressure. It is further preferable to use a target which is enriched in the isotope of interest, e.g., 71Ga as an enriched target increases the yield of the 67Cu photo-production process and reduces contaminating species. The target is mounted in a target apparatus. FIG. 1 illustrates the target apparatus in operation. High beam power requires targets and cooling systems that can adequately handle power dissipation. In a preferred embodiment, the target apparatus 100 consists of a jacket and a target holder 120. In one embodiment, a copper cooling jacket having a clam-shell design is used. The jacket 110 has a plurality of water cooling channels 130 which run through the body of the jacket. This embodiment relies upon the use of a Boron Nitride (BN) cylinder 120 to hold the gallium target 140. The use of BN prevents contamination of the target, i.e., the cylinder is positioned within the jacket and holds the gallium target in order to avoid copper contamination. The cylinder 120 may, however, be composed of any suitable material which has a high melting point (generally in excess of 3,000° C.) and a high thermal conductivity. The preferred embodiment discussed herein would incorporate hexagonal BN which has a higher thermal conductivity. The gallium target is completely encased within the BN cylinder. The clam shell design of the copper jacket facilitates the installation and removal of the cylinder. The target apparatus is designed such that sufficient thermal contact between the BN cylinder and the copper jacket is maintained. FIG. 1 also illustrates the electron beam 160, beam pipe 170, radiator 180 and photons 190 when in operation. Certain parameters of the target assembly may vary but a preferred embodiment would incorporate a BN cylinder with a radius of 10 mm and a length of 100 mm. The water flow rate through the water cooling channels would be 5 GPM per channel. This configuration would accommodate at least 50 kW of total beam power. The electron beam exit window 150 must be able to handle the current density of the beam without losing its thermal and structural integrity. Beryllium is preferable due to its high melting point (1287° C.) and low density. A Be exit window should have sufficient heat handling capacity to maintain its integrity. A Be window of 6.35 cm aperture and 380 μm thickness is satisfactory as it will withstand 1 mA of current and hold accelerator vacuum when the flange and the window are cooled and the electron beam diameter is at least 12 mm. Cooling of the flange can be accomplished by circulating water and cooling of the window can be accomplished by a modest flow of (1 m/s) of nitrogen gas. Applying an appropriate beam optics configuration, it is possible to create a 12 mm beam spot on the window. Modification of the thickness and cooling arrangements would allow the window to accept higher beam currents. Photon irradiation of natural gallium target (60% 69Ga/40% 71Ga) leads to the production of 67Cu mainly by the 71Ga(γ, α) reaction and, depending on photon energy, there will also be a contribution from 69Ga(γ, 2p) reaction, albeit at a much lower level. Irradiation of natural Ga target will also lead to the production of Ga, Zn and Cu isotopes, including 63Cu, 64Cu, and 65Cu by various reactions of gammas and neutrons on the target isotope, such as the 69Ga(γ, α) reaction. Production of undesired copper isotopes and other unwanted radioactivity will be greatly minimized when an enriched 71Ga target is used, leading to significant increase in the specific activity and radiological purity of produced 67Cu. Lower beam energy, approximately 40 MeV, produces fewer contaminants at a reasonable 67Cu production while a higher beam energy, e.g., 100 MeV, has a higher 67Cu yield albeit with higher degree of contamination. Following the irradiation process, isotope separation and purification must be completed. Radiochemical separation of 67Cu from targets is performed using a combination of solvent extraction and ion-exchange chromatography. As noted earlier, production of other Cu isotopes is minimized when an enriched 71Ga target is used, leading to a significant increase in the specific activity and radiological purity of produced 67Cu. As also noted above, the production mechanisms involving photo-nuclear reactions at giant dipole resonance energies have been historically discounted because of the difficulties in separating chemically-identical species that are produced from (γ, n) reactions in the original target. The method set forth herein focuses on the production of species that differ chemically from the target, which are produced from (γ, charged-particle) reactions. These photo-nuclear reactions create daughter species with a different atomic number from the target. This makes chemical separation more feasible and, commensurately, high specific activity can be achieved. One embodiment, using an electron beam having an energy of approximately 40 MeV and 50 kW of power, in conjunction with target of commercially available 99.9999% pure 71Ga, would result in a 67Cu production rate of at least 0.6 mCi/kW-h and a final product having a specific activity of 5.6 Ci/microgram or greater. Further, after separation, at least ninety-nine percent of the radioactive copper would be made up of 67Cu. While the invention has been described in reference to certain preferred embodiments, it will be readily apparent to one of ordinary skill in the art that certain modifications or variations may be made to the system without departing from the scope of invention claimed below and described in the foregoing specification.
	description	This application claims priority to Unites States Non-provisional application Ser. No. 15/431,492, entitled “Grating Magneto Optical Trap,” filed Feb. 13, 2017 for Eric Imhof, which claimed priority to Unites States Provisional Application Ser. No. 62/294,454, also entitled “Grating Magneto Optical Trap,” filed Feb. 12, 2016 for Eric Imhof, both of which are incorporated herein by reference. This invention was made with government support under contract HQ0147-11-D-0052 awarded by the Air Force Research Laboratory. The government has certain rights in the invention. The present disclosure relates to magneto optical traps. A magneto optical trap (MOT) is the primary method by which dilute gasses of atoms and molecules are taken from room temperature to the sub-Kelvin range. It is the first step in many experiments and technologies related to high-accuracy atomic clocks, cold atom gyroscopes and accelerometers used in inertial navigation devices, magnetic field sensors, quantum computing, and gravimeters used to detect underground tunnels, aquifers, or other underground natural resources. A MOT uses laser beams and magnetic fields to collect a high density of atoms with low kinetic energy. For example, a three-dimensional MOT can collect a small cloud, approximately 4 mm across, of super-cooled atoms where the average speed of an atom in the MOT is on the order of 0.1 meters per second. This is compared to atoms at room temperature moving at hundreds of meters per second. Prior methods of creating three-dimensional MOTs used six counter-propagating light beams pointed along the cardinal axes towards a common intersection to capture cold atoms. See, for example, Matthieu Vangeleyn's PhD thesis at the University of Strathclyde, entitled “Atom trapping in non-trivial geometries for micro-fabrication applications.” Another method replaces two of the six beams with mirrors. Still another method uses a single laser with a corner-cube reflector or reflecting right cone to capture atoms within the reflector. The inventor of the present disclosure has identified that present methods for creating magneto optical traps (MOT or MOTs) severely restrict optical access to the experimental chamber containing the cold atom cloud. Using current methods, lines of sight into the experimental chamber are blocked by input light beams or reflectors, leaving little room for imaging cameras, magnetic field sources, experimental lasers, or other methods of experimentally manipulating the cold atom cloud. Prior methods are also limited in their ability to quickly load a MOT with a high number of cold atoms necessary to perform cold-atom applications described above. The present disclosure in aspects and embodiments addresses these various needs and problems by providing a unique grating magneto optical trap (GMOT). Both a two-dimensional (2D) and a three-dimensional (3D) GMOT are described. In embodiments, a 2D GMOT can provide a stream of cold atoms that can be captured in a 3D GMOT above a planar surface, loading the 3D GMOT much more quickly and enabling the experimenter to interact from all sides without obstruction. Additionally, the GMOT requires less laser power as compared to other MOTs. Also, most of the design requirements for a working MOT are satisfied through the design of the grating, alleviating many concerns about alignment, cost, size, and reproducibility. Finally, experimental results of the GMOT show a high-atom number and the ability to perform sub-Doppler cooling. The benefits of using gratings apply equally well to a 3D GMOT as a 2D GMOT. If loaded by a cold atom beam from a 2D GMOT, a 3D GMOT is a compelling source for cold atom experiments. The atomic beam from a 2D GMOT enables higher atom number and loading rates in the 3D GMOT by separating the source vapor from the experimental region. The present disclosure covers apparatuses and associated methods for grating magneto optical traps (GMOTs). In the following description, numerous specific details are provided for a thorough understanding of specific preferred embodiments. However, those skilled in the art will recognize that embodiments can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In some cases, well-known structures, materials, or operations are not shown or described in detail in order to avoid obscuring aspects of the preferred embodiments. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in a variety of alternative embodiments. Thus, the following more detailed description of the embodiments of the present invention, as illustrated in some aspects in the drawings, is not intended to limit the scope of the invention, but is merely representative of the various embodiments of the invention. In this specification and the claims that follow, singular forms such as “a,” “an,” and “the” include plural forms unless the content clearly dictates otherwise. All ranges disclosed herein include, unless specifically indicated, all endpoints and intermediate values. In addition, “optional,” “optionally,” or “or” refer, for example, to instances in which subsequently described circumstance may or may not occur, and include instances in which the circumstance occurs and instances in which the circumstance does not occur. The terms “one or more” and “at least one” refer, for example, to instances in which one of the subsequently described circumstances occurs, and to instances in which more than one of the subsequently described circumstances occurs. FIG. 1 illustrates light beams and a diffraction grating of a 2D GMOT 100. In embodiments, a single input light beam 10 is directed along a first axis, in this figure labeled the z-axis. Input light beam 10 has a width 10c along a second axis, in this figure labeled the x-axis. Input light beam 10 also has an ideal intensity profile 10a distributed across the input light beam width 10c. In practice, input light beam's intensity profile is more like the Gaussian-shaped intensity profile 10b. The intensity profile 10a or 10b is intentionally made to be substantially flat or uniform across the width 10. In this disclosure, a substantially flat or uniform intensity profile means that the intensity of one part of input light beam 10 is substantially equal to another part of input light beam 10 across the effective width 10c of the light beam 10. 2D GMOT 100 also includes a diffraction grating 2 with a diffraction grating surface 2a. The diffraction-grating surface 2a is positioned normal to the first axis, or normal to the incident, input light beam 10. The diffraction-grating surface is also comprised of closely adjacent parallel grooves 2b spread across the width 10c of input light beam 10. In this embodiment, the closely adjacent parallel grooves 2b run parallel to the third axis. The third axis is normal to both the first and second axes, labeled the y-axis in the figures. The diffraction grating surface 2a reflects zeroth order light beams 12b and diffracts first-order and other order light beams 12a and 12c, respectively. In embodiments, the diffraction grating surface 2a diffracts first-order light beams that intersect within an intersection plane 20 that lies within a plane defined by the first and second axis. In this configuration, the input light beam 10 also intersects with the first-order light beams 12a at the intersection plane 20. The cooling of atoms in a magneto-optical trap occurs through Doppler cooling. Opposing beams of light with the correct frequency and polarization may strike an atom such that the atom absorbs a photon and receives a small push in the direction of the striking light beam. In embodiments, the relative light intensities of the input light beam 10 and the first-order diffracted light beams 12a are configured to provide the necessary forces to help push atoms towards the center of the intersection plane 20. In other words, for a trap to form, the sum of the forces on the atoms should be approximately zero. Accordingly, Iup=I1/n cos θ, where Iup is the upward intensity from the diffracted first-order light beams 12a, I1 is the intensity of the single input light beam 10, n is the number of diffracted first-order light beams 12a (in the case of this 2D GMOT embodiment, n equals two), and θ is the angle of the diffracted first-order light beams 12a (in the case of this 2D GMOT embodiment, θ equals 45). Additionally, the diffracted first order light beams 12a are spatially compressed, meaning their intensity is greater within a smaller area, by a factor of cos θ. Thus, in the case of the 2D GMOT described herein, Iup=I1/2, or the diffracted first order light beams 12a should have an intensity that is roughly 50% of the single input light beam 10. In addition, in this embodiment, the diffraction grating surface 2a suppresses reflections 12b and diffractions of all other order light beams 12c. As such, the inventor of the present disclosure has found that small deviations, on the order of +/−10%, in the intensity ratio (between the diffracted first order light beams 12a and the single input light beam 10) still produces a trap but moves the location of the trap with respect to the magnetic field zero. Thus, a trap may still be formed when the diffracted first-order light beams' intensity is between roughly 40 and 60% of the incoming light beam's intensity. The reflection suppression by the diffraction grating surface 2a and the intensity matching of the incoming light beam 10 and first-order diffracted light beams 12a provide a combined force that helps push atoms towards the center of the magneto-optical trap 100 or the center of the intersection plane 20. Doppler cooling alone will slow the motion of an atom but it will not reverse an atom's direction of travel or, in the case of a magneto-optical trap 100, collect cold atoms at the center of the intersection plane 20. Once an atom stops moving, it sees no Doppler shift and will no longer absorb photons from the input light beam 10 or the first-order diffracted light beams 12a. The presence of a magnetic field is necessary to trap atoms at the center of the intersection plane 20. Magneto-optical trap 100 further comprises a quadrupole magnetic field. For clarity purposes, the quadrupole magnetic field that is part of the magneto-optical trap 100 is not shown in FIG. 1 but is shown in FIG. 2 with its position relative to the intersection plane 20. A magnetic field at any given point may be specified as having both a direction and a magnitude. However, if the magnitude is zero at a given point, the direction is also zero. FIG. 2 shows the quadrupole magnetic field 40 with its force and direction being zero at the center of the intersection plane 20. In this embodiment, the quadrupole magnetic field 40 has a magnitude of zero along the third axis and is centered at the center of the input light beam's width 10c, or at the center of the intersection plane 20. FIG. 3 illustrates another embodiment of a magneto-optical trap 200. In this embodiment, the diffraction-grating surface is comprised of two diffraction grating surfaces 4a and 4b separated by a gap 4c, which is formed by the separation between the diffraction grating surfaces 4a and 4b. The gap 4c extends parallel to the third axis and is centered, relative to the second axis, at the center of the intersection plane 20. The diffraction grating surfaces 4a and 4b in 2d GMOT trap 200 need not suppress reflections and diffractions of all other orders because of the gap 4c between the surfaces 4a and 4b. In this embodiment, input light beam 10 is not reflected back into the intersection plane 20 but instead passes through the gap 4c. Instead, this embodiment may use a less expensive or lower quality diffraction grating while achieving the same atom trapping results. The 2D GMOTs 100 and 200 do not constrain atom movement along the third axis. As such, in embodiments, a magneto optical trap such as magneto optical trap 100 or 200 provides a stream of cooled atoms or an atom beam 16 flowing along the third axis that may feed into a three-dimensional magneto-optical trap (3D GMOT). FIG. 4 illustrates a side-view of another magneto optical trap 300. In this embodiment, the input light beam 10 has a vector component 10y that is parallel to the third axis. Vector component 10y helps produce a stream of cooled atoms or an atom beam 16 flowing in the same direction as the vector component 10y. The vector component 10y points opposite the atom beam 16 direction to provide Doppler cooling along the beam 16. This may be done by having a beam opposite along 10y with a mirror reflecting the beam back onto the atom beam (i.e. the mirror, not shown, would be on the far right of the figure). The mirror would have a small hole in it through which the atom beam 16 could pass. Alternatively, in another embodiment, there is no mirror but just an angled beam 10 such that vector 10y is opposite the atom beam 16. FIG. 5 illustrates a 3D GMOT 400. Like the 2D GMOTs 100 and 200, 3D GMOT 400 includes an input light beam 10 directed along a first axis, labeled the z-axis in FIG. 5. Input light beam 10 has an area 10d extending in a second and third axis, the second and third axes are perpendicular to the first axis and labeled as the x and y-axis in FIG. 5. Input light beam 10 in FIG. 5 might have a similar intensity profile across the area 10d as the intensity profile 10a described in relation to 2D GMOTs 100 and 200 illustrated in FIGS. 1 and 3. FIG. 5 further illustrates diffraction gratings 6a, 6b, 6c, and 6d with their respective diffraction grating surfaces. The diffraction grating surfaces of 6a, 6b, 6c, and 6d are comprised of closely adjacent parallel grooves (not shown) that run substantially parallel to their longest outside edge of their respective diffraction grating surface. In other words, the adjacent parallel grooves of diffraction gratings 6a and 6c run along the x-axis and the adjacent parallel grooves of diffraction gratings 6b and 6d run along the y-axis, as illustrated in FIG. 5. Diffraction gratings 6a, 6b, 6c, and 6d are combined to form a gap 6e at the center of the diffraction gratings 6a, 6b, 6c, and 6d. The gap 6e prevents the reflection of zeroth order light beams (not shown) directly above the gap (along the z-axis). As in the 2D GMOTS 100, 200, and 300, the cooling of atoms in the 3D GMOT 400 occurs through Doppler cooling. Opposing beams of light with the correct frequency and polarization may strike an atom such that the atom absorbs a photon and receives a small push in the direction of the striking light beam. Diffraction gratings 6a, 6b, 6c, and 6d diffract first-order light beams 12a. In embodiments, the diffracted first-order light beams 12a and the single input light beam 10 intersect at an intersection region 22 above the gap 6e formed between the surfaces of the diffraction gratings 6a, 6b, 6c, and 6d. A cold atom cloud 18 forms within the intersection region 22. As in the case of the 2D GMOT described above, with respect to the 3D GMOT, the relative light intensities of the input light beam 10 and the first-order diffracted light beams 12a are configured to provide the necessary forces to help push atoms towards the center of the intersection region 22. In other words, for a trap to form, the sum of the forces on the atoms should be approximately zero. Accordingly, Iup=I1/n cos θ, where Iup is the upward force from the diffracted first-order light beams 12a, I1 is the force exerted by the single input light beam 10, n is the number of diffracted first-order light beams 12a (in the case of this 3D GMOT embodiment, n equals four, since there are four diffraction grating surfaces), and θ is the angle of the diffracted first-order light beams 12a (in the case of this 3D GMOT embodiment, 0 equals 45). Additionally, the diffracted first order light beams 12a are spatially compressed, meaning their intensity is greater within a shorter area, by a factor of cos θ. Thus, in the case of the 3D GMOT described herein, Iup=I1/4, or the diffracted first order light beams 12a should have an intensity that is roughly 25% of the single input light beam 10. In addition, in this embodiment, the diffraction grating surface 2a suppresses reflections 12b and diffractions of all other order light beams 12c. As such, the inventor of the present disclosure has found that small deviations, on the order of +/−10%, in the intensity ratio (between the diffracted first order light beams 12a and the single input light beam 10) still produce a trap but move the location of the trap with respect to the magnetic field zero. Thus, a trap may still be formed when the diffracted first-order light beams' intensity is between roughly 15 and 35% of the incoming light beam's intensity. The reflection suppression by the diffraction grating surface 2a and the intensity matching of the incoming light beam 10 and first-order diffracted light beams 12a provide a combined force that helps push atoms towards the center of the magneto-optical trap 400 or the center of the intersection region 22. 3D GMOT 400 further comprises a quadrupole magnetic field. For clarity purposes, the quadrupole magnetic field that is part of the magneto-optical trap 400 is not shown in FIG. 5 but a portion of it is shown in FIG. 6, with its position relative to the intersection region 22 and the diffraction gratings 6a, 6b, 6c, and 6d. A magnetic field at any given point may be specified as having both a direction and a magnitude. However, if the magnitude is zero at a given point, the direction is also zero. For clarity purposes, FIG. 6 does not show all the field vectors of the quadrupole magnetic field 40. However, the force and direction of quadrupole magnetic field 40 are zero at the center of the intersection region 20, or the center 42 of the quadrupole magnetic field 40 is zero. In other embodiments, FIG. 7 illustrates 3D GMOT 500 with a circular diffraction grating 7, diffraction grating surface 7a, and a hole 7b formed in the center of the diffraction grating 7. Diffraction grating surface 7a comprises closely concentric circular grooves. Like previous GMOTs disclosed herein, 3D GMOT 500 comprises a single input light beam 10 directed along a first axis, labeled the z-axis in FIG. 7. Input light beam 10 has an area 10d extending in a second and third axis, the second and third axis being perpendicular to the first axis and labeled as the x and y-axis in FIG. 7. Input light beam 10 in FIG. 7 might have a similar intensity profile across the area 10c as the intensity profile described in relation to FIGS. 1, 3, and 5. Diffraction grating 7 forms a hole in its center. The hole 7 prevents the reflection of zeroth order light beams (not shown) directly above the gap (along the z-axis). Diffraction grating 7 diffracts first-order light beams 12a. In embodiments, the diffracted first-order light beams 12a and the input light beam 10 intersect at an intersection region 22 above the hole 7 formed at the center of diffraction grating 7. A cold atom cloud 18 forms within the intersection region 22. Similar to 3D GMOT 400, 3D GMOT 500 comprises a quadrupole magnetic field that is not shown, however, its description is similar to that described in relation to quadrupole magnetic field 40 illustrated in FIG. 6. FIG. 8 illustrates a 2D GMOT, such as 2D GMOTs 100, 200, or 300, providing a stream of atoms 16 that is captured by a 3D GMOT, such as 3D GMOT 400 or 500. FIG. 8 further illustrates a single input light beam 10 for each of the 2D and 3D GMOTS. As can be seen in FIG. 8, the 2D and 3D GMOTs are configured to enable an experimenter to interact from all sides of the GMOTs without obstruction from other input light sources or other lab equipment necessary to form an atomic beam or an atomic cloud. Additionally, the GMOT configurations illustrated in FIG. 8 require less laser power as compared to other MOTs that have multiple input light beams. In FIG. 8, the 2D GMOT 100, 200, or 300 resides in vacuum cell 30 and the 3D GMOT 400 or 500 resides in a second vacuum cell 32. The 2D GMOT 100, 200, or 300 may be capped by a silicon reflector with a pinhole (not shown). The atom beam 16 travels through the pinhole from the 2D GMOT 100, 200, or 300 to the 3D GMOT 400 or 500. The atomic beam 16 from the 2D GMOT 100, 200, or 300 enables higher atom number capture and loading rates in the 3D GMOT 400 or 500 by separating the source vapor (in vacuum cell 30) from the experimental region (in vacuum cell 32). Separating the source vapor from the experimental region in this configuration further enables greater access by an experimenter to the experimental region. FIGS. 9 and 10 are black and white photographs illustrating the actual results of a 2D and 3D GMOTs, respectively. FIG. 9 shows a 2D GMOT producing an atom beam (shown as the white region). FIG. 10 shows a 3D GMOT producing an atom cloud (also shown as a white region or cloud). The following examples are illustrative only and are not intended to limit the disclosure in any way. The inventor of the present disclosure built functional two-dimensional and three-dimensional grating magneto-optical trap (2D and 3D GMOTs). This included a vacuum chamber of bonded anti-reflection coated borosilicate glass. The six-sided, rectangular chamber measured 89×32×35 mm, with a large hole cut into one of the 32×35 mm faces which was bonded to a vacuum pumping system. One of the 89×32 mm faces of the chamber was a 1 mm thick sapphire wafer. The evacuated chamber operated at pressures low as 10−9 Torr, or lower. The relatively high (45%) efficiency requirements of the 2D GMOT preclude many grating types. Any grating without a preferred direction would have to diffract practically all input into the +/− first orders. Non-direction etched gratings have been fabricated to this standard, albeit with a high input of design time and fabrication cost. Such gratings often require e-beam lithography for small (≈500 nm) feature seizes. E-beam lithography for large area gratings monopolizes clean-room facilities making them prohibitively expensive. Replicated blazed gratings are inexpensive, but design choices are confined to commercially produced masks. Additionally, these gratings are not designed to minimize reflections, which can undermine trap performance by producing an additional beam with a typically anti-trapping polarization. GMOT designs with blazed gratings have gaps between gratings along the central axis to allow light to pass (as shown in FIGS. 3, 5, and 6). The inventor obtained two 45×12 mm, 18-degree blazed diffraction gratings, with parallel grooves along the long axis at 900 grooves/mm and 1000 nm-blaze wavelength, with equal linear polarization efficiencies near 60%. The equal linear polarization resulted in a circularly polarized diffracted beam. The inventor placed the grating surfaces against the glass surface opposite the sapphire wafer. The gratings were aligned parallel to the 89-mm axis of the vacuum chamber and separated from each other by 5 mm. The blazes were oriented towards the gap separating the gratings. The inventor then dispensed 87Rb atoms into the chamber. A laser and amplifier system produced coherent light at 780.246 nm wavelength, while a separate laser produced coherent light at 780.232 nm wavelength. The two beams were combined, linearly polarized, and input into a common polarization-maintaining optical fiber. The fiber output 70 mW of optical power at 780.236 nm and 12 mW at 780.232 nm. The light was expanded with two-inch optics and circularly polarized before being directed through the sapphire window, into the chamber, and towards the gratings. The light diffracted off the gratings at an angle of 44.5 degrees. The intensity of the light impinging on the grating was diffracted into the blaze-preferred first order with an overall efficiency near 60%. The diffracted light was mostly of the opposite circular polarization as the input beam. A region of space was formed inside the vacuum chamber in which the input and preferred first order beams overlapped. The cross-sectional area of this region was approximately 6 mm2. A two-dimensional quadrupole magnetic field was generated using four 2×0.125×0.25 inch permanent magnets arranged at the corners of the vacuum chamber. The two-inch magnet axes were parallel to the 89-mm axis of the chamber. The main axis of the field was directed along the direction of the input light beam. The location where the magnetic field was zero was set within the overlapping area of the input and diffracted light beams. The gradient of the field near the zero location was 30 G/cm. The existence of a 2D-GMOT was verified by observing the atomic fluorescence with a CCD camera imaging the plane of the overlapping beams (as shown in FIG. 8). The high atomic density at the center of the magnetic field was evidenced by a high fluorescence at that location. The high-density region could be moved by displacing the magnetic field's zero region. Additionally, the density could be optimized by shifting the input light's circular polarization. The high-density region disappeared when the 780.232 nm light was removed. These factors are indicative of a magneto-optical trap. In another experimental setup, the inventor of the present disclosure used two glass vacuum cells separated by a mini-conflat flange. The 2D GMOT was produced in a chamber 30×40×72 mm3, which is capped by a silicon reflector with a 1 mm-diameter pinhole. The atom beam traveled through the pinhole, through a second filtering 3 mm pinhole in the copper gasket of the conflat cross. The atoms were then collected on the opposing side of the cross in a 3D GMOT in a chamber that is 25×40×85 mm3. All glass walls were anti-reflection coated on both sides at 780 nm. In this experiment, the inventor located the gratings outside the vacuum chamber. The added optical path through the glass chamber surface modifies the intensity and polarization of the diffracted beams. As a result, the inventor used gratings with 830 grooves/mm for 800 nm wavelength. A normally incident, circularly polarized beam input beam diffraction through the chamber wall will have 64% of the original intensity and be 90% polarized with the opposite handedness. In this same experiment, for the 2D GMOT, the inventor used two 17.5×38 mm2 rectangular gratings with their blazes facing towards their common axis, separated by a 5-mm gap. For the 3D GMOT, the inventor used four trapezoidal gratings such that when combined they produced a 38×38 mm2 square with a 4×4 mm2 gap at its center (as illustrated in FIG. 5). Again, all the blazes point towards the central axis. However, the 3D GMOT requires an efficiency closer to 25%. To reduce the diffracted beam power, a 0.1 ND filter was placed between the gratings and the vacuum chamber wall. A single laser beam was input into each chamber. Each beam carried 11.0 mW/cm2 light at the cooling (detuned 52S1/2→52S3/2, F=2→3, Δ=−1.3 Γ) transition and 3.8 mW/cm2 (F=1→2) at the repump transition for 87Rb. The light was emitted from a single mode, polarization-maintaining fiber and expanded through a negative lens. A wide-angle quarter wave plate provides circular polarization to the expanding beam, which is then reflected from a two-inch mirror and collimated with a 100-mm focal length lens. A “push” beam was directed along the 2D GMOT axis to provide enhanced cooling, using 3.3 mW of cooling light in a beam with a 4-mm waist. The beam was retro-reflected using a silicon mirror. The 2D GMOT magnetic fields were provided by four permanent neodymium magnets arranged on cage rods outside the chamber. They were positioned via a three-axis translation stage and a tip-tilt mirror mount to aid alignment of the 2D GMOT with the silicon pinhole. They provided an extended quadrupole field with a 20 G/cm gradient. The 3D GMOT magnetic fields were produced by an anti-Helmholtz coil pair, centered by the cage rods that aligned the 3D GMOT optics. Running a 1.2 A current, they provided a gradient of 10 G/cm in the axial direction. The system was evacuated to a pressure of 2×10−9 Torr, measured using a residual gas analyzer. The 3D GMOT fluorescence was monitored using a photodiode from Thorlabs (PDA100A). Light from the GMOT was collected using a f=25.4 mm lens positioned 2f from the trap and the sensor surface. Pulsing the 3D GMOT's magnetic field off and on produced a rising fluorescence signal proportional to the number of captured atoms. By monitoring the 3D GMOT fluorescence as a function of time, the 2D GMOT beam could be characterized. An 8-mW “plug” laser beam was positioned just after the exit pinhole. The beam acted to misalign the atomic beam from the 2D GMOT, which reduced the capture rate of the atoms. When the plug beam was turned off for a short period, the 3D GMOT would grow as atoms traversed the distance from the exit pinhole to the 3D GMOT atomic cloud. It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also, various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, and are also intended to be encompassed by the following claims.
	description	This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2016-0126577, filed on Sep. 30, 2016, in the Korean Intellectual Property Office, the disclosure of which is hereby incorporated by reference in its entirety. Example embodiments of the present disclosure relate to a semiconductor manufacturing process, more specifically, to a method of optimizing a mask included in a partial coherent system using a pixel-based learning. An optical lithography process is performed to form a circuit pattern corresponding to mask polygons of a mask on a substrate (e.g., a silicon wafer). In the optical lithography process, light is irradiated through the mask onto the substrate coated with the photoresist. A desired circuit pattern is formed on the substrate by an optical lithography process using a mask having a mask pattern (or an image pattern). The mask pattern can include mask polygons corresponding to the desired circuit pattern. As the integration of a semiconductor device increases, the distance between the mask polygons decreases and the width of each mask polygon becomes narrower. Such proximity can cause interference and diffraction of light, and thus a distorted circuit pattern different from the desired circuit pattern can be printed on the substrate. A resolution enhancement technique for optimizing the mask includes, for example, optical proximity correction, an assist feature method or an inverse lithography technique. The resolution enhancement technique can be used for preventing a distorted circuit pattern. However, in the resolution enhancement technique, multiple simulations are performed. In some embodiments, the disclosure is directed to a method of optimizing a target mask used for a partial coherent system having a plurality of spatial filters, the method comprising: obtaining a trainer mask that is an optimized sample mask by performing a mask optimization on a sample mask; generating a mask optimization estimation model by performing a pixel-based learning using, as a feature vector of each of pixels of the trainer mask, partial signals of each of the pixels of the trainer mask respectively determined based on the plurality of spatial filters and using, as a target value, a degree of overlap between each of the pixels and a mask polygon of the trainer mask; and performing a mask optimization on the target mask using the mask optimization estimation model. In some embodiments, the disclosure is directed to a method of optimizing a target mask used for a partial coherent system having a plurality of spatial filters, the method comprising: obtaining a trainer mask that is an optimized sample mask by performing a mask optimization on a sample mask; obtaining a grey scale value of each of pixels of the trainer mask representing a degree of overlap between a mask polygon of the trainer mask and each of the pixels of the trainer mask by performing a grey scale rasterization on the trainer mask; obtaining a feature vector of each of the pixels of the trainer mask by calculating partial signals of each of the pixels of the trainer mask based on the plurality of spatial filters; generating a mask optimization estimation model by performing a pixel-based learning using the feature vector of each of the pixels of the trainer mask and using the grey scale value of each of the pixels of the trainer mask as a target value of each of the pixels of the trainer mask; and performing a mask optimization on the target mask using the mask optimization estimation model. In some embodiments, the disclosure is directed to a method of optimizing a target mask used for a partial coherent system having a plurality of spatial filters, the method comprising: obtaining a trainer mask by performing a mask optimization on a sample mask; obtaining a grey scale value for each pixel of the trainer mask, wherein the grey scale value represents a degree of overlap between a mask polygon of the trainer mask and the pixel of the trainer mask; obtaining, for each pixel of the trainer mask, a feature vector of the pixel by calculating a partial signal of the pixel based on a corresponding one of the plurality of spatial filters; generating a mask optimization estimation model by performing, for each pixel of the trainer mask, a pixel-based learning using the partial signal of the pixel as a feature vector and the grey scale value of the pixel as a target value; and performing a mask optimization on the target mask using the mask optimization estimation model. Various example embodiments will now be described more fully with reference to the accompanying drawings in which some example embodiments are shown. However, the concepts may be embodied in many alternate forms and should not be construed as limited to only example embodiments set forth herein. It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. Unless the context indicates otherwise, these terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section, for example as a naming convention. Thus, a first element, component, region, layer or section discussed below in one section of the specification could be termed a second element, component, region, layer or section in another section of the specification or in the claims without departing from the teachings of the present invention. In addition, in certain cases, even if a term is not described using “first,” “second,” etc., in the specification, it may still be referred to as “first” or “second” in a claim in order to distinguish different claimed elements from each other. As discussed herein, an integrated circuit device may refer to a semiconductor device, a flat panel display, or other electronic device being manufactured. As used herein, a semiconductor device may refer, for example, to a device such as a semiconductor chip (e.g., memory chip and/or logic chip formed on a die), a stack of semiconductor chips, a semiconductor package including one or more semiconductor chips stacked on a package substrate, or a package-on-package device including a plurality of packages. These devices may be formed using ball grid arrays, wire bonding, through substrate vias, or other electrical connection elements, and may include memory devices such as volatile or non-volatile memory devices. An integrated circuit device may include, for example, a substrate having an integrated circuit thereon, such as a wafer, or a plurality of semiconductor devices formed in an array on a wafer. An electronic device, as used herein, may refer to these semiconductor devices or integrated circuit devices, and may additionally include products that include these devices, such as a memory module, memory card, hard drive including additional components, or a mobile phone, laptop, tablet, desktop, camera, or other consumer electronic device, etc. FIG. 1 is a view illustrating a partial coherent system including a mask on which a mask optimization method is performed according to example embodiments. Referring to FIG. 1, a partial coherent system 100 including a mask 140 on which a mask optimization method is performed may be an optical lithography system for printing a circuit pattern on a wafer WF using the mask 140. The partial coherent system 100 may include a plurality of point light sources 120, the mask 140, a reduction projection apparatus 160 and a wafer stage 180. However, the partial coherent system 100 may further include components that are not illustrated in FIG. 1. For example, the partial coherent system 100 may further include at least one sensor configured to measure a height and an inclination of a surface of the wafer WF. The partial coherent system 100 may include the point light sources 120, including, for example, first through fifth point light sources L1, L2, L3, L4 and L5. The first through fifth point light sources L1, L2, L3, L4 and L5 may each emit light. The light emitted from each of the first through fifth point light sources L1, L2, L3, L4 and L5 may be provided to or illuminated onto the mask 140. For example, the first through fifth point light sources L1, L2, L3, L4 and L5 may each include an ultraviolet (UV) light source a krypton fluoride (KrF) light source having a wave length of 234 nm or an argon fluoride (ArF) light source having a wave length of 193 nm. Each of the first through fifth point light sources L1, L2, L3, L4 and L5 may emit light having a same or different intensity. The point light sources 120 may include five point light sources L1, L2, L3, L4 and L5 as shown in FIG. 1. However, the number of the point light sources 120 may be variously changed according to example embodiments. For example, the point light sources 120 may include a dipole light source or a quadruple light source, but are not limited thereto. In some embodiments, the partial coherent system 100 may include a lens disposed between the point light sources 120 and the mask 140 to adjust an optical focus. The mask 140 may include mask patterns including mask polygons corresponding to a circuit pattern or a device pattern, for example, an interconnection pattern, a contact pattern or a gate pattern to print the circuit pattern or the device pattern on the wafer WF. Mask polygons may be, for example, bitmaps or polygon layers that identify specific areas upon which further processing is to be performed. In some embodiments, the mask polygons of the mask 140 may be a transparent region capable of passing the light emitted from the point light sources 120, and the other region of the mask 140 except the mask polygons may be an opaque region. In other embodiments, the mask polygons of the mask 140 may be the opaque region, and the other region of the mask 140 except the mask polygons may be the transparent region. The mask 140 may be optimized by a mask optimization method according to example embodiment, which is described with reference with FIGS. 4 through 13. The reduction projection apparatus 160 may be provided with the light that passes through the transparent region of the mask. For example, light that passes through the transparent region of the mask may be directed through the reduction projection apparatus 160. The reduction projection apparatus 160 may match the circuit pattern to be printed on the wafer WF with the mask pattern of the mask 140. The wafer stage 180 may support the wafer WF. For example, the wafer stage 180 may provide the base upon which the wafer WF rests and against which the wafer WF is held while the circuit pattern is printed on the wafer WF. The reduction projection apparatus 160 may include an aperture to increase depth of focus of the light (e.g., UV light) emitted from the point light sources 120. The aperture may have different optical characteristics according to positions of the first through point light sources L1, L2, L3, L4 and L5 with respect to one another (e.g., the first through point light sources L1, L2, L3, L4 and L5), and thus the partial coherent system 100 may include a plurality of spatial filters. For example, the partial coherent system 100 may have, as the spatial filters, a plurality of point spread functions or mathematical transformations thereof. An optical characteristic of the partial coherent system 100 are described with reference to FIGS. 2 and 3. A region of the mask 140 corresponding to the mask polygons (or a region except the mask polygons when the mask polygons are the opaque region) may pass the light emitted from the point light sources 120. The light passing through the mask 140 may be irradiated onto the wafer WF through the reduction projection apparatus 160. Thus, the circuit pattern or the device pattern corresponding to the mask polygons of the mask 140 may be printed on the wafer WF. With increasing integration of a semiconductor device, a distance between the mask polygons may be reduced, and a width of each of the mask polygons may become narrower. Due to such proximity, interference and diffraction of the light may be generated, and thus a distorted circuit pattern different from a desired circuit pattern may be printed on the wafer WF. When the distorted circuit pattern is printed on the wafer WF, a manufactured electronic circuit may operate abnormally. A resolution enhancement technique for optimizing the mask 140, such as optical proximity correction, an assist feature method, or an inverse lithography technique, may be used to prevent such a distorted circuit pattern. The resolution enhancement technique may be performed using multiple simulations, and the multiple simulations may take more time for the mask optimization as compared with a single simulation. In the mask optimization method according to example embodiments, a pixel-based learning may be performed using a trainer mask on which a mask optimization is performed by the resolution enhancement technique to generate a mask optimization estimation model. The mask optimization may be performed on a target mask (i.e., the mask 140) using the mask optimization estimation model, and thus mask optimization for the target mask may be quickly and efficiently performed compared to the resolution enhancement technique for optimizing the mask 140. FIG. 2 is a view illustrating an optical characteristic of the partial coherent system of FIG. 1 according to example embodiments. FIG. 3 is a view illustrating an intensity of light irradiated onto a substrate by the partial coherent system of FIG. 1 according to example embodiments. Referring to FIG. 2, light emitted from any one point light source Li of the first through fifth point light sources L1, L2, L3, L4 and L5 may be irradiated onto the mask 140. In some embodiments, a first lens E1 for adjusting the optical focus may be provided between the point light source Li and the mask 140. The transparent region of the mask 140 may pass the light emitted from the point light source Li, and the opaque region of the mask 140 may block the light emitted from the point light source Li. In some embodiments, an optical characteristic of the mask 140 in a space domain may be mathematically modeled in a mask function “O(x,y)” having a value “1” for a region of the mask polygons (e.g., the transparent region) and a value “0” for a region except the mask polygons (e.g., the opaque region). Here, “x” may be a coordinate in a first direction (e.g., a horizontal direction) on a plane (e.g., a wafer plane or a mask plane) and “y” may be a coordinate in a second direction (e.g., a vertical direction) vertical to the first direction on the plane (e.g., the wafer plane or the mask plane). The mask function “O(x,y)” that is a mathematical model representing the optical characteristic of the mask 140 may be referred to as an “object function”. For example, the mask function (or the object function) may have a value “1” (i.e., O(x,y)=1) for the transparent region and a value “0” (i.e., O(x,y)=0) for the opaque region. The mask function (or the object function) may denote a position where the mask 140 may pass or block the light. The reduction projection apparatus 160 of FIG. 1 may include second and third lenses E2 and E3 for adjusting optical focus and an aperture AP to increase depth of focus. The light passing through the transparent region of the mask 140 may be illuminated onto the wafer WF through the second lens E2, the aperture AP and the third lens E3. The aperture AP may include a passing region that may pass the light and a blocking region that may block the light. Thus, the aperture AP may have an optical characteristic capable of passing or blocking the light. In some embodiments, the optical characteristic of the aperture AP in the space domain may be mathematically modeled in a function “φi(fx,fy)” that has a value “1” for the passing region and a value “0” for the blocking region. Herein, “i” may be an index relative to the point light source Li. Thus, for example, the optical characteristic of the aperture AP with respect to the first point light source L1 may be expressed by “φ1(fx,fy)”, where “fx” represents a frequency in the first direction (e.g., the horizontal direction) and “fy” represents a frequency in the second direction (e.g., the vertical direction). The function “φi(fx,fy)” may be a mathematical model representing the optical characteristic of the aperture AP in the space domain and may be referred to as a “pupil function”. The pupil function may denote a position where the aperture AP may pass or block the light. The aperture AP may have different optical characteristics depending on a position of the point light source Li. For example, a path of the light emitted from the second point light source L2 of FIG. 1 may be different from a path of the light emitted from the first light source L1 of FIG. 1, and thus the optical characteristic of the aperture AP caused by the light emitted from the second point light source L2 may be different from the optical characteristic of the aperture AP caused by the light emitted from the first point light source L1. The pupil function “φ1(fx,fy)” representing the optical characteristic of the aperture AP based on the first point light source L1 may have a different value from the pupil function “φ2(fx,fy)” representing the optical characteristic of the aperture AP based on the second point light source L2. For example, when an optical environment based on the second point light source L2 is observed in terms of the first point light source L1, the passing region of the aperture AP may be shifted to the side of the aperture AP. Even if the same aperture AP is used, the optical characteristic of the aperture AP may seem to be changed when the position of the point light source Li is changed. The pupil function representing the optical characteristic of the aperture AP may vary depending on the position of the point light source Li. The light emitted from the point light source Li may pass through the mask 140 and the aperture AP and may be illuminated onto the wafer WF. The light emitted from the point light source Li may be irradiated onto a region corresponding to the mask polygons of the mask 140 (or the other region of except the mask polygons), and thus the circuit pattern (or the device pattern) corresponding to the mask polygons may be printed on the wafer WF. An intensity of the light irradiated onto the wafer WF may be expressed by the following Equation 1. I ⁡ ( x , y ) = ∑ i = 1 N ⁢ λ 1 ⁢  0 ⁢ ( x , y ) ⋆ Φ 1 ⁡ ( x , y )  2 [ Equation ⁢ ⁢ 1 ] In the above Equation 1, “I(x,y)” may represent the intensity of the light irradiated onto the wafer WF, “O(x,y)” may represent the mask function (or the object function), and “Φi(x,y)” may represent a “spatial filter” obtained by performing a Fourier transform on the pupil function “φi(fx,fy)”. As described above, “x” may be a coordinate in the horizontal direction on the plane, and “y” may be a coordinate in the vertical direction on the plane. The term “O(x,y)*Φi(x,y)” may denote a convolution operation of the mask function and the spatial filter (or a point spread function) corresponding to the i-th point light source Li, and may refer to an optical field generated based on the i-th point light source Li. The square of the optical field may refer to a basis intensity based on the i-th point light source Li. By multiplying the basis intensity by a proper coefficient “λi”, the intensity “Ii(x,y)” of the light irradiated onto the wafer WF corresponding to the i-th point light source Li may be calculated. The coefficient “λi” may be obtained by any one of various methods. For example, the coefficient “λi” may be selected to be proportional to the intensity of the point light source Li. The coefficient “λi” may be selected to have a weight value by transforming a calculation space. A singular value decomposition (SVD) technique may be an example of a methodology of transforming the calculation space. A method of obtaining the Equation 1 and the coefficient “λi” may be readily discerned by those skilled in the art, and detailed descriptions thereto are omitted. The intensity of the light irradiated onto the wafer WF or an image formation in the partial coherent system 100 of FIG. 1 may be expressed as shown in FIG. 3. Referring to FIG. 3, the mask 140 of FIG. 1 may have an optical characteristic such as a mask function 210. The aperture AP in the partial coherent system 100 may have different pupil functions relative to the first through fifth point light sources L1, L2, L3, L4 and L5. Thus, the partial coherent system 100 may have a plurality of spatial filters 220, 222, 224, 226 and 228 obtained by performing a Fourier transform on the respective pupil functions. The optical lithography system having the spatial filters 220, 222, 224, 226 and 228 may be referred to as the partial coherent system 100. A convolution operation 230 may be performed on the mask function 210 and each of the spatial filters 220, 222, 224, 226 and 228. When square operations (“( )2”) 240, 242, 244, 246 and 248 are respectively performed on results of the convolution operation 230, a plurality of basis intensities 250, 252, 254, 256 and 258 may be respectively derived from the point light sources L1, L2, L3, L4 and L5 in the partial coherent system 100. By performing multiplication operations 260, 262, 264, 266 and 268 to multiply the basis intensities 250, 252, 254, 256 and 258 by predetermined coefficients λ1, λ2, λ3, λ4 and λ5, respectively, intensities of the lights irradiated onto the wafer WF by the point light sources L1, L2, L3, L4 and L5 in the partial coherent system 100 may be derived. By summing 270 the intensities of the lights irradiated onto the wafer WF by the point light sources L1, L2, L3, L4 and L5, a final intensity 280 of the lights irradiated onto the wafer WF may be calculated. The final intensity 280 of the light may correspond to the circuit pattern (or the device pattern) on the wafer WF. As described above, the partial coherent system 100 may have the spatial filters 220, 222, 224, 226 and 228 representing the optical characteristic. The mask optimization method according to example embodiments may generate the accurate mask optimization estimation model by extracting partial signals corresponding to the spatial filters 220, 222, 224, 226 and 228 in a feature vector and performing the pixel-based learning. Hereinafter, the mask optimization method will be described with reference to FIGS. 4 through 13. FIG. 4 is a flow chart illustrating a mask optimization method according to example embodiments. FIG. 5 is a view illustrating an example of a mask optimization method performed on a sample mask in the mask optimization method of FIG. 4 according to example embodiments. FIG. 6 is a view illustrating another example of a mask optimization method performed on a sample mask in the mask optimization method of FIG. 4 according to example embodiments. FIG. 7 is a view illustrating a pixel-based learning performed in the mask optimization method of FIG. 4 according to example embodiments. FIG. 8 is a view illustrating an example of a mask optimization method performed on a target mask in the mask optimization method of FIG. 4 according to example embodiments. Referring to FIG. 4, in a mask optimization method for optimizing a target mask used for a partial coherent system having a plurality of spatial filters, in operation S310, a trainer mask that is an optimized sample mask may be obtained by performing a mask optimization on a sample mask. The optimization of the sample mask may be performed by a resolution enhancement technique. In some embodiments, the resolution enhancement technique for the optimization of the sample mask may include, for example, optical proximity correction, an assist feature method or inverse lithography technique. In some embodiments, referring to FIG. 5, a sample mask 400 including a first mask polygon 420 having a shape corresponding to an interconnection pattern may be optimized into a trainer mask 450 of which each segment includes a second mask polygon 470 having a bias with respect to the first mask polygon 420 before the optimization by the optical proximity correction. In the example of FIG. 5, two second mask polygons 470 are shown as having a bias with respect to two corresponding first mask polygons 420. In other embodiments, referring to FIG. 6, a sample mask 500 including a third mask polygon 520 having a shape corresponding to a contact pattern may be optimized into a trainer mask 550 including a fourth mask polygon 570 further including an assist feature or an assist pattern by the assist feature method. The mask optimization of the sample mask 400 and 500 as shown in FIGS. 5 and 6 may be exemplary. In some embodiments, the mask optimization on the sample mask may be performed by various methods. The same mask may be an arbitrary mask including mask polygons corresponding to a representative circuit pattern of a circuit pattern (or a device circuit) to be formed by the partial coherent system. In some embodiments, the sample mask may be some of a plurality of masks used to fabricate one electronic circuit in the partial coherent system. For example, the mask optimization may be performed on the some of the plurality of masks by the resolution enhancement technique, and the mask optimization may be performed on the others of the plurality of masks as a target mask using a mask optimization estimation model generated by a pixel-based learning. In other embodiments, the sample mask may be a mask discretionally-generated by a designer based on a circuit pattern to be formed. Referring to FIG. 4, in operation S320, the mask optimization estimation model may be generated by performing the pixel-based learning based on the trainer mask that is the sample mask optimized by the resolution enhancement technique. The pixel-based learning may be performed by dividing the trainer mask into a plurality of pixels, using partial signals of each pixel respectively determined based on the spatial filters in the partial coherent system as a feature vector of each pixel of the trainer mask, and using a degree of overlap between each pixel and the mask polygon of the trainer mask as a target value of each pixel. Herein, the pixel may be a unit area of the mask and may have a size proportional to a minimum resolution of an optical system (i.e., the partial coherent system). For example, a feature vector of a k-th pixel of the trainer mask may be calculated using the following Equation 2 and Equation 3.qk=[ik1,ik2, . . . ,ikn] [Equation 2]:ikj=\|O(x,y)·Φj(x,y)\|m@(xk,yk) [Equation 3]: Herein, “qk” may represent the feature vector of the k-th pixel, “ikj” may represent a partial signal by a j-th point light source (or a j-th spatial filter) of the k-th pixel (e.g., ik1, ik2, . . . ikn), “O(x,y)” may represent a mask function of the sample mask (that is the trainer mask before optimization), and “Φj(x,y)” may represent a spatial filter of the partial coherent system by the j-th point light source. The mask function “O(x,y)” of the sample mask may have a value “1” for a position in which a mask polygon of the sample mask is present and a value “0” for a position in which the mask polygon of the sample mask is not present, as a mathematical model representing an optical characteristic of the sample mask in the space domain. The j-th spatial filter “Φj(x,y)” may be obtained by performing a Fourier transform on the pupil function representing the optical characteristic of the aperture of the partial coherent system by the j-th point light source in the partial coherent system in the space domain. Further, “(xk,yk)” may represent a coordinate of the k-th pixel, “n” may correspond to the number of the point light sources of the partial coherent system as the number of the spatial filters of the partial coherent system, and “m” may be a number determined by a designer to derive an accurate mask optimization estimation model. As shown in the Equation 2, the feature vector of the k-th pixel, “qk” may include partial signals “ik1” through “ikn” corresponding to the spatial filters of the partial coherent system. As shown in the Equation 3, each partial signal “ikj” may be calculated by performing a convolution operation of a corresponding one “Φj(x,y)” of the partial filters and the mask function “O(x,y)” of the sample mask. When “m” is 1, each partial signal “ikj” may physically represent an optical field of a corresponding point light source (i.e., the j-th point light source). When “m” is 2, each partial signal “ikj” may physically represent a basis intensity of the corresponding point light source (i.e., the j-th point light source) as the square of the optical field. The value “m” may be determined by the designer to derive the accurate mask optimization estimation model. As described above, as the feature vector of the k-th pixel of the trainer mask includes the partial signals respectively corresponding to the spatial filters of the partial coherent system, the mask optimization estimation model generated using the feature vector may more closely reflect the optical characteristic of the partial coherent system, and thus performance of the mask optimization estimation model may be enhanced. The pixel-based learning using the trainer mask may be performed using an arbitrary machine learning. For example, the pixel-based learning may be performed using a linear learning, a non-linear learning or a neural network learning. In some embodiments, referring to FIG. 7, the pixel-based learning may be performed by a supervised learning method of the neural network learning. For example, when the feature vector “qk” of each pixel of the trainer mask is inputted to a mask optimization estimation model 600, the mask optimization estimation model 600 may output an output value (e.g., an estimated grey scale value “f(qk,PS)”) corresponding to the feature vector “qk”. The output value may be compared to the degree of overlap (e.g., a grey scale value) between each pixel and the mask polygon of the trainer mask, which is a target value “grk” of each pixel. A difference 620 between the output value “f(qk,PS)” of the mask optimization estimation model 600 and the target value “grk” may be reflected to the mask optimization estimation model 600 as an error value “ek”. Such learning may be performed to derive a parameter set PS (e.g., a weight value) of the mask optimization estimation model 600 to minimize the error value “ek”. For example, the pixel-based learning may be performed to minimize the following Equation 4.Σ\|grk−f(qk,PS)\|l [Equation 4]: Herein, the target value “grk” may represent the degree of overlap between each pixel and the mask polygon of the trainer mask, and “f(qk,PS)” may represent the output value of the mask optimization estimation model 600 when “grk” is inputted. “l” may be a value determined by the designer, for example, 1 or 2, but is not limited thereto. The mask optimization estimation model 600 may be learned such that the difference between the target value “grk” of each pixel and the output value (e.g., the estimated grey scale value “f(qk,PS)”) outputted from the mask optimization estimation model 600 when the feature vector “qk” of each pixel is inputted to the mask optimization estimation model 600, may be minimized. In some embodiments, the mask optimization estimation model 600 may be generated for each type of circuit or element included in an electronic circuit fabricated using the partial coherent system. For example, the mask optimization estimation model 600 may be generated for a contact pattern, an interconnection pattern or a gate pattern of the electronic circuit. The mask optimization estimation model 600 may output the degree of overlap between each pixel and the mask polygon of the optimized mask when the feature vector “qk” of each pixel of the mask before the optimization thereof is inputted. Referring to FIG. 4, in operation S370, a mask optimization may be performed on the target mask using the mask optimization estimation model 600 of FIG. 7. In some embodiments, to perform the mask optimization on the target mask using the mask optimization estimation model 600, for each pixel, a feature vector of the pixel of the target mask may be obtained, a degree of overlap between the pixel and a mask polygon of the optimized target mask may be obtained by inputting the feature vector of the pixel of the target mask to the mask optimization estimation model 600, and a presence or absence of a mask polygon in the pixel may be determined according to the obtained degree of overlap. For example, referring to FIG. 8, a feature vector of each pixel of a target mask 700 including a fifth mask polygon 720 may be extracted. The feature vector of each pixel may be extracted based on a convolution operation of a mask function of the target mask 700 and each corresponding spatial filter of the partial coherent system. Additionally, when the feature vector of each pixel of the target mask 700 is inputted to the mask optimization estimation model 600 of FIG. 7, the mask optimization estimation model 600 may output a degree of overlap of a sixth mask polygon 770 of the optimized target mask 750 with respect to each of the pixels. A presence or absence of the sixth mask polygon 770 at each of the pixels may be determined based on the degree of overlap outputted from the mask optimization estimation model 600. The optimized target mask 750 including the sixth mask polygon 770 may be generated when the pixels at which the presence or absence of the sixth mask polygon 770 is determined are combined. The target mask 700 may not be optimized by the resolution enhancement technique but may be optimized using the mask optimization estimation model 600 generated through the pixel-based learning, and thus the target mask 700 may be quickly and efficiently optimized compared to the resolution enhancement technique described above. Additionally, the target mask 750 optimized using the mask optimization estimation model 600 may be similar to the trainer mask 550 of FIG. 6 optimized by the resolution enhancement technique. A performance of the mask optimization using the mask optimization estimation model 600 may be similar to a performance of the mask optimization by the resolution enhancement technique. As described above, in the mask optimization method according to example embodiments, the mask optimization estimation model 600 may be generated by performing the pixel-based learning using the trainer mask 550 on which the mask optimization is performed, and the target mask 700 may be quickly and efficiently optimized by performing the mask optimization on the target mask 700 using the mask optimization estimation model 600. Additionally, in the mask optimization method according to example embodiments, the partial signals “ij” respectively corresponding to the spatial filters of the partial coherent system may be extracted as the feature vector “qk” for each pixel of the trainer mask 550, and the pixel-based learning may be performed to generate the mask optimization estimation model 600. Thus, the mask optimization estimation model 600 may be generated by reflecting the optical characteristic of the partial coherent system, and the mask optimization may be performed on the target mask 700. FIG. 9 is a flow chart illustrating a mask optimization method according to example embodiments. FIG. 10 is a view illustrating a grey scale rasterization performed in the mask optimization method of FIG. 9 according to example embodiments. Referring to FIG. 9, in operation S810, a trainer mask that is an optimized sample mask may be obtained by performing a mask optimization on a sample mask. In operation S820, a gray scale value of each pixel of the trainer mask representing a degree of overlap of a mask polygon of the trainer mask with respect to a corresponding pixel of the trainer mask may be obtained by performing a gray scale rasterization on the trainer mask. For example, referring to FIG. 10, a trainer mask 900 may be divided into a plurality of first through third pixels 930, 940 and 950. A gray scale rasterization may be performed on the trainer mask 900 such that the first pixel 930 non-overlapped with a mask polygon 920 of the trainer mask 900 may have a gray scale value “0”, the second pixel 940 entirely overlapped with the mask polygon 920 of the trainer mask 900 may have a gray scale value “1”, and the third pixel 950 partially overlapped with the mask polygon 920 of the trainer mask 900 may have a gray scale value between “0” and “1” proportional to a size of the overlapped portion thereof. Referring to FIG. 9, in operation S840, a feature vector including the partial signals of each pixel of the trainer mask may be obtained by respectively calculating partial signals of each pixel of the trainer mask based on the spatial filters of the partial coherent system. In operation S850, a pixel-based learning may be performed using the feature vector of each pixel of the trainer mask and using the gray scale value of each pixel of the trainer mask as a target value of each pixel of the trainer mask, such that a mask optimization estimation model may be generated. In operation S870, a mask optimization for a target mask may be performed using the mask optimization estimation model. Thus, the mask optimization for the target mask may be quickly and efficiently performed compared. FIG. 11 is a flow chart illustrating a mask optimization method according to example embodiments. FIG. 12 is a view illustrating a binary rasterization performed in the mask optimization method of FIG. 11 according to example embodiments. Referring to FIG. 11, in operation S1010, a trainer mask may be obtained by performing a mask optimization on a sample mask. In operation S1020, a grey scale value of each pixel of the trainer mask may be obtained by performing a grey scale rasterization on the trainer mask. In operation S1030, a binary value of each pixel of the trainer mask may be obtained by performing a binary rasterization on the trainer mask. In some embodiments, referring to FIG. 12, a trainer mask 1100 may be divided into a plurality of third and fourth pixels 1130 and 1140. A binary rasterization may be performed on the trainer mask 1100 such that the third pixel 1130 having a central point that is not overlapped with a mask polygon 1120 of the trainer mask 1100 may have a binary value “0” and the fourth pixel 1140 having a central point that is overlapped with the mask polygon 1120 of the trainer mask 1100 may have a binary value “1”. Referring to FIG. 11, a feature vector of each pixel of the trainer mask may be obtained by respectively calculating the partial signals of each pixel based on spatial filers of the partial coherent system, in operation S1040, and a pixel-based learning using the feature vector and the grey scale value may be performed such that a mask optimization estimation model may generated, in operation S1050. In operation S1060, when the feature vector is inputted to the mask optimization estimation model, a mask threshold value may be determined based on an estimated grey scale value outputted from the mask optimization estimation model and the binary value of each pixel. In some embodiments, the mask threshold value may be determined to minimize a sum of the number of the pixels each having the estimated grey scale value that is smaller than the mask threshold value when the binary value is “1” and the number of the pixels each having the estimated grey scale value that is greater than the mask threshold value when the binary value is “0”. The pixels each having the estimated grey scale value that is smaller than the mask threshold value may mean when the estimated grey scale value that is smaller than mask threshold value is outputted although it is desired to determine that a mask polygon exists for the pixel, and the pixels each having the estimated grey scale value that is greater than the mask threshold value may mean when the estimated grey scale value that is greater than mask threshold value is outputted although it is desired to determine that the mask polygon does not exist for the pixel. In operation S1070, a mask optimization for a target mask may be performed using the generated mask optimization estimation model and the mask threshold value. For example, a feature vector of each pixel of the target mask may be extracted, and the feature vector may be inputted to the mask optimization estimation model such that the estimated grey scale value may be obtained. The estimated grey scale value may be compared to the mask threshold value such that it is determined whether the mask polygon is present or not at each pixel of the target mask that is optimized. By combining the pixels at which the presence or absence of the mask polygon is determined, the optimized target mask may be generated using the mask optimization estimation model. Thus, the mask optimization for the target mask may be quickly and efficiently performed. FIG. 13 is a view illustrating a computing system performing a mask optimization method according to example embodiments. Referring to FIG. 13, a computing system 1200 performing a mask optimization method may include a processor 1205 and a memory device 1210. The processor 1205 may load a sample mask data 1230 and a mask optimization tool 1220 in the memory device 1210. The mask optimization tool 1220 may be a tool performing a mask optimization by a resolution enhancement technique. The mask optimization tool 1220 may perform the mask optimization on the sample mask data 1230 such that a trainer mask data 1235 may be generated. The processor 1205 may load a pixel-based learning tool 1240 in the memory device 1210. The pixel-based learning tool 1240 may include a rasterization module 1250, a feature extraction module 1260, a machine learning module 1270 and a model application module 1280. The rasterization module 1250 may obtain a grey scale value and a binary value of each pixel of a trainer mask by performing a grey scale rasterization and a binary rasterization on the trainer mask data 1235. The feature extraction module 1260 may respectively calculate partial signals of each pixel of the trainer mask based on spatial filters of a partial coherent system in which a mask are used and may obtain a feature vector of each pixel including the partial signals. The machine learning module 1270 may generate a mask optimization estimation model 1275 by performing the pixel-based learning using the feature vector of each pixel and using the grey scale value of each pixel as a target value of each pixel. Additionally, the machine learning module 1270 may determine a mask threshold value based on the binary value of each pixel and an estimated grey scale value outputted from the mask optimization estimation model 1275 when the feature vector of each pixel is inputted to the mask optimization estimation model 1275. The processor 1205 may load a target mask data 1290. The model application module 1280 may generate an optimized target mask data 1295 by performing the mask optimization on the target mask data 1290 using the mask optimization estimation model 1275 and the mask threshold value. The computing system 1200 performing the mask optimization method according to example embodiments may generate the mask optimization estimation model 1275 by performing the pixel-based learning using the trainer mask data 1235 on which the mask optimization is performed and may perform the mask optimization on a target mask data 1290 using the mask optimization estimation model 1275 to quickly and efficiently optimize a target mask. FIG. 14 illustrates a method of manufacturing an integrated circuit device using a mask optimized using pixel-based learning according to example embodiments. First, in step 1410, an optimized mask formed by the mask optimization method disclosed herein may be provided to a location where semiconductor manufacturing is performed. For example, the mask may be moved via a loading device (e.g., using an electro-mechanical device connected to a holder such as a hand-gripper, in a manner that allows the mask to be picked up and/or moved) into equipment that uses the mask for photolithography. Next, in step 1420, the optimized mask may be used to perform a step in forming an integrated circuit device on a semiconductor wafer. For example, the mask may be placed in a chamber where a semiconductor wafer is disposed, and may be used for a photolithography process to form a pattern on the semiconductor wafer. Subsequently, additional steps may be performed on the semiconductor wafer, for example to form a semiconductor device (step 1430). For example, additional layers may be deposited and patterned by using the optimized mask, on the semiconductor wafer, to form semiconductor chips, the semiconductor chips may then be singulated, packaged on a package substrate, and encapsulated by an encapsulant to form a semiconductor device. The above steps may be controlled by a control system including one or more computers and one or more electro-mechanical devices for moving a travelling part within a transferring apparatus. Also, though the above steps are described in a particular order, they need not occur in that order necessarily. The mask optimization method according to the disclosed embodiments may be used to optimize the mask used for the partial coherent system. Accordingly, the mask optimization method according to the disclosed embodiments may be usefully used to optimize the mask for fabricating an electronic circuit for a memory device, an integrated circuit or a display device, using the partial coherent system. While the concepts have been particularly shown and described with reference to example embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the following claims.
	claims	1. A collimator comprising:a pair of first plate members, each first plate member having X-ray absorbability and movable in a direction parallel to an end surface thereof, each first plate member comprising an inner surface such that an X-ray passing aperture is defined by a space between the inner surfaces of the first plate members; anda pair of second plate members, each second plate member having X-ray absorbability and comprising a top surface and an opposite bottom surface, each second plate member top surface connected to an outer surface of a respective first plate member via a hinge in order to block X-rays other than the X-rays passing through the X-ray passing aperture, each second plate member supported on a first end and an opposite second end such that each second plate member is movable obliquely in relation to movement of the respective first plate member and such that each second plate member moves with movement of the respective first plate member. 2. A collimator according to claim 1, wherein the first end and the second end of each of the second plate members are supported by guide grooves formed obliquely with respect to the moving direction of the first plate members and pins engaged in the guide grooves. 3. A collimator according to claim 1, wherein the pair of first plate members are movable independently of each other. 4. A collimator according to claim 1, further comprising a pair of arms and a pair of shafts, each arm coupling a first plate member to a respective shaft. 5. A collimator according to claim 4, wherein each arm is threadedly engaged with the respective shaft. 6. A collimator according to claim 1, further comprising a window plate positioned beneath the pair of second plate members, the window plate defining an aperture having at least one of a length that is greater than a width of the X-ray passing aperture and a length that is greater than a length of the X-ray passing aperture. 7. A collimator according to claim 1, wherein the pair of first plate members are movable such that the X-ray passing aperture one of maintains a desired width and changes width as the pair of first plate members moves. 8. An X-ray irradiator comprising:an X-ray tube; anda collimator for collimating X-rays generated from the X-ray tube, the collimator comprising:a pair of first plate members, each first plate member having X-ray absorbability and movable in a direction parallel to an end surface thereof, each first plate member comprising an inner surface such that an X-ray passing aperture is defined by a space between the inner surfaces of the first plate members; anda pair of second plate members, each second plate member having X-ray absorbability and comprising a top surface and an opposite bottom surface, each second plate member to surface connected to an outer surface of a respective first plate member via a hinge in order to block X-rays other than the X-rays passing through the X-ray passing aperture, each second plate member supported on a first end and an opposite second end such that each second plate member is movable obliquely in relation to movement of the respective first plate member and such that each second plate member moves with movement of the respective first plate member. 9. An X-ray irradiator according to claim 8, wherein the first end and the second end of each of the second plate members are supported by guide grooves formed obliquely with respect to the moving direction of the first plate members and pins engaged in the guide grooves. 10. An X-ray irradiator according to claim 8, wherein the pair of first plate members are movable independently of each other. 11. An X-ray irradiator according to claim 8, wherein the collimator further comprises a pair of arms and a pair of shafts, each arm coupling a first plate member to a respective shaft. 12. An X-ray irradiator according to claim 11, wherein each arm is threadedly engaged with the respective shaft. 13. An X-ray irradiator according to claim 8, wherein the collimator further comprises a window plate positioned beneath the pair of second plate members, the window plate defining an aperture having at least one of a length that is greater than a width of the X-ray passing aperture and a length that is greater than a length of the X-ray passing aperture. 14. An X-ray irradiator according to claim 8, wherein the pair of first plate members are movable such that the X-ray passing aperture one of maintains a desired width and changes width as the pair of first plate members moves. 15. An X-ray apparatus comprising:an X-ray tube;a collimator for collimating X-rays emitted from the X-ray tube and applying the collimated X-ray to an object to be radiographed, the collimator comprising:a pair of first plate members, each first plate member having X-ray absorbability and movable in a direction parallel to an end surface thereof, each first plate member comprising an inner surface such that an X-ray passing aperture is defined by a space between the inner surfaces of the first plate members; anda pair of second plate members, each second plate member having X-ray absorbability and comprising a top surface and an opposite bottom surface, each second plate member top surface connected to an outer surface of a respective first plate member via a hinge in order to block X-rays other than the X-rays passing through the X-ray passing aperture, each second plate member supported on a first end and an opposite second end such that each second plate member is movable obliquely in relation to movement of the respective first plate member and such that each second plate member moves with movement of the respective first plate member; the X-ray apparatus further comprising a detector device for detecting X-rays that pass through the object to be radiographed. 16. An X-ray apparatus according to claim 15, wherein the first end and the second end of each of the second plate members are supported by guide grooves formed obliquely with respect to the moving direction of the first plate members and pins engaged in the guide grooves. 17. An X-ray apparatus according to claim 15, wherein the pair of first plate members are movable independently of each other. 18. An X-ray apparatus according to claim 15, wherein the collimator further comprises a pair of arms and a pair of shafts, each arm coupling a first plate member to a respective shaft. 19. An X-ray apparatus according to claim 18, wherein each arm is threadedly engaged with the respective shaft. 20. An X-ray apparatus according to claim 15, wherein the collimator further comprises a window plate positioned beneath the pair of second plate members, the window plate defining an aperture having at least one of a length that is greater than a width of the X-ray passing aperture and a length that is greater than a length of the X-ray passing aperture.
	claims	1. An anti-scatter grid for use in radiography, said anti-scatter grid comprising: a plurality of generally radiation absorbing elements; a plurality of generally non-radiation absorbing elements for passage of primary radiation through said anti-scatter grid spaced between said plurality of generally radiation absorbing elements; and wherein said plurality of generally non-radiation absorbing elements comprises a plurality of voids and a plurality of hollow microspheres defining said plurality of voids. 2. The anti-scatter grid of claim 1 wherein said plurality of generally non-radiation absorbing elements comprises a heat curable material. claim 1 3. The anti-scatter grid of claim 1 wherein said plurality of generally non-radiation absorbing elements comprises at least one of an epoxy and a polymeric material. claim 1 4. The anti-scatter grid of claim 3 wherein said plurality of generally non-radiation absorbing elements has a density of about one-quarter the density of said at least one of said epoxy and said polymeric material. claim 3 5. The anti-scatter grid of claim 1 wherein said plurality of generally radiation absorbing elements comprises a material different from said plurality of generally non-radiation absorbing elements. claim 1 6. The anti-scatter grid of claim 5 wherein said plurality of generally radiation absorbing elements comprises lead, and said plurality of generally non-radiation absorbing elements comprises at least one of an epoxy and a polymeric material. claim 5 7. The anti-scatter grid of claim 1 wherein said plurality of generally radiation absorbing elements and said plurality of generally non-radiation absorbing elements comprise alternating layers thereof. claim 1 8. The anti-scatter grid of claim 1 further comprising a first protective cover and a second protective cover, and wherein said plurality of generally radiation absorbing elements and said plurality of generally non-radiation absorbing elements are disposed between said first protective cover and said second protective cover. claim 1 9. The anti-scatter grid of claim 1 wherein said plurality of generally radiation absorbing elements comprises a plurality of spaced-apart strips and wherein a portion of the spaced-apart strips is angled to align with a radiation source. claim 1 10. An anti-scatter grid comprising first and second anti-scatter grids according to claim 9 and wherein said spaced-apart strips of said first anti-scatter grid is disposable at about a right angle relative to said spaced-apart strips of said second anti-scatter grid. claim 9 11. A structurally robust anti-scatter grid for radiography, said anti-scatter grid comprising: a plurality of spaced-apart generally radiation absorbing elements; a plurality of generally non-radiation absorbing elements for passage of primary radiation through said anti-scatter grid disposed and extending generally entirely between said plurality of spaced-apart generally radiation absorbing elements; and wherein said plurality of generally non-radiation absorbing elements comprising a plurality of voids and a plurality of hollow microspheres defining said plurality of voids. 12. The anti-scatter grid of claim 11 wherein said plurality of generally non-radiation absorbing elements comprises a heat curable material. claim 11 13. The anti-scatter grid of claim 11 wherein said plurality of generally non-radiation absorbing elements comprises at least one of an epoxy and a polymeric material. claim 11 14. The anti-scatter grid of claim 13 wherein said plurality of generally non-radiation absorbing elements has a density of about one-quarter the density of said at least one of said epoxy and said polymeric material. claim 13 15. The anti-scatter grid of claim 11 wherein said plurality of generally radiation absorbing elements comprises a material different from said plurality of generally non-radiation absorbing elements. claim 11 16. The anti-scatter grid of claim 15 wherein said plurality of generally radiation absorbing elements comprises lead, and said plurality of generally non-radiation absorbing elements comprises at least one of an epoxy and a polymeric material. claim 15 17. The anti-scatter grid of claim 11 wherein said plurality of generally radiation absorbing elements and said plurality of generally non-radiation absorbing elements comprise alternating layers thereof. claim 11 18. The anti-scatter grid of claim 11 further comprising a first protective cover and a second protective cover, and wherein said plurality of generally radiation absorbing elements and said plurality of generally non-radiation absorbing elements are disposed between said first protective cover and said second protective cover. claim 11 19. The anti-scatter grid of claim 11 wherein said plurality of generally radiation absorbing elements comprises a plurality of spaced-apart strips and wherein a portion of the spaced-apart strips is angled to align with a radiation source. claim 11 20. An anti-scatter grid comprising first and second anti-scatter grids according to claim 19 and wherein said spaced-apart strips of said first anti-scatter grid is disposable at about a right angle relative to said spaced-apart strips of said second anti-scatter grid. claim 19 21. A method for forming a structurally robust anti-scatter grid for radiography, the method comprising: providing a surface alignable with an axis and moveable along an arc around the axis; providing a plurality of generally radiation absorbing elements; providing a plurality of generally non-radiation absorbing elements comprising a plurality of voids; and using the surface to dispose the plurality of generally radiation absorbing elements in spaced-apart relation with the plurality of generally non-radiation absorbing elements extending generally entirely between the plurality of generally radiation absorbing elements, and to angle the plurality of radiation absorbing elements to align with the axis; wherein said plurality of generally non-radiation absorbing elements comprises a plurality of hollow microspheres defining said plurality of voids. 22. The method of claim 21 wherein providing the plurality of generally non-radiation absorbing elements comprise providing a moldable material. claim 21 23. The method of claim 21 wherein the using the surface comprises using the surface to alternately stack the plurality of generally radiation absorbing elements and the plurality of generally non-radiation absorbing elements. claim 21
	summary
044255080	summary	BACKGROUND OF THE INVENTION The present invention relates to an electron beam lithographic apparatus for the fabrication of semiconducter devices and more particularly to such a system in which the wafer to be exposed is held by and traversed with respect to the electron beam by an air bearing supported puck. The apparatus can also be used to form precision reticles used in more conventional lithographic processes. In its ongoing effort to create increasingly complex integrated circuit devices, the semiconductor industry has moved toward ever finer device geometries. The detail has become so fine, in fact, that the resolution required for lithographic processes is beginning to go beyond the defraction limits imposed by the use of visible or even ultraviolet light. Accordingly, systems are being developed which utilize electron beams or x-rays to effect the exposure of the lithographic resists which are used for the manufacture of semiconducter devices. However, while lithographic exposure with light can occur under atmospheric pressure, electron beam lithography must occur in a high vacuum. Further, since the area which can be scanned and exposed by an electron beam operating at high resolution is highly limited, i.e. a region much smaller than that of the typical semiconducter wafer, it is necessary to physically move the wafer to be exposed in relation to the electron beam source in order to expose different regions on the wafer's surface. While a straightforward solution of this problem would be to place the wafer moving mechanisms within the vacuum system, this is unattractive in practice since these mechanisms typically involve lubricants and organic compounds which can degrade the vacuum and quickly poison the electron emissive cathode employed to generate the electron beam. Accordingly, it is deemed preferable that the stage or other means for carrying the semiconducter wafer extend outside of the vacuum chamber for connection to the mechanical drive mechanisms. Similarly while airbearings have been widely used for supporting both semiconducter wafers and various mechanism elements including X-Y stages, the use of such bearings in connection with vacuum systems has not been widely accepted not only because the vacuum pumping requirements are increased by the gas introduced through the air bearing, but also because the atmospheric pressure opposing the vacuum has typically placed both an unacceptable heavy mechanical load on the system. The atmospheric load places strains on the moving parts which, no matter how heavily constructed, exhibit some distortion. This distortion interferes understandably with the precise positioning of the semiconducter wafer being carried by the mechanism. Further, since the moving parts subjected to the vacuum must be strongly and heavily constructed, they cannot easily be moved at the high speed which is highly desirable in order to effect rapid repositioning of a semiconducter wafer in order to obtain maximum throughput of the lithographic machine. Among the several objects of the present invention there may be noted the provision of an electron beam lithographic system for the manufacture of semiconducter devices; the provision of such a system which provides rapid and precise positioning of a semiconducter wafer with respect to an electron beam source; the provision of such a system in which the wafer transporting stage may be of relatively light construction to facilitate rapid positioning and reasonable power requirements; the provision of such a system in which facilitates the maintenance of a high vacuum in the environment of the electron beam source; the provision of such a system which does not subject the wafer carrying stage to heavy distorting forces; the provision of such a system in which the wafer carrying stage may be moved without substantial friction; the provision of such a system which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.
051587424	claims	1. A reactor steam isolation cooling system comprising: a containment building having a containment wall; a reactor pressure vessel disposed inside said containment building and including a nuclear reactor core therein operable for generating reactor steam; an isolation pool disposed outside said containment building and adjacent to said containment wall and containing pool water, said isolation pool including a vent disposed in flow communication with an atmosphere outside said containment building; an isolation condenser including: means for selectively channeling said reactor steam from said pressure vessel between said hot tubes of said evaporator assembly for removing heat therefrom to form reactor condensate. a shell surrounding said evaporator assembly inside said containment building and sealingly joined to said tube sheet, said shell including a shell inlet for receiving said reactor steam, and a shell outlet; and a plurality of alternating, spaced apart baffles slidingly joined to said hot tubes to form a serpentine flow passage for channeling said reactor steam from said shell inlet transversely back and forth across said hot tubes for absorbing heat therefrom to condense said reactor steam and form said reactor condensate dischargeable from said shell outlet. an inlet conduit disposed in flow communication between said pressure vessel and said shell inlet for selectively channeling said reactor steam to said shell, and including a selectively openable and closable shutoff inlet valve; and an outlet conduit disposed in flow communication between said shell outlet and said pressure vessel for returning said reactor condensate to said pressure vessel. said outlet conduit includes a steam trap for preventing flow of said reactor steam therethrough while allowing flow of said reactor condensate therethrough; and said outlet conduit is disposed in flow communication with said inlet conduit between said inlet valve and said shell inlet. said tube sheet has a plurality of apertures extending therethrough; each of said hot and cold tubes has a proximal end and a distal end; and said proximal ends of said hot and cold tubes are fixedly and sealingly joined to said tube sheet. said hot tubes extend upwardly through said tube sheet apertures with said proximal ends thereof being spaced above a top surface of said tube sheet, and said hot tubes are welded to said top surface of said tube sheet; and said cold tube proximal ends extend downwardly inside said hot tubes, and said cold tubes are welded to said hot tube proximal ends. 2. A system according to claim 1 further comprising: 3. A system according to claim 2 wherein said hot tubes are disposed vertically inside said containment building, and said cold tubes are primarily inclined inside said isolation pool. 4. A system according to claim 3 further comprising: 5. A system according to claim 4 wherein said inlet valve is normally open so that upon failure of power thereto said inlet valve is open, and upon providing power thereto said inlet valve is closed. 6. A system according to claim 5 wherein said outlet conduit includes a selectively openable and closable shutoff outlet valve; and said inlet and outlet conduits are disposed in parallel between said pressure vessel and said shell. 7. A system according to claim 5 wherein: 8. A system according to claim 2 wherein: 9. A system according to claim 8 wherein said hot and cold tube proximal ends extend into said tube sheet apertures and are spaced from each other, and said hot and cold tubes are welded to said tube sheet at respective surfaces thereof. 10. A system according to claim 8 wherein:
054127017	claims	1. A coated zirconium alloy nuclear fuel assembly comprising a zirconium alloy nuclear fuel assembly component in combination with a coating comprising: burnable poison particles in an amount effective to provide a predetermined level of neutron absorption; optional graphite particles in an amount effective to provide abrasion resistance to said dried coating; an alkali metal silicate binder in an amount effective to durably bind said burnable poison particles and said optional graphite particles within said coating; an optional rheology-enhancing component in an amount effective to promote application of said coating to said component; and a polar solvent in an amount effective to disperse said burnable poison particles, said optional graphite particles, said alkali metal silicate binder and said optional rheology-enhancing component. a zirconium alloy nuclear fuel assembly component; and a cured burnable poison containing coating disposed on said zirconium alloy nuclear fuel assembly component, said cured burnable poison containing coating further comprising: 2. The uncured burnable poison containing coating of claim 1, wherein said burnable poison particles are boron carbide particles having a naturally occurring distribution of boron-10 and boron-11. 3. The uncured burnable poison containing coating of claim 1, wherein said burnable poison particles are boron carbide particles which are enriched in boron-10. 4. The uncured burnable poison containing coating of claim 1, wherein said polar solvent is water. 5. The uncured burnable poison containing coating of claim 2, wherein said alkali metal silicate binder is potassium silicate. 6. The uncured burnable poison containing coating of claim 2, wherein said rheology-enhancing component is plate-like hectorite. 7. The uncured burnable poison containing coating of claim 2, wherein about 30 to about 50 parts of boron carbide are provided per 100 parts alkali metal silicate binder. 8. The uncured burnable poison containing coating of claim 2, wherein about 25 to about 50 parts of water are provided per 100 parts of alkali metal silicate binder. 9. The uncured burnable poison containing coating of claim 2, wherein about 434 to about 8 parts graphite are provided per each 100 parts of said alkali metal silicate binder. 10. The uncured burnable poison containing coating of claim 8, wherein about 0.5 to about 2 parts of rheology-enhancing component are provided per 100 parts of alkali metal silicate binder. 11. A coated nuclear fuel assembly component comprising: 12. The coated nuclear reactor fuel assembly component of claim 11, wherein said burnable poison is selected from erbium oxide, gadolinium oxide, boron nitride, titanium boride, and zirconium diboride. 13. The coated nuclear reactor fuel assembly component of claim 11, wherein said burnable poison is boron carbide. 14. The coated nuclear reactor fuel assembly component of claim 13, wherein said boron carbide particles have diameters ranging from about 1 to about 10 microns. 15. The coated nuclear reactor fuel assembly component of claim 11, wherein said alkali metal silicate binder is potassium silicate. 16. The coated nuclear reactor fuel assembly component of claim 11, wherein said graphite particles have diameters ranging from about 1 to about 10 microns. 17. The coated nuclear reactor fuel assembly component of claim 11, wherein about 4 to about 8 parts graphite are provided per 100 parts alkali metal silicate binder. 18. The coated nuclear reactor fuel assembly component of claim 13, wherein about 30 to 50 parts boron carbide are provided per 100 parts alkali metal silicate binder. 19. The coated nuclear reactor fuel assembly component of claim 11, wherein said zirconium alloy nuclear fuel assembly component is a fuel element cladding tube. 20. The coated nuclear reactor fuel assembly component of claim 19, wherein said zirconium alloy is selected from Zircaloy-2 and Zircaloy-4. 21. The coated nuclear reactor fuel assembly component of claim 19, wherein said coating is about 0.0015 inches in thickness. 22. The coated nuclear reactor fuel assembly component of claim 19, wherein said coating comprises about 16 mg of boron carbide having a naturally occurring distribution of boron-10 and boron-11 per square inch and said cladding tube has an inside diameter of about 0.4 inches.
	summary
	claims	1. A method for providing a system health operations analysis model, comprising:determining a first system health operations analysis of a first fleet of vehicles;determining a second system health operations analysis of a second fleet of vehicles, the second system health operations analysis including an alternative health operations system and at least one of hypothetical operational data and hypothetical maintenance data for the second fleet of vehicles;comparing the first and second system health operations analyses; andgenerating a system health operations output of first and second system health operations analyses, wherein the output of the comparison contains data enabling a determination of the impact of the alternative health operations device on the second fleet of vehicles. 2. The method of claim 1, wherein the first and second system health operations analyses include mission data and maintenance data for the first and second fleet of vehicles, respectively. 3. The method of claim 2, wherein the maintenance data of at least one of the first and second fleet of vehicles includes at least one of fault forwarding, event horizon, and condition based maintenance. 4. The method of claim 1, wherein at least one of the first and second system health operations analyses incorporates actual data relating to an operational fleet of vehicles. 5. The method of claim 1, wherein at least one of the first and second system health operations analyses includes generating assumption data for at least one untested fleet characteristic relating to a corresponding at least one of the first and second fleet of vehicles. 6. The method of claim 1, wherein at least one of the first and second system health operations analyses includes:production processes and metrics;mission processes and metrics;maintenance processes and metrics;command and control processes and metrics; andfleet management processes and metrics. 7. The method of claim 1, wherein the generated output includes deriving an optimum health management solution for at least one of the first and second fleet of vehicles. 8. The method of claim 1, wherein at least one of determining a first system health operations analysis and determining a second system health operations analysis includes:providing a plurality of inputs to a computer-based model of system health operations of a vehicle fleet, the plurality of inputs including at least one of actual data and hypothetical data;providing a plurality of system sensitivities to the computer-based model of system health operations of the vehicle fleet, each system sensitivity being associated with a corresponding one of the plurality of inputs;providing a plurality of health management solution assumptions to the computer-based model of system health operations of the vehicle fleet, each health management solution assumption being associated with a corresponding one of the plurality of inputs;providing a plurality of benefit sensitivities to the computer-based model of system health operations of the vehicle fleet, each benefit sensitivity being associated with a corresponding one of the plurality of inputs; andcomputing a system health operations analysis of the vehicle fleet using the computer-based model of system health operations based on the plurality of inputs, the plurality of system sensitivities, the plurality of health management solution assumptions, and the plurality of benefit sensitivities. 9. The method of claim 8, wherein computing a system health operations analysis of the vehicle fleet includes parametrically varying one or more of the plurality of inputs, the plurality of system sensitivities, the plurality of health management solution assumptions, and the plurality of benefit sensitivities. 10. A computer-based system for providing a system health operations analysis comprising:an analysis component configured to compute a first system health operations analysis of a first fleet of vehicles and a second system health operations analysis of a second fleet of vehicles, the system health operations analysis including an alternative health operations system and prognostic data to anticipate unscheduled fleet maintenance;a comparator configured to receive the system health operations analyses from the analysis component and to perform a comparison between the first and second system health operations analyses; andan output component configured to receive the comparison from the comparator and to provide a visual display of the comparison between the first and second system health operations analyses, wherein the output of the comparison contains data enabling a determination of the impact of the alternative health operations device on the second fleet of vehicles. 11. The system of claim 10, wherein at least one of the first and second system health operations analyses includes mission data inputs and maintenance data inputs. 12. The system of claim 10, wherein at least one of the first and second system health operations analysis is configured to implement design maintenance policies and decision tools to support condition based maintenance concepts. 13. The system of claim 10, wherein the second fleet of vehicles includes the alternative health operations system, design, or capability which is not included in the first fleet of vehicles. 14. The system of claim 10, wherein the output provided by the output component includes cost metrics and reliability metrics. 15. The system of claim 10, wherein the analysis component is configured to provide the system health operations analyses based on mission requirements, maintenance requirements, prognostic health indicators, maintenance schedules, and fleet resource availability, and is further configured to determine an optimum health management solution for at least one of the first and second fleet of vehicles. 16. The system of claim 10, wherein the analysis component is configured to provide the system health operations analysis based on a condition-based maintenance. 17. The system of claim 10, wherein the analysis component is further configured to:receive a plurality of inputs into a model of system health operations of a vehicle fleet, the plurality of inputs including at least one of actual data and hypothetical data;receive a plurality of system sensitivities into the model of system health operations of the vehicle fleet, each system sensitivity being associated with a corresponding one of the plurality of inputs;receive a plurality of health management solution assumptions into the model of system health operations of the vehicle fleet, each health management solution assumption being associated with a corresponding one of the plurality of inputs;receive a plurality of benefit sensitivities into the model of system health operations of the vehicle fleet, each benefit sensitivity being associated with a corresponding one of the plurality of inputs; andcompute a system health operations analysis of the vehicle fleet using the model of system health operations based on the plurality of inputs, the plurality of system sensitivities, the plurality of health management solution assumptions, and the plurality of benefit sensitivities. 18. The system of claim 17, wherein the analysis component is further configured to compute the system health operations analysis of the vehicle fleet by parametrically varying one or more of the plurality of inputs, the plurality of system sensitivities, the plurality of health management solution assumptions, and the plurality of benefit sensitivities. 19. One or more computer-readable media comprising computer executable instructions that, when executed, perform a method of health operations analysis, comprising:determining a system health operations analysis of a first fleet of vehicles to determine the operational costs of the first fleet of vehicles;determining a system health operations analysis of a second fleet of vehicles to determine the operational costs of the second fleet of vehicles, the second system health operations analysis including an alternative health operations system, and whereindetermining the system health operations analysis of at least one of the first and second fleets includes determining the system health operations analysis based on at least one of an actual operational data, an actual maintenance data, a hypothetical operational data, and a hypothetical maintenance data;comparing the first and second system health operations analyses and operational costs; andgenerating a system health operations output of the compared first and second system health operations analyses including at least one of cost metrics and reliability metrics, wherein the output of the comparison contains data enabling a determination of the impact of the alternative health operations device on the second fleet of vehicles. 20. The computer-readable media of claim 19, wherein determining the system health operations analysis at least one of at least one of the first and second fleets of vehicles includes:providing a plurality of inputs to a model of system health operations of a vehicle fleet, the plurality of inputs including at least one of actual data and hypothetical data;providing a plurality of system sensitivities to the model of system health operations of the vehicle fleet, each system sensitivity being associated with a corresponding one of the plurality of inputs;providing a plurality of health management solution assumptions to the model of system health operations of the vehicle fleet, each health management solution assumption being associated with a corresponding one of the plurality of inputs;providing a plurality of benefit sensitivities to the model of system health operations of the vehicle fleet, each benefit sensitivity being associated with a corresponding one of the plurality of inputs; andcomputing a system health operations analysis of the vehicle fleet using the model of system health operations based on the plurality of inputs, the plurality of system sensitivities, the plurality of health management solution assumptions, and the plurality of benefit sensitivities.
	abstract	The invention comprises a multiplexed proton tomography imaging apparatus and method of use thereof. In one embodiment, a method for imaging a tumor of a patient comprises the steps of: (1) simultaneously detecting spatially resolved positively charged particle positions passing through each of a set of cross-section planes, where the cross-section planes are both prior to and posterior to the patient along a path of the positively charged particles; (2) determining a prior vector for each of the individual positively charged particles entering a patient using the detected positions; (3) determining a posterior vector for each of the individual positively charged particles exiting the patient using the detected positions; (4) generating a probable path of each positively charged particle through the patient; and (5) generating an image of the patient using the n probable proton paths and optionally a detected residual energy of each proton.
	description	The instant application is a national phase of PCT International Application No. PCT/RU2014/000170 filed Mar. 19, 2014, and claims priority to Russian Patent Application Serial No. 2013148441, filed Oct. 31, 2013, the entire specifications of both of which are expressly incorporated herein by reference. The invention relates to a method for guaranteeing fast reactor core subcriticality under conditions of uncertainty regarding the neutron-physical characteristics thereof with the help of adjustable reactivity rods in nuclear power and can be used in fast-neutron power plants. A method of nuclear reactor control is known, wherein a reflector surrounding the nuclear reactor core is composed of a number of elements mounted so as to allow rotation relative to one another to vary the size of the voids or voids of neutron free path through the reflector for reactivity control of the core (GB 1148093, G21C7/28, 1969). A method of implementation of the nuclear tube reactor fuel cycle by forming a core by means of the loading of fuel assemblies with a distributed neutron absorber in the process of scheduled rearrangements and removals of fuel assemblies, scheduled movements of control and protection system rods and replacement of additional absorbers by partially burnt fuel assemblies, wherein, during reactor operation after the unloading of all additional absorbers, a part of the fully immersed control and protection system rods are replaced by cluster rods, and uranium-erbium fuel with initial U235-enrichment 0.2 to 0.5% above the initial enrichment of uranium-erbium fuel loaded before removal of the control and protection system rods is used as fuel (RU 2218613, G21C7/04, G21D3/08, 2003). A method of examination of physical characteristics of the core of a high-temperature nuclear reactor with spherical fuel elements on a critical assembly is known consisting in that the core is heated by a heater that creates a certain temperature distribution field within the pebble, then the position and dimensions of the core and reflectors are changed in relation to the set temperature field generated by the heater by partial replacement of fuel elements at the core periphery with balls of the reflector material, and vice versa (SU 1831170, G21C17/00, G21S1/00, 1995). A method for constructing subcritical nuclear devices that are controlled by the part of the reflector adjacent to the core and a nuclear reactor implementing the method are known (Patent RU 2167456, G21C 1/00, G2105/00, G21C7/28, May 20, 2001). Cavities in the shape of through channels are made in the core of a nuclear reactor with a core, neutron moderators, fissile elements, reflectors, part of the reflectors are movable. The device design allows to maintain neutron spectra in cores that are characteristic of fast reactor, while obtaining a thermal neutron spectrum in the laser element cavity. Based on the obtained results and known facts on high power channel-type reactors, it has been shown that they may be transformed to subcritical reactor units that may be adequately controlled by a part of the side reflector, thus eliminating the possibility of formation of local critical masses and converting the positive void coefficient into negative one. The above analogs are not intended to guarantee fast reactor core subcriticality under conditions of uncertainty resulting in deviation of the actual characteristics from the design values. Currently, the algorithm of safe control and protection system rod control is used to compensate for the reactivity margin for burnup and control reactor neutron power in some fast-neutron reactor plant designs, according to which some rods immersed in the core and compensating for burnup are disconnected from the control system. Other rods maintain criticality and control power. Thus, the entire shim rod system is divided into two groups: a group of disconnected rods compensating for reactivity variation in the campaign that are not involved in the automatic control of the shim rod group installation, and a group of working shim rods that, together with the control rods, participate in the installation control. The campaign is implemented in intervals (intervals between refuelings) corresponding to the generation of reactivity is equal to the efficiency of one or two groups of shim rods. The closest analog of the invention is a method guaranteeing fast reactor core subcriticality using “light” control rods without strict requirements for response time that are located in the reflector modules near the core boundary, which is trial-run in the BREST-OD-300 fast-neutron reactor design with a core characterized by small margins and effects of reactivity, allowing to use “light” control rods without strict requirements for response time by placing them in the reflector modules near the core boundary (https://www.technics.rin.ru/index/?a=3&id=610). A disadvantage of the closest analog is its limited use in case of uncertainty of physical characteristics of the nuclear reactor core due to either a lack of experimental data on physical characteristics of the core, or a subcriticality margin smaller than a fraction of delayed neutrons for the set fueling of the reactor that is not sufficient to compensate for uncertainties leading to deviation of the actual performance from the design values. The task completed by the invention is based on the need to comply with requirements of regulatory documents on RP core subcriticality after emergency protection arming of at least 1% and requires increased accuracy of justification of the key physical characteristics of the core, namely, accurate determination of core fueling and control and protection system rod weights. The task is required to be completed due to the fact that a number of uncertainties resulting in deviation of the actual performance form the design values are to be considered in the development and justification of neutron-physical and thermohydraulic characteristics of the core: process uncertainties of manufacture of the core elements and RP components; errors in calculation of basic functionalities (effective multiplication factor, control and protection system rod “weights”, power density fields); constant; methodical; systematic. The prior art discloses that only physical experiments on reactors can ensure the accuracy of determination of core fueling and protection system rod weights. The proposed method allows to guarantee fast reactor core subcriticality under conditions of uncertainty regarding neutron-physical characteristics thereof without experiments. This is made possible due to new essential features of the invention, namely, due to placement of adjustable reactivity rods in the core side reflector to increase the subcriticality margin (by a value of not less than the proportion of delayed neutrons) sufficient to compensate for uncertainties resulting in deviation of the actual characteristics from the design values, wherein the enrichment of the core shim rods with B10 boron isotopes is lower than that of the adjustable reactivity rods in the core side reflector. The technical result of the implementation of the claimed method is: elimination of increased conservatism resulting in more stressful operating conditions of absorber elements (AE) of the shim rod bank (SR); elimination of the need to increase the stroke of the shim rods and simplification of control process during the manufacture; elimination of the need to develop AE for each specific nuclear reactor to ensure the required subcriticality margin throughout the whole campaign with required operability for the entire life cycle of the core; simplification of the safe reactor control algorithm. The above technical results are achieved by means of adjustable reactivity rods in the core reflector module slots or in the core reflector slots that are installed at the core fuel portion level, wherein the enrichment of the core shim rods with B10 boron isotopes is lower than that of the adjustable reactivity rods in the core side reflector. If necessary, adjustable reactivity rods with an insufficient enrichment are replaced with adjustable reactivity rods or an assembly thereof with enrichment sufficient to ensure the design subcriticality by replacement of some core reflector modules with replacement reflector modules with adjustable reactivity rods with the desired enrichment. Availability of adjustable reactivity rods improves shim rod bank AE operating conditions, as the adjustable reactivity rods of the core side reflector perform the main part of functions to eliminate deviations of the actual core neutron-physical and thermohydraulic characteristics from the design values. Accordingly, the safe reactor control algorithm is simplified. As the enrichment of the adjustable reactivity rods of the core side reflectors at the fuel portion level is higher than that of the shim rods of the core, a more “rough” adjustment is performed by the adjustment reactivity rods in the core side reflector. At the same time, the core characteristics close to the design values during assembly, commissioning and operation of the core are ensured by shorter rod travel in the shim rod bank. The nuclear reactor comprises a vessel (omitted in the drawing), where the core 1 is located, surrounded by the core reflector 2. The core 1 comprises fuel assemblies made up of rod-type fuel elements (FE), wherein one or several fuel assemblies comprise shim rods with absorber elements (AE) (e.g., compensating rods 10) forming a shim rod bank. The rods of the shim rod bank allow vertical shifting. The core reflector 2 may be constructed of separate replaceable modules (e.g., replacement core reflector modules 20). Slots 30 are made at the core fuel portion level in the core reflector 2 (FIG. 1) or core reflector replacement modules for adjustable reactivity rods. The core reflector 2 or its separate modules may be designed so as to allow insertion and removal of adjustable reactivity rods in/from the slots. Enrichment of the core shim rod bank by B10 boron isotope is selected lower than that of the adjustable reactivity rods 3 installed in the core reflector modules. In accordance with the claimed method, process uncertainties, errors (constant, methodical, systematic) of calculated values of the main functionalities (effective multiplication factor, control and protection system rod “weights”, power density fields) are compensated at the core 1 assembly stage as follows. After assembly of the core 1, physical measurements of core subcriticality are performed according to the known methods and the obtained characteristics are compared with the design values. In case of discrepancy between the obtained and design values, adjustable reactivity rods with enrichment ensuring the design subcriticality are installed in the reactor at the fuel portion 4 level. After installation of the adjustable reactivity rods at the core fuel portion level, additional physical measurements of core subcriticality are performed and, if discrepancies between the obtained and design values are found again, some of the core reflector 2 modules with adjustable rods reactivity are replaced with reflector replacement modules with adjustable reactivity rods with a different enrichment, namely, the one necessary and sufficient to obtain the desired design subcriticality value. Furthermore, process uncertainties, errors may be compensated without partial replacement of core reflector modules. In this case, adjustable reactivity rods are inserted in the slots of the reflector 2 or reflector module (s) of the or are removed from the slots of the reflector 2 or reflector module (s) and replaced with adjustable reactivity rods with the required enrichment that allows to obtain the set subcriticality value. Core characteristics are fine-tuned by means of AE of the core shim rods installed in the fuel assemblies in the core. The number of adjustable reactivity rods and side reflector modules with adjustable reactivity rods installed in the same is determined after neutron-physical measurements are performed in order to check the acceptance characteristics of the core during its assembly. Use of adjustable reactivity rods provides a greater margin during operation of the nuclear reactor due to the fact that the shim rod bank AE control the characteristics of the core operating under conditions close to the design conditions both during commissioning and in the course of operation, which is possible due to a shorter travel of the shim rods. For instance, for a specific core design, enrichment of the adjustable reactivity rods by B10 boron isotope may be higher (up to 80-90%) than that of the core shim rods that may amount to 40-50%. In other cases, the enrichment of the core shim rods by B10 boron isotope may reach 90%, then the enrichment of adjustable rods may reach 96%. However, their efficiency will depend on the number of 93% rods in the core. If they are few and the average enrichment is below 93%, then the higher the enrichment of the adjustable rods is, the higher their efficiency.
	abstract	An illumination optical unit for an EUV projection exposure apparatus has a diaphragm comprising a radiation-transmissive region having a discrete symmetry group. The form of the diaphragm is adapted to the form of the facets of a pupil facet mirror or to the form of the radiation source. The diaphragm is preferably arranged in the region of an intermediate focal plane.
	claims	1. An integrated collimator device, comprising:a) a radiation detector with an anode face and a cathode face;b) an anode disposed at the anode face;c) an insulating layer deposited on one face of the radiation detector and at least one layer of collimator material deposited on the insulating layer; andd) an aperture through the at least one layer of collimator material and defining an exposed area on the radiation detector, the aperture configured to allow radiation to impinge upon the exposed area of the radiation detector. 2. A device as in claim 1, wherein the at least one layer of collimator material comprises at least three layers and each layer comprises a different material. 3. A device as in claim 2, wherein a layer of collimator material closest to the radiation detector has a lowest atomic number of the at least three layers and each successive layer away from the radiation detector has a higher atomic number than an adjacent layer that is nearer the radiation detector. 4. A device as in claim 3, wherein:a) the insulating layer is deposited on the anode face of the radiation detector. 5. A device as in claim 1, further comprising a hermetically sealed container surrounding the integrated collimator device and a window in the container configured to allow x-rays to pass into the container and impinge upon the exposed area of the radiation detector. 6. A device as in claim 1, wherein the insulating layer is a continuous layer. 7. A device as in claim 1, wherein a thickness of the insulating layer is less than about 50 micrometers. 8. A device as in claim 1, wherein the aperture extends through the insulating layer. 9. A device as in claim 1, wherein the insulating layer and the at least one layer of collimator material are deposited on the cathode face. 10. A method of making the integrated collimator device of claim 1, the method comprising:a) depositing at least one layer of insulating material on one face of the radiation detector;b) depositing at least one layer of collimator material on the insulating material;b) patterning and etching the collimator material to create an exposed area on the radiation detector;c) boundaries of the exposed area correspond to the boundaries of the anode. 11. A method of making the integrated collimator device as in claim 10, wherein the at least one layer of collimator material is deposited on the anode face. 12. A radiation detection system, comprising:a) an integrated collimator device comprising:i) a radiation detector with an anode face and a cathode face;ii) an anode disposed at the anode face;iii) an insulating material deposited on the anode face;iv) at least three layers of collimator material deposited on the insulating material;v) an aperture through the at least three layers of collimator material and defining an exposed area on the radiation detector, the aperture configured to allow radiation to impinge upon the exposed area of the radiation detector;vi) a layer of collimator material closest to the radiation detector has a lowest atomic number of the at least three layers and each successive layer away from the radiation detector has a higher atomic number than an adjacent layer that is nearer the radiation detector; andb) a hermetically sealed container surrounding the integrated collimator device and a window in the container configured to allow x-rays to pass into the container and impinge upon the exposed area of the radiation detector. 13. An integrated collimator device, comprising:a) a radiation detector with an anode face and a cathode face;b) an anode disposed at the anode face;c) at least one layer of collimator material deposited on the anode face;d) an aperture through the at least one layer of collimator material and defining an exposed area on the anode face, the aperture configured to allow radiation to impinge upon the anode face of the radiation detector; ande) an area of the anode is substantially the same as an area of the aperture of the collimator material. 14. A device as in claim 13, wherein the anode face of the radiation detector further comprises an insulating material which is deposited on the anode. 15. A device as in claim 14, wherein the insulating material is a continuous layer. 16. A device as in claim 14, wherein the aperture extends through the insulating material such that the exposed area on the radiation detector is the anode. 17. A device as in claim 13, wherein:a) the at least one layer of collimator material comprises at least three layers and each layer comprises a different material; andb) a layer of collimator material closest to the radiation detector has a lowest atomic number of the at least three layers and each successive layer away from the radiation detector has a higher atomic number than an adjacent layer that is nearer the radiation detector. 18. An integrated collimator device, comprising:a) a radiation detector with an anode face and a cathode face;b) an anode disposed at the anode face;c) at least one layer of collimator material deposited on the cathode face; andd) an aperture through the at least one layer of collimator material and defining an exposed area on the radiation detector, the aperture configured to allow radiation to impinge upon the exposed area of the radiation detector. 19. A device as in claim 18, wherein the cathode face of the radiation detector further comprises an insulating material which is deposited on the cathode. 20. A device as in claim 18, wherein an area of the anode is substantially the same as an area of the aperture of the collimator material. 21. A device as in claim 18 further comprising a hermetically sealed container surrounding the integrated collimator device and a window in the container configured to allow x-rays to pass into the container and impinge upon the exposed area of the radiation detector.
	summary
	abstract	In one characterization, the present invention relates to a radiation-shielding assembly for holding a container having a radioactive material disposed therein. The assembly may, at least in one regard, be referred to as an elution shield and/or a dispensing shield. The assembly includes a body at least partially defining a cavity. There is at least one opening through the body into the cavity. The assembly may include a cap that at least generally hinders escape of radiation from the assembly through the opening. The cap may be releasably attached to the body in one orientation and may establish non-attached engagement with the body in another orientation. The assembly may include an adjustable spacer system for adapting the assembly for use with containers having different heights.
	summary
053612884	description	DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a spacer cell S according to this invention is shown. Spacer cell S includes upper octagonal crown C.sub.1 and lower octagonal crown C.sub.2. In the following description, crown C.sub.1 will first be described. Thereafter, the differences between crown C.sub.1 and crown C.sub.2 will be set forth. Finally the respective spring legs 22 and stop legs 26 extending between the crowns C.sub.1 and C.sub.2 will be described. Crown C.sub.1 is octagonal in shape. It includes full height panels 12, 14, 16, and 18. These respective panels are interconnected by half height panels 11 between full height panels 18 and 12, half height panel 13 between full height panels 12 and 14, half height panel 15 between full height panels 14 and 16, and finally half height panels 17.sub.a and 17.sub.b between full height panels 16 and 18. A complete octagon having equal length sides is formed. Crown C.sub.2 differs from crown C.sub.1 in that the respective half height panels 11', 13', 15' and 17.sub.a ', 17.sub.b ', all extend upwardly with respect to cell S of FIG. 1. Thus it can be seen that the half height panels of crown C.sub.1 are defined to the inside of cell S. Likewise, it can be seen that the half height panels of crown C.sub.2 are defined to the outside of cell S. These features will become important when considering the mating relationship of the respective cells illustrated in FIGS. 2 and 3. Paired spring legs 22 are easy to understand. Each leg begins at a full height panel 16 or 18 in crown C.sub.1 and extends to a corresponding full height panel 16' or 18' in crown C.sub.2. For biasing a fuel rod, a bias point is formed by inwardly arcuate portion 24 medially located in each leg 22. It will be observed that the spring legs 22 are adjacent one another. Paired stop legs 26 are likewise easy to understand. Each leg begins at a full height panel 12 or 14 in crown C.sub.1 and extends to a corresponding full height panel 12' or 14' in crown C.sub.2. For stopping a biased fuel rod in a centered disposition with respect to cells, stop points are formed by inwardly arcuate portions 28 distally located in each leg against a crown C.sub.1 or C.sub.2. It will be observed that the stop legs 26 are adjacent one another. Thus it will be understood that each cell S includes at its two stop legs four inwardly arcuate stop portions 28 for the centering of the fuel rods. Further, it will be seen that each cell S includes at its spring legs two inwardly biased spring portions 24. Consequently, bias of a fuel rod R onto the four stops by two spring portions occurs. Referring to FIG. 2, cells S.sub.1 and S.sub.2 are shown about to be joined. Cell S.sub.1 has crown C.sub.1 at the top and crown C.sub.2 at the bottom. Conversely, cell S.sub.2 has crown C.sub.2 at the top and crown C.sub.1 at the bottom. Turning to FIG. 3, the fitting between the mating horizontal edges of respective half height walls of respective crowns C.sub.1 and C.sub.2 can easily be understood. Specifically, it will be seen that respective half height walls 11 of first crown C.sub.1 fits with half height wall 15' of crown C.sub.2. Likewise, half height wall 13 of second crown C.sub.1 fits with vertically aligned and substantially co-planar half height walls 17.sub.a ' and 17.sub.b ' of crown C.sub.2. It takes little imagination to understand that a continuum of joined crowns C.sub.1 and C.sub.2 will form a crown plane at the top and bottom of each spacer matrix. Referring to respective FIGS. 4A, 4B and 4C, two cells S.sub.1 and two cells S.sub.2 are shown joined to form a matrix of four such cells. Cells S.sub.1 have respective crowns C.sub.1 on top and crowns C.sub.2 on the bottom. Conversely, cells S.sub.2 have respective crowns C.sub.2 on top and crowns C.sub.1 on the bottom. It will further be understood that just as crown C.sub.1 and C.sub.2 form a crown plane on the top, crowns C.sub.2 and C.sub.1 will form a crown plane on the bottom. Joining of the respective crowns C.sub.1 and C.sub.2 is easy to understand. Referring to FIG. 3, welds are made at the top of crown C.sub.1 and C.sub.2 at the junctions of the full height walls. Referring to FIG. 4A, welds are made at the junctions 30. Referring to FIG. 5, a spacer Z having an outside band B.sub.o for abutting a fuel bundle channel and an inside band B.sub.i for abutting a water rod is illustrated. For the convenience of the reader, the orientation of cells S.sub.1 and S.sub.2 is illustrated in the lower left corner of the spacer array--the remainder of the array being a continuum. Adjacent band B.sub.o and B.sub.i it is desirable to have full height walls in order to weld at the tops of the cells S.sub.1 to the bands. Accordingly in FIG. 6, a full height wall 13" is illustrated in crowns C.sub.1. It will be noted that since on crown C.sub.2, half height wall 13' is formed to the outside of cell S.sub.1, a full height wall is not needed. Referring to FIG. 7, a fuel bundle B is illustrated surrounded by a channel C. Channel C is broken away to show a matrix of fuel rods R having a central water rod W. Fuel rods extend between lower tie plate P.sub.1 and upper tie plate P.sub.u. The locations of two spacers Z is schematically illustrated. The disclosed invention will admit of modification. For example, the half height walls here preferred will admit of modification. Crowns C.sub.1 and C.sub.2 could be provided with other mating upper and lower edges. For example, such edges could include repeating curved patterns. All that is required is that when the respective edges are juxtaposed, mating of the crowns to form a single layer occurs. It will be further observed that compared to the Inconel spacers of the prior art, the Zircaloy construction here utilized requires a heavier and thicker metallic construction, especially for the Zircaloy spring legs 22. Accordingly, and over Inconel equivalents, the legs are on the order of 100% thicker.
039986934	description	DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawing, FIGS. 1A and 1B comprise a functional block diagram of a preferred embodiment of the present invention as employed with a pressurized water reactor. The reactor is indicated schematically and generally at 10 and consists of a core 12 and control rods 14, only one of which is shown, which are movable into the core for reactor control. The core is constructed of a multitude of fuel pins 20, only a few of which are shown, which define coolant channels 22 through which the coolant is circulated. The reactor coolant system 25 will typically include a plurality of coolant loops. In the drawing only a single loop, which includes a cold leg conduit 34 and a "hot leg" conduit 28, has been shown. In a typical installation the reactor coolant system may include four loops defined by four cold legs, each having associated therewith a circulator or pump, and two hot legs. After being heated by energy transfer from the fuel elements in the core, the pressurized coolant will be delivered by the hot leg conduit or conduits to a stream generator 26. Heat is transferred from the primary coolant circulated through the core to a secondary coolant in the stream generator 26 to form steam which is contained in a secondary coolant system 40. The steam is delivered to a turbine 42 which converts the thermal energy of the steam into mechanical rotation for subsequent conversion into electrical energy in a generator. The secondary coolant, after passing through the turbine, is delivered to a condenser 44 and recirculated by feed water pump 46 back to the stream generator where it again absorbs thermal energy from the circulating primary coolant. After passing through the steam generator 26 the primary reactor coolant is circulated back to the reactor through the cold leg conduit or conduits, such as conduit 34, by coolant pumps such as pump 32. A pressurizing system, not shown, is provided to maintain the pressure of the primary coolant within certain acceptable limits. After being delivered to the reactor pressure vessel through the cold leg 34, the coolant is forced to circulate downwardly around the outside of the core 12 and then upwardly through the interior of the core, through coolant channels 22, whereby thermal energy is transferred to the coolant and the fuel pins 20 are simultaneously cooled sufficiently to maintain the integrity of the cladding thereof. Proper control of the nuclear reactor system required the sensing of all of those parameters necessary for a computation of the various design limit indices. External (ex-core) neutron detectors 16 are provided to monitor the neutron flux originating in the reactor core. Such ex-core detectors are commerically available devices, produce by Reuter Stokes, Inc. or the electronic tube division of Westinghouse Electric Corporation, which typically comprise split uncompensated ion chambers and associated signal generating circuitry. The reactor is also provided with "strings" of internal (in-core) neutron detectors 18 for monitoring the local power of individual sectors of the reactor core. Such in-core detectors are also commerically available devices produced, for example, by Reuter Stokes Canada Ltd. Information from the in-core detectors is necessary for the calculation of azimuthal tilt magnitude and is also used to calculate the axial power distribution. Temperature detectors 36 and 38, which may comprise commercially available platinum resistance temperature detectors (RTDs), are provided in hot leg 28 and cold leg 34 respectively to generate signals indicative of the temperature of the coolant as it enters and leaves the core. As will be described in detail below, signals commensurate with the sensed temperatures are employed in the calculation of core thermal power B. The cold leg temperature T.sub.C is also used in the calculation of DNBR. The reactor is also provided with a pressure sensor, not shown, which generates a signal commensurate with reactor primary coolant system pressure P.sub.Pri. The reactor 10 is further provided with a control rod position detection system 54. This system, which is conventional in the art, typically will be comprised of a plurality of reed switches positioned adjacent to and outside of each control rod housing 52. The rod position indicator may, for example, be similar to the position indicating apparatus of U.S Pat. No. 3,594,740. Information regarding coolant mass flow rate, azimuthal tilt magnitude, and the position of the control rods will be employed in the calculation of the locus of points at which DNB will occur. Periodically during plant operation the assumptions employed in plotting DNB will be verified. Under normal conditions, considering a reactor installation wherein the coolant system includes four cold legs with associated circulator pumps, all four coolant circulator pumps will be operating. There may, however, be circumstances where less than all of the pumps will be utilized. A "pump selector" switch S3 is provided in order to permit the operator to coordinate the thermal margin protection system instrumentation with the actual pump operating configuration. The pump selector switch S3 is ganged with a plurality of switches in the thermal margin control. It is to be understood that FIGS. 1A and 1B depict one of four indentical circuits or channels which will be employed with reactor 10 to predict the occurrence of DNB or excessive void fraction. For purposes of explanation, FIGS. 1A and 1B may be considered to disclose the process instrumentation for channel A of the thermal margin protection system. Each channel of the thermal margin protection system will have associated therewith a plurality of sensors which provide signals commensurate with the following reactor operating parameters: T.sub.c1 = coolant input or cold leg 34 temperature (sensor 38) PA1 T.sub.C2 = coolant input or cold leg 34' (not shown) temperature PA1 T.sub.H1 = coolant output or hot leg 38 temperature (sensor 36) PA1 T.sub.H2 = coolant output or hot leg 38' (not shown) temperature PA1 P.sub.Pri = primary coolant pressure (measured at the pressurizer) PA1 .phi. = reactor power computed as a function of measured neutron flux PA1 U = upper ex-core neutron flux PA1 L = lower ex-core neutron flux PA1 B = percent of maximum core thermal power, and PA1 F = a dimensionless constant having a value dependent upon the number of coolant circulator pumps in operation. The sensors for providing signals commensurate with temperature, pressure and neutron flux have been discussed above. The means for calculating core power .phi. in percent of full power as a function of neutron flux, measured by the out-of-core flux detectors 16, is a state-of-the-art subsystem such as the "Instrumentation for Nuclear Reactor" of aforementioned U.S. Pat. No. 3,752,735 of C. R. Musick and Richard P. Remshaw and assigned to the assignee of the present invention. The .phi. or nuclear core power calculator is indicated at 60. The T.sub.H1 and T.sub.H2 signals generated by the temperature sensors associated with the hot legs are delivered to an averaging device 62 associated with the pump selector switch S3. It is necessary that the averaging circuit 62 be ganged with the pump selector switch so that an output signal may be generated which is either the average of the hot leg temperatures or the temperature of the hot leg of the active loop in the situation where only the pumps in a single coolant loop are being operated. The average or selected hot leg temperature T.sub.H signal is employed as an input signal to a second core power calculator indicated generally at 64; calculator 64 being the thermal power calculator. A pair of channel A cold leg temperature signals T.sub.C1 and T.sub.C2 are delivered to an auctioneering circuit 66. Circuit 66 may, for example, comprise a commerically available amplitude selector such as Bell & Howell type 19-502. Circuit 66 selects the highest of the two cold leg temperature signals applied at its input terminals and the output of circuit 66 is the T.sub.C cold leg temperature signal. This maximum cold leg or upstream coolant temperature signal is applied as a second input to the thermal power calculator 64. In calculator 64 the selected T.sub.C signal is subtracted from the hot leg temperature T.sub.H, in a summing circuit 68, to determine the temperature rise of the coolant across the core. The thermal power calculator 64 provides an output signal commensurate with core power as a function of the increase in temperature of the coolant between the upstream or cold leg side of the reactor core and the reactor output or hot leg. For a further and more detailed description of a core power calculator which is responsive to T.sub.C and T.sub.H input signals, reference may be had to aforementioned U.S. Pat. No. 3,752,735. The calculator 64 generates signals proportional to the first and second powers of temperature rise .DELTA.T and a signal proportional to the product of .DELTA.T and T.sub.C. These three terms represent thermal power for four pump operation and steady state conditions taking coolant density, specific heat and flow rate variations with temperature and power into account. Restated, in order to utilize coolant temperature differential as a measure of core power, it is necessary to account for a number of variables which affect the rate at which thermal energy will be transferred to the coolant. The required compensation is accomplished in the course of synthesizing a steady state .DELTA.T power measure signal and a signal which provides dynamic compensation for the steady state signal; a dynamic response term being added so as to provide an accurate core power indication during mild transients such as ramp load changes. In generating the steady state .DELTA.T signal, the output of summing circuit 68 is applied to a first compensation network 70 wherein it is multiplied by a constant K.sub..alpha.. Compensation circuit 70 may comprise merely a potentiometer. The signal resulting from the multiplication in circuit 70, K.sub..alpha..DELTA.T, represents the first power or primary component of a composite steady state .DELTA.T power or B signal. The .DELTA.T signal from summing circuit 68 is also applied as an input to compensation circuits 72 and 74. In compensation circuit 74 the .DELTA.T signal is multiplied by a constant K.sub..gamma.. Compensation circuit 74 may be identical to compensation circuit 70. The output of compensation circuit 74, a K.sub..gamma..DELTA.T signal, is applied to a summing circuit 76. A second input to summing circuit 76 is provided by a compensation circuit 78 which has applied, as the input thereto, the T.sub.C signal. The output of compensation circuit 78 is a signal commensurate with K.sub..beta.T.sub.C. Summing circuit 76 provides an output signal commensurate with the following term: EQU K.sub..gamma..DELTA.T + K.sub..beta..DELTA.T (1) the signal from summing circuit 76 is multiplied by the .DELTA.T signal in compensation circuit 72 to generate a signal proportional to the second power of temperature rise and the product of temperature rise and cold leg temperature. This signal is as follows: EQU K.sub..gamma..DELTA.T.sup.2 + K.sub..beta.T.sub.C .DELTA.T (2) as previously noted, the measure of core power as calculated from measured coolant thermal parameters may be made more accurate for slow and intermediate speed power transients by dynamically compensating the steady state signal for the rate of heat addition to the stored thermal energy content of the primary coolant. This may be accomplished by differentiating any primary coolant thermal parameter or combination thereof, multiplying by the appropriate gain factor and adding the product to the steady state .DELTA.T expression of power. In the disclosed embodiment of the invention the .DELTA.T signal from summing circuit 68 is applied to a multiplier 82 where it is multiplied by a gain factor "a". The gain factor a is selected during field tests to match "thermal" power B to "nuclear" power.phi.; .phi. being determined during the field test. The output of multiplier 82 and the T.sub.C signal from selector circuit 66 are applied to a summing circuit 84 to generate a signal proportional to the following relationship: EQU T.sub.X = a .DELTA.T + T.sub.C = aT.sub.H + (1-a) T.sub.C (3) the T.sub.X signal is applied to a differentiating network 86 and the output of differentiator 86 is a signal commensurate with the following expression: EQU .tau. [a.DELTA.T + T.sub.C ] (4) the output of differentiator 80 and the signals provided by multiplication circuits 70 and 72 are applied to a summing circuit 88. The output of summing circuit 88 is thus a measure of power as a function of the thermal energy added to the primary loop coolant and this signal may be expressed as follows: EQU = K.sub..alpha..DELTA.T +K.sub..beta..DELTA.T (T.sub.Cmax - 490) + K.sub..gamma..DELTA.T.sup.2 + .tau. (T.sub.Cam + a .DELTA.T) where Summing circuit 88 may comprise an operational amplifier with input and feedback resistors such as, for example, Bell & Howell Adder-Subtractor Model No. 19-301-A. It will, of course, be obvious to those skilled in the art that constants may be added to or subtracted from the various measured temperature parameters or terms so that the circuitry may operate on signals that are referenced to some temperature in or near the normal operating range of the reactor. Thus, for example, prior to application to the multiplier 78, the T.sub.C signal may be compared with a selected design condition temperature such as 490.degree.F. This temperature adjustment is reflected in equation (5) above. The signal from summing circuit 88 represents the core power as a function of thermal energy output for four-pump operation under steady state or mild transient conditions. This quotient is multiplied by a factor F, which is unity for four-pump operation and less than unity for other pump configurations, in a multiplication circuit 90. The multiplication factor F compensates for the fact that, for a given power, the temperature rise is greater for reduced flow. A multiplying factor is selected by the flow dependent set point selector switch S3; i.e., the factor F will be varied simultaneously with the selection of the operating circulator pump configuration in such a manner as to effectively attenuate the gain constants in equation (5) to thereby adjust the power signal to accommodate the fact that .DELTA.T rises as the coolant flow rate is reduced with core power being held constant. The thermal power B signal passed by multiplier 90 and the nuclear power .phi. signal provided by calculator 60 are auctioneered in an auctioneering circuit 92. Circuit 92, which may be identical to circuit 66, selects the highest of the applied power signals and passes this Q signal on to the thermal margin set point calculator. The two separate measures of power are also applied to a null meter relay 94, which is a commerically available device produced by Sigma Corporation having an analog meter with two adjustable alarm points, via a summing circuit 96. The null meter relay 94 displays the difference between B and .phi.. Meter relay 94 also establishes high and low alarm set points. Violation of these set points will cause generation of an alarm signal indicative of a need to recalibrate the .phi. channel. Restated, under normal steady state operating conditions the .DELTA.T power signal is assumed to be more accurate than power measured as a function of neutron flux. Thus, a predetermined deviation between the two measures of power, as indicated by meter relay 94, is an indication of a need to recalibrate the .phi. channel. The B power signal passed by multiplier 90 is also applied to a further compensation circuit 98. Compensation circuit 98 may comprise a multiplier wherein the thermal power signal is multiplied by a stratification constant K.sub.C. The stratification error in reactor primary coolant measurements is known to linear with power. Accordingly, the output of multiplier 98, the stratification compensation factor K.sub.C B, will also vary linearly with power. The constant K.sub.C is established through a standard procedure wherein the actual value of T.sub.C CAL is determined utilizing all available temperature measurements; K.sub.C thereafter being adjusted so that the sum of T.sub.C and K.sub.C B as computed in a summing circuit 100, is equal to the determined value of T.sub.C CAL. Thus, the output of summing circuit 100 is the selected T.sub.C signal compensated for stratification effects. The Q power signal selected by auctioneering circuit 92 is applied as the input to a radial peaking factor function generator 106. In function generator 106 the signal commensurate with the maximum of nuclear or thermal power is modified in accordance with a control rod or control element assembly (CEA) position function. Function generator 106 thus generates an output signal R which is a compensation factor commensurate with a predetermined integral radial peaking factor versus power. A plot of peaking factor versus power is, of course, a function of the position of the control rods. In actual practice function generator 106 may comprise a plurality of function generators connected in parallel since radial peaking factor will also vary with the selected pump configuration. Alternatively, the curve or function generated by a single function generator 106 may be biased in accordance with operating pump configuration. In either case, the pump selector switch S3 will be ganged to the input selector switch for function generator or generators 106 so as to select the appropriate bias or function commensurate with the existing pump configuration. The curve shown in the drawing within function generator 106 is the radial peaking factor versus power curve for four pump operation. The manner in which the CEA or radial peaking factor function is calculated is well known in the art. It is also to be noted that a delay may be imparted to the input signal to function generator 106 so as to inhibit application of the power signal to the function generator during periods when power is being changed. As explained in U.S. Pat. No. 3,791,922, a delay in application of the power signal to function generation 106 enhances reactor. safety by causing application of a conservatively high power signal to the thermal margin control during increases in power. The compensation signal R provided by function generator 106 will vary in accordance with the amount of CEA insertion allowed for at various power levels. The signal R will thus vary between extremes of rod position. Compensation signal R and the selected power signal are multiplied in a multiplication circuit 108 to generate a power signal QR compensated for radial peaking factor. This radial peaking factor compensated power signal is thereafter applied to a further multiplication circuit 110 for the purposes to be described below. The conditions under which DNB will occur, as discussed above, are also dependent on the axial power distribution that exists in the reactor core. In calculating axial power distribution the core is divided into two equal parts; the lower half of the core and the upper half of the core. The axial power distribution is integrated; by means not shown in the drawing but well known in the art, such means being responsive to the information provided by the ex-core neutron detectors; over each half of the core to produce upper and lower half power signals respectively U and L. Using the two values, U and L, a signal commensurate with the axial power offset Y can be generated. Thus, the axial offset Y can be generated, employing summing circuits 112 and 114 and division circuit 116, in accordance with the following equation: ##EQU1## (6) An examination of equation (6) shows that the axial power offset will be negative when the power distribution is peaked toward the top of the core and positive when the power distribution is peaked toward the bottom of the core. The axial offset is applied to an axial peaking factor function generator 118. Function generator 118 may, like radial peaking factor generator 106, in actual practice comprise either a plurality of function generators ganged with the pump selector switch or means for selectively biasing a single function whereby an axial peaking factor versus axial offset curve commensurate with the instantaneous coolant mass flow conditions will be selected. In the drawing the curve commensurate with four pump operation is depicted within function generator 118. The output of axial peaking factor function generator 118 is a compensation signal A.sub.1 which varies continuously with the axial offset or axial power distribution and the pump configuration in accordance with curves plotted by the reactor designer. This technique may be contrasted with methods wherein normal set points are overriden and biased downwardly in the presence of grossly skewed axial power distribution. The A.sub.1 signal commensurate with axial peaking factor is applied as an input to multiplication circuit 110 wherein it is employed to modify the maximum QR power signal previously compensated for radial peaking factor. The output of multiplication circuit 110 is thus a QRA.sub.1 signal; this signal also being known as the DNB power signal Q.sub.DNB. The output of multiplication circuit 110 is applied to a further compensation circuit 120 wherein it is multiplied by a gain factor .alpha..sub.4. The gain factor .alpha..sub.4 is also selected by the flow dependent set point selector switch S3. The constant .alpha..sub.4 is commensurate with the relationship between Q.sub.DNB and P.sub.Pri for a fixed DNB ratio when cold leg temperature is held consent. The output of multiplication circuit 120, an .alpha..sub.4 Q.sub.DNB signal, is applied as a first input to a summing circuit 104. The T.sub.C CAL signal from summing circuit 100 is delivered to a compensation circuit 102 wherein it is multiplied by a factor .beta..sub.4 ; the factor .beta..sub.4 being a constant commensurate with the relationship between P.sub.Pri and cold leg temperature for a constant DNB ratio when Q.sub.DNB is held constant. The constant .beta..sub.4 is thus a function of the number of circulator pumps in operation and is selected by the flow dependent set point selector switch S3. This further compensation of the T.sub.CAL signal is for the purpose of adjusting the gain of the T.sub.C CAL input in such a fashion as to approximate the predetermined DNB locus for the particular pump operating configuration. The output of compensation circuit 102, a .beta..sub.4 T.sub.C CAL signal, is applied as the second input to summing circuit 104. A third input to summing circuit 104 is provided directly from the flow dependent set point selector switch S3. This third input, a .gamma..sub.4 signal, is a constant commensurate with the desired pressure (thermal margin) trip set point for specified design values of TC .sub.CAL and Q.sub.DNB design values. Referring to FIG. 2 of U.S. Pat. No. 3,791,922 the locus of points which the 1.3 DNBR or void fraction limit occurs for various conditions of reactor inlet temperature, core power and primary coolant pressure is shown. This locus of points will be calculated by the reactor designer. Upon fueling and operation of the reactor the accuracy of the design data will, of course, be verified and the families of curves commensurate with 1.3 DNBR will be adjusted as necessary. The plot of 1.3 DNBR or void fraction limit, as is well known, establishes pressure limit curves commensurate with the violation of the DNBR or void fraction limit; the curves being plotted on the basis of the hot channel in the reactor core and with a substantial margin of safety. DNB may thus be expressed as follows: EQU DNB = f(Q.sub.DNB, T.sub.CAL, P.sub.Pri) (7) In accordance with the present invention, a thermal margin protection system is provided wherein reactor trip is programmed as a function of coolant pressure. Summing circuit 104 calculates the pressure trip or thermal margin set point. This pressure trip point may be expressed as follows: EQU P.sub.VAR = .alpha..sub.4 Q.sub.DNB + .beta..sub.4 T.sub.CAL +.gamma..sub.4 (8) wherein the constants .GAMMA..sub.4, .DELTA..sub.4 and .gamma..sub.4 are, as described above, provided by signal generators ganged to the pump selector switch. In accordance with the present invention the potential effects of temperature saturation of the coolant may also be accommodated. As is well known, as water changes state from liquid to gas the temperature remains constant; i.e., in the temperature saturation state energy is used to change the state rather than to raise the temperature. In a nuclear steam supply system the primary coolant could conceivably receive enough energy to reach the temperature saturation state. Should this happen power measurments based upon the temperature rise of the coolant would be meaningless. Restated, it is possible that power can increase to the point where T.sub.H is pushed into saturation and thus becomes a constant independent of power level. In order to insure the accuracy of the warning and control system of the present invention, the maximum hot leg temperature T.sub.H.sbsb.m.sbsb.a.sbsb.x is selected by an amplitude selector circuit 130. The selected maximum hot leg temperature signal is delivered as a first input to a summing circuit 134. A second input to summing circuit 134 is a calibrated .DELTA.T power signal B from core power calculator 64; the power signal being adjusted in a multiplication circuit 132 by a K.sub.H bias. The compensation signal K.sub.H is an adjustable field calibrated constant related to hot leg stratification. The output of multiplication circuit 132 is thus a temperature biasing term which is employed to correct the selected maximum hot leg temperature signal T.sub.H.sbsb.m.sub..upsilon..sbsb.x for the effects of stratification. A third input to summing circuit 134 is a K.sub.S bias signal; the K.sub.S signal being commensurate with an adjustable coefficient which defines the relationship between the corrected hot leg temperature and the precalculated reactor cooling system pressure at temperature saturation. The output of multiplication circuit 134 is thus a maximum hot leg temperature signal which has been calibrated for the effects of stratification and biased to take into account the relationship between the calibrated hot leg temperature and the saturation pressure. The output of summing circuit 134 is applied to a further multiplication circuit 136 where it is further adjusted by a constant K.sub.T commensurate with the relationship between hot leg temperature and reactor cooling system pressure at saturation. The output of multiplication circuit 136 is a P.sub.SAT signal commensurate with the pressure at which temperature saturation will occur. The P.sub.SAT signal from compensation circuit 136 is applied as a first input to an amplitude selector circuit 122. The P.sub.VAR output signal from summing circuit 104 is applied as a second input to amplitude selector circuit 122. a minimum pressure trip point signal from an adjustable voltage source indicated schematically at 124 is also applied as an input to selector circuit 122. The P.sub.MIN signal provided by source 124 will be commensurate with the minimum permissible primary coolant pressure. Amplitude selector 122, which may be a Bell & Howell Model 19-502 amplitude selector, will select the input signal having the greatest magnitude for passage to a tripping control circuit indicated generally at 125. The output of selector circuit 122 will thus be the P.sub.TRIP signal which, in the manner to be described below, will provide a reactor trip when the coolant approaches the temperature saturated condition, or when the actual coolant pressure falls below a minimum permissible pressure or when a pressure trip set point calculated as a function of power exceeds the actual primary coolant pressure. The signal passed by selector circuit 122 will also be applied to a summing circuit 126 in control 125. A signal commensurate with a pre-trip bias will be applied as the second input to summing circuit 126. The pre-trip bias will typically be commensurate with 100 psi and will cause the generation, in the manner to be described below, of a pre-trip alarm signal indicative of the fact that the core thermal limits are being approached. The pre-trip alarm signal will, of course, lead the actual reactor trip signal as a result of the bias provided by the pre-trip input to summing circuit 126. A signal commensurate with the actual measured value of primary coolant pressure P.sub.Pri, the P.sub.PRETRIP output signal from summing circuit 126 and the P.sub.TRIP signal from selector circuit 122 are applied as inputs to a "trip" unit 128. The trip unit 128 may comprise a plurality of bistable circuits wherein the pre-trip signal from summing circuit 126 is compared with the actual pressure signal P.sub.Pri and, when the biased set point signal exceeds the actual pressure signal, an alarm output will be provided. Similarly, the P.sub.TRIP signal will be compared with the P.sub.Pri signal in order to generate a trip command signal whenever the calculated signal exceeds the actual primary coolant pressure signal. The pre-trip and trip pressure signals will be applied to suitable alarm and control rod "scram" circuits which do not comprise part of the present invention. FIG. 2 depicts an alternate method for the calculation of Q.sub.DNB in accordance with the present invention. In the embodiment of FIG. 1 the radial peaking factor function generator 106 infers rod or control element assembly (CEA) position from the measured power signal Q applied thereto. In the FIG. 2 embodiment CEA group position is measured directly. To accomplish such a direct measurement output signals from rod position detection system 54 are applied to an averaging circuit 150; the output of averaging circuit 150 as well known in the art being an average rod position signal. This average rod position signal is applied to a radial peaking factor function generator 106' to generate the compensation signal R. The R signal, the A.sub.1 axial peaking factor compensation signal from function generator 118 and the Q power signal from selector circuit 92 are applied to a multiplication circuit 110' to generate the Q.sub.DNB signal. As an alternative to averaging the position of all rods, the position of any one control rod in each control bank may be sensed and summed and the reactor may include a rod block circuit which keeps all of the control element assemblies within a control bank aligned and which assures that a predefined control bank sequencing program is followed. While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.
	abstract	An axial power distribution control device includes an axial offset calculation unit 52, a parameter calculation unit 53, and an axial offset determining unit 55. The axial offset determining unit 55 predicts whether a core axial offset of the power distribution is increased or decreased after a current time, based on a major axis of an ellipse drawn by the xenon parameter and the iodine parameter calculated by the parameter calculation unit 53 and the xenon parameter and the iodine parameter at the current time. This makes it possible to predict a change of the axial offset of the power distribution of a reactor for suppressing a xenon oscillation in the reactor.
	description	This application is a continuation in part of application Ser. No. 10/683,885, filed Oct. 10, 2003, now Pending. This invention concerns therapeutic radiation treatment of living tissue, usually but not necessarily within a body cavity, which may be a surgical cavity following a resection of a tumor. In one aspect the invention is concerned with use of a switchable, miniature electronic x-ray source, which may be controllable as to depth and intensity, for administering such therapeutic treatment. Treatment of surgical cavities, such as after malignant tumor excision, has been accomplished with applicators which are inserted usually into a newly formed opening through the skin, a conveniently located opening into the surgical resection cavity. Generally the location is different from the surgical closure itself. Applicators have been disclosed which essentially comprise a balloon of known and relatively rigid geometry, essentially spherical, expandable generally to about four to six centimeters, that is, designed to have an inflated size of about four to six centimeters diameter. Some of the generally spherical balloon catheters were described as having multiple walls to form inner and outer spaces, for reasons relating to the objective of delivering a uniform dose to tissue surrounding the balloon. In the prior art such known-geometry balloons were inflated with a liquid, with an applicator guide positioned within the balloon and in the liquid, so that the applicator guide could receive a radiation source comprising a radioactive isotope. With balloons limited to known geometries, there are limitations in the ability to treat a cavity margin thoroughly. In some cases, the patient cannot take advantage of such a treatment protocol because the known-geometry balloon applicator simply cannot fill many surgical cavities that are irregular in shape. Other measures have to be used in those cases, such as external radiation therapy. Another limitation of known procedures using balloon catheters is in regard to locating the balloon correctly within a cavity of the patient, such as a resection cavity. The saline solution used to inflate the balloon contains contrast material which will be visible by taking an external x-ray. With the contrast material contained in the balloon's solution, the surgeon or technician can detect a pale “shadow” in the x-ray to determine the location of the balloon and to correct its position if needed. The procedure typically calls for use of the contrast material at about 3% in the saline solution. Dose planning for the known-geometry balloon is based on specific concentration of contrast. However, because the balloon shape is difficult to see in the x-ray, surgeons usually add the contrast material in a much higher concentration, not as contemplated by the dose plan, so as to better detect the balloon in the x-ray. The concentration may be up to about 20%-30% in practice. As a result, the therapeutic radiation from the x-ray source placed into the center of the balloon becomes attenuated to the extent that the actual dose profile received in a patient's tissue may be significantly less than the prescribed dose. The use of isotopes has been the practice in administering x-ray radiation to patients prior to the present invention. The isotopes must be handled carefully and reliably shielded between uses. With the isotopes they are always “on”, and only one setting is available for all dwell locations where a dose is to be administered. In many cases it would be convenient to have a better procedure and source that would allow modulation and more accurate dose delivery. The invention now disclosed provides improved procedures for therapeutic radiation treatment of tissue, which may be following resection of a tumor or which may involve administering the radiation within an existing body cavity or in other locations. Although isotopes can be used in some of the procedures of the invention, in some, the radiation is emitted from an electronic switchable x-ray source that can be modulated as to dose depth, via voltage in the x-ray source, and preferably also as to intensity, via current in the x-ray source. In a preferred form the source is a miniature x-ray tube, having a diameter on the order of roughly about ½-3 mm, and a length of about 5-15 mm. Pursuant to the invention a miniature x-ray tube is inserted into a balloon catheter, either before or after the balloon has been placed at the desired location in the patient. The x-ray source is switched on via a control unit outside the patient only when the balloon has been inserted, inflated and confirmed as to position, and with the patient and physician ready to administer the prescribed dose profile to the patient. Radiation dose delivery can be high compared to prior practice, about 5 to 50 Gy/hour. The x-ray source can operate in the range of about 40 kVp to 80 kVp. In another aspect of the invention, either a switchable x-ray source or an isotope can be used in a therapeutic radiation treatment procedure. The balloon of the catheter is doped with contrast medium, in or on the skin of the balloon. The inflation medium for the balloon, which may be a saline solution, need not have any contrast medium added. The balloon catheter is placed in a cavity of living tissue, i.e. in a patient, and the balloon is inflated and then verified as to position in the cavity. This can be done by an x-ray taken exteriorly to the patient, since the balloon skin with contrast medium will have its outline visible by x-ray, after which the position of the balloon can be adjusted, if necessary. Once the correct balloon position has been verified by external imaging, the x-ray source, which may be an isotope source or a switchable source, is placed in the balloon catheter (if a switchable tube the source can be placed in the balloon before insertion). The source preferably is moved through a series of positions within the balloon catheter to administer radiation to tissue adjacent to the balloon, in accordance with a prescribed dose profile. This can be done in a series of iterations of placing the x-ray source and subsequently removing the source, for a series of dose fractions, over a treatment period that can extend over several days. The use of a balloon catheter with contrast medium in or on the skin of the balloon, as opposed to being contained in a saline solution within the balloon, is a strong departure from the prior art. The advantage is that the physician will not over-dope the saline solution with contrast medium, thus maintaining the strength of the therapeutic radiation emitted from inside the balloon. The balloon wall has virtually no attenuating effect on the therapeutic radiation, when the radiation passes through the balloon in a normal or generally normal direction to the skin of the balloon. However, when the x-ray is taken from outside, the outline of the balloon will show up sharply because of the tangential direction of viewing that outline and the fact that the outline represents many times the wall thickness of the balloon, perhaps 20-40 times the density of contrast medium, thus contributing to the visible outline in the x-ray. In the drawings, FIG. 1 shows somewhat schematically an applicator 10 according to one embodiment of the invention, the applicator including a flexible control line or cable 12 leading from a controller, not shown, and a catheter or applicator portion 14. A balloon 16 of the applicator and catheter is shown inflated in FIG. 1. The applicator device is generally as shown in co-pending application Ser. No. 10/683,885, filed Oct. 13, 2003. As shown, at the proximal end 18 of the applicator is a branch 20. The three ports 22, 24 and 26 of this branch device may comprise a service port, a drainage port and a balloon inflation port, respectively. The functions of these ports are explained further below with reference to other drawings. A flexible main shaft 28 extends from the branch device 20 to the balloon 16, and is sealed to the balloon at 30. The balloon in FIG. 1 is shown partially cut away to reveal an electronic x-ray source 32 within the balloon, at the end of the control line 12 and moveable longitudinally within the balloon 16 and catheter 10. In preferred embodiments the x-ray tube 32 is less than 4 mm in diameter, preferably no greater than about 3 to 3.2 mm in diameter, and in some embodiments this tube is as small as 1 mm in diameter or even smaller. The shaft 28 is flexible, and may be highly flexible and pliable near the proximal end 18, as explained in the co-pending application referenced above, for the purpose of folding the applicator over against the breast when not in use, when the control line 12 and x-ray source 32 are not inserted into the applicator, particularly for breast irradiation involving several dose fractions such that the applicator need not be removed between fractions. The flexible shaft provides a lumen for admitting a fluid to inflate the balloon 16, while also providing a duct or lumen for insertion of the radiation source 32, via guides connected to the balloon. The shaft 24 also preferably provides a channel for drainage of liquids from the body cavity within which the applicator is inserted. A drainage receptacle can be connected to the end of the drainage port or an aspirator can be used when needed to withdraw liquids. The applicator 10 is shown schematically in FIGS. 2, 3 and 4 as inserted into a resection cavity of a breast for treatment. FIGS. 5A, 5B and 5C show the applicator 10 in greater detail, and with the balloon 16 deflated and collapsed. The service port 22, in line with the flexible shaft 28, as well as the drainage port 24 and the balloon inflation port 26, are illustrated. Also shown is a distance scale preferably included, with distances shown at 6 cm, 7 cm, 8 cm, etc., up to about 15 cm, to indicate to the physician the total depth of the applicator into cavity and opening wound. This provides a direct and easily used means to determine the position of the distal end 35 of the applicator as it is being inserted. As shown in FIGS. 5B and 5C, drainage is provided for the resection cavity via drain holes 36 at the distal end 35 of the applicator, beyond the balloon 16, communicating internally to the drain port 24, and also preferably via drain holes 38 shown just proximal of the balloon, for draining fluids which travel over the surface of the balloon. As in co-pending application Ser. No. 10/683,885, the balloon preferably has some form of liquid channeling means on its outer surface. This could be a multiplicity of bumps, allowing for liquid travel even though the balloon is engaged against the tissue, or a series of longitudinal ridges on the balloon surface to form channels. The drain holes 38 catch most of the liquid flowing in this manner, and these holes communicate with the drain port 24. The balloon 16 may advantageously be formed of a silicone material, although other appropriate biocompatible materials can be used. The balloon material is bonded to the outside surface of the flexible shaft 28 in sealed relationship thereto, by known procedures. FIGS. 2, 3 and 4 indicate somewhat schematically the use of the applicator device 10 in a resection cavity of a human breast 41, for radiation therapy. In FIG. 2 the catheter 10 is shown with its balloon 16 shown in dashed lines, and the shaft 28 in the balloon forming a guide for an x-ray source which may either be a miniature x-ray tube or an isotope. A seal 40 is shown in FIG. 2, for sealing the flexible shaft 28 of the catheter/applicator against the surface of the skin where it enters the body. Also shown in FIG. 2 is a connector 42 for connecting the applicator shaft, via the service port 22, to an exterior cable 44 that contains the control cable 12, leading to the controller (not shown) for the applicator and for the x-ray source, if the source is a controllable miniature tube. FIGS. 3 and 3A illustrate the ability of the invention to achieve a more exact dose profile by use of a miniature electronic x-ray source in the applicator 10, a source which is capable of voltage variation and thus variation of the depth of dose. As one rather simple example, four dwell positions are shown in FIG. 3 and represented in a bar graph in FIG. 3A. The deepest dwell position, position 1, is closest to the lungs of the patient. Thus, the voltage is relatively low for this dwell position, controlling the depth of penetration into the surrounding tissue such that radiation will not reach the lungs to any appreciable degree. The second dwell position is farther from the lungs, and FIG. 3A shows that the voltage is increased for this dwell position, for a greater depth of penetration. Similarly, dwell positions 3 and 4 are progressively farther from the lungs and the voltage and depth of dose are progressively higher. FIGS. 4 and 4A illustrate schematically the use of a switchable, controllable electronic x-ray source in the catheter 10, wherein current is varied at different dwell positions in order to vary the dose intensity at different positions. In the schematic drawing of FIG. 4, four different dwell positions are again indicated for the electronic x-ray source, within the balloon 16 of the catheter 10, the balloon positioned in a resection cavity in a patient's breast 41. The control current does not vary the depth of penetration of the radiation, only the dose intensity. In the illustrated procedure, the current is varied in order to produce a uniform isodose profile. Thus, at positions 1 and 4 where the x-ray source is closest to tissue, the current is set at a lower level, while at dwell positions 2 and 3, close to the center of the balloon 16 and of the resection cavity, where the tube is more distant from tissue, the current is set higher. Note that dose intensity can be controlled also by controlling the length of time the source is “on” at each dwell position, or simply by controlling the length of dwell at each position assuming the source remains “on”. These profiles of FIGS. 4 to 5A are just examples of how the variation of voltage and current using an electronic x-ray source can be beneficially used accurately to create a required isodose profile. FIGS. 6 and 7 illustrate the balloon 16 having an x-ray contrast medium in or on the balloon wall. As explained above, this differs from prior practice in which a saline solution within the balloon contained a weak solution of contrast medium so that the balloon would show up in external x-ray imaging, for location of the balloon. In this case the contrast medium is only in or on the balloon wall, and this medium will absorb radiation, indicated at 46, during external imaging; it will also absorb radiation from the therapeutic source and thus will attenuate the radiation delivered from inside the balloon to some extent. However, with a low concentration of such contrast medium in the balloon wall, the attenuating effect of the medium for radiation passing through the balloon at an angle normal or generally normal to the balloon wall will be small and essentially negligible. On the other hand, the effect of radiation, particularly x-ray radiation, passing tangentially through the edges of the balloon as indicated in FIGS. 6 and 7, will be at a maximum, since the radiation must pass through the balloon edge wise at this tangential angle, a much longer effective path length. The result is that a balloon 16 with such contrast medium can be located by external x-ray, visible in an x-ray image by its edges. This is demonstrated in FIG. 7 showing effective path length of x-rays through balloon material as a function of distance from the center of the balloon. The densest outline of the balloon will be at its circumference, especially at distal and proximal ends of the balloon itself, where the wall material may be somewhat thicker at its attachment to the flexible shaft 28 and in any event, where the balloon has areas that are stretched far less due to the geometry of the balloon and its attachment to the flexible shaft 28 of the catheter device. FIG. 6 shows in a schematic approximation a graph of x-ray density (darkness or density of the line appearing in an x-ray image) on a vertical axis, versus position. For clarity the balloon 16 is represented directly adjacent to the graph, and showing the direction of x-ray radiation 46. As illustrated, density is low in the x-ray image of the balloon at a region 48 in FIG. 6 where the radiation passes generally normally through the balloon wall; however, spikes of extreme density are shown at 50 and 52, where the rays must pass through considerable distance of the balloon wall on edge. As can be seen from the graph of FIG. 7 (showing effective path length through both 4 and 5 cm diameter balloons), the effective path length at these tangent regions can be about 15 to 25 times greater than the normal path length. Thus, the contrast-doped balloon wall provides a far superior imaging arrangement than the prior saline solution, without adversely affecting therapeutic radiation. The procedures and apparatus described above are applicable to natural body cavities (e.g., bladder, uterus, vaginal), and naturally occurring lumens, as well as surgically created cavities. The term cavity in the claims is intended broadly to refer to natural or surgical cavities or lumens. Also, except where a switchable x-ray source is specifically called for herein for the advantages it offers in modulation or other purposes, the described procedures can ordinarily be performed using isotopes. The term brachytherapy device refers to either type of radiation source. The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to these preferred embodiments will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined in the following claims.
	description	The invention relates to device diagnostics applied to industrial processes in general and particularly to process control systems and to management systems of field devices employing a field bus. Process control systems control industrial processes by means of various field devices connected to the process, such as regulating devices, control devices, transducers, transmitters, and the like. A typical field device is a control valve provided with a valve controller, such as the valve controller ND800 of Neles Automation. Devices known as intelligent field devices are equipped with control logic or software which allow for local control of the field device by means of a suitable control algorithm, for example, collection of both status and measurement data, and communication with an automation system or a specific field device management system by means of a field communication protocol, such as HART (Highway Addressable Remove Transducer). In addition, current intelligent field devices already comprise a sufficient amount of diagnostics to allow the field device to indicate when it malfunctions. This information can be utilized for focusing maintenance operations, which reduces unnecessary equipment testing and, thereby, the costs of maintenance. In addition, the utilization ratio of the plant (factory) increases as unpredictable down time is reduced. A typical automation system comprises a control room with computers, databases, process control programs and user interfaces. There are various alternative ways to provide a connection between field devices and the rest of the system. Field devices are conventionally connected to the control system by two-wire twisted pair loops, each device being connected to the control system by a single twisted pair producing an analog 4 to 20 mA input signal. A process controller (PID) is arranged into a centralized computer system located in the control room. This type of process control system is often referred to as Direct Digital Control (DDC). In the next phase of control system evolution, a Distributed Control System (DCS) will be used, in which the process controllers (PID) are decentralized into a plural number of computers at the plant. The decentralized computers and the central computer located in the control room may be interconnected through a local data network or data bus, for example, whereas separate field devices remain connected to the process controllers through two-wire twisted pairs. Recently, new solutions have been adopted for the control systems, such as the Highway Addressable Remote Transducer (HART) protocol which allows digital data and a conventional analog 4 to 20 mA signal to be transmitted together in a twisted-pair loop. The most recent development phase involves a Field Control System (FCS) which employs a high-speed digital network or data bus for interconnecting the control room computer and the field devices. Conventional analog 4 to 20 mA signals have been omitted from the FCS, and a new communication protocol, commonly referred to as Fiedlbus, has been defined by the Instruments Society of America (ISA). In principle, a field bus can be connected to any process device, thus allowing the devices to report their self-diagnostic data over the field bus to a maintenance computer, for example. However, all process devices do not support bus interfacing and self-diagnostic. For example, it has often not been necessary to connect devices such as pumps, mixers, refiners, screens, drums and switches to the field bus, although in some cases it would be useful to also monitor the diagnostics data of these devices in order to obtain timely information about their servicing needs, for example. To provide field bus cabling for these devices solely for this purpose would, however, often be a too high cost factor. Field bus cabling of dozens of meters to a device that is in a more remote location at the plant and the related mounting works may incur costs of thousands of dollars. In addition, in order for the device to be connected to and communicate with the field bus, it needs to be provided with I/O electronics. For example, Fieldbus typically requires a 16-bit processor and the related external electronics. The interface electronics involved also adds to costs considerably. U.S. Pat. No. 5,793,963 teaches a control system comprising field devices which are connected to the control room with a Fieldbus cabling. In addition, some of the field devices are provided with a wireless Fieldbus gate through which a field device can be controlled over a wireless link using a portable control device or a workstation. The field device is thus provided with both a wireless and wired Fieldbus. The function of this wireless connection is to serve as a secondary, redundant control path, instead of a redundant, hardwired bus and to enable the field devices to be controlled directly by the service personnel using portable devices. This allows double cabling to be avoided. The wireless Fieldbus gate can use common interface electronics with the wired bus interface, and power supply to the field device can also be provided through the wired fieldbus. The use of the described wireless Fieldbus gate without a wired Fieldbus would remove the above-mentioned cabling problem in diagnostics applications. Along with the cabling, also power supply to the interface and diagnostics electronics would be disposed of, and therefore power supply would have to be arranged locally. The power consumption of interface electronics is particularly high. But even if it were possible to arrange the power supply, the diagnostics and bus interface electronics would raise the price of the diagnostics unit to a considerably high level. The price would be too high in a case of several process devices, even though it would otherwise be interesting to automate their diagnosing. It is an object of the present invention to provide an affordable and simple solution for process device diagnostics in a field bus environment. This is achieved with a system according to claim 1, a field device according to claim 7, and a diagnostics device according to claim 14. An underlying idea of the invention is that the process device to be monitored is provided with a simple remote diagnostics device incorporating primarily only the electronics and transducers needed for collecting diagnostics data, and a transmitter part allowing for a short-range transfer of the diagnostics data with simple and inexpensive wireless transfer technology. In the vicinity (within said short range) of the process device to be monitored at the plant, such as a factory, there is provided an intelligent field device connected to a wired field bus, the field device being provided with a receiver allowing the diagnostics data transmitted by the remote diagnostics device to be received. This intelligent field device is, for example, a valve controller used for controlling a valve at the point in question. The field device comprises the necessary intelligence for controlling the valve and for field bus communication, as well as a field bus interface. In the invention, this capacity is also used for receiving diagnostics data from the remote diagnostics device and for processing the data at least to the extent that a diagnostics report can be sent through the field bus to the desired control computer. This allows the remote diagnostics device to be implemented without any processing capacity and electronics needed for data analysis and field bus interfacing, whereby the device can be made very simple and inexpensive. Consequently, these devices can be arranged in connection with any processing devices having a field device supporting this feature in their vicinity. No field bus cabling of any kind is needed. Since the invention preferably employs existing processing capacity and electronics, a conventional intelligent field device in its simplest form only requires a receiver for the wireless link, and some re-programming. This is why the additional cost incurred by the field device of the invention is almost solely restricted to the price of the wireless receiver. A wireless link based on the Bluetooth technology, for example, will be most affordable. This allows all new intelligent field devices, in principle, to be provided with such a receiver, or at least with the required ability, whereby they are flexible to configure through the field bus, for example, to support nearby remote diagnostics devices. In a preferred embodiment of the invention the field device carries out analysis of raw data received from the diagnostics device as much as possible. This means that processed diagnostics reports are only transmitted through the field bus, which reduces the load on the field bus. The field bus may send a diagnostics report at predetermined intervals, for example, in response to a request received from the control computer and/or when the diagnostics data indicate a need for servicing or abnormal function of a process device. On the other hand, in another preferred embodiment of the invention the field device forwards the diagnostics data substantially unprocessed, the processing being mainly restricted to rendering the diagnostics data to a format that can be transferred on the field bus. The remote diagnostics device is probably often at such a location that it is not easy to provide the device with a fixed electric power supply. Since one of the objectives of the invention is to avoid additional cabling, it is typically not reasonable to use long cables to provide the electric power supply. The remote diagnostics device will therefore typically be battery-operated and/or it will generate the required electric energy locally. This is another reason why the minimal electronic circuitry provides a significant advantage in the remote diagnostics device of the invention. The electric energy may be generated in a conventional manner, using solar cells for example. However, in connection with a process device to be monitored, there usually appears mechanic energy which can be converted to electric energy. One example is kinetic energy, such as vibration. Also noise, i.e. variations in air pressure, can be converted to electric energy. Process devices are often provided with pneumatic or hydraulic controls, whereby the compressed air or hydraulic pressure in the piping involved can be used for producing electric energy. In a preferred embodiment of the invention the power source of the remote diagnostics device generally comprises an energy converter which converts mechanical energy of the process device, such as kinetic energy or noise, or the hydraulic pressure or compressed air supplied to the process device into electric energy which is used for providing the operating voltage of the diagnostics electronics and the transmitter part. The present invention can be applied to all industrial processes, or the like, comprising intelligent field devices connected to a field bus. In this context, intelligent field devices refer to devices used in connection with any process or automated system, or the control thereof, which is to be monitored and which is capable of producing data describing, either directly or indirectly, the condition of the device, i.e. condition data. A typical example of this kind of an intelligent field device is a control valve provided with a valve controller. FIG. 1 is a schematic block diagram illustrating a process automation system with a field device diagnostics system of the invention connected thereto. The automation system comprises control room programs and databases 11, and process control programs and an I/O part 12. The control and I/O part 12 is connected through HART-standard buses to intelligent field devices comprising control valves 14, 15 and 16 and valve controllers 14A, 15a and 16A. The valve controller may be for example ND 800 of Neles Automation. HART (Highway Addressable Remote Transducer) is based on the simultaneous transmission of digital data and a conventional analog 4 to 20 mA signal. HART enables bi-directional communication which allows intelligent field devices to be controlled and data to be read from them. The HART protocol complies with the reference model of the OSI (Open System Interconnection) protocol stack developed by the International Organization for Standardization (ISO). HART commands are transferred in layers 7 (application layers). A HART instruction set comprises general instructions that all field devices understand, and device-specific instructions producing functions restricted to a specific device (device type). The HART protocol allows for both point-to-point configuration, in which each field device and master unit are interconnected by a specific bus (wire pair), or a multidrop configuration, in which even 15 field devices are connected to one and the same field bus (wire pair). The HART protocol is described in greater detail for example in the publication HART Field Communication Protocol: An Introduction for Users and Manufacturers, HART Communication Foundation, 1995. The HART protocol has also been adopted as an industrial standard. However, it should be appreciated that the type of the field communication interface, i.e. the field bus and the protocol it employs, or the implementation thereof is not relevant to the present invention. The condition of the field devices is monitored with a field device diagnostics system 10 according to the invention which collects data from the field devices. For this purpose, each field device 14, 15 and 16 is provided with a separate field bus connecting the field device to a conventional HART multiplexer 9, which is in turn connected through an RS-485 bus 8 to a PC 6 running on Windows 95/98 or Windows NT operating system, for example. The workstation 6 is also connected to the local area network LAN of the plant (which the workstation can use for communicating with the control room programs, for example). Remote diagnostics modules 1 of the invention, placed on top of pumps 2, for example, transmit diagnostics data over a Bluetooth link 17 to field devices 14A, as will be described in greater detail below. The pump 2 moves a material flow forward in piping 4. Reference numeral 3 designates the pump motor. The pump is, however, only one example of process devices in connection with which the remote diagnostics module can be used. The invention is suitable for diagnosing any devices, such as mixers, refiners, screens, drums and switches. The workstation 6 comprises field device control monitoring software for collecting data from the intelligent field devices 14-16. This data collection is a fully automated operation where no human intervention is needed. The collected data can be used for analysing the condition of the device, and a message reporting the condition can be transmitted to another system, for example to other parts, such as a control room application display, of the plant automation system. FIG. 2 illustrates, by way of example, the architecture of a second automation system based on the field bus. A number of computers, for example a control room computer 21, business computer 21, service department computer 23 and an Internet link 24 are connected to a high-speed (100 Mbps) Ethernet network with an Ethernet switch 20. A number of linking devices 25A, 25B and 25C are also connected to the Ethernet network, the linking devices connecting the network to H1 Fieldbus-type field bus blocks 27 of a rate of 31.25 kbps. Diverse intelligent field devices are connected to the field bus 27, such as transmitters 28A and 28B, or positioners 29A and 29B. Diagnostics modules 1 of the invention connected to the pumps 2 form a wireless link 17 with the positioners 29, for example. It is to be noted, however, that the precise structure of the field bus, diagnostics system or automation system is not relevant to the basic idea of the invention, and the invention is not meant to be restricted to the above examples. The more detailed description given below will therefore be only restricted to the implementation and operation of the remote diagnostics module 1 and an intelligent field device, such as the positioner 29. FIG. 3 is a schematic block diagram illustrating a remote diagnostics module of the invention. The diagnostics module 1 always comprises some kind of a device for measuring or monitoring a given characteristic, or characteristics, of a target device. The diagnostics equipment in question typically comprises a transducer of some kind. Monitoring and measuring of different characteristics of devices, such as changes in pressure, temperature, vibration frequency, etc. allows flaws, damage caused by wear, or mounting faults appearing in a device to be detected at a sufficient reliability. For example, most products have inherent vibration frequencies on the basis of which their condition can be concluded. The reason for this is that the devices comprise a plural number of separate parts which together form a complex vibration system. These frequencies are easily affected by even the slightest mechanical changes, and it is impossible to construct two individual products with exactly the same vibration frequencies. Consequently, by studying the characteristic vibration frequencies of devices it is easy to detect even the slightest changes in them, their wearing, damage caused to them, and similar faults. FIG. 3 shows a preferred embodiment of the invention which is provided with an accelerometer 31 to be attached to the side of a pump or some other device to be diagnosed. The accelerometer measures acceleration caused by the vibration of the pump and produces samples proportional to the frequency and amplitude of the vibration. Other typical transducers include a pressure transducer and a temperature transducer. From the point of view of the basic idea of the invention, the type of variable to be measured or the transducer or other device used in the measurement are irrelevant. The control unit 32 reads samples from the accelerometer 31 on a continuous basis, at suitable intervals, or on the basis of some other criteria, and transfers the samples to a wireless transmitter 33 for further transmission over the wireless link 17 to the field device. The transmitter 33 is preferably a transmitter based on Bluetooth technology. Bluetooth is defined in the standard “Specification of the Bluetooth system, v1.0B, Dec. 1st 1999” which is being developed by a group of companies to provide short-range radio frequency data transmission between different devices, such as wireless data transmission between a mobile station and a computer, or wireless data transmission between a computer and peripheral equipment, such as a printer. Bluetooth technology aims at high manufacturing volumes, whereby an individual Bluetooth transmitter/receiver component can be provided at a very low price. However, in principle the wireless transmitter 33 can be implemented in the form of any wireless radio or infra-red transmitter offering a range of coverage sufficient for the application concerned. In the simplest configuration of the remote diagnostics module 1, the sample data from the transducer 31 can be in a format suitable for the Bluetooth transmitter 33 as such, in which case the control unit 32 is not needed at all. If the control unit 32 is included, in the simplest alternative it may convert a sample signal from the accelerometer 31 to a format suitable for the Bluetooth transmitter 33 and/or carry out the coordination and timing of the transmission of the samples. In a more complicated case, the control unit 32 may also comprise diverse sample processing, or rough analysis even. Since the first preferred embodiment, however, aims at providing a remote diagnostics device which is as simple and affordable as possible and which consumes as little energy as possible, the control unit 32 is provided with small processing capacity. The Bluetooth transmitter 33 and the control unit 32 can be implemented for example by means of one Bluecore01 integrated circuit manufactured by Cambridge Silicon Ltd (CSR). Bluecore01 comprises both a Bluetooth transmitter and a 16-bit Risc processor. The power source 34 produces the required operating voltage or voltages for the electronics of the remote diagnostics module. If the power source can be plugged to the mains voltage system at its location, it may be a conventional mains power supply unit. Mains voltage supply is typically not easily available at a module mounting site, and thus the diagnostics module must be battery-operated and/or it must produce the electric energy it needs by itself. A pump, for example, always vibrates when it is running. Similarly, a mixer, refiner or drum vibrates or causes noise when it is in operation. Vibration and noise represent forms of energy. Vibration (kinetic energy) can be converted to electric energy for example by arranging a magnet to move inside a coil by impact of the vibration, voltage being thereby induced into the coil. Voltage induced into the coil can be used for charging a battery or it may be charged into a capacitor. When the capacitor or battery has been charged to a sufficient level, the control unit 32 is activated and it reads from the accelerometer 31 measurement data relating to a fairly short period of time and transfers the data to the transmitter 33 for transmission as a Bluetooth packet to the field device. In other words, the diagnostics module “wakes up” always when the charge level of the capacitor or battery is sufficient. Correspondingly, noise can also be converted to electric energy by means of a microphone, for example. Piezoelectric crystals can also be used for generating voltage. In addition, many process devices that are to be monitored are coupled to a pneumatic or hydraulic piping, in which case electric energy can be produced from compressed air or hydraulic pressure by means of a mechanic generator, such as a turbine-type solution. Valves, for example, typically operate pneumatically on compressed air. FIG. 4 illustrates the field device of the invention. In the example of FIG. 4, the functionality of the invention is implemented into an existing field device, such as a digital valve controller or positioner ND800. The digital valve controller comprises a pneumatic control part 42 which provides a pneumatic feed pressure through tubes C1 and C2 into a cylinder of an actuator 46, above and below a piston 460. If the pressure above the piston 460 increases, the piston moves downward, and vice versa. The movement of the piston, in turn, changes the valve opening. On the basis of the piston movement, a signal proportional to the valve position can be generated with a transducer 431. The digital valve controller further comprises an electric control part 43 built around a microprocessor 430. In addition, the digital valve controller comprises a bus interface 44 connecting the controller to a 40–20 mA HART bus 45 leading to the multiplexer 18, for example, as illustrated in FIG. 1. The bus 45 may also be another kind of bus, such as a Foundation Fieldbus. A conventional digital valve controller receives the control through the HART bus into a bus interface 44 from where the microprocessor 430 reads the control data. On the basis of this, the microprocessor 430 then generates control signals for the pneumatic control 42. The microprocessor 430 also makes it possible to construct diverse diagnostics characteristics inside the valve controller. For example, the microprocessor 430 may carry out real-time monitoring by collecting diagnostics data and detecting deviations, if any, from accepted performance values. The digital valve controller thus has, already in its current form, both all the electronics and processing capacity needed for interfacing with a field bus and data processing capacity for analysing and reporting diagnostics data. In the embodiment of FIG. 4 the only additional component that is needed in the current digital valve controller ND800 is a wireless receiver circuit 41, such as a Bluetooth receiver component (for example Bluecore01, Cambridge Silicon Radio Ltd). The receiver 41 receives the diagnostics data over the wireless link 17 from the remote diagnostics module 1. The microprocessor 430 reads the received diagnostics data from the receiver 41 through a line or the bus 47. The microprocessor 430 stores the diagnostics data into a memory and analyses them. In the preferred embodiment of the invention, the microprocessor 430 carries out as much diagnostics data analysis as possible. The microprocessor 430 then transmits only processed diagnostics reports to a control computer 6 (FIG. 1), for example, over the bus interface 44 and field bus 45. For example, the microprocessor 430 may send the diagnostics report at predetermined intervals, in response to a request from the control computer and/or when the analysis shows that the monitored device needs to be serviced or that it functions abnormally. In the preferred embodiment of the invention, the analysis of the diagnostics data carried out by the microprocessor 430 is based on the TESPAR (Time Encoded Signal Processing and Recognition) method. TESPAR is a modern signal analysis method utilizing a precise description of waveforms in the time domain, which description is based on polynomial theory and the location of zeros. The TESPAR allows samples provided by the accelerometer, for example, to be subjected to a kind of a statistical processing to produce for example a one-dimensional or two-dimensional histogram or matrix illustrating the operation of the device in a given situation. The matrix thus provides a kind of a fingerprint identifying the device. Any changes in the operation of the device, caused by malfunction for example, also change the vibration frequency of the device, and thereby the TESPAR matrix. A comparison between the TESPAR matrix based on the measured diagnostics data and the stored TESPAR matrix of an appropriately functioning device allows the malfunctioning or need for servicing of the device to be detected. In FIG. 3 the microprocessor 430 calculates TESPAR matrices from the received diagnostics data, and the matrices are then compared with the matrices stored in the memory. If the comparison shows that the monitored device needs to be serviced, or that it functions abnormally, the microprocessor 430 sends a notification to the control computer 6 through the field bus 45. This service notification may also contain the current TESPAR matrix, for example. In addition, the microprocessor 430 may send the TESPAR matrix to the control computer 6 at suitable intervals, or when the computer 6 requests for it. The TESPAR method is described in article “Time for TESPAR”, Condition Monitor No 105, pp. 6 to 8. A digital valve controller equipped with a Bluetooth receiver and a basic program supporting it allows the microprocessor 430 to be easily configured through the field bus 45 to operate according to the invention. In a field-bus-based system, the functionality of the field devices is typically described by means of function blocks. For example, in FIG. 4 the microprocessor 430 comprises a separate pneumatic control and actuator 46 function block, i.e. a kind of a parameter definition. Foundation Fieldbus, for example, has determined about 60 standard function blocks. Equipment manufacturers may also define function blocks of their own, provided that they conform to the general Fieldbus Foundation specification. A proprietary function block, DIAG_MODULE, supporting four remote diagnostics modules 1 of the invention could comprise for example the following parameters. Module 1 is attached to a pump and module 2 to a mixer. NR_OF_CONNECTED_DIAG_MODULES″4″MODULE_1.DEVICE_TAG″Pump_001″MODULE_1.DEVICE_STATUS″OK / warning / alarm″MODULE_1.LAST_RECEIVED_PACKET.″0x0BA7FAEF″VALUEMODULE_1.LAST_RECEIVED_PACKET.″21/03/2000/16:35:001″TIME_STAMPMODULE_4.TESPAR_SETTINGSMODULE_2.DEVICE TAG″Mixer_001″MODULE_2.DEVICE_STATUS″OK″ / warning / alarm″MODULE_2.LAST_RECEIVED_PACKET.″0x0BA7FAEF″VALUEMODULE_2.LAST_RECEIVED_PACKET.″21/03/2000/17:37:003″TIME_STAMPMODULE_2.TESPAR_SETTINGSMODULE_3 . . . With this kind of a function block, the field device, such as a digital valve controller, can be easily configured to support any remote diagnostics module and a device monitored by it. If there is a wireless link 17 connecting a plural number of remote diagnostics modules to the field device, each remote diagnostics module is provided with separate definitions. The invention and its embodiments are not restricted to the above example, but they may vary within the scope of the claims.
	description	This invention pertains generally to management of an electrical energy storage device. More particularly, the invention is concerned with achieving a target life for an electric energy storage device. Various hybrid propulsion systems for vehicles use electrical energy storage devices to supply electrical energy to electrical machines, which are operable to provide motive torque to the vehicle, often in conjunction with an internal combustion engine. An exemplary hybrid powertrain architecture comprises a two-mode, compound-split, electro-mechanical transmission which utilizes an input member for receiving power from a prime mover power source and an output member for delivering power from the transmission to a vehicle driveline. First and second electric machines, i.e. motor/generators, are operatively connected to an energy storage device for interchanging electrical power therebetween. A control unit is provided for regulating the electrical power interchange between the energy storage device and the electric machines. The control unit also regulates electrical power interchange between the first and second electric machines. One of the design considerations in vehicle powertrain systems is an ability to provide consistent vehicle performance and component/system service life. Hybrid vehicles, and more specifically the battery pack systems utilized therewith, provide vehicle system designers with new challenges and tradeoffs. It has been observed that service life of an electrical energy storage device, e.g. a battery pack system, increases as resting temperature of the battery pack decreases. However, cold operating temperature introduces limits in battery charge/discharge performance until temperature of the pack is increased. A warm battery pack is more able to supply required power to the vehicle propulsion system, but continued warm temperature operation may result in diminished service life. Modern hybrid vehicle systems manage various aspects of operation of the hybrid system to effect improved service life of the battery. For example, depth of battery discharge is managed, amp-hour (A-h) throughput is limited, and convection fans are used to cool the battery pack. Ambient environmental conditions in which the vehicle is operated has largely been ignored. However, the ambient environmental conditions may have significant effect upon battery service life. Specifically, same models of hybrid vehicles released into various geographic areas throughout North America would likely not result in the same battery pack life, even if all the vehicles were driven on the same cycle. The vehicle's environment must be considered if a useful estimation of battery life is to be derived. Additionally, customer expectations, competition and government regulations impose standards of performance, including for service life of battery packs, which must be met. End of service life of a battery pack may be indicated by ohmic resistance of the battery pack. The ohmic resistance of the battery pack is typically flat during much of the service life of the vehicle and battery pack however, thus preventing a reliable estimate of real-time state-of-life (‘SOL’) of the battery pack throughout most of the service life. Instead, ohmic resistance is most useful to indicate incipient end of service life of the battery pack. It is desirable to have a method and apparatus to provide a control of operation of an electrical energy storage system, including for application on a gasoline/electric hybrid vehicle that controls operation based upon a targeted service life of the electrical energy storage device. A method for determining a preferred operating gradient for use in attaining a life objective for an electrical energy storage device includes providing present state-of-life of the electrical energy storage device and establishing a life target for the electrical energy storage device as a predetermined limit in a predetermined metric at a predetermined state-of-life of the electrical energy storage device. A state-of-life gradient is then determined with respect to the predetermined metric which converges the state-of-life of the electrical energy storage device to the life target. Preferably, the predetermined state-of-life of the electrical energy storage device is indicative of the end of life of the electrical energy storage device. In accordance with one alternative, the metric includes elapsed service time of the electrical energy storage device. In accordance with another alternative wherein the electrical energy storage device is a vehicular battery, the metric comprises vehicle distance traveled. Yet another alternative wherein the electrical energy storage device is a vehicular battery bases the life target upon a respective predetermined limit in one of elapsed service time of the electrical energy storage device and vehicle distance traveled. The life target is preferably normalized with respect to the one of elapsed service time of the electrical energy storage device and vehicle distance traveled upon which the life target is based. Referring now to the drawings, wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, FIG. 1 shows a control system and an exemplary hybrid powertrain system which has been constructed in accordance with an embodiment of the invention. The exemplary hybrid powertrain system comprises a plurality of torque-generative devices operable to supply motive torque to a transmission device, which supplies motive torque to a driveline. The torque-generative devices preferably comprise an internal combustion engine 14 and first and second electric machines 56, 72 operable to convert electrical energy supplied from an electrical storage device 74 to motive torque. The exemplary transmission device 10 comprises a two-mode, compound-split electro-mechanical transmission having four fixed gear ratios, and includes a plurality of gears operable to transmit the motive torque to an output shaft 64 and driveline through a plurality of torque-transfer devices contained therein. Mechanical aspects of exemplary transmission 10 are disclosed in detail in U.S. Pat. No. 6,953,409, entitled “Two-Mode, Compound-Split, Hybrid Electro-Mechanical Transmission having Four Fixed Ratios”, which is incorporated herein by reference. The control system comprises a distributed control module architecture interacting via a local area communications network to provide ongoing control to the powertrain system, including the engine 14, the electrical machines 56, 72, and the transmission 10. The exemplary powertrain system been constructed in accordance with an embodiment of the present invention. The hybrid transmission 10 receives input torque from torque-generative devices, including the engine 14 and the electrical machines 56, 72, as a result of energy conversion from fuel or electrical potential stored in electrical energy storage device (ESD) 74. The ESD 74 typically comprises one or more batteries. Other electrical energy storage devices that have the ability to store electric power and dispense electric power may be used in place of the batteries without altering the concepts of the present invention. The ESD 74 is preferably sized based upon factors including regenerative requirements, application issues related to typical road grade and temperature, and, propulsion requirements such as emissions, power assist and electric range. The ESD 74 is high voltage DC-coupled to transmission power inverter module (TPIM) 19 via DC lines referred to as transfer conductor 27. The TPIM 19 transfers electrical energy to the first electrical machine 56 by transfer conductors 29, and the TPIM 19 similarly transfer electrical energy to the second electrical machine 72 by transfer conductors 31. Electrical current is transferable between the electrical machines 56, 72 and the ESD 74 in accordance with whether the ESD 74 is being charged or discharged. TPIM 19 includes the pair of power inverters and respective motor control modules configured to receive motor control commands and control inverter states therefrom for providing motor drive or regeneration functionality. The electrical machines 56, 72 preferably comprise known motors/generator devices. In motoring control, the respective inverter receives current from the ESD and provides AC current to the respective motor over transfer conductors 29 and 31. In regeneration control, the respective inverter receives AC current from the motor over the respective transfer conductor and provides current to the DC lines 27. The net DC current provided to or from the inverters determines the charge or discharge operating mode of the electrical energy storage device 74. Preferably, machine A 56 and machine B 72 are three-phase AC electrical machines and the inverters comprise complementary three-phase power electronic devices. The elements shown in FIG. 1, and described hereinafter, comprise a subset of an overall vehicle control architecture, and are operable to provide coordinated system control of the powertrain system described herein. The control system is operable to gather and synthesize pertinent information and inputs, and execute algorithms to control various actuators to achieve control targets, including such parameters as fuel economy, emissions, performance, driveability, and protection of hardware, including batteries of ESD 74 and motors 56, 72. The distributed control module architecture of the control system comprises an engine control module (‘ECM’) 23, transmission control module (‘TCM’) 17, battery pack control module (‘BPCM’) 21, and the Transmission Power Inverter Module (‘TPIM’) 19. A hybrid control module (‘HCP’) 5 provides overarching control and coordination of the aforementioned control modules. There is a User Interface (‘UI’) 13 operably connected to a plurality of devices through which a vehicle operator typically controls or directs operation of the powertrain, including the transmission 10. Exemplary vehicle operator inputs to the UI 13 include an accelerator pedal, a brake pedal, transmission gear selector, and, vehicle speed cruise control. Within the control system, each of the aforementioned control modules communicates with other control modules, sensors, and actuators via a local area network (‘LAN’) communications bus 6. The LAN bus 6 allows for structured communication of control parameters and commands between the various control modules. The specific communication protocol utilized is application-specific. By way of example, one communications protocol is the Society of Automotive Engineers standard J1939. The LAN bus and appropriate protocols provide for robust messaging and multi-control module interfacing between the aforementioned control modules, and other control modules providing functionality such as antilock brakes, traction control, and vehicle stability. The HCP 5 provides overarching control of the hybrid powertrain system, serving to coordinate operation of the ECM 23, TCM 17, TPIM 19, and BPCM 21. Based upon various input signals from the UI 13 and the powertrain, the HCP 5 generates various commands, including: an engine torque command; clutch torque commands for various clutches of the hybrid transmission 10; and motor torque commands for the electrical machines A and B, respectively. The ECM 23 is operably connected to the engine 14, and functions to acquire data from a variety of sensors and control a variety of actuators, respectively, of the engine 14 over a plurality of discrete lines collectively shown as aggregate line 35. The ECM 23 receives the engine torque command from the HCP 5, and generates an axle torque request. For simplicity, ECM 23 is shown generally having bi-directional interface with engine 14 via aggregate line 35. Various parameters that are sensed by ECM 23 include engine coolant temperature, engine input speed to the transmission, manifold pressure, ambient air temperature, and ambient pressure. Various actuators that may be controlled by the ECM 23 include fuel injectors, ignition modules, and throttle control modules. The TCM 17 is operably connected to the transmission 10 and functions to acquire data from a variety of sensors and provide command control signals, i.e. clutch torque commands to the clutches of the transmission. The BPCM 21 interacts with various sensors associated with the ESD 74 to derive information about the state of the ESD 74 to the HCP 5. Such sensors comprise voltage and electrical current sensors, as well as ambient sensors operable to measure operating conditions of the ESD 74 including, e.g., temperature and internal resistance of the ESD 74. Sensed parameters include ESD voltage, VBAT, ESD current, IBAT, and ESD temperature, TBAT. Derived parameters preferably include, ESD internal resistance, RBAT, ESD state-of-charge, SOC, and other states of the ESD, including available electrical power, PBAT—MIN and PBAT—MAX. The Transmission Power Inverter Module (TPIM) 19 includes the aforementioned power inverters and machine control modules configured to receive motor control commands and control inverter states therefrom to provide motor drive or regeneration functionality. The TPIM 19 is operable to generate torque commands for machines A and B based upon input from the HCP 5, which is driven by operator input through UI 13 and system operating parameters. Motor torques are implemented by the control system, including the TPIM 19, to control the machines A and B. Individual motor speed signals are derived by the TPIM 19 from the motor phase information or conventional rotation sensors. The TPIM 19 determines and communicates motor speeds to the HCP 5. Each of the aforementioned control modules of the control system is preferably a general-purpose digital computer generally comprising a microprocessor or central processing unit, read only memory (ROM), random access memory (RAM), electrically programmable read only memory (EPROM), high speed clock, analog to digital (A/D) and digital to analog (D/A) circuitry, and input/output circuitry and devices (I/O) and appropriate signal conditioning and buffer circuitry. Each control module has a set of control algorithms, comprising resident program instructions and calibrations stored in ROM and executed to provide the respective functions of each computer. Information transfer between the various computers is preferably accomplished using the aforementioned LAN 6. Algorithms for control and state estimation in each of the control modules are typically executed during preset loop cycles such that each algorithm is executed at least once each loop cycle. Algorithms stored in the non-volatile memory devices are executed by one of the central processing units and are operable to monitor inputs from the sensing devices and execute control and diagnostic routines to control operation of the respective device, using preset calibrations. Loop cycles are typically executed at regular intervals, for example each 3.125, 6.25, 12.5, 25 and 100 milliseconds during ongoing engine and vehicle operation. Alternatively, algorithms may be executed in response to occurrence of an event. The action described hereinafter occurs during active operation of the vehicle, i.e. that period of time when operation of the engine and electrical machines are enabled by the vehicle operator, typically through a ‘key-on’ action. Quiescent periods include periods of time when operation of the engine and electrical machines are disabled by the vehicle operator, typically through a ‘key-off’ action. In response to an operator's action, as captured by the UI 13, the supervisory HCP control module 5 and one or more of the other control modules determine required transmission output torque, To. Selectively operated components of the hybrid transmission 10 are appropriately controlled and manipulated to respond to the operator demand. For example, in the exemplary embodiment shown in FIG. 1, when the operator has selected a forward drive range and manipulates either the accelerator pedal or the brake pedal, the HCP 5 determines how and when the vehicle is to accelerate or decelerate. The HCP 5 also monitors the parametric states of the torque-generative devices, and determines the output of the transmission required to effect a desired rate of acceleration or deceleration. Under the direction of the HCP 5, the transmission 10 operates over a range of output speeds from slow to fast in order to meet the operator demand. Referring now to FIG. 2, a method and apparatus to estimate a state-of-life (‘SOL’) of an energy storage device useable in a hybrid control system in real-time is described. The exemplary method and apparatus to estimate state-of-life (‘SOL’) of the energy storage device in the hybrid control system in real-time is disclosed in detail in U.S. patent application Ser. No. 11/422,652, entitled “Method and Apparatus for Real-Time Life Estimation of an Electric Energy Storage Device”, which is incorporated herein by reference. The exemplary method and apparatus to estimate state-of-life comprises an algorithm that monitors an electrical current and a state-of-charge and temperature of the electrical energy storage device 74 during operation. Temperature of the electrical energy storage device 74 is further monitored during quiescent periods of ESD operation. Quiescent periods of ESD operation are characterized by ESD power flow that is de minimus whereas active periods of ESD operation are characterized by ESD power flow that is not de minimus. That is to say, quiescent periods of ESD operation are generally characterized by no or minimal current flow into or out of the ESD. With respect to an ESD associated with a hybrid vehicle propulsion system for example, quiescent periods of ESD operation may be associated with periods of vehicle inactivity (e.g. powertrain, including electric machines, is inoperative such as during periods when the vehicle is not being driven and accessory loads are off but may include such periods characterized by parasitic current draws as are required for continuing certain controller operations including, for example, the operations associated with the present invention). Active periods of ESD operation in contrast may be associated with periods of vehicle activity (e.g. accessory loads are on and/or the powertrain, including electric machines, is operative such as during periods when the vehicle is being driven wherein current flows may be into or out of the ESD). The state-of-life (‘SOL’) of the electrical energy storage device 74 is determined based upon the ESD current, the state-of-charge of the ESD, and the temperature of the ESD during quiescent and active periods of operation. The inputs to calculation of SOL, include ESD internal resistance RBAT, ESD temperature TBAT, ESD state-of-charge SOC, and ESD current IBAT. These are known operating parameters measured or derived within the distributed control system. From these parameters, an A-h integration factor 110, a depth of discharge (‘DOD’) factor 112, a driving temperature factor, TDRIVE, 114 and a resting temperature factor, TREST, 116 are determined, and provided as input to determine a parameter for SOL. The operating parameters used to calculate SOL include: ESD current, IBAT, which is monitored in real-time, measured in amperes, and integrated as a function of time; magnitude of electrical current flowing through the ESD 74 during each active charging and discharging event; ESD state-of-charge (‘SOC’), including depth-of-discharge (‘DOD’); ESD temperature factor during active periods of operation, TDRIVE, and ESD temperature factor during inactive periods of operation, TREST. Referring again to FIG. 2, a schematic diagram is shown, demonstrating an exemplary method for estimating the state-of-life of the ESD 74 in real-time, based upon monitored inputs. The method is preferably executed as one or more algorithms in one of the controllers of the control system, typically the HCP 5. The estimated state-of-life of the ESD 74 (‘SOLK’) is preferably stored as a scalar value in a non-volatile memory location for reference, updating, and for resetting, each occurring at appropriate points during life of the vehicle and the ESD 74. Overall, determining a parametric value for the SOL comprises monitoring in real-time an ESD current IBAT (in amperes), an ESD temperature TBAT, an ESD voltage VBAT, an ESD resistance RBAT, and a ESD state-of-charge (‘SOC’). Each of the aforementioned factors, i.e. the integrated ESD current, depth of discharge, driving temperature factor, and resting temperature factor, are combined, preferably by a summing operation, with a previously determined state-of-life factor, SOLK, to determine a parametric value for the SOL, i.e. SOLK+1, shown as an output to block 120. The algorithm to determine the state-of-life factor, SOLK+1, is preferably executed multiple times during each trip. When the engine/vehicle is initially started or turned on, there is an initial state-of-life factor, SOLK, which is used in calculating subsequent values for SOL, and is shown as SOLSAVED 128. The SOLSAVED factor 128 is only used once during each trip, and is supplanted in future calculations during the trip the SOLK+1 factor output from Blocks 120, 122, and 124, which is shown as Block 130. Similarly, the resting temperature factor output from Block 116 is only used during the first execution of the algorithm to calculate SOL after the engine/vehicle is initially started or turned on, as is indicated by the INIT block 126. On subsequent executions of the algorithm to calculate SOL, the resting temperature factor is omitted from the calculation of SOL. Referring now to FIG. 3, a method and apparatus to predict or estimate a plurality of future or potential life gradients of a state-of-life parameter of an energy storage device useable in a hybrid control system in real-time is described. The exemplary method and apparatus to estimate the plurality of future life gradients of the state-of-life (‘SOL’) of the energy storage device in the hybrid control system in real-time is disclosed in detail in U.S. patent application Ser. No. 11/422,665, entitled “Method and Apparatus for Predicting Change in an Operating State of an Electric Energy Storage Device”. Therein is described a method and apparatus for calculating, a priori, a range of effects on state-of-life of an electrical energy storage device for a hybrid vehicle. The method includes determining potential changes in an operating state for the electrical energy storage device. This includes selecting an array of potential values for an operating parameter e.g. electrical current, over a continuum from a maximum charging current to a maximum discharging current, from which is determined or predicted a corresponding array of effects or changes upon operating state values, e.g. effects upon state-of-life. Each predicted change in the operating state is determined based upon and corresponding to one of the array of values for the operating parameter of the electrical energy storage device. The predicted change in the state-of-life is based upon: time-based integration of the electrical current, depth of discharge of the energy storage device, and, operating temperature of the electrical energy storage device, which are determined for each of the array of potential values for electrical current. Referring now to FIG. 4, a control algorithm for hybrid vehicle operation which targets a life objective for the electrical energy storage device 74 is now described. The algorithm is preferably executed in the aforementioned control system of the hybrid vehicle, preferably during one of the loop cycles, to effect real-time control and adjustments to the operation of the powertrain based upon prior use of the hybrid vehicle and the ESD 74. A primary control objective of the algorithm comprises controlling operation of the electrical machines 56, 72, including motive torque outputs, in charging and discharging, to manage life of the ESD 74. In the exemplary system, ESD power, PBAT, as a parameter that affects service life of the energy storage system 74, and is controllable by the hybrid control system. ESD power, PBAT=IBAT^2/RBAT. A relationship between the parametric value for ESD power, PBAT and a target life objective for the ESD is established. This permits generation of a control algorithm which is operative to ongoingly and regularly control electrical power exchanged between ESD 74 to the electrical motors 56, 72 such that the operating state, e.g. state-of-life (SOL), of the ESD is less than a predetermined value when the target life objective for the ESD is attained. The control algorithm is preferably executed by the control system during one of the previously described preset loop cycles. This algorithm is described in detail hereinbelow. Referring again to FIG. 4, in overall operation, the algorithm uses as input parameters a normalized value for state-of-life (SOL) of the ESD, a time-based state-of-life gradient based upon ESD power, an accumulated elapsed time in service, and an accumulated distance. A normalized life factor is calculated based upon the accumulated time, and accumulated distance (Block 200). The normalized life factor, output from block 200, and the normalized value for state-of-life are used to calculate a required, desired or target gradient for life (Block 210). The time-based state-of-life gradient based upon ESD power is normalized along the time axis (Block 220). The required gradient for life, output from block 210 and the normalized state-of-life gradient based upon ESD power output from block 220, both converted to a z-domain, comprising a normalized domain ranging from 0.0 to 1.0, are input to a cost function (block 230) which generates an output of cost associated with ESD power, PBAT. The preferred operating state, i.e. the state-of-life (SOL) parameter described hereinabove, is normalized as follows: SOL=0, for a new unused ESD, e.g. at start of service life; and, SOL=1, for a fully expended ESD, e.g. at an end of service life (‘EOL’). The normalized life factor output (in the z-domain) from Block 200 is determined as follows. The energy storage system has a target life objective defined in terms of time and/or distance. For example, a hybrid vehicle might specify a target life objective in terms of time of 8 years and a target life objective in terms of distance of 160,000 kilometers (100,000 miles). In this example, an exemplary ESD which remains in service for eight years or 160,000 kilometers (100,000 miles) of operation has met the target life objective. The accumulated time, also referred to as a Total ESD Time, is defined as the total cumulative time that the energy storage system has been in service, including all periods of vehicle activity and inactivity and all active and quiescent periods of ESD operation. In this embodiment, the ECM preferably includes a timing device which is able to measure and record elapsed operation time, including time when the vehicle ignition is off and the system powered down. Under a circumstance wherein a particular ESD is replaced with a new ESD, the accumulated time value is reset to zero. Under a circumstance wherein a particular ESD is replaced with a partially expended or used ESD, the accumulated time is reset to an estimated total cumulative time that the partially expended ESD had previously been in service. A normalized time life parameter is defined, using the same time units, as: Normalized ⁢ ⁢ Time ⁢ ⁢ Life ⁢ ⁢ Parameter = Total ⁢ ⁢ ESD ⁢ ⁢ Time ESD ⁢ ⁢ Time ⁢ ⁢ Life ⁢ ⁢ Target The ESD target life objective for time is 8 years for the exemplary system being described. The accumulated distance, also referred to as a Total ESD Distance, is defined as a total cumulative distance of operation with the ESD, which is measurable in the ECM or other controller of the distributed control architecture. Under a circumstance wherein a particular ESD is replaced with a new system, the accumulated distance is reset to zero. Under a circumstance wherein a particular ESD is replaced with a partially expended or used ESD, the accumulated distance can be reset to an estimated total cumulative distance that the expended or used ESD previously experienced. A normalized distance life parameter is defined, using the same distance units, as the following: Normalized ⁢ ⁢ Distance ⁢ ⁢ Life ⁢ ⁢ Parameter = Total ⁢ ⁢ ESD ⁢ ⁢ Time ESD ⁢ ⁢ Distance ⁢ ⁢ Life ⁢ ⁢ Target The ESD target life objective for distance is 160,000 kilometers (100,000 miles) for the exemplary system being described. Determining the Normalized Life Factor (in z-domain), output from block 200, comprises capturing parametric values for accumulated time, i.e. Total ESD Time, and accumulated distance, i.e. Total ESD Distance, and normalizing them as described herein above and wherein z=0 at the Start of Life Cycle of the ESD, i.e. when the timer for accumulated time and the distance monitor for accumulated distance each begin counting; and, z=1 at the ESD target life objective, or Targeted End of Life (‘EOL’). A preferred method for calculating the Normalized Life Parameter comprises selecting a maximum value between the Normalized Time Life Parameter and the Normalized Distance Life Parameter, shown below:Normalized Life Parameter=MAXIMUM(Normalized Time Life Parameter, Normalized Distance Life Parameter) In the exemplary embodiment, wherein ESD Time Life Target is 8 years and the ESD Distance Life Target is 160,000 kilometers (100,000 miles), a linear budget of substantially 20,000 kilometers (12,500 miles) per year of service is assumed. The Normalized Life Parameter could simply be defined as follows, in Table 1: TABLE 1DominatingTotal ESDTotal ESDFactorNormalized LifeTimeDistance(Time or Distance)Parameter (z)4 years32,000 kmTime0.50(20,000 miles)2 years80,000 kmDistance0.50(50,000 miles)4 years80,000 kmBoth0.50(50,000 miles)9 years112,000 kmTime1.00 = Target(70,000 miles)EOL5 years160,000 kmDistance1.00 = Target(100,000 miles)EOL Although the preferred embodiment of this invention involves the use of time and/or distance in defining the definition of targeted end of life (‘EOL’), other parameters can be used. The time domain parameters are converted to normalized life parameters, in the z-domain. It is desirable to be able to convert a differential amount of run time (in dt) to a differential amount of Normalized Life Parameter (in dz), for ease of comparisons. The percent of time the vehicle is operated, i.e. Total Vehicle Run Time, is compared to total in-service time of the vehicle, i.e. Total Vehicle Time, to estimate a percent of vehicle run time versus total vehicle time. Total vehicle time ideally has the same value as Total ESD Time. The Total Vehicle Run Time Percentage is defined as follows: Total ⁢ ⁢ Vehicle ⁢ ⁢ Run ⁢ ⁢ Time ⁢ ⁢ Percentage = Total ⁢ ⁢ Vehicle ⁢ ⁢ Run ⁢ ⁢ Time Total ⁢ ⁢ Vehicle ⁢ ⁢ Time In the exemplary embodiment, a vehicle that is determined to be operating or running for 5% of total time (Total Vehicle Run Time Percentage=5%), the following analysis is shown with reference to Table 2, below: TABLE 2NormalizedTotalTotalTotalTotalLifeESDESD RunESDESDDominatingParameterTime toTime toTimeDistanceFactor(z)EOLEOL4 years20,000Time0.504 years/8 × 0.05 =miles0.5 = 80.40 yearsyears2 years50,000Distance0.502 years/4 × 0.05miles0.5 = 40.20 yearsyears Referring again to Table 2, examples are provided to explain system operation. Exemplary values for two vehicles are shown, wherein Total ESD Time and Total ESD Distance are known. One of ESD Time and Distance is determined to be a dominating factor based upon whether the exemplary vehicle is likely to attain a target life objective of time or distance, as determinable based upon the Normalized Life Parameter. When the dominating factor is time, then the Total ESD Time to EOL equals the Target Total ESD Time. When the dominating factor is Distance, then Total ESD Time to EOL equals is determined based upon Distance, and is less than the ESD Target time life objective. When a new ESD is installed, thus setting z=0, Total ESD Run Time to EOL is the following:Total ESD Run Time to EOL=Total Vehicle Run Time %×ESD Time Life Target After the ESD has been used (z>0), the Total ESD Run Time to End of life (‘EOL’) is Total ⁢ ⁢ ESD ⁢ ⁢ Run ⁢ ⁢ Time ⁢ ⁢ to ⁢ ⁢ EOL = Total ⁢ ⁢ Vehicle ⁢ ⁢ Run ⁢ ⁢ Time ⁢ ⁢ % ⁢ × ( Total ⁢ ⁢ ESD ⁢ ⁢ Time Normalized ⁢ ⁢ Life ⁢ ⁢ Parameter ⁡ ( z ) ) The Total ESD Run Time to EOL effectively converts differential changes in run time (dt) to differential changes in the Normalized Life Parameter (dz), i.e., d ⁢ ⁢ z = ⅆ t ⁡ ( sec ) Total ⁢ ⁢ ESD ⁢ ⁢ Run ⁢ ⁢ Time ⁢ ⁢ to ⁢ ⁢ EOL ⁡ ( sec ) The state-of-life gradient (dSOL/dt) estimated as a function of electrical current and ESD power (PBAT), is described hereinabove, and comprises estimating ESD state-of-life time gradient as a function of ESD Power for an array of preselected current levels. Referring again to FIG. 4, it is relatively straightforward to normalize time and transform a time gradient to a normalized gradient (notated as dSOL/dz). By example, when the targeted ESD life objective is defined as a run time, in seconds of Total ESD Run Time to EOL, the normalized state-of-life gradient is defined as follows: ⅆ SOL ⅆ z = ⅆ SOL ⅆ t ⁡ [ 1 sec ] × Total ⁢ ⁢ ESD ⁢ ⁢ Run ⁢ ⁢ Time ⁢ ⁢ to ⁢ ⁢ EOL ⁡ [ sec ] Note that normalized gradient is defined in such a way that if the energy storage system averages a normalized gradient of one (1) or less, then the life objective is met. Similarly, if the normalized gradient averages greater than one, then the life objective is not met. This provides a way of coupling the target objective to a key control variable gradient. A control system must be designed to control ESD power in such a way that at the end of the energy storage system life target (z=1), the SOL is less than 1. That is, over the life of the energy storage system (from z=0 to z=1), the average, and since normalized, the integral of dSOL/dz must be less than or equal to 1 for life objectives to be met. More particularly, as shown in Eq. 1, which is executable as an algorithm in the control system: P BAT ⁢ ⁢ such ⁢ ⁢ that ⁢ ⁢ SOL ⁡ ( 1 ) = ∫ 0 1 ⁢ ⅆ SOL ⅆ z ⁢ ⁢ ( P BAT ) ⁢ ⅆ z ⁢ < _ ⁢ 1 [ 1 ] Referring now to FIG. 5, a datagraph showing performance of an exemplary system with an ESD operating using the system described herein, wherein the x-axis comprises the normalized life factor of time or distance, converted to the z-domain, and the y-axis comprises the state-of-life (SOL). Line 90 comprises a representative system wherein a change in the state-of-life of the ESD increases linearly with a change in the normalized life factor in the z-domain, such that end of life criteria are just met. Line 96 shows an actual system, having exemplary Points A and B. Point A represents a system wherein ambient conditions or operation of the system led to aggressive use of the ESD, and thus to advanced aging of the ESD or high SOL of the ESD, such that it is possible that the ESD may be expended before the target service life. A first line 92 comprises a normalized target gradient line for Point A, calculated from Point A to the end of life of the device which comprises the SOL meeting the normalized life factor. In the condition wherein the system has reached an operating condition shown as point A, the control system estimates the array of parametric values for future SOL based upon the array of ESD current levels, IBAT. The system is operable to match a parametric value for PBAT and corresponding value for IBAT that accomplishes the normalized gradient, using the algorithm developed in Eq. 1, above. This likely leads to less aggressive use of the ESD during vehicle operation. Point B represents a system wherein ambient conditions or operation of the system led to less aggressive use of the ESD, thus leading to retarded aging of the ESD or low SOL of the ESD, such that it is possible that the ESD will not be expended upon reaching the target service life. A second line 94 comprises a normalized target gradient line for Point B, calculated from Point B to the end of life of the device which comprises the SOL meeting the normalized life factor. In the condition wherein the system has reached an operating condition shown as point B, the control system estimates the array of parametric values for future SOL based upon the array of ESD current levels, IBAT. The system is operable to match a parametric value for PBAT and corresponding value for IBAT that accomplishes the normalized gradient, using the algorithm developed in Eq. 1, above. This likely leads to more aggressive use of the ESD during vehicle operation. Referring now to FIGS. 6A, 6B, and 6C, further details of the operation of the system are provided. FIG. 6A shows a normalized SOL gradient plotted as a function of ESD power, PBAT, over a range that is a continuum from charging to discharging the ESD, with exemplary target gradient Points A and B, from FIG. 5. FIG. 6C shows a line demonstrating an operating cost as a function of the normalized SOL gradient, wherein the target line, at the target gradient value, corresponds to the Line 90 shown in FIG. 5. Operating costs generally comprise costs associated with fuel and electrical energy consumption associated with a specific operating point of the powertrain system for the vehicle. This graph demonstrates that there is a low operating cost associated with a normalized SOL gradient that is less than the target, i.e. falling below Line 90 of FIG. 5. Conversely, operating cost increases as the normalized SOL gradient increases greater than the target line. FIG. 6B can be constructed using information from FIGS. 6A and 6C, wherein operating cost is plotted as a function of ESD power, PBAT, with lines representing costs associated with operating the exemplary system starting at Points A and B plotted, and correlated to analogous operating points shown in FIG. 6A. It is readily demonstrated the relative magnitude of a cost differential associated with the same ESD power, PBAT, at different initial starting points. In other words, operating with SOL above the target gradient, i.e. Line 90 of FIG. 5 is generally more costly and less preferred than operating with SOL at or below the target gradient. Thus, the control system can execute an algorithm operative to control the power transmitted from the electrical energy storage device such that the electrical energy storage device generally tracks and converges on the target gradient, preferably avoids SOL in excess of the target gradient, and does not reach end-of-life when the target life objective, e.g. time or distance, is attained. The invention has been described with specific reference to the preferred embodiments and modifications thereto. Further modifications and alterations may occur to others upon reading and understanding the specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the claims.
056217765	claims	1. A system for initiating safety action in response to monitoring of a critical parameter, comprising: first through fourth sensors for independently detecting the value of a critical parameter and outputting first through fourth sensor readings respectively; first through fourth division electronics respectively connected to said sensors for processing said first through fourth sensor readings respectively; and cross communication channels for interconnecting said first through fourth division electronics such that each one of said first through fourth division electronics receives the processed sensor readings from the other division electronics, wherein said first division electronics comprises means for determining when its own sensor reading is not valid due to a fault, means for storing its own valid sensor reading as a spare, means for outputting a safety actuation inhibition signal, and means for terminating the output of said safety actuation inhibition signal in response to any two of three valid sensor readings communicated from said second, third and fourth division electronics being in excess of a set point, or in response to an invalid or missing sensor reading from one of said second, third and fourth division electronics and at least two of three valid sensor readings--consisting of the spare valid sensor reading and the two valid sensor readings from the remaining two of said second, third and fourth division electronics--being in excess of said set point. a respective ac-powered battery charger for supplying dc power via respective isolation diodes to said corresponding division electronics and one other division electronics during normal operation, each battery charger receiving ac power from a respective ac power bus, each ac power bus in turn receiving ac power from dual ac power sources, and a respective backup battery for supplying dc power to said corresponding division electronics and said one other division electronics via said isolation diodes in the event that ac power should fail, said respective battery being charged by said respective battery charger during normal operation. first through fourth sensors for independently detecting the value of a critical parameter and outputting first through fourth sensor readings respectively; first through fourth division electronics respectively connected to said sensors for processing said first through fourth sensor readings respectively, each of said first through fourth division electronics comprising means for determining when its own sensor reading is not valid due to a fault and means for outputting a safety actuation inhibition signal; and cross communication channels for interconnecting said first through fourth division electronics such that each one of said first through fourth division electronics receives the processed sensor readings from the other division electronics, wherein said first division electronics comprises means for terminating the output of a safety actuation inhibition signal in response to receipt from at least two of said second through fourth division electronics of sensor readings in excess of a set point when all of said first through fourth division electronics are in service; or in response to the following set of conditions: (a) one of said second through fourth division electronics is out of service; (b) the sensor readings from at least two of the remaining three division electronics are valid; and (c) at least two of said three valid sensor readings are in excess of said set point. a respective ac-powered battery charger for supplying dc power via respective isolation diodes to said corresponding division electronics and one other division electronics during normal operation, each battery charger receiving ac power from a respective ac power bus, each ac power bus in turn receiving ac power from dual ac power sources, and a respective backup battery for supplying dc power to said corresponding division electronics and said one other division electronics via said isolation diodes in the event that ac power should fail, said respective battery being charged by said respective battery charger during normal operation. first through fourth sensors for independently detecting the value of a critical reactor parameter and outputting first through fourth sensor readings respectively; first through fourth division electronics respectively connected to said sensors for processing said first through fourth sensor readings respectively, each of said first through fourth division electronics comprising means for determining when its own sensor reading is not valid due to a fault and means for outputting a scram inhibition signal; and cross communication channels for interconnecting said first through fourth division electronics such that each one of said first through fourth division electronics receives the processed sensor readings from the other division electronics; wherein each of said first through fourth division electronics further comprises means for selectively terminating the output of said scram inhibition signal in accordance with a first routine when all of said first through fourth division electronics are in service and in accordance with a second routine different than said first routine when only three of said first through fourth division electronics are in service, each of said first and second routines requiring the presence of at least two valid sensor readings in excess of a set point before terminating the output of said scram inhibition signal. 2. The system as defined in claim 1, wherein said safety actuation inhibition signal terminating means of said first division electronics alternatively terminates a safety actuation inhibition signal in response to an invalid or missing sensor reading from two of said second, third and fourth division electronics and either one of two valid sensor readings--consisting of the spare valid sensor reading and the valid sensor reading from the remaining one of said second, third and fourth division electronics--being in excess of said set point. 3. The system as defined in claim 1, further comprising a hardware logic circuit connected to receive an output from each of said first through fourth division electronics, wherein said hardware logic circuit changes from a normal state to a safety actuation state in response to discontinuance of receipt of safety actuation inhibition signals from at least two of said first through fourth division electronics. 4. The system as defined in claim 3, further comprising a safety actuator and redundant first and second actuator power supply circuits, wherein said safety actuator is coupled to said first and second actuator power supply circuits via said hardware logic circuit. 5. The system as defined in claim 4, wherein said hardware logic circuit comprises first through fourth sets of circuit breakers each having an open state and a closed state and electrical connections for connecting the circuit breakers within each of said first through fourth sets in series, the state of the circuit breakers of said first through fourth sets being respectively controlled as a function of the results of processing said first through fourth sensor readings by said first through fourth division electronics respectively. 6. The system as defined in claim 5, further comprising first through fourth instrumentation vaults for respectively housing said first through fourth division electronics and said first through fourth sets of circuit breakers, wherein said cross communication channels and said electrical connections penetrate the walls of said instrumentation vaults, and said first and second power supply circuits are respectively housed in said first and second instrumentation vaults. 7. The system as defined in claim 4, wherein said hardware logic circuit comprises first through fourth sets of circuit breakers having an open state and a closed state and electrical connections for connecting the circuit breakers within each of said first through fourth sets in series, the state of the circuit breakers of said first through fourth sets being respectively controlled as a function of the results of processing said first through fourth sensor readings by said first through fourth division electronics respectively. 8. The system as defined in claim 7, further comprising first through fourth instrumentation vaults for respectively housing said first through fourth division electronics and said first through fourth sets of circuit breakers, wherein said cross communication channels and said electrical connections penetrate the walls of said instrumentation vaults, and said first and second power supply circuits are respectively housed in said first and second instrumentation vaults. 9. The system as defined in claim 1, further comprising first through fourth dc electrical power supply circuits, and first through fourth instrumentation vaults for respectively housing said first through fourth division electronics and said first through fourth dc electrical power supply circuits, wherein said first division electronics receives dc electrical power from said first and fourth dc electrical power supply circuits, said second division electronics receives dc electrical power from said first and second dc electrical power supply circuits, said third division electronics receives dc electrical power from said second and third dc electrical power supply circuits, and said fourth division electronics receives dc electrical power from said third and fourth dc electrical power supply circuits. 10. The system as defined in claim 9, wherein each of said first through fourth dc electrical power supply circuits comprises: 11. A system for initiating safety action in response to monitoring of a critical parameter, comprising: 12. The system as defined in claim 11, further comprising a hardware logic circuit which changes from a normal state to a safety actuation state in response to discontinuance of receipt of safety actuation inhibition signals from at least two of said first through fourth division electronics. 13. The system as defined in claim 12, further comprising a safety actuator and redundant first and second actuator power supply circuits, wherein said safety actuator is coupled to said first and second actuator power supply circuits via said hardware logic circuit. 14. The system as defined in claim 11, further comprising first through fourth dc electrical power supply circuits, and first through fourth instrumentation vaults for respectively housing said first through fourth division electronics and said first through fourth dc electrical power supply circuits, wherein said first division electronics receives dc electrical power from said first and fourth dc electrical power supply circuits, said second division electronics receives dc electrical power from said first and second dc electrical power supply circuits, said third division electronics receives dc electrical power from said second and third dc electrical power supply circuits, and said fourth division electronics receives dc electrical power from said third and fourth dc electrical power supply circuits. 15. The system as defined in claim 14, wherein each of said first through fourth dc electrical power supply circuits comprises: 16. A reactor protection system for initiating a scram in a nuclear reactor in response to monitoring of a critical reactor parameter, comprising: 17. The reactor protection system as defined in claim 16, wherein said first division electronics further comprises means for storing its own valid sensor reading as a spare, and means for terminating the output of said scram inhibition signal in response to any two of three valid sensor readings communicated from said second, third and fourth division electronics being in excess of a set point, or in response to an invalid or missing sensor reading from one of said second, third and fourth division electronics and at least two of three valid sensor readings--consisting of the spare valid sensor reading and any valid sensor reading from said second, third and fourth division electronics being in excess of said set point. 18. The reactor protection system as defined in claim 17, wherein said scram inhibition signal terminating means of said first division electronics alternatively terminates a scram inhibition signal in response to an invalid or missing sensor reading from two of said second, third and fourth division electronics and either one of two valid sensor readings consisting of the spare valid sensor reading and the valid sensor reading from the remaining one of said second, third and fourth division electronics--being in excess of said set point. 19. The reactor protection system as defined in claim 16, further comprising a hardware logic circuit connected to receive an output from each of said first through fourth division electronics, wherein said hardware logic circuit changes from a normal state to a scram state in response to discontinuance of receipt of scram inhibition signals from at least two of said first through fourth division electronics. 20. The reactor protection system as defined in claim 19, further comprising a safety actuator and an actuator power supply circuit, wherein said safety actuator is coupled to said actuator power supply circuit via said first hardware logic circuit, and said first hardware logic circuit comprises circuit breakers for selectively making or breaking the electrical connection between said safety actuator and said actuator power supply circuit in response to receipt of scram signals from at least two of said first through fourth division electronics.
052260658	description	DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS Disinfection The present invention relates to a device for disinfecting medical materials. By medical materials, we mean medical and veterinary waste as well as medical products. Medical and veterinary wastes are disinfected, or rendered incapable of causing an infection. The present device inactivates microorganisms in medical and veterinary waste so that the waste can no longer cause an infection. The present device can be used to sterilize or completely kill all bacteria and viruses in, medical products. Both disinfection and sterilization are accomplished through heating and applying gamma radiation by device 1 shown in FIGS. 1 and 2. Preliminary to the use of the present invention, medical material arrives at a processing and recycling facility. Preferably, the material is shipped in sealed containers. This means of shipping medical materials is known in the art and has the advantages that medical waste does not infect its handlers and that contamination of medical products in transit is minimized. At the facility the containers are preferably arranged on pallets and shrink-wrapped with plastic. The pallets are then moved into a heating chamber 10 which is capable of delivering heat by any of a variety of methods, such as radio-frequency, infrared and microwaves and electrical and gas radiant heating. A preferred embodiment of this chamber is a tunnel configuration and means, such as a track 2, for moving the material through the tunnel. This arrangement permits the material to be gradually heated as it travels through. The pallets are held in the heat chamber 10 and exposed to the heat source for a sufficient time to raise the temperature of the medical materials to at least approximately 60.degree. C. It will be recognized by those skilled in the art that temperatures as high as 170.degree. C. may be used without adversely affecting the process. Next, the pallets are moved into a shielded gamma irradiation chamber 20. The gamma chamber is insulated to prevent radiation from escaping into the environment. The same type of facility that is in current use for gamma irradiation of medical supplies may be used for this step. For example, a suitable gamma irradiator is Model #RT 4101, available from Radiation Technology, Inc., Rockaway, N.J. In the chamber 20, a core of radioactive matter (preferably cobalt 60) emerges from a liquid bath and emits ionizing radiation that is relatively constant during the period when any sample is being irradiated. For subsequent loads, the time is gradually increased to account for radioactive decay of the cobalt 60. Absorbed radioactivity is measured in rads. The amount to be delivered to medical materials is measured in megarads (Mrads), or millions of rads. Doses may range from as little as about 0.25 Mrads to as high as about 2.5 Mrads or more. It will be recognized by those skilled in the art that higher radiation doses will not adversely affect the process. In one embodiment, the medical materials are moved along a trackway 2, through the heat chamber 10 and the gamma-irradiation chamber 20. In this arrangement, the distance from radiation sources varies but is additive for the journey through each chamber. The total dose of radiation to which the waste is exposed during its dwell time in the chamber is planned to provide sufficient disinfection. With a track arrangement, the entrance and exit of the chambers are open but additional walls are arranged to block the escape of radiation into the surrounding areas. Such chambers are in common use for cobalt 60 sterilization of medical products. Validation Preferably, a medical material disinfecting facility using the present invention is validated to assure the adequacy of the disinfection process. Validation may be performed when each facility is constructed and at intervals during its operation. Validation may consist of placing heat detecting devices such as thermocouples and/or known amounts of particular microorganisms which are resistant to heat and to gamma radiation respectively into a maximally loaded pallet of medical materials. Sufficient heat to raise the temperature of a sterilizer's load to about 60.degree. C. and a gamma radiation dose of about 0.50 Mrads are delivered to the test pallet. If thermocouples are used, they should all record at least the minimum temperature of about 60.degree. C. After the entire disinfection cycle is complete, the microorganism samples are removed from the pallet and cultured (given nutrients and other appropriate conditions for growth) to determine survival. A typical heat-resistant microorganism which may be used in validation is Bacillus stearothermophilus. A typical radiation-resistant microorganism is Bacillus pumilus. If more than 1 in 10,000 of either microorganism survives the timed cycles, the exposure to heat and/or gamma radiation is increased about 5%, or about 200,000 rads, and another pallet is tested. Device for Recycling Another embodiment of the invention consists of starting with medical or veterinary waste that has been pre-sorted int containers of plastic and general medical waste, respectively. High-grade plastics are used in medical products and can be shredded and remolded into a variety of products. This waste is subjected to heat and gamma radiation as described above. Then the containers of disinfected plastic are moved to a "plastics" shredder 30. For example, an electrically powered shredder with pneumatic ram assist and negative pressure canopy reduces medical waste to small particles and is available as Model Dual 1000 E from Shredding Systems, Inc., Wilsonville, Oreg. The negative pressure canopy minimizes particles entering the surrounding air. The containers are opened and the disinfected plastic is placed in the shredder and shredded to particles of about one quarter to one half inch. This disinfected, shredded material is transferred into 55-gallon drums for shipment to re-users of plastic. Likewise, the containers of disinfected general medical waste are moved to the "general medical waste" shredder. After the containers are opened, the general medical waste is placed in the shredder 30 and shredded to particles of about one quarter to one half inch. The disinfected waste is placed in further containers. This waste contains a mixture of paper, plastic, and metal and can be used as fuel. Possible users include cement kilns which operate at temperatures of about 2,500.degree. F. or more, and which would otherwise use high-sulfur coal. Because this general medical waste is low in sulfur, its use as fuel will decrease sulfur-caused acid rain. Another preferred embodiment of this invention has a heat chamber 10 which is a radio-frequency chamber having a tunnel configuration with the following approximate dimensions: 50 feet long, 20 feet wide and 20 feet high. The tunnel is lined with 3 mm-thick copper sheeting. The copper lining and the arrangement of the electrodes inside the tunnel are designed to confine the radio-frequency waves to the tunnel. In the radio-frequency chamber 10, a system of exciter and ground electrodes generate electromagnetic waves in the radio-frequency band. The radio-frequency band is between audio and infrared frequencies and comprises approximately 10 hertz (Hz) to 300 gigahertz (GHz). When the electrode system is supplied with electricity, it launches an electromagnetic wave into the target medical materials. The radio-frequency waves penetrate the pallets of medical materials. The medical materials absorb these waves whose energy is thought to produce heat by inducing dipole rotation and molecular vibration. When radio-frequency waves are absorbed, they may cause differential heating. Moist articles and metal objects absorb more waves and may create "hot spots," or uneven heating. In closed containers or boxes, the steam and heat from these objects are redistributed to the entire contents of the containers. The pallets are held in the radio-frequency chamber 10 and exposed to radio-frequency waves for a sufficient time to raise the temperature of the medical materials to at least approximately 60.degree. C. It will be recognized by those skilled in the art that temperatures as high as 170.degree. C. will not adversely affect the process. Preferably, the exposure to radio-frequency waves would last about 5 to 30 minutes. More preferably, the medical materials are exposed to the radio-frequency waves for approximately 12 minutes. However, the optimal time in the chamber 10 and amount of radio-frequency waves for a particular facility will vary and may be determined as described in "Validation." Another embodiment of the invention as shown in FIG. 2 arranges the heating elements (for example, the radio-frequency generating system of exciters and grounds) inside the gamma radiation chamber 20 for simultaneous exposure of the medical materials to heat or radio-frequency waves and gamma radiation. Another embodiment of the invention orients the heat or radio-frequency chamber with respect to the gamma radiation chamber so that the medical material is first exposed to gamma radiation and then heated. Another embodiment of the invention shown in FIG. 2 employs a system of tracks and/or conveyor belts 4 to move medical or veterinary waste from the sterilization chambers to the shredders 30. The foregoing descriptions of the preferred embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many other modifications and variations are possible in light of the above teachings. The embodiments were chosen and described to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to best utilize the invention in its various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims, including all equivalents.
	claims	1. A melting apparatus for melt-decontaminating radioactive metal waste, the melting apparatus comprising:a melting furnace comprisinga crucible into which a metal waste is input, andan induction coil wound around the crucible and having a hollow hole in a center therealong, wherein a high-frequency current flows through the induction coil to melt the metal waste in the melting furnace and a cooling fluid flows through the hollow hole to reduce heat generated in the induction coil;a high frequency generator applying the high-frequency current to the induction coil;a ladle of which a lower portion is firmly fixed in a position adjacent to the melting furnace such that a molten metal is directly supplied from the crucible to the ladle, the ladle supplying the molten metal, from the crucible, into molds while the lower portion is fixed in the position;a bogie disposed adjacent to the ladle so as to be movable in a horizontal direction, the bogie being provided with the molds, each of which forms an ingot using the molten metal supplied thereinto by the ladle;a cooling unit cooling the cooling fluid and circulating the cooling fluid along the hollow hole of the induction coil; anda dust collector provided in the melting furnace, the dust collector filtering out dust and purifying gas generated while melting the metal waste, before discharging the gas,wherein the molds are provided on the bogie such that each of the molds is able to be turned upside down and includes a rotational shaft on which the each of the molds rotates, a lever protruding from a side surface of the each of the molds, a fixing bracket for coupling to an adjacent mold. 2. The melting apparatus as set forth in claim 1, wherein the bogie is provided on a guide rail so as to be movable in the horizontal direction, the bogie being operated by a motor. 3. The melting apparatus as set forth in claim 1, wherein the melting furnace comprises:a first support member rotatably supporting a first rotational shaft provided on the melting furnace; anda rotation drive unit rotating the melting furnace around the first rotational shaft. 4. The melting apparatus as set forth in claim 1, wherein the ladle comprises:a second support member disposed in the lower portion of the ladle and rotatably supporting a second rotational shaft provided on the ladle; anda second rotation drive unit rotating the ladle around the second rotational shaft.
	abstract	An electron beam exposure system for exposing a pattern on a wafer using a plurality of electron beams, comprising a section for generating a plurality of electron beams, an electron lens section having a plurality of apertures for passing a plurality of electron beams and focusing the plurality of electron beams independently, and a magnetic field formation section provided at least one of the plurality of apertures and forming a magnetic field in a direction substantially perpendicular to the irradiating direction of an electron beam passing through the aperture.
050531875	summary
	summary
	description	This application is based upon and claims the benefit of priority from Japanese Patient application No. 2011-152266, filed on Jul. 8, 2011, the entire contents of each of which are incorporated herein by reference. Embodiments of the present invention relate to a technology for monitoring nuclear thermal hydraulic stability of a boiling water reactor. In the boiling water reactor (BWR), output power can be controlled by changing a core flow and thereby changing a steam ratio (void fraction) inside a boiling reactor core. However, it is known that depending on the core flow and other operating conditions, neutron flux distribution and liquidity in the reactor core are destabilized by delayed transportation of voids and a negative feedback effect caused by negative void reactivity coefficients in the reactor core. There is concern that occurrence of such a nuclear thermal hydraulic destabilization phenomenon may result in considerable oscillation of output power and flow rate, which may deteriorate cooling characteristics in terms of fuel rod surface temperature and may damage the soundness of fuel rod cladding tubes. Accordingly, in designing fuels and reactor cores for the boiling water reactor, the nuclear thermal hydraulic stability is analyzed to produce a design that gives sufficient margin to stability so as to prevent such an oscillation phenomenon from occurring in any of the expected operating ranges. In such a range where deterioration in nuclear thermal hydraulic stability is expected, limited operation is preset for safety. Nuclear reactors of some types are provided with a safety setting so that in the unlikely event where the nuclear reactor reaches the operation limited range, output power is lowered by insertion of control rods and the like so that the nuclear reactor can get out of the operation limited range. As the boiling water reactors are designed to have a larger size, a higher power density and a higher burn-up, their nuclear thermal hydraulic stability is generally lowered. However, measures for such boiling water reactors are not included in the above-stated safety setting. In the case of operating the nuclear reactors which show good results in the U.S. at higher power, an operation control curve is expanded to a high-power side, which tends to increase a power/flow rate ratio and to deteriorate nuclear thermal hydraulic stability. In this case, according to the aforementioned safety setting, an operation control curve may possibly intersect a stability control curve in a low flow rate range. Consequently, an operable range on a low flow-rate side is largely limited, and operation at the time of activation and stop of the nuclear reactors may also be affected. Under these circumstances, there are a large number of nuclear power plants which allow, from a viewpoint of Detect and Suppress, power oscillation phenomena while accurately detecting the power oscillation phenomena attributed to nuclear thermal hydraulic destabilization and suppressing the oscillations before the fuel soundness is damaged. Accordingly, a power oscillation detection algorithm with use of dedicated detection signals for detecting the power oscillation phenomenon, which is referred to as OPRM (Oscillation Power Range Monitor), has been proposed (see, for example, U.S. Pat. No. 5,555,279 and U.S. Pat. No. 6,173,026). As the performance of the boiling water reactors is reinforced to have a larger size, a higher power density, a higher burn-up and a higher power as described before, the substantial operating range is expanded, and thereby degree of allowances for nuclear thermal hydraulic stability is inevitably declined. In order to fully demonstrate an advantage of the reinforced performance of such boiling water reactors, it is required to further enhance accuracy and reliability in monitoring nuclear thermal hydraulic stability more than before. The embodiments of the present invention will be described hereinbelow with reference to the accompanying drawings. A nuclear power generation system shown in FIG. 1 includes: a nuclear reactor 10 which heats furnace water by the heat generated through nuclear fission of nuclear fuel and thereby generates steam; a main line 21 which guides the generated steam to a turbine 22; a generator 23 coaxially connected with the turbine 22 which is rotationally driven by the steam to convert rotational kinetic energy to electric energy; a condenser 24 which cools and condenses the steam, which was expanded in the process of doing its work in the turbine 22, into condensate water; and a water supply line 26 which sends the condensate water to the nuclear reactor 10 with a pump 25. Feed water returned to the nuclear reactor 10 is reheated as furnace water, and the above-stated process is repeated to perform continuous power generation. To sustain the power generation in a stable manner, a nuclear thermal hydraulic stability monitoring apparatus 50 (hereinafter referred to as “monitoring apparatus 50”) of the nuclear reactor 10 is provided. The nuclear reactor 10 includes: a pressure vessel 11 filled with furnace water and provided with a shroud 15 fixed to the inside thereof; a core support plate 17 fixed to the shroud 15; a reactor core 16 enclosed by the shroud 15 which is supported by the core support plate 17; and a steam separator 13 which performs gas-liquid separation of the furnace water which has been changed into a gas-liquid two-phase flow by passing through the reactor core 16. The steam as the one product obtained by steam separation in the steam separator 13 is guided to the main line 21 as described above so as to contribute to power generation, while the other product obtained as separated water joins the feed water returned through the water supply line 26. The thus-joined furnace water is made to flow down an area (downcomer D) between the shroud 15 and the pressure vessel 11 with a plurality of recirculation pumps 18 (only one pump is described in the drawing) provided in a circumferential direction, and is guided to a lower plenum area L. The furnace water guided to the lower plenum area L again passes the reactor core 16, where the water is heated into a gas-liquid two-phase flow before reaching an upper plenum area U. The gas-liquid two-phase flow that reached the upper plenum area U is again guided to the steam separator 13, where the aforementioned process is repeated. As shown in a horizontal sectional view of FIG. 2, the reactor core 16 includes: a square cylinder-shaped fuel assembly 33 containing a large number of fuel rods (omitted in the drawing); a control rod 32 which absorbs neutrons generated by a nuclear fission reaction to control output power; and an instrumentation pipe 34 whose upper and lower ends are respectively fixed to an upper grid plate 14 and the core support plate 17 and which supports nuclear instrumentation detectors 31 (31A, 31B, 31C, 31D) for detecting the neutrons as shown in FIG. 1. A large number of these component members are arrayed to structure the reactor core 16. One instrumentation pipe 34 is generally provided for 16 fuel assemblies 33. For example, an advanced boiling water reactor including 872 fuel assemblies is equipped with 52 instrumentation pipes 34. The nuclear instrumentation detectors 31A, 31B, 31C, 31D provided at four positions in a perpendicular direction of the instrumentation pipe 34 are each referred to as a level A, a level B, a level C, and a level D in accordance with a height position from the lower side. The furnace water which circulates inside the reactor core 16 flows into the furnace from the level A, where the furnace water is heated with fuel and starts to boil. The furnace water reaches the level B, the level C, and the level D in sequence while its water/steam two-phase state is being changed. The nuclear thermal hydraulic stability is greatly influenced by pressure propagation in the water/steam two-phase state. More specifically, due to a delay in pressure propagation of the furnace water which flows from the lower side to the upper side in the reactor core 16 as shown in FIG. 1, the two-phase state (water and steam ratio) is changed. This causes a response delay of the nuclear instrumentation detectors 31A, 31B, 31C, 31D, which in turn causes phase difference between the respective nuclear instrumentation signals S (SA, SB, SC, SD) detected at the level A, the level B, the level C, and the level D. Such phase difference in power oscillations in a flow direction of furnace water has a mechanism of causing mutual cancellation of the responses of the nuclear instrumentation signals S. Therefore, from the viewpoint of accuracy and reliability in monitoring the nuclear thermal hydraulic stability, it is preferable that a plurality of the nuclear instrumentation signals S at the same height level are grouped and evaluation is performed for each group. The necessity of performing stability monitoring on all the levels from the level A to level D is low. Accordingly, in each of the embodiments, evaluation of the nuclear thermal hydraulic stability is performed by targeting a level B group, which is generally said to have the highest sensibility for stability monitoring. The power oscillations relating to the nuclear thermal hydraulic stability are a macroscopic phenomenon which occurs in the entire reactor core due to destabilization of flow conditions inside a fuel channel which encloses the fuel assembly 33, the destabilization being caused by reactivity feedback to dynamic responses of neutron fluxes. It is considered that the reactivity feedback excites a neutron flux space mode, which results in occurrence of power oscillations. When the excited space mode is a basic mode, the power oscillations caused thereby are called core-wide oscillations. The core-wide oscillations basically have the same phase in each of the reactor core cross section at the same height level. In this case, a plurality of nuclear instrumentation signals S measured in the same cross section have almost no phase difference from each other. They are not cancelled by addition, and therefore oscillations can sufficiently be detected with use of average power range monitor (APRM) signals. In contrast, when the excited space mode is a higher order mode, the oscillations thereby are called regional oscillations. According to the higher order space mode distribution, the nuclear instrumentation signals S in the reactor core cross section at the same height have phase difference from each other. With a node of the higher order space mode distribution as a center line of oscillations, 180-degree phase difference appears across the center line, and oscillations are reversed at this center line. FIG. 3A shows a higher order space mode distribution in the regional oscillations. As shown in the horizontal cross sectional view of FIG. 3B, two areas a and b across an oscillation center line c, which corresponds to a node, are opposite in phase from each other, i.e., they oscillate with 180-degree phase difference from each other. In this case, if a plurality of the nuclear instrumentation signals S across these two areas a and b are averaged, oscillations are cancelled due to the phase difference. Accordingly, the amplitude of the averaged signals is flattened and this makes it difficult to detect oscillations. In short, it is not suitable for detection of such regional oscillations to use the APRM signal outputted as a signal formed by averaging all the reactor core signals. Although not shown in the drawings, use of the APRM signal is also unsuitable in the case of detecting local power oscillations which occur in a narrow area centering around a certain specific fuel assembly 33 (FIG. 2). As shown in FIGS. 1 and 2, the monitoring apparatus 50 includes: a calculation unit 52 which calculates a stability index (indicated as a decay ratio γ) of a nuclear thermal hydraulic phenomenon based on nuclear instrumentation signals S, the signals S being outputted by a plurality of nuclear instrumentation detectors 31 placed at regular intervals in a reactor core 16; a simulation unit 70 which simulates the nuclear thermal hydraulic phenomenon based on a physical model by using information on an operating state of the nuclear reactor as an input condition 75; a limit value updating unit 58 which updates a limit value D of the nuclear thermal hydraulic phenomenon based on a result of the simulation; and a determination unit 53 which determines, based on the stability index (indicated as a decay ratio γ) and the limit value D, whether or not to activate a power oscillation suppressing device 60. Since the monitoring apparatus 50 is structured in this way, the limit value D is updated to be optimal for the plant state based on a result of estimating the plant state or a result of predicting the state shift with use of the physical model. The determination unit 53 reads every updated limit value D, and determines whether or not a nuclear thermal hydraulic destabilization phenomenon is occurring with reference to a stability index (indicated as a decay ratio γ). When it is determined that the nuclear thermal hydraulic destabilization phenomenon is occurring, the determination unit 53 commands an activation instruction unit 56 to activate the power oscillation suppressing device 60 (e.g., warning devices and control rod insertion devices). Accuracy and reliability in monitoring the power oscillation phenomenon with the monitoring apparatus 50 are enhanced by combining the physical model which phenomenalizes the nuclear thermal hydraulic stability and the nuclear instrumentation signals S that are actual measured data. Now, with reference to FIG. 4, a decay ratio, an oscillation period, and amplitude will be defined by using an oscillatory impulse response at the time of applying disturbance to a system. Assuming that peaks of the impulse response are set in order as X1, X2, X3, X4, . . . , and their appearing time are each set as t1, t2, t3, t4, . . . , the decay ratio, the oscillation period, and the amplitude, which are generally used as indexes indicating the stability of the nuclear thermal hydraulic stability, are defined as follows:Decay ratio=(X3−X4)/(X1−X2)Oscillation period=(t3−t1) or (t4−t2)Amplitude=(X3−X4) or (X1−X2) As for the phase difference, a time difference in tn between a plurality of signals is defined as an angle with one period being 360 degrees. If the decay ratio is less than 1, the impulse response is attenuated and therefore the system is stable, whereas if the decay ratio is more than 1, oscillations grow and the system becomes unstable. When the decay ratio is 1, the oscillations continue with constant amplitude. With a shorter oscillation period, oscillations grow or attenuate more quickly. An inverse of the oscillation period is generally referred to as a resonance frequency or a natural frequency, which is expressed in the unit of Hz or cps. The calculation unit 52 shown in FIG. 2 can obtain a decay ratio, an oscillation period, and amplitude of each nuclear instrumentation signal S as stability indexes. Further, the decay ratio, the oscillation period, the amplitude and the like may statistically be processed for every group of the nuclear instrumentation detectors 31 grouped by a grouping unit 51, and the data obtained by the statistic processing may be used as a stability index. The physical model executed by the simulation unit 70 includes: a three-dimensional reactor core simulator 71 which simulates a three-dimensional distribution of the nuclear thermal hydraulic phenomenon inside the reactor core; a plant heat balance model 72 which simulates a heat balance of the entire plant including a BOP (Balance Of Plant) system; a plant transition analysis code 73 which simulates a transient characteristic of the plant focusing on a reactor system; and a stability analysis code 74 which analyzes stability of the nuclear thermal hydraulic phenomenon in an arbitrary operating state based on results of these simulations. Although not shown in the drawings, the monitoring apparatus 50 further includes: a data interface unit which transmits the input condition 75 and data between the respective codes; and a man machine interface unit which displays or outputs an analysis result based on an instruction from an operator. In these physical models, values of non-observing parameters inside the reactor core are estimated by reflecting the latest state (plant heat balance and control rod insertion condition) of the actual plant as the input condition 75. These physical models also make it possible to perform prediction and like of the plant state in the case of a transient event such as trip of a recirculation core flow pump in the present operating state and the like. An operation example with the physical models in the latter case (prediction of the plant state in a transient event) is shown below. First, the present plant state is read in from a process computer, measurement signals and the like. A heat balance of the present plant is estimated with the model 72, and then the detailed states of the present reactor core are presumed with the three-dimensional reactor core simulator 71. As a consequence, the detail of the present plant and reactor core states are simulated with the physical models. Next, assuming a transient state which may possibly be generated in this plant state, an operating state in which the nuclear thermal hydraulic stability state is predicted is set. A transient state corresponding to the operating state is simulated by the plant transition analysis code 73, and a plant operating state to be shifted as a result of the transient event is predicted. Then, the reactor core state in this plant operating state is again simulated by the three-dimensional reactor core simulator 71. Based on the reactor core state acquired as a result of the simulation, the stability analysis code 74 is executed to predict the stability after the transient event. With use of the results of such simulations in the simulation unit 70, the limit value updating unit 58 changes the limit value D. A band pass filter 57 is to extract frequency components corresponding to power oscillations in the nuclear instrumentation signal S. The stability index is calculated based on the extracted frequency components. Various fluctuation components are included in the nuclear instrumentation signal S outputted by the nuclear instrumentation detector 31. A fluctuation period of the nuclear thermal hydraulic phenomenon is correlated with time at which the two-phase flow passes the reactor core in a perpendicular direction, and takes a typical value in accordance with the operating state. More specifically, when the core flow is large as in a rated operation state, the oscillation period is about 1 second, i.e., the oscillation frequency takes a typical value of around 1 Hz. In contrast, in a partial power output state where the nuclear thermal hydraulic stability tends to decline, the core flow is lower than that in the rated operation state. Consequently, the oscillation period is about several seconds, and the oscillation frequency takes a typical value of about 0.3 to 0.6 Hz. The period of such power oscillations of the reactor core can be evaluated by the stability analysis code 74 in the simulation unit 70. Thus, if the period or the frequency band of the oscillatory phenomenon to be monitored is predicted, it is possible to remove fluctuation components not included in the monitoring objects from the nuclear instrumentation signal S to enhance monitoring accuracy. FIG. 5 shows a characteristic graph view of the band pass filter 57. A description is now given of a method for setting a time constant of the filter, i.e., a method for setting a lower limit value fcmin and an upper limit value fcmax of a frequency pass-band. Before setting the lower limit value fcmin and upper limit value fcmax, fuel assemblies similar in fuel characteristics are grouped into channel groups as shown in a FIG. 6A, and stability analysis is carried out for every group. FIG. 6B shows a result of analyzing thermal hydraulic stability for every channel group. Since the frequency is estimated for every channel group, it can be concluded that such a frequency range may be set as a frequency pass-band of the band pass filter 57. In FIG. 6, the nuclear thermal hydraulic stability is evaluated based on a core stability decay ratio. However, grouping the fuel assemblies into channel groups makes it possible to conduct analysis with respect to a regional stability decay ratio other than the core stability decay ratio. The regional stability decay ratio and the frequency of each channel group are obtained in a similar manner. Assuming the minimum value of the frequency to be f1 and the maximum value to be f2, fcmin≦f1<f2≦fcmax is set as an index for use in setting the time constant of the band pass filter 57. As an index of setting a reference oscillation period TREF, 1/f2≦TREF≦1/f1 can be set. Thus, determination based on the stability index and the limit value is performed for at least one object among not only the aforementioned core stability decay ratio and the regional stability decay ratio, but also a decay ratio of the nuclear instrumentation signal which is representative of those grouped by characteristics of fuel assemblies placed in the reactor core, a decay ratio of the nuclear instrumentation signal which reflects a thermal hydraulic phenomenon of a most thermally severe fuel assembly, and natural frequencies of these nuclear instrumentation signals. In the aforementioned inequalities, only the upper limit value or the lower limit value of a set point was specified. However, in order to provide concrete set values, it is necessary to take the following two uncertainties into consideration. The two uncertainties are an uncertainty at the time of predicting an actual phenomenon in the stability analysis code as a physical model, and an uncertainty of an operating state in which the stability is predicted. The latter uncertainty includes an uncertainty relating to measurement errors of detectors which measure the operating state and an uncertainty relating to errors at the time of estimating operation parameters based on measurement results of the detectors. As for the uncertainty of the stability analysis code (simulation result), data on a stability test performed in an actual plant or data on a stability test performed in a testing device, which can simulate observed power oscillation phenomena and nuclear thermal hydraulic stability phenomena, are used as reference data, and results of simulating and analyzing these states are compared with the reference data so that an error between the analysis data and the reference data is evaluated. An error εa is composed of a bias and a standard deviation and is expressed as εa=<εa>±σa, where the first term in the right hand side represents the bias, and the second term represents the standard deviation of the error. These values are all known values obtained by verification of the stability analysis code 74. It is to be noted that the bias is herein defined as (true value−analytic value). The uncertainty of the stability at an operating point is more complicated. Since evaluation of the uncertainty with use of actual data is difficult, the uncertainty evaluation with use of the stability analysis code 74 is also necessary therefor. More specifically, first of all, there is an uncertainty with respect to specification of the operating points. There are a large number of parameters which influence the nuclear thermal hydraulic stability and these parameters intricately relate to each other. Herein, the uncertainty is considered particularly with respect to the parameters having a large influence. The parameters such as output power, flow rate, pressure, and reactor core inlet temperature have an uncertainty relating to measurement. As for power distribution, there is an uncertainty caused by overlap of measurement errors of detectors and errors in prediction of a distribution based on detector data. As for eigenvalue separation of the higher order mode required for regional stability analysis, an estimation method based on observational data with sufficient accuracy has not yet been established. Accordingly, the uncertainty thereof is considered to be attributed to errors of a higher order mode analysis function which is incorporated in the three-dimensional reactor core simulator 71. With respect to these observation errors or calculation errors, uncertainties (variations from a true value) of targeted parameters are specified, and then stability analysis is conducted in consideration of the variations of those parameters. As a result, stability error εb resulting from the uncertainty of the operating condition is evaluated. This error is also composed of a bias and a standard deviation and can be expressed as εb=<εb>±σb. In an operation line of the nuclear reactor shown in FIG. 7, a stability monitoring range R that is a monitoring object of the power oscillation phenomenon is shown with a dashed dotted line. In this case, an operating point 41 on the operation line is set as a monitoring object. The operating point 41 has an uncertainty range 42 shown with a broken line. The uncertainty range includes an uncertainty attributed to measurement errors in measuring output power and flow rate and an uncertainty attributed to an uncertainty of setting conditions at the time of shifting from a normal operation state to a pertinent operating state. The uncertainty attributed to the latter (uncertainty of setting conditions) can be evaluated with use of the plant transition analysis code 73. When the uncertainty of the operating condition can be specified in this way, associated parameters can be changed at random within a range of the variations, and stability analysis can be performed multiple times. FIG. 8 shows a frequency distribution of the stability (decay ratio and natural frequency) obtained multiple times based on the uncertainty of the operating condition. As shown in the graph view, the stability forms a normal distribution, in which a central value represents a bias <ε>, and the right and left ranges represent variations or standard deviations σ. In this case, if 95% is taken as a variation limit for example, the standard deviation is increased 1.96 times. Thus, it becomes possible to decide a final error by overlapping an error of the stability based on the uncertainty of the operating state and a prediction error of the stability analysis code. In FIG. 9, both distributions of analysis results of the stability include prediction errors of the analysis code. Accordingly, when these prediction errors are added thereto, the distribution of the analysis result of the stability is further expanded. When the oscillation period is again taken as an example, the aforementioned uncertainty is added to the upper and lower limit values of the frequency, which is an inverse of the oscillation period. In this case, the bias and the standard deviation need to be set in the direction of expanding the variation range. More specifically, if the bias is positive, operation is performed so that the bias is taken into consideration on the right-hand side of the center of the normal distribution in FIG. 9, whereas the bias is not taken into consideration on the left-hand side. If the bias is negative, reversed operation is performed. Since the standard deviation is a positive value, the value can be added as it is. FIG. 9 shows an example of the oscillation period when the bias is positive. An upper limit value is obtained by adding a frequency bias fa of the analysis code to an average value <f> of the periods in consideration of the uncertainty of the operating state, and then adjusting the average value <f> with a square root sum of a standard deviation σ of frequency in the operating state and a standard deviation σa of a frequency error of the analysis code, the value being expressed by fmax=<f>+fa+X√(σ2+σa2). In this equation, X is an adjustment factor for a fiducial interval. If the adjustment factor is 95%, the value X is set at 1.96. In contrast, a lower limit value is obtained by fmin=<f>−fa+X√(σ2+σa2). As for the average value <f> of the periods, a value corresponding to the maximum value f2 is used as an upper limit, while a value corresponding to the minimum value f1 is used as a lower limit. When these values are not preinstalled, the values obtained by the stability analysis code 74 may be used as they are, and only correction concerning variations may be performed. Another important parameter of the stability is a decay ratio. When the decay ratio value is large, it indicates high probability that power fluctuation is a phenomenon based on the nuclear thermal hydraulic stability. Conversely, when the decay ratio value is small, it indicates a high likelihood that power fluctuation is a phenomenon based on mechanisms other than the nuclear thermal hydraulic stability. Accordingly, it is possible to set a severe determination criterion for the power oscillations. More specifically, the limit value D is a factor used in combination of the stability index in the determination unit 53 to determine whether or not to activate the power oscillation suppressing device 60. Activation conditions of the power oscillation suppressing device 60 can be optimized by changing the limit value D based on the factors, other than the stability index, which contribute to the power fluctuation mechanisms. Here, there is considered a case where the number of times that the stability index exceeds a predetermined specified value is set as the limit value D in the determination unit 53. A probability of erroneous determination with a smaller decay ratio is lowered by setting the set number larger than an initial set value of the limit value D. On the contrary, when an estimated decay ratio value is large, and particularly when the value is estimated to be more than 1 and in an unstable state, extremely swift detection can be achieved by setting the limit value D at a minimum value of 2. In this case, in consideration of an uncertainty as in the case of the aforementioned oscillation frequency, an upper limit value of the decay ratio γ is set as γmax=<γ>+γa+X√(σ2σa2). If this value is over 1 and a set value of the oscillation frequency is N, then γmaxN/2 is a maximum growth rate of amplitude during that time. Therefore, if an allowed maximum growth rate is set as Gmax, then N<2 log(Gmax)/log(γmax) is obtained. As for the maximum growth rate, if allowed maximum amplitude from a viewpoint of fuel soundness is Smax and an amplitude threshold at the start of oscillation detection is Smin, an upper limit value is set as Gmax≦Smax/Smin. Therefore, if a value smaller than a reference oscillation frequency set value Np is acquired from the above calculation, the set frequency is lowered to that value.Np=Np(N≧Np)Np=N(N<Np) If N is a value as small as 2 or less in the above equation, only the amplitude Smax is used and general oscillation detection process including oscillation detection determination and trip activation can be bypassed. However, the general oscillation detection process is not bypassed if the stability is determined not in the actual plant operating state but in the state after a transient state that can be expected, such as pump stop, from the current plant operating state. Next, if X takes a large value, e.g., 6, and γmax=<γ>+γa+X√(σ2+σa2) is less than 1, then it indicates a high probability of oscillations not growing but attenuating. In this case, the upper limit value Nmax is provided and the set value is changed between Np and Nmax in proportion to divergence of γmax from 1.Np=Np(γmax=1)Np=Np−2 log(Gmax)/log(1−γmax)Np=Nmax(Np−2 log(Gmax)/log(1−γmax)>Nmax) For the criteria for changing the above set value, the amplitude of the nuclear instrumentation signals S is important. The amplitude of the nuclear instrumentation signals S is automatically calculated upon execution of peak detection. The standard deviations that represent signal variations may also be used as the criteria for changing the setting. A standard deviation contains noise components other than an oscillation component, and the noise component strength of these background noise components depends on a plant and the operating state of the plant. FIG. 10 shows distributions of standard deviations of nuclear instrumentation signals at different four operating points in the same plant. The distributions are roughly divided into three groups. The distribution in FIG. 10A has small amplitude and variations, while in FIG. 10B the amplitude is relatively large and the variations are expanded. In two operating states in FIGS. 10C and 10D, the amplitude and the variations are almost the same, though the amplitude is larger than that in FIGS. 10A and 10B, and the variations are also expanded. A ratio between output power and flow rate at the operating points gradually increases from FIG. 10A toward FIG. 10D. It can be estimated that the nuclear thermal hydraulic stability is also gradually deteriorated in this order. However, since power oscillations have not occurred in the example of FIG. 10, it is possible in this case to avoid erroneous detection of power oscillations other than nuclear thermal hydraulic power oscillations with high probability even with the amplitude of 2% being set as a criterion for determining occurrence of power oscillations. In the states close to the normal operation state shown in FIGS. 10A and 10B, an average value of standard deviations is about 0.5 to 0.7, and this value is considered to be equivalent to a background noise level. Therefore, if this value is set as Smin and the aforementioned 2% is set as Smax, then Gmax equals to about 3.0 to 4.0. FIG. 11 shows an example in which nuclear instrumentation system signals are gradually destabilized and result in power oscillations. In FIG. 11, the transition of fractional standard deviations of the signals is divided into six stages. It is considered that the reactor core is gradually destabilized from FIG. 11A toward FIG. 11F. Since the reactor core is considered to be in a destabilized state at the stage of shifting from FIG. 11E to FIG. 11F, it can be said that Smax is appropriately set at 2% based on the distribution of FIG. 11E. Since the background noise level in the normal operation state of this plant is considered to be smaller than that in FIG. 11A, Smin takes a value of about 0.6. Therefore, Gmax is about 3.3, which is almost comparable to that in the example of FIG. 10. FIG. 12 shows a trip determination frequency Np updated with respect to a maximum decay ratio γmax which is estimated by the stability analysis code on the premise that an initial value of the trip determination frequency (limit value D) is 10. When the maximum decay ratio is 0.4, the trip determination frequency is 15, which is 1.5 times larger than the initial value. When the maximum decay ratio is 0.2, the trip determination frequency is doubled. In the core state estimated to clearly and sufficiently be stable, erroneous detection is avoidable by setting a severe trip determination criterion (limit value D). It is also possible to set a determination frequency, as a criterion for determining occurrence of power oscillations, in consideration of a detection delay of the nuclear instrumentation detectors, an activation delay in power oscillation suppression operation, a delay until power oscillation suppression operation becomes effective, and a delay in cooling characteristics improvement. While the aforementioned delays depend on specifications of hardware, operating states and the like, they are not so large a value, typically in the range of about 2 to 4 seconds. These delays are taken into consideration based on a ratio between an oscillation period derived from the physical models and an oscillation period derived from the nuclear instrumentation signals S. More specifically, when a time delay is set as TD and an oscillation period (which is an inverse of the frequency estimated by the stability analysis code or which can be estimated by the peak detection function of instrumentation signals) is set as TP, a correction frequency NC is equal to a ratio of TD/TP. Therefore, NC=TD/TP (fraction rounded up) may be subtracted from the updated trip determination frequency Np. Since the oscillation period is also about 2 to 3 seconds, a delay correction frequency is a value of about 1 to 2. As is clear from FIGS. 10 and 11, an average value of the amplitude of a plurality of nuclear instrumentation signals increases and the distribution thereof is more expanded as the nuclear thermal hydraulic stability becomes poorer. Therefore, it becomes possible to use this characteristic for monitoring the nuclear thermal hydraulic stability. FIG. 13 shows fluctuation of standard deviation in all the nuclear instrumentation response signals due to destabilization. Although the standard deviation values gradually increase in connection with destabilization, it is indicated that the increasing rate demonstrates nonsequential change. In short, it is indicated that the increasing rate grows nonsequetially at an arrow A portion and an arrow B portion in FIG. 13. It can be considered that these portions demonstrate an indication that the nuclear thermal hydraulic stability is significantly deteriorated. That is, around these two portions, the inclination nonsequetially increases about 10 times and 5 times, respectively. Actually, the decay ratio also nonsequetially increases in the vicinity of arrow A portion in FIG. 13. In the area around this point, destabilization starts to be notable. Accordingly, the point can be used as a timing to strengthen the stability monitoring level, i.e., to loosen the criterion for determining power oscillations. In the vicinity of arrow B portion, the core is in the state where power oscillations are likely to grow after this point. Accordingly, power oscillation suppression operation is activated at this point. According to at least one of the embodiments disclosed, it becomes possible to provide a technology for monitoring nuclear thermal hydraulic stability of a nuclear reactor with enhanced monitoring accuracy and reliability. Although some embodiments of the present invention were described, these embodiments are in all respects illustrative and are not considered as the basis for restrictive interpretation. It should be understood that these embodiments can be performed in other various forms and various removals, replacements and modifications are possible without departing from the meaning of the present invention. These embodiments and their modifications are intended to be embraced in the range and meaning of the present invention, and particularly are intended to be embraced in the invention disclosed in the range of the claims and the equivalency thereof.
053234294	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of corrosion assessment in a metal by monitoring electrical activity between the metal and an electrode, both being subjected to an electrolyte. More particularly, the invention concerns monitoring localized corrosion of circular structural penetrations of vessels, for example the structures penetrating the vessel of a nuclear reactor for coupling control and sensing devices through a vessel wall. 2. Prior Art There are various reasons for providing structures penetrating vessels, such as a conduit attached to an opening in the vessel at one or more welds. The conduit may be arranged, for example, to provide a flow path, to pass a mechanical device, or to couple electrical conductors through a vessel wall. Where the vessel contains an electrolyte and is subject to thermal and/or mechanical stress, the penetration structure is subject to corrosion. Where an asymmetric weld or similar structure affixes a penetration to a pressurized vessel containing an electrolyte, corrosion-stress cracking can be a problem, particularly in the area of the attachment of the penetration structure to the vessel. A pressurized water nuclear reactor vessel is an example. A pressurized water nuclear reactor comprises a pressure vessel containing nuclear fuel and a conduit system whereby a coolant such as water or water containing cobalt is fed into and out of the vessel. The fuel comprises a plurality of long vertical rods that are closely spaced and interspersed with control rods that are movable into the spaces between the fuel rods to damp a selected proportion of nuclear flux and thereby control the rate of nuclear decay of the fuel as well as the amount of heat generated. The coolant is fed to the bottom of the vessel, flows upwardly over the fuel rods and exits at a level above the fuel rods, being heated in the process. The coolant is heated to a high temperature (e.g., 600.degree. F.) and develops substantial pressure (e.g., 2,200 psi). Instrumentation and control devices are mounted in and on the reactor vessel to ensure proper operation. Although it is possible to provide penetrations of the reactor vessel wall at various places to accommodate the mechanical and electrical couplings needed for these devices, it is preferable to place the penetrations at the top of the vessel and thereby provide higher integrity at the bottom, for improved safety characteristics. Typically, the reactor vessel comprises a generally cylindrical hollow body of relatively thick steel (e.g., about 13 cm or 5 inches) with a lid or reactor vessel head attached at the top to define a sealed pressure vessel. Penetrations for mechanical and electrical couplings across the pressure boundary are provided in the form of fittings that extend through the head or lid of the reactor vessel. Penetrations of the vessel head are provided, for example, to accommodate movable control rod guide devices, and to pass conductors that couple electrically to sensors located inside the vessel, such as temperature and nuclear flux level sensors disposed in thimble tubes interspersed among the fuel rods. The tubes or similar structures penetrating the head may terminate flush with the inside wall of the head or may protrude into the internal volume. They may also traverse the plane of the head perpendicularly or at an angle. Typically, the penetration tubes are aligned vertically, parallel to one another and in alignment with the fuel rods. The control rods, for example, can thereby be engaged by actuators that are movable upwardly or downwardly in the penetration tubes, to accomplish corresponding displacement of the control rods relative to the fuel. Whether movable or static, the structures passing through the vessel head have associated penetration tubes that are arranged to withstand the pressure developed by the coolant and to maintain a pressure boundary. The penetration tubes extend through the vessel head and include pressure fittings adapted to pass the control rod mechanisms or electrical signal couplings, respectively. The collection of penetrations and couplings are known as the reactor vessel head adaptor. All the tubing and conduits of the reactor which carry the coolant are subject to corrosion over time. There are a number of reasons for such corrosion, including chemical reaction with the coolant (which is an electrolyte), the effect of nuclear radiation, mechanical stresses due to temperature and pressure variations, etc. Penetrations of the reactor vessel head are subject to stress-corrosion cracking, leading to potential leakage. The vessel head is dome shaped, as appropriate for withstanding pressure. Whereas the penetrations typically are vertical and the head is a dome, those penetrations which are radially spaced from the center of the dome pass through the dome at an angle relative to a tangent to the dome surface. Welds which attach the penetration tube to the vessel head are therefore not placed at the same axial level on the penetration tube, and/or are characterized by different sized weldments on opposite sides of the tube. This is especially pronounced at the penetrations located at the outer radius of the vessel head. Thermal stresses are created by the welds for this reason. The thermal stresses further subject the penetration tubes to stress-corrosion cracking, and potential leakage of coolant as a result of through-wall stress corrosion cracking of the tubes, particularly in the area adjacent axially spaced or differently sized welds. It would be beneficial to monitor cracking at vulnerable locations such as the vessel head penetrations in an on-line and automated manner, to determine when actual crack propagation is taking place and to assess the effectiveness of corrective measures taken to arrest corrosion of the reactor vessel. An on-line crack monitoring system could also provide information to evaluate the relative severity of corrosion at different locations in the reactor head to help determine and correct the root causes. Electrochemical corrosion measurements have been taken to generally monitor the level of corrosion of metals that are exposed to an electrolyte. In high temperature environments such as boilers, corrosion may be encountered due to exposure to flue gases or to an aqueous coolant. U.S. Pat. No. 4,575,678--Hladky discloses a general method for analyzing deterioration of metal structures carrying electrolytes, for example, a pipe or conduit, a storage tank, process vessel, heat exchanger, pump or valve. An electrochemical probe intended for ongoing collection of corrosion data, that protrudes from a vessel wall into the electrolyte, is disclosed for example, in international application PCT/GB87/00500--Cox et al. A probe that is structured to form a section of conduit through which the electrolyte passes is disclosed in U.S Pat. No. 4,426,618--Ronchetti et al. In each case, the probe comprises a plurality of corrosion sensing electrodes that are exposed to the electrolyte. The electrical potentials of the electrodes and the current passing between the electrodes is sensed and related to the extent of chemical corrosion of the electrodes. Corrosion of the electrodes is comparable to corrosion of the vessel, conduit or other structure that holds the electrolyte. Therefore, by sensing the level of corrosion of the electrodes and integrating the results, the probe can be used to estimate the instantaneous rate of corrosion of the structure as a whole. Such information can be incorporated as a part of a maintenance program as disclosed in U.S. Pat. No. 4,935,195--Palusamy et al. Specific sensing and monitoring for electrochemical resistance, galvanic current between electrodes, electrochemical potential noise and electrochemical current noise are disclosed for measuring the deterioration of a combustion vessel in "On-Line Materials Surveillance for Improved Reliability in Power Generation Systems," Paper No. 254, NACE Annual Conference and Corrosion Show, March 1991. Electrode structures which are useful for such monitoring are disclosed, for example, in U.S. Pat. Nos. 3,504,323--Meany, Jr.; 3,491,012--Winslow, Jr.; and 2,834,858--Schaschl. These teachings and these patents, and the foregoing patents to Palusamy and Hladky, are hereby incorporated in their entireties. The present invention is intended to apply the art of electrochemical monitoring to the specific problems of penetration structures traversing the walls of vessels, and is particularly applicable to monitoring localized corrosion of penetrations traversing a wall of a nuclear reactor vessel. It has been discovered according to the invention that by instrumenting a subset of a plurality of penetrations of a vessel or similar electrolyte-holding structure, in particular the control and instrumentation penetrations of a nuclear reactor vessel head, one can assess the status of the penetrations generally, and thereby obtain information on this critical area of the reactor. Furthermore, the corrosion characteristics of particular areas of the penetration tubes can be selectively monitored, for distinguishing corrosion occurring at different locations in the penetration tubes. The invention is useful for assessing present corrosion level, status and integrity of the vessel penetrations, and for providing information whereby the useful life of penetration structures can be decremented for planning and executing required maintenance steps. SUMMARY OF THE INVENTION It is an object of the present invention to enable on-line monitoring of stress-corrosion cracking associated with vessel penetrations, i.e., structures that couple through the wall of a vessel, conduit or similar structure carrying an electrolyte. It is a further object of the invention to use at least one exemplary structure penetrating a vessel as one of the electrodes of an electrochemical sensor, for assessing deterioration of a plurality of such penetrating structures due to chemical and mechanical stress on the structures. It is another object of the invention to sense for corrosion at different locations on the inside or protruding outside wall of a vessel penetration, for example at different axial positions and circumferential positions around penetration having a circular cross section. It is also an object of the invention to assess the deterioration of vessel penetrations by electrochemical monitoring of a subset of the penetrations using an on-line data collection system. It is another object of the invention to monitor the penetrations of a nuclear reactor head adaptor at critical or vulnerable locations, particularly by instrumenting circular penetrations at and adjacent passage through a vessel head structure at an angle relative to the plane of the head. These and other aspects are found in the stress-corrosion damage monitoring method and apparatus according to the invention. Stress-corrosion damage is monitored in the penetrations traversing the wall of a vessel containing an electrolyte, such as the penetrations of the head adaptor of a nuclear reactor vessel containing a coolant and nuclear fuel. The vessel wall has a number of tubular penetrations for coupling mechanical or electrical external devices to internal structures of the vessel while maintaining a pressure barrier, such as control rod guides and sensor signal cables. The penetrations are subject to stress-corrosion damage, especially at and adjacent the passage through the head, where the penetrations may be welded or similarly attached to the vessel head in a manner generating thermal stresses. One or more of the penetrations is provided with at least one, and preferably a plurality of electrodes that define electrochemical sensor cells. A series of electrode pairs detect corrosion activity on the surface of the penetration tube material, primarily the areas most nearly adjacent the respective electrodes of the probe, making it possible to distinguish between corrosion levels at different positions on the probe. The electrodes of each pair represent a working electrode and a reference electrode. The corroding surface of the penetration tube nearby the pair represents another working electrode. These electrodes are exposed to the electrolyte, as is the corroding wall of the penetration. The electrodes and the corroding wall are otherwise electrically insulated, and are wired to a detector circuit developing signals as a function of electrochemical activity due to stress and corrosion. Electrochemical potential, impedance, current, and particularly noise levels in the potential and current signals are detected for each pair of electrodes and each distinguishable monitored area of the corroding tube. The signals are analyzed and/or read out for assessing deterioration of the penetration wall as a function of the electrochemical activity. In this manner, the condition of all the vessel penetrations is assessed in a manner that enables identification of areas of the penetrations where corrosion is occurring preferentially, facilitating appropriate corrective action when necessary.
	summary
	claims	1. An apparatus for irradiating patients with x-rays, the apparatus comprising:a lowerable patient support;an x-ray apparatus that is positionable below the lowerable patient support,wherein at least part of the x-ray apparatus moves upwards guided by a guide coupled to the lowerable patient support when the lowerable patient support is lowered. 2. The apparatus as claimed in claim 1, wherein the x-ray apparatus comprises an aperture housing, andwherein the lowerable patient support is configured to accommodate at least one part of the aperture housing during lowering of the lowerable patient support. 3. The apparatus as claimed in claim 2, further comprising a mechanism that establishes a releasable contact between the lowerable patient support and the x-ray apparatus such that the x-ray apparatus is subject to a vertical change in position of the lowerable patient support. 4. The apparatus as claimed in claim 2, further comprising a motor for lowering the patient support,wherein the x-ray apparatus comprises an aperture housing, andwherein the motor is arranged laterally in the aperture housing. 5. The apparatus as claimed in claim 1, further comprising a mechanism that establishes a releasable contact between the lowerable patient support and the x-ray apparatus such that the x-ray apparatus is subject to a vertical change in position of the lowerable patient support. 6. The apparatus as claimed in claim 5, wherein the releasable contact is configured by effecting a force counteracting a lowering. 7. The apparatus as claimed in claim 6, wherein the mechanism is configured to establish the releasable contact in a defined relative position of the lowerable patient support and the x-ray apparatus. 8. The apparatus as claimed in claim 7, further comprising a safety system,wherein the safety system is operable to detect whether the releasable contact is established, andwherein the x-ray apparatus for the x-ray recordings is blocked by the safety system provided the releasable contact is not established. 9. The apparatus as claimed in claim 6, further comprising a safety system,wherein the safety system is operable to detect whether the releasable contact is established, andwherein the x-ray apparatus for the x-ray recordings is blocked by the safety system provided the releasable contact is not established. 10. The apparatus as claimed in claim 6, wherein the mechanism comprises a detent and a detent lever. 11. The apparatus as claimed in claim 5, wherein the mechanism is configured for detecting a height and releasing the contact according to a threshold value for the detected height. 12. The apparatus as claimed in claim 11, further comprising a safety system,wherein the safety system is operable to detect whether the releasable contact is established, andwherein the x-ray apparatus for the x-ray recordings is blocked by the safety system provided the releasable contact is not established. 13. The apparatus as claimed in claim 11, wherein the mechanism is configured to establish the releasable contact in a defined relative position of the lowerable patient support and the x-ray apparatus. 14. The apparatus as claimed in claim 11, wherein the mechanism comprises a detent and a detent lever. 15. The apparatus as claimed in claim 5, wherein the mechanism comprises a detent and a detent lever. 16. The apparatus as claimed in claim 15, further comprising a safety system,wherein the safety system is operable to detect whether the releasable contact is established, andwherein the x-ray apparatus for the x-ray recordings is blocked by the safety system provided the releasable contact is not established. 17. The apparatus as claimed in claim 5, further comprising a safety system,wherein the safety system is operable to detect whether the releasable contact is established, andwherein the x-ray apparatus for the x-ray recordings is blocked by the safety system provided the releasable contact is not established. 18. The apparatus as claimed in claim 5, further comprising a motor for lowering the patient support,wherein the x-ray apparatus comprises an aperture housing, andwherein the motor is arranged laterally in the aperture housing. 19. The apparatus as claimed in claim 7, wherein the mechanism comprises a detent and a detent lever. 20. The apparatus as claimed in claim 1, further comprising a motor for lowering the patient support,wherein the x-ray apparatus comprises an aperture housing, andwherein the motor is arranged laterally in the aperture housing.
	abstract	A modeling process includes providing blocks, each of the blocks representing functional entities that operate on input signal values, output signal values from the blocks, grouping the output signal values as an ordered set in a multiplexer as a first composite signal and outputting the first composite signal.
	claims	1. A radiation shielding sheet comprising:a shielding material mixed with an organic polymer material,wherein said shielding material is an oxide powder containing at least one element selected from the group consisting of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu) and gadolinium (Gd), said oxide powder having an average grain size of 1 to 20 μm, andwherein a volumetric ratio of the shielding material in said radiation shielding sheet is 40 to 80 vol. %. 2. A radiation shielding sheet comprising:an organic polymer material; anda shielding material mixed with said organic polymer material,wherein said shielding material is an oxide powder of a single substance of metal element or metal compound, and has a composition containing lanthanum (La) and cerium (Ce), andwherein the metal compound powder has a composition containing 10 to 40 mass % of lanthanum (La) oxide and 30 to 60 mass % of cerium (Ce) oxide. 3. The radiation shielding sheet according to claim 2, wherein a volumetric ratio of the shielding material filled in said radiation shielding sheet is 40 to 80 vol. %. 4. The radiation shielding sheet according to claim 1, wherein the average grain size of said shielding material grains existing in a structure of the radiation shielding sheet is A μm, where A is no less than 1 μm and no more than 20 μm, such that a quantity of said shielding material grains existing within a straight line segment range having a length of 50 μm is at least equal to 30/A,wherein the straight line segment range is arbitrarily drawn on a surface of the structure of the radiation shielding sheet. 5. The radiation shielding sheet according to claim 1, wherein the organic polymer material is further mixed with at least one powder selected from the group consisting of tungsten (W), bithmus (Bi), tin (Sn) and compounds thereof. 6. The radiation shielding sheet according to claim 1, wherein the radiation shielding sheet is used as a material in a wall of an X-ray room. 7. The radiation shielding sheet according to claim 2, wherein the average grain size of said shielding material grains existing in a structure of the radiation shielding sheet is A μm, where A is no less than 1 μm and no more than 20 μm, such that a quantity of said shielding material grains existing within a straight line segment range having a length of 50 μm is at least equal to 30/A,wherein the straight line segment range is arbitrarily drawn on a surface of the structure of the radiation shielding sheet. 8. The radiation shielding sheet according to claim 2, wherein the organic polymer material is further mixed with at least one powder selected from the group consisting of tungsten (W), bithmus (Bi), tin (Sn) and compounds thereof. 9. The radiation shielding sheet according to claim 2, wherein the radiation shielding sheet is used as a material in a wall of an X-ray room. 10. The radiation shielding sheet according to claim 5, wherein when one of tungsten (W), bithmus (Bi), tin (Sn), or compounds thereof, is included in the radiation shielding material, a weight part ratio of the one of tungsten (W), bithmus (Bi), tin (Sn), or compounds thereof is not greater than 30 weight parts. 11. The radiation shielding sheet according to claim 8, wherein when one of tungsten (W), bithmus (Bi), tin (Sn), or compounds thereof, is included in the radiation shielding material, a weight part ratio of the one of tungsten (W), bithmus (Bi), tin (Sn), or compounds thereof is not greater than 30 weight parts. 12. The radiation shielding sheet according to claim 5, wherein when tin (Sn) is included in the radiation shielding material, a weight part ratio of the tin (Sn) is not greater than 40 weight parts. 13. The radiation shielding sheet according to claim 8, wherein when tin (Sn) is included in the radiation shielding material, a weight part ratio of the tin (Sn) is not greater than 40 weight parts.
	summary
	claims	1. An aberration correction system for use in an electron microscope, said aberration correction system comprising:three stages of multipole elements arranged in a row along an optical axis, each of the multipole elements having a thickness along the optical axis, the three stages of multipole elements including a front stage of multipole element, a middle stage of multipole element, and a rear stage of multipole element,wherein said front stage of multipole element produces a first magnetic or electric field of 3-fold symmetry with respect to the optical axis,wherein said middle stage of multipole element produces a second magnetic or electric field of 3-fold symmetry with respect to the optical axis,wherein said rear stage of multipole element produces a third magnetic or electric field of 3-fold symmetry with respect to the optical axis,wherein in the second magnetic or electric field, a distribution of a magnetic or electric field of 3-fold symmetry is created in a direction not to cancel out an astigmatism of 3-fold symmetry produced from the first magnetic or electric field or from the third magnetic or electric field,wherein in the third magnetic or electric field, a distribution of a magnetic or electric field of 3-fold symmetry is created in a direction not to cancel out an astigmatism of 3-fold symmetry produced from the first magnetic or electric field or from the second magnetic or electric field,wherein an aberration of 3-fold symmetry produced in the front stage of multipole element is rotated using the middle stage of multipole element,wherein an aberration of 3-fold symmetry produced from the middle stage of multipole element is rotated using the rear stage of multipole element, andwherein the astigmatisms of 3-fold symmetry are canceled out by combining the fields produced by the three stages of multipole elements, whereby spherical aberration and a higher-order aberration are corrected. 2. An aberration correction system for use in an electron microscope as set forth in claim 1,wherein any one of said second magnetic or electric field and said third magnetic or electric field is distributed to have been rotated through 120°×m±40° (where m is an integer) relative to said first magnetic or electric field within a plane perpendicular to the optical axis, taking account of a rotating action of an electron optical lens,wherein the other of the second magnetic or electric field and the third magnetic or electric field is distributed to have been rotated through 120°×m±80° relative to the first magnetic or electric field within the plane perpendicular to the optical axis, taking account of the rotating action of the electron optical lens, andwherein the second magnetic or electric field and the third magnetic or electric field are distributed to have been rotated in the same direction. 3. An aberration correction system for use in an electron microscope as set forth in claim 1, wherein said second magnetic or electric field is distributed to have been rotated through 120°×m±about 72° (where m is an integer) relative to said first magnetic or electric field within the plane perpendicular to the optical axis, taking account of a rotating action of an electron optical lens, and wherein said third magnetic or electric field is distributed to have been rotated through 120°×m±about 24° relative to the first magnetic or electric field within the plane perpendicular to the optical axis, taking account of the rotating action of the electron optical lens. 4. An aberration correction system for use in an electron microscope as set forth in any one of claims 1 to 3, further comprising:a pair of first transfer lenses mounted between said front stage of multipole element and said middle stage of multiple element and having two stages of axisymmetric lenses; anda pair of second transfer lenses mounted between the middle stage of multipole element and said rear stage of multipole element and having two stages of axisymmetric lenses. 5. An aberration correction system for use in an electron microscope as set forth in claim 4, further comprising a pair of third transfer lenses mounted ahead of or behind said three stages of multipole elements arranged in a row along an optical axis. 6. An aberration correction system for use in an electron microscope as set forth in any one of claims 1 to 3, wherein each of said three stages of multipole elements has a magnetic polepiece capable of being excited independently or an electrode capable of being applied with a voltage independently. 7. An aberration correction system for use in an electron microscope as set forth in any one of claims 1 to 3, wherein each of said three stages of multipole elements has a hexapole element. 8. An aberration correction system for use in an electron microscope as set forth in any one of claims 1 to 3, wherein each of said three stages of multipole elements has a dodecapole element. 9. An aberration correction system for use in an electron microscope as set forth in any one of claims 1 to 3, further comprising means for rotating the three stages of multipole elements within the plane perpendicular to the optical axis. 10. An aberration correction system for use in an electron microscope as set forth in any one of claims 1 to 3, wherein said three stages of multipole elements are uniform in thickness.
	claims	1. A light source comprising:a system for generating a train of light pulses and delivering the light pulses into a chamber along a beam path, the system including a gain medium for amplifying light of a source wavelength;an optic within the chamber defining a first focus at an irradiation region and a second focus at an intermediate region;a target material delivery system delivering a target material to the irradiation region; anda multichannel structure within the chamber and disposed between the irradiation region and the intermediate region and including a plurality of conical shaped vanes. 2. The light source of claim 1, wherein the plurality of conical shaped vanes allow light to travel from the optic to the intermediate region. 3. The light source of claim 1, wherein the plurality of conical shaped vanes condense target material vapors. 4. The light source of claim 1, wherein the plurality of conical shaped vanes are maintained at a temperature above the melting point of the target material. 5. The light source of claim 1, wherein the target material includes tin. 6. The light source of claim 1, wherein the plurality of conical shaped vanes are maintained at a temperature below the melting point of the target material. 7. The light source of claim 1, further comprising one or more radial members configured to support the plurality of conical shaped vanes. 8. The light source of claim 1, wherein the optic comprises a collector mirror. 9. The light source of claim 8, wherein the collector mirror is formed from a truncated ellipsoid. 10. The light source of claim 8, wherein the collector mirror includes a through hole to allow the light pulses generated by the system to pass through the optic to reach the irradiation region. 11. The light source of claim 1, wherein the plurality of conical shaped vanes are concentric. 12. A chamber system comprising:a multichannel structure supported within a chamber and disposed between an irradiation region and an intermediate region, defined by an optic that includes a first focus at the irradiation region and a second focus at the intermediate region, the multichannel structure comprising a plurality of concentric conical shaped vanes that are arranged to allow a train of light pulses generated from a system to travel from the optic to the intermediate region.
06084938&	claims	1. An X-ray projection exposure apparatus, comprising: a mask chuck for holding a reflection X-ray mask having a mask pattern thereon; a wafer chuck for holding a wafer onto which the mask pattern is transferred; an X-ray illuminating system for illuminating the reflection X-ray mask, held by said mask chuck, with X-rays; an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer held by said wafer chuck with a predetermined magnification, wherein said mask chuck comprises a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic force; and a detection mechanism for detecting an attraction force with which the reflection X-ray mask is held as a result of the electrostatic force generated by said static electricity generating mechanism. a mask chuck for holding a reflection X-ray mask having a mask pattern thereon, wherein said mask chuck comprises a mask holding surface and a plurality of projections formed on said mask holding surface, wherein the reflection X-ray mask is supported by said plurality of projections, and wherein the ratio of the area of contact portions where the distal ends of said plurality of projections contact the mask to the entire area of the mask is equal to or less than 10%; a wafer chuck for holding a wafer onto which the mask pattern is transferred; an X-ray illuminating system for illuminating the reflection X-ray mask, held by said mask chuck, with X-rays; and an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer held by said wafer chuck with a predetermined magnification, wherein said mask chuck comprises a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic force. a mask chuck for holding a reflection X-ray mask having a mask pattern thereon, wherein said mask chuck is subjected to scanning movement, and wherein said mask chuck comprises a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic attracting force; a wafer chuck for holding a wafer onto which the mask pattern is transferred; an X-ray illuminating system for illuminating the reflection X-ray mask, held by said mask chuck, with X-rays; an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer held by said wafer chuck with a predetermined magnification; a driving control unit for controlling the scanning movement of said mask chuck; and an attraction control unit which changes the electrostatic attracting force generated by said static electricity generating mechanism in accordance with the movement controlled by said driving control unit. wherein said attraction control unit calculates the acceleration of said mask chuck from position information relating to the mask chuck detected by said driving control unit, and wherein said attraction control unit changes the electrostatic attracting force generated by said static electricity generating mechanism in accordance with calculated acceleration. {(the mass of the reflection X-ray mask).times.(acceleration due to gravity of the reflection X-ray mask+the maximum acceleration of the reflection X-ray mask while being moved)/(the maximum coefficient of static friction between the reflection X-ray mask and said mask chuck)}.times.(safety factor)<(the attracting force of the reflection X-ray mask). generating static electricity with the static electricity generating mechanism of the mask chuck to hold the reflection X-ray mask with the mask chuck by an electrostatic attracting force; detecting the electrostatic attracting force with which the reflection X-ray mask is held with the mask chuck as a result of the static electricity generated in said generating step and controlling the amount of the electrostatic attracting force in accordance with said detection; holding the wafer with the wafer chuck; illuminating the reflection X-ray mask with X-rays using the X-ray illuminating system; and projecting the mask pattern of the reflection X-ray mask onto the wafer held by the wafer chuck with a predetermined magnification with the X-ray projection optical system to transfer the mask pattern onto the wafer. controlling the scanning movement of the mask chuck; generating static electricity with the static electricity generating mechanism of the mask chuck to hold the reflection X-ray mask with the mask chuck by an electrostatic attracting force; controlling the electrostatic attracting force generated in said generating step in accordance with the movement controlled by said controlling step of controlling the scanning movement; holding the wafer with the wafer chuck; illuminating the reflection X-ray mask with X-rays using the X-ray illuminating system; and projecting the mask pattern of the reflection X-ray mask onto the wafer held by the wafer chuck with a predetermined magnification with the X-ray projection optical system to transfer the mask pattern onto the wafer. detecting position information of the mask chuck; calculating the acceleration of the mask chuck from the position information detected in said detecting step; and controlling the electrostatic attracting force generated in said generating step in accordance with the acceleration calculated in said calculating step. {(the mass of the reflection X-ray mask).times.(acceleration due to gravity of the reflection X-ray mask+the maximum acceleration of the reflection X-ray mask while being moved)/(the maximum coefficient of static friction between the reflection X-ray mask and said mask chuck)}.times.(safety factor)<(the attracting force of the reflection X-ray mask). a mask stage for holding a reflection X-ray mask having a mask pattern thereon, wherein said mask stage is subjected to scanning movement, and wherein said mask stage comprises a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic attracting force; a wafer stage for holding a wafer onto which the mask pattern is to be transferred, wherein said wafer stage is subjected to scanning movement; an X-ray illuminating system for illuminating the reflection X-ray mask, held by said mask stage, with X-rays; an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer held by said wafer stage with a predetermined reduced magnification; a driving control unit for controlling the scanning movement of said mask stage; a detection mechanism for detecting an attraction force with which the reflection X-ray mask is held as a result of the electrostatic force generated by said static electricity generating mechanism; and an attraction control unit which controls the electrostatic attracting force generated by said static electricity generating mechanism in accordance with the detection by said mechanism. generating static electricity with the static electricity generating mechanism of the mask stage to hold the reflection X-ray mask with the mask stage by an electrostatic attracting force; detecting the electrostatic attracting force with which the reflection X-ray mask is held with the mask stage as a result of the static electricity generated in said generating step and controlling the amount of the electrostatic attracting force in accordance with the detection; holding the wafer with the wafer stage; illuminating the reflection X-ray mask with X-rays using the X-ray illuminating system; projecting the mask pattern of the reflection X-ray mask onto the wafer held by the wafer stage with a predetermined reduced magnification with the X-ray projection optical system to transfer the mask pattern onto the wafer; and controlling the scanning movement of the mask stage and the wafer stage. generating static electricity with the static electricity generating mechanism of the mask stage to hold the reflection X-ray mask with the mask stage by an electrostatic attracting force; detecting an electrostatic attracting condition with which the reflection X-ray mask is held with the mask stage as a result of the static electricity generated in said generating step, and controlling the amount of the electrostatic attracting force in accordance with the detection; holding the wafer with the wafer stage; illuminating the reflection X-ray mask with X-rays using the X-ray illuminating system; projecting, with the X-ray projection optical system, the mask pattern of the reflection X-ray mask onto the wafer held by the wafer stage with a predetermined reduced magnification to transfer the mask pattern onto the wafer, and controlling the scanning movement of the mask stage and the wafer stage. a mask chuck for holding a reflection X-ray mask having a mask pattern thereon; a wafer chuck for holding a wafer onto which the mask pattern is transferred; an X-ray illuminating system for illuminating the reflection X-ray mask, held by said mask chuck, with X-rays; an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer held by said wafer chuck with a predetermined magnification, wherein said mask chuck comprises a static electrically generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic force; and a detection mechanism for detecting an attraction condition with which the reflection X-ray mask is held as a result of the electrostatic force generated by said static electricity generating mechansim. generating static electricity with the static electricity generating mechanism of the mask chuck to hold the reflection X-ray mask with the mask chuck by an electrostatic attracting force; detecting an electrostatic attracting condition with which the reflection X-ray mask is held with the mask chuck as a result of the static electricity generated in said generating step and controlling the amount of the electrostatic attracting force in accordance with the detection; holding the wafer with the wafer chuck; illuminating the reflection X-ray mask with X-rays using the X-ray illuminating system; and projecting, with the X-ray projection optical system, the mask pattern of the reflection X-ray mask onto the wafer, held by the wafer chuck, with a predetermined magnification to transfer the mask pattern onto the wafer. a mask stage for holding a reflection X-ray mask having a mask pattern thereon, wherein said mask stage is subjected to scanning movement, and said mask stage comprises a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic attracting force; a wafer stage for holding a wafer onto which the mask pattern is to be transferred, wherein said wafer stage is subjected to scanning movement; an X-ray illuminating system for illuminating the reflection X-ray mask, held by said mask stage, with X-rays; a driving control unit for controlling the scanning movement of said mask stage; a detection mechanism for detecting an attraction condition with which the reflection X-ray mask is held as a result of the electrostatic force generated by said static electricity generating mechanism; and an attraction control unit which controls the electrostatic attracting force generated by said static electricity generating mechanism in accordance with the detection by said detection mechanism. 2. An apparatus according to claim 1, wherein said static electricity generating mechanism controls the amount of generated static electricity in accordance with the amount of attraction force detected by said detection mechanism. 3. An apparatus according to claim 1, wherein said detection mechanism comprises a pressure sensor provided on an attracting surface of said mask chuck. 4. An apparatus according to claim 1, further comprising means for performing scanning exposure by moving both of said mask chuck and said wafer chuck. 5. An apparatus according to claim 1, wherein said mask chuck holds the mask against gravity. 6. An apparatus according to claim 1, further comprising means for changing the electrostatic force for attracting the reflection X-ray mask by said mask chuck in accordance with the movement of said mask chuck. 7. An apparatus according to claim 6, wherein the relationship of {(the mass of the reflection X-ray mask).times.(acceleration due to gravity+the maximum acceleration of the reflection X-ray mask while being moved)/(the maximum coefficient of static friction between the reflection X-ray mask and said mask chuck)}.times.(safety factor)<(the attracting force of the reflection X-ray mask) is satisfied. 8. An apparatus according to claim 1, wherein said mask chuck comprises a mask holding surface and a plurality of projections formed on said mask holding surface, and wherein the reflection X-ray mask is supported by said plurality of projections. 9. An apparatus according to claim 8, wherein the ratio of the area of contact portions where the distal ends of said plurality of projections contact the mask to the entire area of the mask is equal to or less than 10%. 10. An apparatus according to claim 8, wherein a plurality of voids are formed between said plurality of projections, said apparatus further comprising means for supplying the plurality of voids with a cooling gas when the reflection X-ray mask is supported on said plurality of projections. 11. An apparatus according to claim 1, further comprising a temperature control mechanism for controlling the temperature of said mask chuck. 12. An apparatus according to claim 11, wherein said temperature control mechanism comprises means for supplying the inside of said mask chuck with a temperature controlled medium, and a temperature sensor for detecting the temperature of said mask chuck. 13. An apparatus according to claim 1, wherein said mask chuck comprises a ceramic material or a glass material. 14. An apparatus according to claim 1, further comprising a grounded earth pawl provided at least at a side of said mask chuck for supporting the mask. 15. An apparatusa according to claim 1, wherein the reflection X-ray mask comprises an X-ray reflecting multilayer film and wherein the mask pattern is made of an absorbing member formed on the X-ray reflecting multilayer film. 16. An apparatus according to claim 1, wherein said X-ray illuminating system comprises a radiation source and a reflecting mirror. 17. An apparatus according to claim 1, wherein said X-ray projection optical system comprises a reduction projection optical system having a plurality of X-ray reflecting mirrors. 18. An apparatus according to claim 1, wherein the X-rays include vacuum-ultraviolet rays or soft X-rays. 19. An X-ray projection exposure apparatus, comprising: 20. An apparatus according to claim 19, wherein the X-rays include vacuum-ultraviolet rays or soft X-rays. 21. An X-ray projection exposure apparatus, comprising: 22. An apparatus according to claim 21, wherein said driving control unit detects position information of the mask chuck, 23. An apparatus according to claim 22, wherein said attraction control unit controls the electrostatic attracting force of said static electricity generating mechanism to satisfy the following expression: 24. An apparatus according to claim 21, wherein the X-rays include vacuum-ultraviolet rays or soft X-rays. 25. A device manufacturing method using an X-ray projection exposure apparatus comprising a mask chuck for holding a reflection X-ray mask having a mask pattern thereon, a wafer chuck for holding a wafer onto which the mask pattern is transferred, an X-ray illuminating system for illuminating the reflection X-ray mask, held by the mask chuck, with X-rays, and an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer held by the wafer chuck with a predetermined magnification, the mask chuck comprising a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic attracting force, said method comprising the steps of: 26. A method according to claim 25, wherein the X-rays include vacuum-ultraviolet rays or soft X-rays. 27. A device manufacturing method using an X-ray projection exposure apparatus comprising a mask chuck for holding a reflection X-ray mask having a mask pattern thereon, a wafer chuck for holding a wafer onto which the mask pattern is transferred, an X-ray illuminating system for illuminating the reflection X-ray mask, held by the mask chuck, with X-rays, and an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer held by the wafer chuck with a predetermined magnification, wherein the mask chuck is subjected to scanning movement and comprises a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic attracting force, said method comprising the steps of: 28. A method according to claim 27, further comprising the steps of: 29. A method according to claim 28, wherein said electrostatic attracting force controlling step comprises the step of controlling the electrostatic attracting force to satisfy the following expression: 30. A method according to claim 27, wherein the X-rays include vacuum-ultraviolet rays or soft X-rays. 31. An x-ray projection exposure apparatus comprising: 32. An apparatus according to claim 31, wherein the reflection X-ray mask comprises an X-ray reflecting multilayer film, and wherein the mask pattern is made of an absorbing member formed on the X-ray reflecting multilayer film. 33. An apparatus according to claim 31, wherein the X-rays include vacuum-ultraviolet rays or soft X-rays. 34. An apparatus according to claim 31, further comprising a grounded earth pawl provided at least at a side of said mask stage for supporting the reflection X-ray mask. 35. An apparatus according to claim 31, wherein said mask stage comprises a ceramic material or a glass material. 36. An apparatus according to claim 31, further comprising a temperature control mechanism for controlling the temperature of said mask stage. 37. An apparatus according to claim 36, wherein said temperature control mechanism comprises means for supplying the inside of said mask stage with a temperature controlled medium, and a temperature sensor for detecting the temperature of said mask stage. 38. A device manufacturing method using an X-ray projection exposure apparatus comprising a mask stage for holding a reflection X-ray mask having a mask pattern thereon, a wafer stage for holding a wafer onto which the mask pattern is to be transferred, an X-ray illuminating system for illuminating the reflection X-ray mask, held by the mask stage, with X-rays, and an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer, wherein the mask stage comprises a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic attracting force, said method comprising the steps of: 39. A method according to claim 38, wherein the X-rays include vacuum-ultraviolet rays or soft X-rays. 40. A device manufacturing method using an X-ray projection exposure apparatus comprising a mask stage for holding a reflection X-ray mask having a mask pattern thereon, a wafer stage for holding a wafer onto which the mask pattern is to be transferred, an X-ray illuminating system for illuminating the reflection X-ray mask, held by the mask stage, with X-rays, and an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer, wherein the mask stage comprises a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic attracting force, said method comprising the steps of: 41. An X-ray projection exposure apparatus comprising: 42. A device manufacturing method using an X-ray projection exposure apparatus comprising a mask chuck for holding a reflection X-ray mask having a mask pattern thereon, a wafer chuck for holding a wafer onto which the mask pattern is transferred, an X-ray illuminating system for illuminating the reflection X-ray mask, held by the mask chuck, with X-rays, and an X-ray projection optical system for projecting the mask pattern of the reflection X-ray mask onto the wafer held by the wafer chuck with a predetermined magnification, the mask chuck comprising a static electricity generating mechanism for generating static electricity for attracting and holding the reflection X-ray mask by an electrostatic attracting force, said method comprising the steps of: 43. An X-ray projection exposure apparatus comprising:
	claims	1. A radiation shielding panel, comprising:a tungsten powder including tungsten particles having three different specific diameters; anda polyurea material, the tungsten powder being mixed and dispersed into the polyurea material, the mixture of the polyurea material and the tungsten powder shields radiation greater than about 6 MeV. 2. The radiation shielding panel as set forth in claim 1, wherein:the three different specific diameters of the tungsten particles are about 0.9 microns, about 9.0 microns, and about 90.0 microns. 3. The radiation shielding panel as set forth in claim 2, wherein:about 5% of the powdered tungsten is the tungsten particles having diameters of about 0.9 microns;about 15% of the powdered tungsten is the tungsten particles having diameters of about 9.0 microns; andabout 80% of the powdered tungsten is the tungsten particles having diameters of about 90.0 microns. 4. The radiation shielding panel as set forth in claim 1, wherein:the panel includes ≧ about 70% and about 90% of the tungsten powder; andthe panel includes ≦ about 10% and about 30% of the polyurea material. 5. The radiation shielding panel as set forth, in claim 4, wherein:the panel is about ⅛″ thick;the panel includes between about 80% and about 90% of the tungsten powder; andthe panel includes about 10% and about 20% of the polyurea material. 6. The radiation shielding panel as set forth in claim 4, wherein:the panel is about ¼″ thick;the panel includes between about 80% and about 90% of the tungsten powder; andthe panel includes about 10% and about 20% of the polyurea material. 7. A radiation shielding panel, comprising:a tungsten powder including tungsten particles having three different specific diameters of about 0.9 microns, about 9.0 microns, and about 90.0 microns; anda polyurea material, the tungsten powder being mixed and dispersed into the polyurea material, the panel being pliable without cracks when a first side of the panel is folded to be adjacent a second side of the panel. 8. The radiation shielding panel as set forth in claim 7, wherein:the mixture of the polyurea material and the tungsten powder shielding radiation greater than about 6 MeV. 9. The radiation shielding panel as set forth in claim 7, wherein:about 5% of the powdered tungsten is the tungsten particles having diameters of about 0.9 microns;about 15% of the powdered tungsten is the tungsten particles having diameters of about 9.0 microns; andabout 80% of the powdered tungsten is the tungsten particles having diameters of about 90.0 microns. 10. The radiation shielding panel as set forth in claim 7, wherein:the panel includes ≧ about 70% and about 90% of the tungsten powder; andthe panel includes ≦ about 10% and about 30% of the polyurea material. 11. The radiation shielding panel as set forth in claim 10, wherein:the panel is about ⅛″ thick;the panel includes between about 80% and about 90% of the tungsten powder; andthe panel includes about 10% and about 20% of the polyurea material. 12. The radiation shielding panel as set forth in claim 10, wherein:the panel is about ¼″ thick;the panel includes between about 80% and about 90% of the tungsten powder; andthe panel includes about 10% and about 20% of the polyurea material. 13. A method of forming a radiation shielding panel, the method including:forming a tungsten powder mixture including tungsten particles having three different specific diameters;mixing a polyurea with the tungsten powder mixture;adding an accelerant to the polyurea and tungsten powder mixture; andpressurizing the accelerant, polyurea, and tungsten powder mixture at about 6,000 lbs/in2 for between about 4 hours and about 4½ hours. 14. The method of forming a radiation shielding panel as set forth in claim wherein claim 13, wherein the step of mixing the polyurea and tungsten powder mixture includes:mixing the polyurea and the tungsten powder mixture for between about 4 minutes and about 7 minutes. 15. The method of forming a radiation shielding panel as set forth in claim 13, further including:forming the panel to about 30″ high by about 30″ wide by ⅛″ thick. 16. The method of forming a radiation shielding panel as set forth in claim 13, wherein the step of forming the tungsten powder mixture includes:preparing the tungsten powder mixture to include the three different sized tungsten particles having, by volume, about 80% of tungsten particles having a diameter of about 90.0 microns, about 15% of tungsten particles having a diameter of about 9.0 microns, and about 5% of tungsten particles having a diameter of about 0.9 microns. 17. The method of forming a radiation shielding panel as set forth in claim 13, wherein the step of adding the accelerant includes:mixing the accelerant into the polyurea and tungsten powder mixture for about 4 minutes. 18. The method of forming a radiation shielding panel as set forth in claim 17, wherein the step of forming the polyurea and tungsten powder mixture includes:mixing the polyurea and tungsten powder mixture for between about 4 minutes and about 7 minutes.
	abstract	A method of performing microbeam radiosurgery on a patient whereby target tissue within a patient is irradiated with high energy electromagnetic radiation via one or more microbeam envelopes with photons having respective energy magnitudes in excess of 200 keV, and maximum defined beam widths sufficiently narrow to yield a biological damage width which does not exceed a predetermined value.
052001431	abstract	The invention relates to a fuel assembly (1) for a nuclear reactor and comprises a number of parallel fuel rods (2) which are held together by means of spacers (4,5) arranged along the fuel rods as well as guide tubes (3) arranged between the fuel rods (2) and parallel thereto. The guide tubes extend through the spacers (4) and are fixed between a top nozzle (6) and a bottom nozzle (7). According to the invention, bottom sleeves (8) for the guide tubes (3) are arranged in the bottom spacer (5). These bottom sleeves (8) are rigidly fixed to the bottom spacer (5) and rest against the bottom nozzle (7). Each bottom sleeve (8) is provided with a first locking member (9) for receiving a second locking member (10), arranged at the end of the respective guide tube (3), in order to rigidly lock the guide tube (3) to the bottom sleeve (8).
	claims	1. An x-ray analysis apparatus for illuminating a sample spot with an x-ray beam, comprising:an x-ray tube having a source spot from which a diverging x-ray beam is produced, the source spot requiring alignment along a transmission axis passing through the sample spot;a first housing section to which the x-ray tube is attached along a first axis thereof, the first housing section including adjustable mounting features for adjustably mounting the x-ray tube therein such that the source spot coincides with the first axis, the first housing section further including mating surfaces aligned to the first axis;a second housing section having a second axis coinciding with the transmission axis, and mating surfaces aligned to the second axis; andat least one x-ray optic attached to the second housing section for receiving the diverging x-ray beam and directing the beam toward the sample spot, the at least one x-ray optic requiring alignment along the transmission axis;the first housing section and second housing section being matable along their respective mating surfaces to thereby align the first and second axes with the transmission axis, thereby aligning the source spot, x-ray optic, and sample spot. 2. The apparatus of claim 1, wherein the second housing section is tubular in shape, with the second axis running longitudinally therein. 3. The apparatus of claim 2, wherein the x-ray tube is tubular in shape, having its source spot at one end thereof. 4. The apparatus of claim 2, wherein the first and second housing sections are tubular in shape, and the mating surfaces of the first and second housing sections comprise surface portions in contact with each other upon attachment of the first and second tubular housing sections. 5. The apparatus of claim 4, wherein the x-ray tube is tubular in shape, having its source spot at one end thereof. 6. The apparatus of claim 1, wherein the at least one x-ray optic is at least one curved diffracting optic or polycapillary optic, for receiving the diverging x-ray beam from the x-ray tube and focusing the beam at the sample spot. 7. The apparatus of claim 6, wherein the at least one optic is at least one focusing monochromating optic. 8. The apparatus of claim 7, wherein the at least one focusing monochromatic optic is a doubly curved crystal optic or doubly curved multi-layer optic, mounted along a surface of the second housing section, and separated from the second axis. 9. The apparatus of claim 1, wherein the at least one x-ray optic comprises a plurality of x-ray optics, each optic of the plurality of optics attached to the second housing section for receiving the diverging x-ray beam and directing a respective portion of the beam toward the sample spot, and requiring alignment along the transmission axis, mounted along a surface of the second housing section, and separated from the transmission axis. 10. The apparatus of claim 9, wherein each optic of the plurality of x-ray optics is a focusing monochromatic optic. 11. The apparatus of claim 10, wherein each optic of the plurality of x-ray optics is a doubly curved crystal optic or doubly curved multi-layer optic, mounted along a surface of the second housing section, and separated from the second axis. 12. The apparatus of claim 1, further comprising at least one carriage for mounting the at least one x-ray optic to the second housing section to receive the diverging x-ray beam, the at least one carriage mountable either directly or indirectly to the second housing section, such that an active surface of the at least one x-ray optic is aligned along, and positioned a desired distance from, the transmission axis. 13. The apparatus of claim 12, wherein a surface of the second housing section to which the at least one carriage is mounted is fabricated such that the at least one x-ray optic is positioned the desired distance from the transmission axis. 14. The apparatus of claim 13, wherein the second housing section is tubular in shape, and wherein the surface of the second housing section to which the at least one carriage is mounted comprises and outer diameter of the second housing section. 15. The apparatus of claim 12, wherein the carriage comprises mounting features, and/or a shim to position the optic a desired distance from the transmission axis. 16. The apparatus of claim 1, further comprising a third housing section, the third housing section including an aperture along the transmission axis through which the x-ray beam passes when illuminating the sample spot, the second housing section and third housing section being matable along respective mating surfaces to thereby align the aperture with the transmission axis and therefore the sample spot. 17. The apparatus of claim 16, further comprising an x-ray detector mounted to the third housing section in alignment with the sample spot. 18. An x-ray analysis apparatus for illuminating a sample spot with an x-ray beam, comprising:an x-ray tube having a source spot from which a diverging x-ray beam is produced, the source spot requiring alignment along a transmission axis passing through the sample spot;a first tubular housing section to which the x-ray tube is attached along a first axis thereof, such that the source spot coincides with the first axis, the first housing section further including mating surfaces aligned to the first axis;a second tubular housing section having a second axis coinciding with the transmission axis, and mating surfaces aligned to the second axis; andat least one focusing x-ray optic attached to the second housing section for receiving the diverging x-ray beam and directing the beam toward the sample spot, the at least one x-ray optic requiring alignment along the transmission axis;the first housing section and second housing section being matable along their respective mating surfaces to thereby align the first and second axes with the transmission axis, thereby aligning the source spot, x-ray optic, and sample spot. 19. The apparatus of claim 18, wherein the at least one focusing x-ray optic is at least one curved diffracting optic or polycapillary optic, for receiving the diverging x-ray beam from the x-ray tube and focusing the beam at the sample spot. 20. The apparatus of claim 19, wherein the at least one optic is at least one focusing monochromating optic. 21. The apparatus of claim 20, wherein the at least one focusing monochromatic optic is a doubly curved crystal optic or doubly curved multi-layer optic, mounted along a surface of the second housing section, and separated from the second axis. 22. The apparatus of claim 18, wherein the at least focusing one x-ray optic comprises a plurality of focusing x-ray optics, each optic of the plurality of optics attached to the second housing section for receiving the diverging x-ray beam and directing a respective portion of the beam toward the sample spot, and requiring alignment along the transmission axis, mounted along a surface of the second housing section, and separated from the transmission axis. 23. The apparatus of claim 18, further comprising a third housing section, the third housing section including an aperture along the transmission axis through which the x-ray beam passes when illuminating the sample spot, the second housing section and third housing section being matable along respective mating surfaces to thereby align the aperture with the transmission axis and therefore the sample spot.
048204790	summary	BACKGROUND OF THE INVENTION The invention relates to a guide pin assembly for aligning the upper hold down plate of the top nozzle of a fuel assembly with the upper core plate of a pressurized water nuclear reactor. Fuel assemblies for pressurized water nuclear reactors are supported within the reactor core by upper and lower core plates. The upper and lower core plates are supported by a core support barrel, which in turn surrounds the reactor core and extends between the ends thereof. The number of fuel assemblies within the reactor core varies according to the size of the reactor core. Such fuel assemblies include a plurality of guide tubes through which the control rods are inserted and withdrawn from the reactor core. The guide tubes are supported between a top nozzle and a bottom nozzle. The top nozzle includes an upper hold down plate, a lower adapter plate, and an enclosure forming a sidewall and extending between the upper hold down plate and the lower adapter plate. Generally, the top nozzle has a square cross-section, and includes a plurality of guide tubes, the number of which varies according to the size of the fuel assembly. The upper hold down plates of a plurality of top nozzles are aligned with, and secured to, the upper core plate to support a plurality of fuel assemblies below the upper core plate. The upper core plate and upper hold down plates of the top nozzles include aligned bores therethrough for the guide tubes. As further described in U.S. Pat. No. 4,534,933 to Gjertsen et al., and assigned to the assignee of the present invention, guide pins are disposed between the upper hold down plate of the top nozzle of each fuel assembly and the upper core plate to properly align the upper core plate and the upper hold down plate of the top nozzle of the fuel assembly so that the guide tubes extend vertically. U.S. Pat. No. 4,534,933 is incorporated herein by reference. These guide pins must sometimes be replaced. The replacement of missing, broken or damaged guide pins is difficult without risking the exposure of plant personnel to dangerous levels of radiation. It is an object of the invention to develop a remotely installable guide pin assembly for aligning the upper core plate of the reactor with the upper hold down plate of the top nozzle of a fuel assembly. SUMMARY OF THE INVENTION The present invention is a guide pin assembly for aligning the upper hold down plate of the top nozzle of a fuel assembly with the upper core plate of a pressurized water nuclear reactor. The guide pin assembly includes a guide pin, a nut and a locking cup. The guide pin has a generally circular cross-section and includes a nose, a threaded portion, a shaft, and an end. The nose has engagement means thereon. The threaded portion, adjacent the nose, has a threaded outer surface. The shaft, adjacent the threaded portion, has an upper section, a lower section, and a radial alignment section between the upper and lower sections. The radial alignment section of the shaft has a diameter that is approximately the diameter of a first bore in the upper core plate of a nuclear reactor, and the lower section of the shaft has a diameter less than that of the radial alignment section. The end, adjacent the shaft, includes a top having a diameter greater than that of the diameter of the first bore in the upper core plate. The guide pin is adapted to be inserted within a second bore in the upper hold down plate of the top nozzle of the fuel assembly and through the first bore in the upper core plate of a nuclear reactor from the bottom of the first bore in the upper core plate so that the nose and at least a portion of the threaded portion of the guide pin protrude above te upper core plate. The nut is adapted to be threaded onto the threaded surface of the guide pin, and includes a top and a bottom. The locking cup is securable about the nut and is adapted to engage the engagement means on the nose of the guide pin when the nut has been tightened onto the threaded surface of the threaded portion of the guide pin so that the bottom of the nut abuts the upper surface of the upper core plate. The guide pin assembly of the invention is remotely installable within the second bores and first bores of the upper hold down plate of the top nozzle and the upper core plate, respectively, in an operating nuclear reactor without the risk of exposing plant personnel to dangerous levels of radiation.
	claims	1. Charged particle beam energy width reduction system for a charged particle beam with a z-axis along an optical axis, comprisinga first element acting in a focusing and dispersive manner in an x-z-plane, being a first Wien filter, and having a first z-position z1;a second element acting in a focusing and dispersive manner in the x-z-plane, being a second Wien filter, and having a second z-position z2;a charged particle selection element with a z-position between z1 and z2;a focusing element with a z-position between z1 and z2, wherein the charged particle selection element has substantially the same z-position as the focusing element, and wherein the charged particle selection element is adapted to be a charged particle energy dependent selection element. 2. Charged particle beam energy width reduction system according to claim 1, wherein the z-positions of the charged particle selection element and the focusing element are essentially the middle of the z-positions z1 and z2. 3. Charged particle beam energy width reduction system according claim 1, wherein the charged particle selection element is a slit. 4. Charged particle beam energy width reduction system according to claim 1, wherein the charged particle selection element has at least one property selected from the group consisting of a variable selection width and a variable position. 5. Charged particle beam energy width reduction system according to claim 1, wherein the charged particle selection element has at least one property selected from the group consisting of a fixed selection width and a fixed position. 6. Charged particle beam energy width reduction system according to claim 1, wherein the charged particle selection element comprises a knife edge. 7. Charged particle beam energy width reduction system according to claim 1, wherein the focusing element is suitable for focusing in a y-z-plane. 8. Charged particle beam energy width reduction system according to claim 7, wherein the focusing element is an astigmatic focusing element, suitable for focusing in the y-z-plane and defocusing or not focusing in the x-z-plane. 9. Charged particle beam energy width reduction system according to claim 3, wherein the slit of the energy selection element extends essentially in a y-direction. 10. Charged particle beam energy width reduction system according to claim 8, wherein the focusing element includes an electrostatic cylinder lens in decel mode. 11. Charged particle beam energy width reduction system according to claim 8, wherein the focusing element includes an electrostatic quadrupole in decel mode. 12. Charged particle beam energy width reduction system according to claim 1, wherein the focusing element is suitable for focusing stigmatically and the projection of the charged particle beam in the x-z-plane crosses the optical axis of the charged particle beam energy width reduction system in the center of the focusing element. 13. Charged particle beam energy width reduction system according to claim 12, wherein the focusing element includes an electrostatic round lens in decel mode. 14. Charged particle beam energy width reduction system according to claim 1, further comprising: a first quadrupole element; and a second quadrupole element. 15. Charged particle beam energy width reduction system according to claim 14, wherein the first quadrupole element acts in a focusing or defocusing manner in the x-z-plane, and the second quadrupole element acts in a focusing or defocusing manner in the x-z-plane. 16. Charged particle beam energy width reduction system according to claim 15, wherein the first quadrupole element is positioned so that the field of the first quadrupole element essentially superimposes with the field of the first element acting in a focusing and dispersive manner; and the second quadrupole element is positioned so that the field of the second quadrupole element essentially superimposes with the field of the second element acting in a focusing and dispersive manner. 17. Charged particle beam energy width reduction system according to claim 16, wherein the first element acting in a focusing and dispersive manner and the first quadrupole element are formed by one multipole element and the second element acting in a focusing and dispersive manner and the second quadrupole element are formed by one multipole element. 18. Charged particle beam energy width reduction system according to claim 17, wherein additional deflection or aberration correction elements are superimposed in the multipole elements. 19. Charged particle beam energy width reduction system according to claim 1, wherein the charged particle beam reduction system is a straight vision system. 20. Charged particle beam energy width reduction system according to claim 19, wherein the energy width reduction system is an energy width reduction system for a primary charged particle beam. 21. Charged particle beam energy width reduction system according to claim 1, wherein the charged particle beam energy width reduction system is a retarding field energy width reduction system. 22. Charged particle beam device comprising a charged particle beam energy width reduction systems according to claim 1. 23. Charged particle beam device according to claim 22, wherein a magnification lens illuminates the charged particle beam energy width reduction system. 24. Charged particle beam energy width reduction system positioned prior to an objective lens for a charged particle beam with a z-axis along an optical axis, comprising:a first element acting in a focusing and dispersive manner in an x-z-plane, being a first Wien filter, and having a first z-position z1;a second element acting in a focusing and dispersive manner in the x-z-plane, being a second Wien filter, and having a second z-position z2;a charged particle selection element with a z-position between z1 and z2;a focusing element with a z-position between z1 and z2,wherein the charged particle selection element has substantially the same z-position as the focusing element. 25. Charged particle beam energy width reduction system according claim 24, wherein the charged particle selection element is a slit. 26. Charged particle beam energy width reduction system according to claim 24, wherein the charged particle selection element comprises a knife edge. 27. Charged particle beam energy width reduction system according to claim 24, wherein the focusing element is suitable for focusing in a y-z-plane. 28. Charged particle beam energy width reduction system according to claim 27, wherein the focusing element includes an electrostatic cylinder lens in decel mode. 29. Charged particle beam energy width reduction system according to claim 27, wherein the focusing element includes an electrostatic quadrupole in decel mode. 30. Charged particle beam energy width reduction system according to claim 24, wherein the focusing element is suitable for focusing stigmatically and the projection of the charged particle beam in the x-z-plane crosses the optical axis of the charged particle beam energy width reduction system in the center of the focusing element. 31. Charged particle beam energy width reduction system according to claim 30, wherein the focusing element includes an electrostatic round lens in decel mode. 32. Charged particle beam energy width reduction system according to claim 24, further comprising:a first quadrupole element; anda second quadrupole element, wherein the first quadrupole element acts in a focusing or defocusing manner in the x-z-plane; and wherein the second quadrupole element acts in a focusing or defocusing manner in the x-z-plane. 33. Charged particle beam energy width reduction system according to claim 32, wherein the first element acting in a focusing and dispersive manner and the first quadrupole element are formed by one multipole element and the second element acting in a focusing and dispersive manner and the second quadrupole element are formed by one multipole element. 34. Charged particle beam energy width reduction system according to claim 24, wherein the energy width reduction system is an energy width reduction system for a primary charged particle beam. 35. Charged particle beam energy width reduction system according to claim 24, wherein the charged particle beam energy width reduction system is a retarding field energy width reduction system. 36. Charged particle beam energy width reduction system with a z-axis along an optical axis comprising:a first element acting in a focusing and dispersive manner in a x-z-plane, being a first Wien filter element, and having a first z-position z1;a second element acting in a focusing and dispersive manner in the x-z-plane, being a second Wien filter element, and having a second z-position z2;a charged particle selection element with a z-position essentially in the middle of z1 and z2;a first quadrupole element acting in a defocusing manner in the x-z-plane;a second quadrupole element acting in a defocusing manner in the x-z-plane;wherein the first element acting in a focusing and dispersive manner, the second element acting in a focusing and dispersive manner, the first quadrupole element, the second quadrupole element, and the charged particle selection element are positioned to allow a stigmatic and dispersion-free imaging of the trespassing charged particles, and wherein the charged particle selection element is adapted to be a charged particle energy dependent selection element. 37. Charged particle beam energy width reduction system according to claim 36 wherein the first and the second elements acting in a focusing and dispersive manner have essentially a symmetrical position with regard to the center plane of the system; and wherein the first and the second quadrupole elements have essentially a symmetrical position with regard to the center plane of the system. 38. Charged particle beam energy width reduction system according to claim 36, further comprising:a focusing element with a z-position between z1 and z2;andwherein the first element acting in a focusing and dispersive manner, the second element acting in a focusing and dispersive manner, the first quadrupole element, the second quadrupole element, the charged particle selection element, and the focusing element are positioned to allow a stigmatic and dispersion-free imaging of the trespassing charged particles. 39. Method of operating a charged particle beam energy width reduction system for a charged particle beam comprising a z-axis along an optical axis, comprising:providing a first element acting in a focusing and dispersive manner in a x-z-plane, being a first Wien filter element, at a z-position z1;providing a second element acting in a focusing and dispersive manner in the x-z- plane, being a second Wien filter element, at a z-position z2;providing a charged particle selection element with a z-position between Z1 and z2; andproviding a focusing element at substantially the same z-position as the charged particle selection element;exciting the first element acting in a focusing and dispersive manner so that charged particles with a nominal energy pass through the charged particle selection element and the center of the focusing element;exciting the second element acting in a focusing and dispersive manner;exciting the focusing element so that an essentially stigmatic imaging is obtained, andselecting charged particles with the charged particle selection element. 40. Method of operating a charged particle beam energy width reduction system for a charged particle beam according to claim 39, further comprising:exciting a first quadrupole element to substitute a desired portion of the focusing effect of the first element acting in a focusing and dispersive manner and exciting a second quadrupole element to substitute a desired portion of the focusing effect of the second element acting in a focusing and dispersive manner. 41. Method of operating a charged particle beam energy width reduction system for a charged particle beam according to claim 40, further comprising:adjusting the dispersion depending on the excitation of the elements acting in a focusing and dispersive manner in relation to the excitation of the quadrupole elements. 42. Method of operating a charged particle beam energy Width reduction system for a charged particle beam according to claim 39, further comprising:adjusting a beam current depending on the excitation of the elements acting in a focusing and dispersive manner in relation to the excitation of quadrupole elements. 43. Method of operating a charged particle beam energy width reduction system for a charged particle beam according to claim 39, wherein the charged particle selection element is provided with a z-position essentially acting in a focusing and dispersive manner is excited to obtain an essentially symmetric imaging in the x-z-plane. 44. Method of operating a charged particle beam energy width reduction system for a charged particle beam, comprising a z-axis along an optical axis, a first element acting in a focusing and dispersive manner, being a first Wien filter element, at a z-position z1, a second element acting in a focusing and dispersive manner, being a second Wien filter element, at a z-position z2, a charged particle selection element, a first quadrupole element, and a second quadrupole element, comprising:exciting the first Wien filter to act in a focusing and dispersive manner in a x-z-plane so that charged particles with a nominal energy pass through the energy selection element;exciting the second Wien filter to act in a focusing and dispersive manner in the x-z-plane;exciting the first and the second quadrupole elements to act in an imaging manner in the x-z-plane; andselecting charged particles with the charged particle selection element essentially in the middle of z1 and z2. 45. Method of operating a charged particle beam energy width reduction system for a charged particle beam according to claim 44, wherein the first Wien filter element and the second Wien filter element are excited so that the combination of the field of the first Wien filter element and the field of the second Wien filter element result in an essentially symmetric imaging in the x-z-plane; and exciting the first and the second quadrupole element so that the combination of the field of the first quadrupole element and the field of the second quadrupole element result in an essentially symmetric imaging in a y-z-plane. 46. Method of operating a charged particle beam energy width reduction system for a charged particle beam according to claim 45 further comprising: exciting the first and the second Wien filter elements and the first and the second quadrupole elements so that a stigmatic imaging is obtained. 47. Method of operating a charged particle beam energy width reduction system for a charged particle beam according to claim 44, further comprising the step of:exciting a focusing element positioned between z1 and z2 so that an essentially stigmatic imaging is obtained. 48. Method of operating a charged particle beam energy width reduction system for a charged particle beam according to claim 44, further comprising: exciting a first quadrupole element to obtain a desired focusing effect combined of the first quadrupole element charged particle beam deflection and the first Wien filter element charged particle beam deflection and exciting a second quadrupole element to obtain a desired focusing effect combined of the second quadrupole element charged particle beam deflection and the second Wien filter element charged particle beam deflection; wherein the desired focusing effect is defined by a beam path so that the charged particles with a nominal energy pass through the energy selection element. 49. Method of operating a charged particle beam energy width reduction system for a charged particle beam according to claim 44, wherein the first and second elements acting in a focusing and dispersive manner and the first and second quadrupole elements are excited to one of a plurality of discrete values.
	summary
	summary
059463678	claims	1. A neutron absorbing pin, comprising: at least, a neutron absorber, a pipe surrounding the neutron absorber, and a cladding disposed at a distance from the pipe; wherein the difference between the coefficient of thermal expansion (.alpha.1) of the neutron absorber and the coefficient of thermal expansion (.alpha.2) of the pipe has an absolute value of .vertline..alpha.2-.alpha.1.vertline..ltoreq.10.times.10.sup.-6 /K. 2. A neutron absorbing pin according to claim 1, wherein the pipe comprises a fiber-reinforced ceramic. 3. A neutron absorbing pin according to claim 2, wherein the fiber-reinforced ceramic is fiber-reinforced silicon carbide (SiC) or fiber-reinforced alumina (Al.sub.2 O.sub.3). 4. A neutron absorbing pin according to claim 1, wherein the neutron absorber comprises boron carbide (B.sub.4 C).
	description	With reference to FIG. 1, a computed tomography (CT) imaging apparatus or CT scanner 10 includes a gantry 12. An x-ray source 14 and a source collimator 16 cooperate to produce a fan-shaped, cone-shaped, wedge-shaped, or otherwise-shaped x-ray beam directed into an examination region 18 which contains a subject (not shown) such as a patient arranged on a subject support 20. The subject support 20 is linearly movable in a Z-direction while the x-ray source 14 on a rotating gantry 22 rotates around the Z-axis. In an exemplary helical imaging mode, the rotating gantry 22 rotates simultaneously with linear advancement of the subject support 20 to produce a generally helical trajectory of the x-ray source 14 and collimator 16 about the examination region 18. However, other imaging modes can also be employed, such as a single- or multi-slice imaging mode in which the gantry 22 rotates as the subject support 20 remains stationary to produce a generally circular trajectory of the x-ray source 14 over which an axial image is acquired. After the axial image is acquired, the subject support optionally steps a pre-determined distance in the Z-direction and the axial image acquisition is repeated to acquire volumetric data in discrete steps along the Z-direction. A radiation detector 30 is arranged on the gantry 22 across from the x-ray source 14. In the exemplary CT scanner 12, the radiation detector 30 spans a selected angular range that preferably comports with a fan angle of the x-ray beam. The radiation detector 30 includes several rows of detectors along the Z-direction for acquiring imaging data along a portion of the Z-direction in each projection view. The radiation detector 30 is arranged on the gantry 22 opposite to the x-ray source 14 and rotates therewith so that the radiation detector 30 receives x-rays that traverse the examination region 14 as the gantry 22 rotates. A plurality of anti-scatter elements 32, such as spaced anti-scatter plates, are arranged on the radiation detector 30 and are oriented with respect to a spatial focal point 34 generally corresponding to an origin or convergence point of the x-ray beam. The spatial focal point 34 is typically on the anode of the x-ray source 14. The detector 30 is a focus-centered detector centered on the spatial focal point 34. Instead of the arrangement shown in FIG. 1, it is also contemplated to arrange the radiation detector on a stationary portion of the gantry encircling the rotating gantry such that the x-rays continuously impinge upon a continuously shifting portion of the radiation detector during source rotation. With continuing reference to FIG. 1, the gantry 22 and the subject support 20 cooperate to obtain selected projection views of the subject along a helical trajectory or other trajectory of the x-ray source 14 relative to the subject. The path of the x-ray source 14 preferably provides substantial angular coverage for each voxel of the imaged region of interest to reduce image artifacts. Projection data collected by the radiation detector 30 are communicated to a digital data memory 40 for storage. A reconstruction processor 42 reconstructs the acquired projection data, using filtered backprojection, an n-PI reconstruction method, or other reconstruction method, to generate a three-dimensional image representation of the subject or of a selected portion thereof which is stored in an image memory 44. The image representation is rendered or otherwise manipulated by a video processor 46 to produce a human-viewable image that is displayed on a graphical user interface (GUI) 48 or another display device, printing device, or the like for viewing by an operator. Preferably, the GUI 48 is additionally programmed to interface a human operator with the CT scanner 12 to allow the operator to initialize, execute, and control CT imaging sessions. The GUI 48 is optionally interfaced with a communication network such as a hospital or clinic information network via which image reconstructions are transmitted to medical personnel, a patient information database is accessed, or the like. With continuing reference to FIG. 1 and with further reference to FIG. 2, the anti-scatter elements 32 are arranged between first and second generally symmetrical, substantially planar, alignment plates or boards 601, 602. The alignment plates 601, 602 are preferably arranged in a large arc, generally parallel to one another. The alignment plates 601, 602 are thin metallic plates, preferably made of a corrosion-resistant metal, such as stainless steel, which are supported by corresponding rigid support elements 621, 622, respectively. Preferably, the support elements 621, 622 are components or cast portions of a detector support frame that mechanically supports, secures, and/or retains functional components of the radiation detector 30 including the anti-scatter elements 32. With continuing reference to FIG. 2 and with further reference to FIGS. 3 and 4, each alignment plate 601, 602, numbered generally as 60, includes a plurality of anti-scatter element alignment openings 70 formed therein. As shown in FIG. 4, the anti-scatter element module alignment openings 70 are arranged in pairs along radial lines 72 that converge at the spatial focal spot 34 which coincides with the x-ray source 14 or a convergence of the fan-shaped, cone-shaped, wedge-shaped, or otherwise-shaped x-ray beam produced by the cooperating x-ray source 14 and source collimator 16. In FIG. 4, a few exemplary radial lines 72 are shown to indicate the alignment of pairs of anti-scatter element alignment openings 70 with the spatial focal point 34. In the embodiment of the alignment plate 60 shown in FIG. 3, an additional opening 74 is arranged between each pair of anti-scatter element alignment openings 70. The extra opening 70 is preferably aligned along the radial line 72 of the pair of anti-scatter element alignment openings 70, and provides a pass-through for a fastener that secures the anti-scatter element or module 32 to the rigid support element 62. Further additional alignment openings 76 in the alignment plates 60 are optionally included to align the alignment plates 60 with the support elements 621, 622 or to align other elements of the radiation detector 30. With continuing reference to FIGS. 2-4 and with further reference to FIGS. 5A, 5B, and 5C, the anti-scatter elements or modules 32 each include a plurality of anti-scatter plates or vanes 80 arranged generally in conformity with the rays or planes 72 and separated by spacer plates 82 that are generally parallel to the anti-scatter plates 80 and define a selected spacing and convergence angle between anti-scatter plates 80. The non-scattered radiation is directed parallel to the anti-scatter plates 80 and pass therebetween, while scattered radiation angularly deviates from parallel with the anti-scatter plates 80 and is typically absorbed by the anti-scatter plates 80. Although the anti-scatter plates or vanes 80 are generally parallel to one another, those skilled in the art will recognize that precisely parallel plates do not exactly align with the spatial focal point 34. That is, precisely parallel planes do not contain any points in common, and hence cannot contain the spatial focal point 34 in common. Preferably, the generally parallel anti-scatter plates or vanes 80 are each aligned with a plane that intersects the spatial focal point 34. Such planes are close to, but not exactly, parallel over a length L of the anti-scatter plate 80 since L is short compared a distance between the anti-scatter module 32 and the spatial focal point 34. In a preferred embodiment for obtaining the preferred generally parallel arrangement of anti-scatter plates 80 in the module 32, the sides of the spacer plates 82 that contact the anti-scatter plates 80 are preferably slightly non-parallel. An angle of the non-parallel sides is selected to provide a slight tilt of the contacting anti-scatter plates 80 relative to one another to closely align each anti-scatter plate 80 with a plane that intersects the spatial focal point 34. The anti-scatter plates or vanes 80 are preferably formed of a material with a high atomic number that is highly absorbing for radiation produced by the x-ray source 14, such as tantalum, tungsten, lead, or the like. The spacer plates 82 are formed of a material that is substantially translucent to radiation produced by the x-ray source 14, and are suitably formed of a plastic material. In a preferred embodiment, the spacer plates 82 are substantially hollow molded plastic frames, rather than full molded plastic slabs, to further reduce radiation absorption in the spacer plates 82. The arrangement of generally parallel anti-scatter plates 80 and spacer plates 82 is secured at the sides by two end caps 841, 842. Each end cap 84 includes alignment pins or other alignment protrusions 86 that are aligned along the radial line or plane 72, as best seen in FIG. 5A. In a preferred embodiment, the protrusions 86 of one end cap 842, align with the protrusions 86 of the other end cap 842, as best seen in FIG. 5B, so that the two end caps 841, 842 are interchangeable. Optionally, an adhesive such as a pressure-sensitive adhesive is disposed between contacting surfaces of the anti-scatter plates 80 and the spacer plates 82 to provide additional structural support. With continuing reference to FIGS. 2-5C and with further reference to FIGS. 6 and 7, the alignment protrusions 86 of the anti-scatter modules 32 mate with the anti-scatter alignment openings 70 of the alignment plates 601, 602 to align the anti-scatter modules 32 with the spatial focal point 34. Because both the openings and the protrusions are defined with precision, the modules are precisely aligned upon insertion. No adjustment in the alignment is necessary. As best seen in FIGS. 2 and 6, the rigid support elements 621, 622 include recess troughs 90 aligned with the anti-scatter alignment openings 70 that provide space for the protrusions 86 to pass through the alignment openings 70. The recess troughs 90 do not provide precise alignment and hence need not be formed with close tolerances. In the preferred illustrated embodiment the two alignment plates 601, 602 cooperate in aligning the anti-scatter modules 32. However, it is also contemplated to employ only a single alignment plate 60. With reference to FIGS. 8 and 9, the anti-scatter elements 32 are aligned using the alignment protrusions 86 and fastened in the radiation detector 30 using threaded fasteners 100 that pass through the openings 74. It should be noted that in FIG. 8, the side that faces the x-ray tube 14 is facing down. Although in FIG. 8 the support elements 621, 622 are omitted to show the alignment openings 70, 74, the fasteners 100 preferably secure to the support elements 621, 622. Additional protrusions or pins 102 preferably extend from a backside of each anti-scatter module 32 to provide alignment for photodetector array modules 104 that align with the anti-scatter modules 32. The pins 102 of each anti-scatter module 32 precisely mate with precision openings 106 of a corresponding photodetector array module 104 to provide alignment of the photodetector array module 104 with its corresponding anti-scatter module 32. With continuing reference to FIG. 9 and with further reference to FIG. 10, each photodetector array module 104 includes a substrate 108 on which is disposed a photodetector array 110. A scintillator layer or array 112 is disposed on the photodetector array 110 to provide conversion of x-rays to light that is detectable by the photodetector array 110. The photodetector array 110 is preferably a monolithic array of silicon photodiodes, amorphous silicon, charge-coupled devices, or other semiconductor photodetectors that is divided into individual detector elements 114 by wafer-level photolithographic processing of the monolithic photodiode array, by a mask 116 of tungsten or other x-ray absorbing material, or by a combination of processing and masking. The alignment of the photodetector array module 104 to the anti-scatter module 32 arranges the detector elements 114 in the gaps between the anti-scatter plates 80 as shown in FIG. 10. The detector elements 114 view between the anti-scatter plates 80, i.e. view through the spacer plates 82 such that scattered radiation which angularly deviates from the unscattered radiation is substantially absorbed by the anti-scatter plates 80 and does not reach the detector elements 114. With continuing reference to FIGS. 1-10 and with further reference to FIG. 11, a preferred method 120 for assembling the radiation detector 30 is described. In a step 122, the alignment plates 601, 602 are aligned onto the corresponding support elements 621, 622 using at least some of the additional alignment openings 76, and are secured thereto, e.g. using fasteners that pass through selected openings 76. In a step 124, the anti-scatter elements or modules 32 are aligned with the anti-scatter alignment openings 70 by coupling the alignment projections 86 with the anti-scatter alignment openings 70 of the alignment plates 601, 602, and the anti-scatter modules 32 are secured to the support elements 621, 622 using the fasteners 100. In a step 126, each photodetector array module 104 is aligned to each corresponding anti-scatter module 32 using the mating alignment pins 102 and openings 106, and the photodetector array module 104 is secured to the anti-scatter module 32, the support elements 62, or another suitable support. It will be appreciated that if the photodetector array modules 104 are secured to corresponding anti-scatter modules 32, then the alignment steps 124, 126 are optionally reversed. That is, the step 126 of aligning the photodetector array modules 104 to the anti-scatter modules 32 can be performed first, with each photodetector array module 104 aligned and secured to a corresponding anti-scatter module 32, followed by alignment of the anti-scatter modules 32 with attached photodetector array modules 104 to the alignment plates 60 in the step 124. In a step 128, the assembled radiation detector 30 is aligned and mounted to the computed tomography scanner gantry 22. The aligned anti-scatter modules 32 of the radiation detector 30 cooperatively define a spatial focal spot 34, as best seen in FIGS. 4, 5A, and 7. The radiation detector 30 is aligned on the rotating gantry 22 such that the spatial focal spot 34 coincides with a spatial convergence of the rays of the x-ray cone-, wedge-, or otherwise-shaped beam produced by the cooperating x-ray source 14 and source collimator 16. Alternatively, in the step 128 the x-ray source 14 and the source collimator 16 are aligned with respect to the spatial focal spot 34 associated with the radiation detector 30. The assembly method 120 described with particular reference to FIG. 11 relies upon the alignment plates 601, 602 accurately and precisely defining the alignment of the anti-scatter modules 32 through the anti-scatter alignment openings 70. The support elements 621, 622 similarly are aligned with respect to the alignment plates 601, 602 using at least some of the additional alignment openings 76. The alignment openings 70, 76 are precisely and accurately positioned. Furthermore, for manufacturing purposes, the alignment plates 601, 602 are preferably mass-produced with close tolerances in the positioning and sizing of the alignment openings 70, 76. In a preferred embodiment, the alignment plates 601, 602 are interchangeable, so that a single part is mass-produced for manufacturing quantities of the radiation detector 30. With reference to FIG. 12, a preferred photolithographic method 150 for manufacturing the alignment plate 60 is described. The method 150 operates on a stock metal plate 152, which is preferably thin (e.g., about 0.025 cm thick) and cut to at least approximately correspond to the desired lateral dimensions of the alignment plate 60. The stock metal plate 152 is preferably a stainless steel plate which is advantageously strong and corrosion-resistant. However, an aluminum alloy or other material can also be used. In one suitable embodiment, the stock metal plate 152 is cut mechanically to define the shape of the alignment plate 60. In a preferred embodiment, however, the mechanical cutting of the stock metal plate is limited to defining a rectangular or other regular shape whose dimensions exceed the outer dimensions of the desired alignment plate 60. In this latter embodiment, the photolithographic method 150 described below precisely defines the outer dimensions of the alignment plate simultaneously with formation of the openings 70, 74, 76. A selected photoresist film is applied to both sides of the metal plate 152. The photoresist is preferably applied using evaporation, a spin-on photoresist application method, or other method that produces a uniform and well-controlled thickness of photoresist on both sides of the stock metal plate 152. The photoresist film is exposed to a selected light using a pattern mask in a step 156. As is known in the art, photoresist is a light-sensitive substance whose resistance to certain types of etching chemicals is altered by exposure to light. With positive photoresists, exposure to light weakens resistance to the chemical etching. With negative photoresists, exposure to light strengthens resistance to the chemical etching. Interposing the pattern mask between the light and the photoresist film during the exposure step 156 causes selective exposure of the photoresist film. For a positive photoresist, the pattern mask blocks exposure except in the areas to be etched, i.e. the openings 70, 74, 76. For a negative photoresist, the mask blocks exposure only in the areas to be etched, i.e. the openings 70, 74, 76. The pattern mask is preferably constructed from a computer-assisted drawing (CAD) design using known methods. The pattern mask can also be generated by photographic replication and optional reduction or enlargement of a precise and accurate manual drawing of the target light exposure pattern. The exposed photoresist is developed in a step 158. The developing step 158 includes optional annealing or other curing of the exposed photoresist to optimize etching characteristics of the light-exposed and unexposed regions, followed by chemical etching in a developer chemical that selectively removes the light-exposed regions of the photoresist film (for positive photoresist) or the regions of the photoresist film which were not exposed to light (for negative photoresist). The developing step 158 causes the photoresist to be patterned such that those areas of the metal plate 152 which are to be removed, i.e. the openings 70, 74, 76, are not covered by photoresist, while the remainder of the metal plate 152 remains covered. The metal plate 150 with the patterned photoresist is etched in a step 160 using an etchant that etches the metal plate 150 but leaves the developed photoresist substantially unaffected. Hence, the exposed regions of the patterned photoresist corresponding to the openings 70, 74, 76 are etched, while the photoresist-coated remainder of the metal plate 150 is left substantially unaffected. For the preferred embodiment in which the photolithography process 150 defines the outer dimensions of the desired alignment plate 60, the photoresist pattern preferably additionally includes a continuous contour exposed region through which the etchant can cut out the alignment plate 60 in a precise and accurate fashion. Similarly, the through-holes 74 for the fasteners 100 or other features of the alignment plate 60 are suitably incorporated into the photoresist pattern and hence formed in the metal plate 150 during the etching step 160. After the etching step 160, the developed photoresist 162 is removed in a step 162. Typically a solvent such as acetone or the like suitably removes the developed photoresist while leaving the metal substantially unaffected. It will be appreciated that a small amount of residual photoresist contamination will typically remain after the cleaning step 162. Since small amounts of residual contamination do not affect the functional use of the alignment plate 60, the photoresist removal step 162 preferably uses a solvent exposure which leaves small amounts of residue contamination remaining on one or more surfaces of the alignment plate 60. Such residual contamination can be detected, for example, using sensitive chemical surface analysis techniques such as Auger electron spectroscopy, x-ray photoemission spectroscopy (XPS), or the like. The photoresist application, exposure, developing, metal etching, and photoresist removal steps 154, 156, 158, 160, 162 are well-known in the photolithographic arts, and the skilled artisan can select an appropriate photoresist, metal etchant, and photoresist solvent, and corresponding appropriate photolithographic parameters such the photoresist thickness, exposure time, etching time, and the like to optimize the method 150 for selected types of stock metal plates, for available photolithography facilities, and so forth. In one suitable embodiment, although the photoresist is applied to both sides of the metal plate 152 in the step 154, the pattern-defining step 156 is applied to only one side of the metal plate 152. In this case the developed photoresist has openings only on the exposed side, and the etching step 160 etches the openings 72, 74, 76 from the exposed side. In another suitable embodiment, the pattern-defining step 156 is applied to both sides of the metal plate 152 so that the etching step 160 etches the openings 72, 74, 76 simultaneously from both sides of the metal plate 152. This embodiment beneficially reduces the etching time by about a factor of two. However, precise relative alignment of the exposed patterns on the two sides should be achieved using known pattern mask alignment techniques, so that during the etching step 160 the simultaneously etched openings from the two opposite sides line up and properly join. In actually constructed embodiments, the alignment plate 60 has an accuracy in hole placement that is better than 0.0025 cm across a 100 cm area. However, undercutting or other imperfections introduced during the etching step 160 may produce openings 72, 76 which are not optimally defined with respect to circularity and diameter. To improve circularity and diameter accuracy of the openings 72, 76, the openings 72, 76 are optionally mechanically reamed in a step 164 to more precisely define the shape and size of the openings. The starting stock metal plate has been found to have an optimal thickness of about 0.025 centimeters for stainless steel. Thicker plates result in reduced hole diameter accuracy, while thinner plates result in reduced mechanical strength of the alignment plate 60. In addition to high precision and accuracy in the placement of alignment openings, those skilled in the art will recognize substantial additional advantages in using photolithography to define the alignment openings and other structures of the alignment plates 60. One particular advantage is that the manufacturing cost of the alignment plate is generally independent of the number of alignment openings formed therein. Hence, the conventional arrangement of a restricted number of anti-scatter modules which each include a plurality of anti-scatter plates is not necessary. Rather, the anti-scatter plates 80 and spacer plates 82 can be directly installed without the module-defining end caps 84. With reference to FIG. 13, an anti-scatter element 32xe2x80x2 which omits the end caps 84 is described. Components of the anti-scatter module 32xe2x80x2 that generally correspond with elements of the anti-scatter module 32 are designated by corresponding primed reference numbers herein. Spacer plates 82xe2x80x2 are modified compared with the spacer plates 82 to include alignment nubs or pins 86xe2x80x2 that mate with alignment openings in alignment plates 601xe2x80x2, 602xe2x80x2, which are modified compared with the alignment plates 601, 602 by including a higher density of anti-scatter alignment openings corresponding to the alignment nubs or pins 86xe2x80x2 of the spacer plates 82xe2x80x2. The anti-scatter plates or vanes 80xe2x80x2 are substantially similar to the anti-scatter plates 80, and are held between contacting spacer plates 82xe2x80x2 frictionally or using an adhesive such as a pressure-sensitive adhesive. The support elements 621xe2x80x2, 622xe2x80x2 include recess troughs 90xe2x80x2 dimensioned to provide space for the nubs or pins 86xe2x80x2 that project through the anti-scatter plates 601xe2x80x2, 602xe2x80x2. With reference to FIG. 14, another anti-scatter element 32xe2x80x3 which omits the end caps 84 is described. Components of the anti-scatter module 32xe2x80x3 which generally correspond with elements of the anti-scatter module 32 and the anti-scatter module 32xe2x80x2 are designated by corresponding double-primed reference numbers herein. The anti-scatter plates or vanes 80xe2x80x3 are modified compared with the anti-scatter plates 80 and the anti-scatter plates 80xe2x80x2 to include alignment nubs, pins, or extensions 86xe2x80x3 that mate with alignment openings in alignment plates 601xe2x80x3, 602xe2x80x3, which are modified compared with the alignment plates 601, 602 by including a higher density of anti-scatter alignment openings corresponding to the alignment nubs, pins, or extensions 86xe2x80x3 of the anti-scatter plates 80xe2x80x3. The spacer plates 82xe2x80x3 are substantially similar to the spacer plates 82, and preferably do not include nubs or projections. The spacer plates 82xe2x80x3 are held between contacting anti-scatter plates 80xe2x80x3 frictionally or using an adhesive such as a pressure-sensitive adhesive. The support elements 621xe2x80x3, 622xe2x80x3 include recess troughs 90xe2x80x3 dimensioned to provide space for the nubs, pins, or extensions 86xe2x80x3 that project through the anti-scatter plates 601xe2x80x3, 602xe2x80x3. In the various anti-scatter elements 32, 32xe2x80x2, 32xe2x80x2, it is to be appreciated that the alignment protrusions, nubs, pins, or extensions 86, 86xe2x80x2, 86xe2x80x3 can be cylindrical extensions, slots, or the like. The extensions 86xe2x80x2, 86xe2x80x3 can be correspond to extensions of the spacer plate 82xe2x80x2 or the anti-scatter plate 80xe2x80x3, respectively, to a length greater than the separation of the alignment plates 60xe2x80x2, 60xe2x80x3, such that the extensions 86xe2x80x2, 86xe2x80x3 are planar tabs substantially spanning a length of a side of the spacer plate 82xe2x80x2 or the anti-scatter plate 80xe2x80x3. In this arrangement the alignment openings of the alignment plates 60xe2x80x2, 60xe2x80x3 corresponding to each spacer plate 82xe2x80x2 or anti-scatter plate 80xe2x80x3 are single long slots each receiving a planar tab. Although the radiation detector 30 has been described with reference to a computed tomography imaging scanner, it is readily modified for use in other imaging systems. For example, a gamma camera for nuclear medical imaging typically includes detector arrays substantially similar to the detector array 110 with scintillators suitable for converting radiation produced by an administered radiopharmaceutical to light detectable by the detector array. Gamma cameras further typically include radiation collimators that define radial directions or narrow viewing cones corresponding to each detector element. Those skilled in the art can readily adapt the alignment plates 60, 60xe2x80x2, 60xe2x80x3 to precisely and accurately align collimators on a gamma camera. In such an adaptation, since the collimators of a gamma camera preferably define precisely parallel projections, the spatial focal point 34 described herein is suitably located at mathematical infinity, corresponding to precisely parallel radial lines 72. Analogously, these techniques can be applied to conventional x-ray, digital x-ray, fluoroscopy, and the like. The invention has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the 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.
	claims	1. A pattern definition device for use in a particle-beam exposure apparatus, said device being adapted to be irradiated with a beam of electrically charged particles and pass the beam through a plurality of apertures defining the shape of beamlets passing though said apertures, wherein the apertures are arranged within a pattern definition field comprising a plurality of lines of apertures, wherein the apertures are spaced apart along said lines of apertures by a first integer multiple of the width of an aperture and are offset between neighboring lines of apertures by a fraction of said integer multiple of the width, wherein said apertures are associated with corresponding blanking openings arranged along lines of blanking openings, wherein each blanking opening is associated with a deflector controllable by a blanking signal such that said deflector is switchable between a first deflection state in which particles passing through said blanking opening are allowed to travel along a path and a second deflection state in which particles passing through said blanking opening are deflected off said path, and wherein for the lines of blanking openings, the blanking openings of a line of blanking openings are partitioned into multiple groups such that the deflectors of the blanking openings of each group are fed a common group blanking signal, wherein the group blanking signal of each group of a line of blanking openings is controlled independently of the group blanking signals of the other groups of the same line of blanking openings. 2. The device of claim 1, comprising an aperture plate for forming said beamlets and a blanking plate for controlling the passage of selected beamlets. 3. The device of claim 1, wherein the groups have at least two different sizes with regard to the numbers of blanking openings in the respective groups. 4. The device of claim 3, wherein the numbers of blanking openings in the groups correspond to powers of two multiplied with a uniform base number. 5. The device of claim 3, wherein the numbers of blanking openings in all groups except one group correspond to powers of two multiplied with a uniform base number. 6. The device of claim 3, wherein the number of all groups in a line is smaller than 16 and the size of the largest group with regard to the respective number of blanking openings is at least four times the size of the smallest group. 7. The device of claim 1, wherein the partitioning of blanking openings into groups is the same for all lines. 8. The device of claim 7, wherein corresponding groups of the lines of blanking openings are positioned adjacent to each other, forming stripes arranged perpendicular to the orientation of the lines of blanking openings. 9. The device of claim 7, wherein the partition of blanking openings into groups is the same for all lines of blanking openings, but with at least two different sequences of the groups within the respective lines of blanking openings. 10. The device of claim 1, wherein the pattern definition field is divided perpendicularly to the orientation of lines of blanking openings into at least two domains, each domain being composed of a plurality of staggered lines of blanking openings, wherein the lines of one domain are offset to the lines of the next domain by a fraction of the width of the lines, the apertures of each line of each domain representing at least one group. 11. The device of claim 10 wherein the pattern definition field is divided into two domains, wherein each group of the first domain has a corresponding group of the second domain with equal number of blanking openings in the respective group, wherein the lines of the second domain are offset to the lines of the first domain by a fraction of the width of the lines. 12. The device of claim 1, wherein the blanking signal is applied to the individual blanking openings through time delay circuitry for generating a time delay of said signal corresponding to the offsets of the respective blanking openings along the line. 13. The device of claim 1, wherein the width of the apertures is equal to the width of the lines. 14. The device of claim 1, wherein the width of the apertures associated with selected groups of blanking openings have a width smaller than the width of the lines, the remaining apertures having a width equal to the width of the lines. 15. The device of claim 1, wherein the group blanking signals are fed to the pattern definition field partly at a side running parallel to the orientation of lines, partly at a side running perpendicular. 16. The device of claim 1, wherein the shape of the apertures is substantially equivalent to a two-dimensional geometrical base shape of a contiguous covering of the plane. 17. The device of claim 16, wherein the base shape is a square. 18. The device of claim 1, wherein a group comprises at least one blanking opening for which the line feeding the group blanking signal to said blanking opening(s) comprises a component which is accessible on a surface of the device by a structural modification and which is adapted to change its transmissivity for the group blanking signal between a electrical connecting state and a blocking state upon treatment by said structural modification. 19. The device of claim 18, wherein the component is realized as a conductor segment adapted to be irreversibly modified between an electrical well-conducting and a non-conducting state. 20. The device of claim 1, wherein the deflection means are adapted to deflect, in the switched off state, the particles to an absorbing surface of said exposure apparatus mounted after the device as seen in the direction of the particle beam. 21. The device of claim 16, wherein the shape of the apertures is equivalent to a two-dimensional polygonal base shape of a contiguous covering of the plane, with rounded and/or beveled edges. 22. The device of claim 21, wherein the area of the shape of the apertures is the same as that of the original polygonal base shape. 23. The device of claim 21, wherein the shape of the apertures is a corner-rounded square. 24. A charged particle beam exposure apparatus, comprising:a charged particle source for generating a beam of charged particles; andan aperture plate comprising a plurality of openings and a plurality of deflectors, each deflector being associated with a corresponding opening, wherein each is controllable by a signal so as to be switchable between a first state and a second state, wherein, in said first state, a given deflector allows particles of the beam of charged particles to pass through a corresponding opening along a predetermined path and wherein, in said second state, the given deflector deflects particles of the beam of charged particles away from the predetermined path;wherein the plurality of openings are arranged in plural groups such that each group comprises multiple openings, and wherein the openings of a given group are electrically connected with each other so as to be commonly controlled by said signal. 25. The charged particle beam exposure apparatus of claim 24, wherein at least two groups of openings have a different number of openings. 26. The charged particle beam exposure apparatus of claim 25, wherein the number of openings of each of the at least two groups corresponds to a power of two multiplied with a common integer number. 27. The charged particle beam exposure apparatus of claim 25, wherein the number of openings of all except one groups corresponds to a power of two multiplied with a common integer number. 28. The charged particle beam exposure apparatus of claim 24, wherein the openings of each group are disposed directly adjacent to each other. 29. The charged particle beam exposure apparatus of claim 24, wherein pairs of openings of each group are electrically connected by electrical delay elements. 30. The charged particle beam exposure apparatus of claim 29, wherein the electrical delay element is configured to generate the signal to control the deflection electrode of an opening. 31. The charged particle beam exposure apparatus of claim 24, further comprising an absorbing surface disposed such that the particles of the beam of charged particles passing through an opening and deflected away from the predetermined path are incident on the absorbing surface. 32. The charged particle beam exposure apparatus of claim 24, further comprising a wafer stage for mounting a wafer thereon, and charged particle optics configured to direct the particles of the beam of charged particles passing through an opening and along the predetermined path onto a wafer mounted on the wafer stage. 33. The charged particle beam exposure apparatus of claim 24, wherein each deflector comprises a deflection electrode.
	description	The reference signs within FIGS. 1, 2 and 3 are defined as follows: The tasks of the different sections of FIG. 1 and FIG. 2 of an apparatus for generating and selecting ions to supply an injector system and the corresponding components can be summarized in the following items: 1. The production of ions, pre-acceleration of the ions to a kinetic energy of 8 keV/u and formation of ion beams with sufficient beam qualities are performed in two independent ion sources and the ion source extraction systems. For routine operation, one of the ion sources can deliver a high-LET ion species (12C4+ and 16O6+, respectively), whereas the other ion source may produce low-LET ion beams (H2+, H3+ or 3He1+). 2. The charge states to be used for acceleration in the injector linac are separated in two independent spectrometer lines. Switching between the selected ion species from the two ion source branches, beam intensity control (required for the intensity controlled raster-scan method), matching of the beam parameters to the requirements of the subsequent linear accelerator and the definition of the length of the beam pulse accelerated in the linac are done in the low-energy beam transport (LEBT) line. 3. The linear accelerator consists of a short radio-frequency quadrupole accelerator (RFQ) of about 1.4 m in length, which accelerates the ions from 8 keV/u to 400 keV/u, a compact beam matching section of 0.25 m in length and a 3.8 m long IH-type drift-tube linac (IH-DTL) for effective acceleration to the linac end energy of 7 MeV/u. 4. Remaining electrons are stripped off in a thin stripper foil located about 1 m behind of the IH-DTL to produce the highest possible charge states before injection into the synchrotron in order to optimize the acceleration efficiency of the synchrotron (Table 1). The design of the apparatus for generating and selecting ions and the injector system of the present invention has the advantage to solve the special problems on a medical machine installed in a hospital environment, which are high reliability as well as stable and reproducible beam parameters. Additionally, compactness, reduced operating and maintenance requirements. Further advantages are low investment and running costs of the apparatus. Both the RFQ and the IH-DTL are designed for ion mass-to-charge ratios A/qxe2x89xa63 (design ion 12C4+) and an operating frequency of 216.816 MHz. This comparatively high frequency allows to use a quite compact LINAC design and, hence, to reduce the number of independent cavities and RF power transmitters. The total length of the injector, including the ion sources and the stripper foil, is around 13 m. Because the beam pulses required from the synchrotron are rather short at low repetition rate, a very small rf duty cycle of about 0.5% is sufficient and has the advantage to reduce the cooling requirements very much. Hence, both the electrodes of the 4-rod-like RFQ structure as well as the drift tubes within the IH-DTL need no direct cooling (only the ground plate of the RFQ structure and the girders of the IH structure are water cooled), reducing the construction costs significantly and improving the reliability of the system. To provide very stable beam currents without any pronounced time structures as well as high beam quality an Electron Cyclotron Resonance Ion Source (ECRIS) is used for the production of 12C4+ and 16O6+ ions (ECRIS 1 in FIG. 1 and FIG. 2). For the production of proton and helium beams two different ion source types can be used. Either an ECR ion source of the same type as used for the production of the high-LET ion beams will be applied here as well (ECRIS 2 in FIG. 1 and FIG. 2) or a special low-cost, compact, high brilliance filament ion source may be used. In case of an ECR ion source, molecular H2+ ions will be produced in the ion source and used for acceleration in the linac. In case of the filament source, H3+ ions are proposed, providing the same mass-to-charge ratio of A/q=3 as of the 12C4+ ions. For production of the helium beam, 3He1+ ions will be extracted from the source in both cases. To avoid contaminations of the beam with other light ions produced simultaneously in the ion source, 3He is proposed instead of 4He. The maximum beam intensities discussed for the synchrotron are about 109 C6+ ions per spill at the patient. Assuming a multi-turn injection scheme using 15 turns at 7 MeV/u, a bunch train of about 25 xcexcm length delivered by the LINAC is injected into the synchrotron. Taking into account beam losses in the synchrotron injection line, the synchrotron and the high energy beam line, this corresponds to a LINAC output current of about 100 excexcA C6+. Considering further beam losses in the LEBT, the LINAC and the stripper foil, a minimum C4+ current of about 130 excexcA extracted out of the ion source is required. The minimum ion currents required for all ion species discussed here are listed in Table 2 (called Imin). However, the ion sources taken into consideration should be tested with an ion current including a safety margin of at least 50%. These values are called Isafe in Table 2 and range between 150 excexcA for 16O6+ and 1 emA for H2+. For the sake of stability, DC operation is proposed for the ECR ion sources. For the extraction system, a diode extraction system consisting of a fixed plasma electrode and a single moveable extraction electrode is proposed for the ECR ion sources. The extraction voltages Uext necessary for a beam energy of 8 keV/u are also listed in Table 2. In case of 12C4+ and 3He1+ extraction voltages of 24 kV are required. In case of a proton beam delivered directly from the ion source, the required extraction voltage of 8 kV would be rather small to achieve a proton current of 2 mA. Furthermore, significant space-charge problems have to be handled within the low-energy beam transport line and the RFQ accelerator in such a case. Hence, the production and acceleration of molecular H2+ and H3+ ions, respectively, is proposed. The independent first and second electron cyclotron resonance ion sources (ECRIS1 and ECRIS2) provide a very well suited solution for an injector linac installed at a hospital, the magnetic fields are provided exclusively by permanent magnets. This has the large advantage that no electric coils are required, which would have a very large power consumption of up to about 120 kW per ion source. In addition to the large power consumption, the coils have the disadvantage to need an additional high-pressure (15 bar) water cooling cycle, which is not as safe as the permanent magnet ion sources of the present invention. Both aspects have the advantage to reduce the operating costs and increase the reliability of the present system. The main parameters of a suitable high-performance permanent magnet ECRIS of a 14,5 GHz SUPERNANOGAM are listed in Table 3, and are compared to the data of two ECR ion sources using electric coils, which are the ECR4-M (HYPERNANOGAN) and the 10 GHz NIRS-ECR used for routine production of 12C4+ beams for patient irradiation at HIMAC and at Hyogo Ion Beam Medical Center. For SUPERNANOGAN, the plasma confinement is ensured by a minimum-B magnetic structure with magnetic parameters quite close to the ECR4-M ones, but with a reduced length of the magnetic mirror (about 145 mm instead of 190 mm) and a smaller diameter of the plasma chamber (44 mm instead of 66 mm). The maximum axial mirror-fields are 1.2 T at injection and 0.9 T at extraction. The weight of the FeNdB permanent magnets amount to roughly 120 kg, the diameter of the magnet body is 380 mm and its length is 324 mm. For our purpose, SUPERNANOGAN has been tested at an ECR ion source test bench. For all ion species proposed here, the required ion currents could be achieved in a stable DC operating mode using extraction voltages close to the values required for the injector linac and at moderate rf power levels between about 100 W and 420 W. For O6+ as well as for He1+ even about twice the required currents Isafe could be achieved easily. For the production of 12C4+ CO2 has been used as main gas as also applied at GSI for the production of 12C2+. Experimental investigations at HIMAC have shown that the yield of 12C4+ ions can be enhanced significantly using CH4 as main gas. Further improvements of the C4+ production performance can be expected for SUPERNANOGAN as well if CH4 would be used as main gas. The measured geometrical emittances of around 90% of the beams range between 110 mm mrad for 16O6+ and up to 180 mm mrad for He1+ and 12C4+, corresponding to normalized beam emittances of 0.4 to 0.7 mm mrad. Two results obtained with ECR4-M for C4+ and O6+ are also listed in Table 3, demonstrating that the required ion currents can be exceeded by a certain amount. Some ion currents obtained with NIRS-ECR are also listed in Table 3. The values in brackets are obtained with the upgraded version which consists of an improved sextupole magnet. Again, all values exceed the currents required here by a certain amount. The measured normalized beam emittances range from about 0.5 mm mrad for C4+ to roughly 1 mm mrad for a 2.1 emA H2+ beam. The NIRS-ECR has a number of advantages: For the comparatively light ions proposed for patient irradiation like carbon, helium and oxygen, a 10 GHz ECR source seems to be powerful enough to produce sufficiently high ion currents if the diameter of the plasma chamber is large enough. On the other hand, the confining magnetic field can be smaller at 10 GHz as compared to 14.5 GHz (used for ECR4-M), reducing the power consumption of the electric coils by about 40%. Furthermore, the NIRS-ECR is in operation at HIMAC especially for the production of 12C4+ beams. Like at the project proposed here, the injection energy at the HIMAC injector is also 8 keV/u and the extraction voltage applied for the production of 12C4+ beams is 24 kV. These parameters are the same in the present case. Additionally, a number of improvements have been applied to NIRS-ECR mainly in order to increase the reliability of the source as well as the lifetime of critical source components and the maintenance intervals. The electron cyclotron resonance ion sources of the present invention comprises: 1. a DC bias system: In order to increase the source efficiency for high charge state ions, both SUPERNANOGAN as well as HYPERNANOGAN are equipped with a DC bias system. The inner tube of the coaxial chamber is DC biased at a voltage of about 200-300 V, 2. a gas supply system: To ensure a sufficient long-term stability of the extracted ion current, the thermo-valves for the main and the support gas are regulated by suitable thermo-valve controllers. Furthermore, temperature regulated heating jackets are applied to the thermo-valves to stabilize their temperature. Pressure reducers are used between the main gas reservoirs and the thermo-valves. 3. an RF system: High power klystron amplifiers with an rf output power of about 2 kW are used (14.5 GHz or 10 GHz depending on the ion source model). To guarantee a high availability, one additional generator is available for substitution in case of a failure of the amplifier in operation. Therefore three generators are provided in case of the present invention for the two ECR ion sources (ECRIS1 and ECRIS2). Fast switching between the individual generators is possible. Remote control of the output power levels of the generators between 0 and maximum power is provided. The output power levels are controlled by active control units to a high stability of xcex94P/Pxe2x89xa61%. The total rf power transmitted from the generators can be reflected by the ion source plasmas in some cases. Hence, the generators of the present invention can be equipped with circulators and dummy loads which are able to absorb the complete power transmitted from the generators without causing a breakdown of the generators. The measurement of the reflected power is possible for routine operation. Such an ECR ion source is a preferred solution for the production of the highly charged C4+ and O6+ ion beams for a therapy accelerator. In principle, the same source model can also be used for the production of H2+ and He+ beams, providing some additional redundancy. Alternatively, a gas discharge ion source especially developed for the production of high-brilliant beams of singly charged ions can be provided for the production of H3+ and 3H1+ beams. The plasma generator of the source is housed in a water-cooled cylindrical copper chamber of 60 mm in diameter and about 100 mm in length. For plasma confinement, the chamber is surrounded by a small solenoid magnet with a comparatively low power consumption of less than 1 kW. On the back of the chamber, the gas inlet system is mounted, and, close to the axis, a tungsten filament is installed. The front end of the chamber is closed by the plasma electrode, which can be negatively biased with respect to the anode (chamber walls). For ion extraction, a triode system in accel/decel configuration is used. The geometry of the extraction system of the present invention has been carefully optimized (supported by computer simulations) for different extraction voltages around 22 kV and 55 kV. If the source is operated with hydrogen at small arc currents of xe2x89xa610 A, the H3+ fraction of the beam is as high as about 90% with a minor amount of H+ ions (xe2x89xa610%) and only a very small fraction of H2+ ions. The H+ portion increases with increasing arc current. However, for the production of an H3+ current of a few mA only, an arc power of less than 1 kW at small arc currents of a few amperes is sufficient, providing an ideal solution for the therapy injector. For these parameters, a lifetime of the tungsten filament of roughly 1000 h is expected for DC operation. To further increase the lifetime, a pulsed operation mode of the source is proposed. The stability of the extracted ion current in pulsed mode with a measured beam noise level of only about 1% is even better than for DC operation. The use of this ion source has a number of economical and technical advantages as compared to an ECR ion source of the state of the art: 1. The investment costs for the gas discharge ion source of the present invention are at least about five times lower than for an ECR ion source (including the RF generator). In addition, the costs for operational maintenance are lower, in particular, compared to an ECR ion source with electrical coils. For example, the klystron of the RF generator for an ECR ion source of the state of the art must be replaced regularly. 2. The use of H3+ for acceleration in the linac has several advantages: Because it has the same mass-to-charge ratio of A/Q=3 as of the 12C4+ ions, the linac cavities are operated at the same rf power level in both cases. This ensures a very stable operation of the linac, increasing the reliability of the system. Furthermore, a very fast switching between 12C4+ and H3+ beams would be possible. In addition, space-charge problems along the LEBT and the RFQ accelerator are minimized for H3+ beams as compared to H2+ or H+ beams. 3. Much higher beam currents are available. 4. High-brilliant ion beams with normalized beam emittances of xcex5n less than 0.1xcfx80 mm mrad, i.e. about one order of magnitude smaller as compared to the H2+ beams from the ECR ion sources. E.g. a normalized 80% beam emittance of 0.003xcfx80 mm mrad was measured for a 9 mA He+ beam at an extraction voltage of 17 kV. FIG. 3 shows examples for beam envelops of an apparatus for generating and selecting ions and along a low energy beam transport line. In FIG. 3 beam envelopes in horizontal direction (upper part) and vertical direction (lower part) are plotted for two transverse beam emittances of a) 120xcfx80 mm mrad (xcex5n=0.50xcfx80 mm mrad) and b) 240xcfx80 mm mrad (xcex5n=1.0xcfx80 mm mrad). The beam emittances are identical in x and y direction and are based on the values measured for the ECR ion sources used in the present invention, which range between about xcex5n≈0.5-0.7xcfx80 mm mrad for carbon, oxygen and helium ion beams and up to about xcex5n≈1.0xcfx80 mm mrad for H2+ beams. The boxes in FIG. 3 mark the different magnets and their aperture radii. The simulations start at an object focus located in the extraction system of the ion source and end at the beginning of the RFQ electrodes. The beam parameters at the starting point of the simulations are determined by the geometry of the ion source extraction system including the aperture of the plasma electrode as well as by the operating parameters of the ion source, which influence the shape of the plasma surface in the extraction aperture of the plasma electrode. To provide a flexible matching of beam parameters at the starting point of the spectrometer system, i.e. different beam radii, different divergence angles as well as a displacement of the object focus in axial direction, two focusing magnets are used in front of the spectrometer magnets SP1, SP2 as shown in FIG. 1 and FIG. 2. First of all, the ion beams extracted from each ion source are focused by a solenoid magnet SOL as shown in FIG. 1 and FIG. 2 into the object point of the subsequent spectrometer. The beam size and location in the bending plane of the spectrometer at this point can be defined by a variable horizontal slit (SL). To increase the resolving power of the spectrometer, which is proportional to the maximum horizontal beam size within the bending magnet, and to reduce the vertical beam width along the spectrometer magnets SP1, SP2 a single horizontally defocusing quadrupole magnet QS is located in between the object focus of the spectrometer and the spectrometer magnets SP1, SP2. The subsequent double focusing 90xc2x0 spectrometer magnets SP1, SP2 have a radius of curvature of 400 mm and edge angles of 26.6xc2x0. For ion beams with a mass-to-charge ratio of A/Q=3 and an energy of 8 keV/u, it is excited to 0.1 T only. The theoretical mass resolving power of the system at the following image slit (ISL) of A / Q Δ ⁡ ( A / Q ) ≈ 140 is sufficient to separate the desired 12C4+ ions from other charge states and from several other light ions. Following the image slits ILS as shown in FIG. 1 and FIG. 2, a magnetic quadrupole triplet QT1, QT2 focuses the beams to an almost circular symmetry along the common part of the LEBT between the switching magnet SM and the RFQ. Finally, a solenoid magnet is focusing the ion beam into a small matched waist at the beginning of the radio frequency quadrupole (RFQ) accelerator. A pair of chopper plates for macro-pulse formation is placed in between the switching magnet And the RFQ. Beam diagnostic means BD comprise profile grids and Faraday cups which are located behind the extraction system of the ion sources ECRIS1 and ECRIS2 at the object foci of the spectrometers SP1, SP2 and at the image slits ISL. Further beam diagnostic boxes are positioned behind of the switching magnet and upstream of the solenoid magnet in front of the RFQ. For on-line beam current measurements, a beam transformer is provided in each of the ion source branches in front of the magnetic quadrupole triplets QT1 and QT2.
049960172	abstract	A neutron generating system comprising a hermetically sealed housing containing an ionizable gas and a ring anode and target cathode of a Penning ion source. The housing is provided with a recess axially oriented relative to the ring anode and target cathode and adapted to accept a removable samarium/cobalt magnet such that degassing and sealing of the housing can be performed in the absence of the permanent magnet. The cathode target is an OHFC copper rod of substantially the same cross-sectional area as the target with one polished end of the rod containing a titanium film within the housing to serve as the target and the other end of the rod extending out of the housing such as to remove thermal energy from the target during operation. An ion screen between the anode ring and cathode target containing an axially positioned gridded aperture provides a broad ion beam of reduced power per unit area. Optionally, a means to control the potential on this ion screen is provided to assist in ignition of the ion source. Such a system is particularly useful in oil and gas well logging procedures.
053902173	abstract	A carbon fiber-reinforced carbon composite material, wherein carbon fibers are oriented substantially in the thickness direction, the ratio of the thermal conductivity in the thickness direction to the thermal conductivity in a direction perpendicular to the thickness direction is at least 2, and the thermal conductivity in the thickness direction is at least 3 W/cm.multidot..degree.C.
	summary
	description	The invention generally relates to pressurisers for pressurised water nuclear power stations. More precisely, the invention relates to a pressuriser for a pressurised water nuclear power station, of the type comprising: an outer casing which delimits an inner space; a duct which extends beneath the casing and which is capable of being tapped from the coolant system of the nuclear power station; a tap which places the inner space of the casing in communication with the duct, this tap being welded to the duct by means of a weld seam; a sleeve for protecting the weld seam, which sleeve is arranged inside the tap and which has a lower peripheral edge which is engaged in the duct, the sleeve defining with the tap and the duct an annular space which is capable of being filled with the primary liquid. Radioactive particles may accumulate in the annular space, close to the weld seam. These particles create a high metering rate in the proximity of the base of the pressuriser, which complicates inspection and maintenance operations on the base of the pressuriser. In this context, the object of the invention is to provide a pressuriser which can be more readily maintained. To this end, the invention proposes a pressuriser of the above-mentioned type, wherein the annular space is open along at least a portion of the lower peripheral edge of the sleeve and thus opens inside the duct. The pressuriser may also have one or more of the following features, taken individually or according to any technically possible combination: the annular space is open along the entire lower peripheral edge of the sleeve; the tap defines an inner channel which places the duct and the inner space of the casing in communication, the pressuriser comprising a crown which is rigidly fixed to the inner side of the casing around the inner channel, the sleeve having an upper end portion which is fixed to the crown; the crown and/or the upper end portion of the sleeve comprise(s) circulation holes which place the annular space in communication with the inner space of the casing; the passage cross-section of the circulation holes is calibrated in order to limit the flow rate of primary liquid through the annular space to a maximum predetermined value; the total passage cross-section of the circulation holes is between 0.5% and 2% of the passage cross-section of the inner channel of the tap; the annular space has, along the lower peripheral edge of the sleeve, a passage cross-section of between 2% and 10% of the passage cross-section of the inner channel of the tap; the sleeve is mounted so as to be able to be removed on the crown; the pressuriser comprises a strainer which covers the inner channel of the tap and which is mounted so as to be able to be removed on the crown; the upper end portion of the sleeve is engaged between the strainer and the crown. FIG. 1 illustrates a primary coolant system 1 for a pressurised water nuclear reactor. This system 1 comprises a vessel 2 in which nuclear fuel assemblies are located, a steam generator 4 which is provided with primary and secondary portions, a primary pump 6 and a pressuriser 8. The vessel 2, the steam generator 4 and the pump 6 are connected by portions of primary pipe 10. The system 1 contains primary water, this water being delivered by the pump 6 towards the vessel 2, passing through the vessel 2 and being heated by means of contact with the fuel assemblies, then passing through the primary portion of the steam generator 4 before returning to the intake of the pump 6. The primary water heated in the vessel 2 transfers its heat in the steam generator 4 to secondary water which is passing through the secondary portion of this generator. The secondary water flows in a closed loop in a secondary system which is not illustrated. It evaporates whilst passing through the generator 4, the steam produced in this manner driving a steam turbine. The pressuriser 8 is mounted so as to branch off from the primary pipe via a duct 11 which is tapped from the portion 10 which connects the vessel 2 to the generator 4. It is arranged at a higher level than that of the pump 6 and the vessel 2. The pressuriser 8 comprises a fabricated outer casing 12 which is substantially cylindrical and has a vertical axis, and which is provided with a dome 13 and a lower base 14. The lower base 14 comprises a central hole 16 which is connected to the duct 11 by means of a tap 18 (FIG. 2). The pressuriser 8 also comprises spraying means 19 which comprise a tap 20 which extends through the dome 13, a spray nozzle 21 which is arranged inside the casing 12 and which is mounted on the tap 20, a pipe 22 which connects the tap 20 to the primary pipe, in the region of the discharge of the pump 6, and means (not illustrated) for selectively authorising or preventing the flow of primary water in the pipe 22 as far as the nozzle 21. The coolant system 1 also comprises a safety system 23 which comprises a relief tank 24, a pipe 25 which connects the tank 24 to the dome 13 of the pressuriser and a safety valve 26 which is interposed in the pipe 25 between the tank 24 and the pressuriser 8. The inner space of the pressuriser 8 is in communication with the coolant system 1 by means of the tap 18 and the duct 11 so that the pressuriser 8 is permanently partially filled with the primary water, the level of water inside the pressuriser being in accordance with the current operating pressure of the coolant system. The roof of the pressuriser 8 is filled with the water vapour, at a pressure which is substantially equal to the pressure of the water flowing in the primary pipe 10 which connects the generator 4. In the case of excess pressure in the pressuriser, the valve 26 opens and the water vapour is discharged as far as the tank 24 in which it condenses. The pressuriser 8 is equipped with several tens of electrical heaters 28. These heaters are arranged vertically and are mounted on the lower base 14. They pass through the base 14 via holes which are provided for this purpose, sealing means being interposed between the heaters and the base 14. The pressuriser 8 has the function of controlling the pressure of the water in the coolant system. Owing to the fact that it communicates with the primary pipe via the duct 11, it acts as an expansion vessel. In this manner, when the volume of water flowing in the coolant system increases or decreases, the level of water inside the pressuriser 8 will, depending on the circumstances, rise or fall. This variation of the volume of water may result, for example, from an injection of water in the coolant system, or a variation of the operating temperature of the coolant system. The pressuriser 8 also has the function of increasing or decreasing the operating pressure of the coolant system. In order to increase the operating pressure of the coolant system, the heaters 28 are supplied with electrical power so that they heat the water which is contained in the lower portion of the pressuriser and bring it to its boiling temperature. A portion of this water boils so that the pressure in the roof of the pressuriser 8 increases. Owing to the fact that the vapour is constantly in a state of hydrostatic equilibrium with the water which circulates in the coolant system 1, the operating pressure of this coolant system 1 increases. In order to reduce the operating pressure of the coolant system 1, the spray nozzle 21 is operated which is arranged in the roof of the pressuriser 8 by authorising the flow of water in the pipe 22 using means which are provided to this end. The water which is taken in the primary pipe 10 by the lift of the pump 6 is projected into the top of the pressuriser 8 and brings about the condensation of a portion of the water vapour which is located there. The pressure of the water vapour in the roof of the pressuriser 8 reduces so that the operating pressure of the coolant system 1 is also reduced. As can be seen in FIG. 2, the tap 18 places the inner space of the casing 12 of the pressuriser in communication with the duct 11. The tap 18 comprises a portion 30 which is generally cylindrical with a vertical axis, and which has a lower end which is rigidly fixed to the duct 11 by means of a weld seam 32. The cylindrical portion 30 extends upwards via a portion 34 which forms a collar and which is welded to the edges of the opening 16. The substantially cylindrical portion 30 of the tap delimits an inner channel 36 which has a vertical axis and which connects the inner space of the casing 12 to the duct 11. The tap 18 is a component which is forged from ferritic steel. The duct 11 is produced from austenitic steel. The pressuriser also comprises a cylindrical crown 38 which has an axis X and which surrounds the inner channel 36 of the tap. The crown 38 is arranged inside the casing 12 and is welded to the face 40 of the collar 34 which is directed towards the inner side of the casing 12. This face 40 has an annular form and surrounds the inner channel 36. The pressuriser further comprises a sleeve 42 for protecting the weld seam 32. The sleeve 42 is of a generally cylindrical form having a centre axis X, and is arranged in the inner channel 36 of the sleeve. It comprises a lower end portion 44 which is engaged in the duct 11 and which has a free lower peripheral edge 46. It also comprises an upper end portion 48 which extends in the inner space of the casing 12. The portion 48 extends radially outwards via a collar 50 which is rigidly fixed to the crown 38. As shown in FIG. 4, the crown 38 has an upper portion 52 which radially has a substantial thickness, and a lower portion 54 which has a reduced thickness and which is welded to the face 40. The portion 52 is delimited upwards by a unit 56 which is perforated, for example, by twenty threaded holes 58 having vertical axes. The holes 58 are regularly distributed about the axis X. The collar 50 of the sleeve rests on the face 56 and has holes 60 which are arranged so as to be coincident with the holes 58. Furthermore, the pressuriser also comprises a strainer 62 which is arranged inside the casing 12 and which covers the inner channel 36 of the tap. The strainer 62 comprises a hemispherical portion 64, which is perforated by filtration holes which are distributed over the entire surface thereof, and which is extended by a cylindrical portion 66 which is fixed to the crown 38 by means of a collar 68. As illustrated in FIG. 4, the collar 50 of the sleeve is engaged between the collar 68 of the strainer and the face 56 of the crown. The collar 68 is perforated by holes 70 which are arranged so as to be coincident with the threaded holes 58. Screws 72 extend through the holes 70 and 60 and are screwed into the holes 58. They fix both the strainer 62 and the sleeve 42 to the crown 38. The strainer 62 secures elements which may be carried in the coolant system by the primary liquid. It also acts as a diffuser and breaks the vortexes which are capable of being formed in the flow of primary liquid entering or leaving the pressuriser. The sleeve 42 defines with the cylindrical portion 30 of the tap and with the duct 11 an annular space 74 having an axis X. As shown in FIG. 3, the annular space 74 is open downwards along the entire lower peripheral edge 46. As shown in FIGS. 2 and 3, a peripheral shoulder 76 is formed on the inner face 77 of the duct 11, in the region of the lower peripheral edge 46 of the sleeve. The shoulder 76 is delimited upwards by a face 78 which extends below the edge 46 and which defines therewith an inner hole 79 of the annular space 74. The face 78 is slightly inclined downwards and is connected upwards to the inner face 77 of the duct 11 by a curved surface. The lower portion 54 of the crown 38 is perforated by four holes 80 which place the annular space 74 in communication with the inner space of the casing 12 (FIG. 5). Furthermore, the collar 50 is perforated by eight holes 82 (FIG. 4) which place the annular space 74 in communication with the inner space of the casing 12. The holes 80 and 82 are distributed regularly about the axis X. The holes 82 act as vents during the filling of the pressuriser. The passage cross-section of the holes 80 is calibrated in order to limit the flow rate of primary liquid through the annular space 74 to a maximum predetermined value. This value is selected on a case by case basis, in accordance with the operating temperature range of the nuclear reactor and the geometry of the pressuriser. The passage cross-section of the lower hole 79 of the annular space is selected to be between 2% and 10% of the passage cross-section of the inner channel 36 of the sleeve. In a typical embodiment, the spacing between the face 78 and the edge 46 is approximately 5 mm and the passage cross-section is approximately 10000 mm2. The passage cross-section of the annular space 74 is typically between 10% and 15% of the passage cross-section of the channel 36. The cumulative passage cross-section of the holes 80 is preferably between 0.5% and 2% of the passage cross-section of the channel 36. In a typical embodiment, the total passage cross-section of the holes 80 is approximately 600 mm2. Finally, four anti-vibration pads 84 which are regularly distributed about the axis X, are welded to the inner surface of the tap 18 (FIGS. 2 and 5). Their height corresponds substantially to the radial thickness of the annular space 74 so that the sleeve 42 normally rests freely on the pads 84. The pressuriser described above has a number of advantages. Owing to the fact that the annular space 74 is open downwards, along at least a portion of the lower peripheral edge of the sleeve 42, and thus opens in the duct 11, the radioactive particles cannot accumulate in this annular space and are discharged in the duct 11. Furthermore, the holes 80 which are provided in the crown 38 allow a flow of primary fluid to be created in the annular space 74. The radioactive particles which are capable of accumulating in the annular space are therefore carried by the primary liquid, which further reduces the likelihood of an accumulation of radioactive particles being produced between the sleeve and the tap or the duct. Furthermore, the lower portion of the annular space 74 is directed substantially radially towards the centre of the duct 11 and the transition between the axial portion and the radial portion of the annular space is carried out along a curve so as not to form blind angles in which the particles would be likely to accumulate. Furthermore, the face 78 which delimits the radial portion of the annular space downwards is slightly inclined downwards relative to the horizontal which facilitates the carrying of the particles by the primary fluid flowing in the annular space. The passage cross-sections of the holes 80 at the top of the sleeve are selected so as to create a predetermined localised pressure drop for the primary fluid which is passing through the annular space. The flow rate of primary fluid through the annular space is thus limited to a maximum predetermined value. The holes 80 could also be arranged in the collar 50 of the sleeve. It should be noted that the primary fluid is capable of circulating in the annular space from the duct 11 to the inner side of the casing 12 (upwards) or in the opposite direction from the inner side of the casing 12 towards the duct 11 (downwards). The geometry of the holes 80 and the lower hole 79 allows a pressure drop to be created in the two flow directions of the fluid and therefore allows the flow rate to be limited in the two possible flow directions. The fact that the lower portion of the annular space 74 is directed in a substantially radial manner contributes to limiting the flow rate of primary liquid in the annular space 74 when this liquid circulates from the primary pipe to the pressuriser. This orientation also makes it more difficult for radioactive particles carried by the primary fluid to penetrate from below into the annular space. The limitation of the flow rate of primary fluid in the annular space 74 allows the speed of the temperature variations in the region of the weld seam 32 to be limited. This is significant since the weld seam is interposed between two components (tap 18 and duct 11) which are produced from different materials and which have different coefficients of thermal expansion. The impact of the thermal and mechanical stresses in the region of the weld seam and in the entire tap 18 is therefore greatly limited as a result. Finally, the presence of the crown 38 for fixing the sleeve 42 is advantageous for mounting the strainer 62 on this crown. The strainer 62 and the sleeve 42 can be readily disassembled. The screws 72 which are readily accessible are first removed. The strainer 62 is then removed, then the sleeve 42 is extracted upwards from the tap 30. In a variant, it is possible to select the passage cross-section of the lower hole 79 so as to create a localised pressure drop to complement that created by the holes 80. It is possible that the lower hole 79 extends over the entire periphery of the lower peripheral edge 46, or over only a portion thereof. The hole 79 may be continuous or may be divided into a plurality of openings which are separated from each other.
046876057	claims	1. In an automated system of nuclear fuel rod production, the combination comprising: (a) a powder formulation and processing stage including (b) a pellet fabrication stage including (c) a pellet processing stage including (v) means for receiving said loaded boats in a successive manner after discharged from said sintering furnaces for sampling at least one of said sintered pellets therein; (vi) a plurality of pellet grinding units for grinding said sintered pellets to precise predetermined dimensions; (vii) means for unloading sintered pellets from said boat on said conveying means in single file into said pellet grinding units; (viii) a plurality of inspection units for inspecting said ground pellets; (ix) a pellet storage and retrieval unit for receiving said inspected pellets and storing the same; and (x) means for conveying said pellets in single file from said grinding units through said inspection unit to said storage and retrieval unit. (a) a radioactive powder formulation and processing stage including (b) a pellet fabrication stage including (c) a pellet processing stage including (d) a tube preparation stage including (e) a fuel rod fabrication and inspection stage including (a) a plurality of vaporization units for supplying a radioactive material in the form of a gas; (b) a plurality of kiln units connected in flow communication with said vaporization units for receiving said gas from said vaporization units and converting said radioactive material from the form of said gas to the form of a powder, said plurality of kiln units being less in number than said plurality of vaporization units, one of said kiln units being connected with a pair of said vaporization units; (c) a plurality of check hopper units being connected in flow communication with said kiln units for receiving said powder from said kiln units, for holding said powder for sampling and inspection and for dispensing said powder therefrom, said plurality of check hopper units being greater in number than said plurality of kiln units, a pair of said check hopper units being connected with one of said kiln units such that as at least one of said check hopper units of said pairs thereof is being filled from its respective one kiln unit, at least another of said check hopper units of said pairs thereof is dispensing its powder while the powder in at least still another of said check hopper units of said pairs thereof is being sampled whereby powder can be continuously dispensing from at least one of said check hopper units while in-line sampling of said powder is being carried out, each of said check hopper units being of a predetermined capacity less than geometric control of radioactive material; (d) a plurality of blending units connected in flow communication with said check hopper units for receiving said powder from said check hopper units and for blending said powder into a radioactive composition suitable for use as nuclear reactor fuel, said plurality of blending units being fewer in number than said check hopper units and greater in number than said plurality of kiln units, said blending units each having a capacity which exceeds geometric control of the radioactive material but which maintains said material under moderation control; and (e) valve means for causing the filling of one of said plurality of blending units at a time with powder from said check hopper units such that as one of said blending units is being filled, another of said blending units is being analyzed and yet another of said blending units is being dispensed whereby blended powder can be dispensed continuously from said blending units. 2. The automated system as recited in claim 1, said pellet processing state further including: 3. The automated system as recited in claim 2, wherein said pellet storage and retrieval unit contains sufficient capacity for storing said inspected pellets until needed in fuel rod fabrication. 4. In an automated system of nuclear fuel rod production, the combination comprising: 5. In an automated system of nuclear fuel rod production, a powder formulation and processing stage comprising the combination of: 6. The automated system as recited in claim 5 wherein said plurality of said blending units includes yet another blending unit containing blended powder which can be analyzed as said one of said blending units is being filled with powder and as blended powder is being dispensed from said another of said blending units.
	claims	1. An X-ray diffraction apparatus comprising:a device for generating an X-ray parallel beam to be made incident on a sample;a mirror for reflecting diffracted X-rays from the sample, wherein the mirror utilizes a diffraction phenomena and has a reflective surface which is formed so that: (i) an angle that is defined in a plane parallel to a diffraction plane becomes constant, wherein the angle is between a tangential line of the reflective surface at any point on the reflective surface and a line segment connecting said any point on the reflective surface and the sample, and (ii) a crystal lattice plane that causes reflection is parallel to the reflective surface at any point on the reflective surface; andan X-ray detector for detecting the reflected X-rays from the mirror, wherein the X-ray detector is one-dimensional position sensitive in a plane parallel to the diffraction plane;wherein a relative positional relationship between the mirror and the X-ray detector is determined, in the plane parallel to the diffraction plane, so that the reflected X-rays from different points on the reflective surface of the mirror reach different points on the X-ray detector respectively. 2. The X-ray diffraction apparatus according to claim 1, wherein the reflective surface of the mirror is shaped in an equiangular spiral in the plane parallel to the diffraction plane, a center of the equiangular spiral being located on a surface of the sample. 3. An X-ray diffraction method for an X-ray diffraction apparatus including: (i) a device for generating an X-ray parallel beam to be made incident on a sample; (ii) a mirror for reflecting diffracted X-rays from the sample, wherein the mirror utilizes a diffraction phenomena and has a reflective surface which is formed so that: (a) an angle that is defined in a plane parallel to a diffraction plane becomes constant, wherein the angle is between a tangential line of the reflective surface at any point on the reflective surface and a line segment connecting said any point on the reflective surface and the sample, and (b) a crystal lattice plane that causes reflection is parallel to the reflective surface at any point on the reflective surface; and (iii) an X-ray detector for detecting the reflected X-rays from the mirror, wherein the X-ray detector is one-dimensional position sensitive in a plane parallel to the diffraction plane; said X-ray diffraction method comprising:determining a relative positional relationship between the mirror and the X-ray detector, in the plane parallel to the diffraction plane, so that the reflected X-rays from different points on the reflective surface of the mirror reach different points on the X-ray detector respectively;allowing the X-ray parallel beam to be incident on the sample; anddetecting different diffracted X-rays, which have been reflected at the mirror and have different diffraction angles, distinctly and simultaneously. 4. The X-ray diffraction method according to claim 3, wherein the reflective surface of the mirror is shaped in an equiangular spiral in the plane parallel to the diffraction plane, a center of the equiangular spiral being located on a surface of the sample. 5. An X-ray diffraction apparatus comprising:a device for generating an X-ray parallel beam to be made incident on a sample;a mirror for reflecting diffracted X-rays from the sample, wherein the mirror utilizes diffraction phenomena and has a reflective surface comprising a combination of plural flat reflective surfaces which are located so that: (i) an angle that is defined in a plane parallel to a diffraction plane becomes constant among the plural flat reflective surfaces, wherein the angle is between each flat reflective surface and a line segment connecting a center of each respective flat reflective surface and the sample, and (ii) a crystal lattice plane that causes reflection is parallel to each respective flat reflective surface; andan X-ray detector for detecting the reflected X-rays from the mirror, wherein the X-ray detector is one-dimensional position sensitive in a plane parallel to the diffraction plane;wherein a relative positional relationship between the flat reflective surfaces and the X-ray detector is determined, in the plane parallel to the diffraction plane, so that the reflected X-rays that have been reflected at different flat reflective surfaces reach different points on the X-ray detector respectively. 6. The X-ray diffraction apparatus according to claim 5, wherein the respective centers of the flat reflective surfaces are located, in the plane parallel to the diffraction plane, on an equiangular spiral having a center that is located on a surface of the sample. 7. The X-ray diffraction apparatus according to claim 5, wherein a center of at least one of the flat reflective surfaces is shifted, in the plane parallel to the diffraction plane, from a point on an equiangular spiral having a center that is located on a surface of the sample. 8. The X-ray diffraction apparatus according to claim 5, wherein capture angular ranges of the respective flat reflective surfaces are equal to one another. 9. The X-ray diffraction apparatus according to claim 5, wherein mirror lengths L of the respective flat reflective surfaces are equal to one another. 10. The X-ray diffraction apparatus according to claim 5, wherein detection widths W assigned to the respective flat reflective surfaces are equal to one another. 11. An X-ray diffraction method for an X-ray diffraction apparatus including: (i) a device for generating an X-ray parallel beam which can be made incident on a sample; (ii) a mirror for reflecting diffracted X-rays from the sample, wherein the mirror utilizes diffraction phenomena and has a reflective surface comprising a combination of plural flat reflective surfaces which are located so that: (a) an angle that is defined in a plane parallel to a diffraction plane becomes constant among the plural flat reflective surfaces, wherein the angle is between each flat reflective surface and a line segment connecting a center of each respective flat reflective surface and the sample, and (b) a crystal lattice plane that causes reflection is parallel to each respective flat reflective surface; and (iii) an X-ray detector for detecting the reflected X-rays from the mirror, wherein the X-ray detector is one-dimensional position sensitive in a plane parallel to the diffraction plane; said X-ray diffraction method comprising:determining a relative positional relationship between the flat reflective surfaces and the X-ray detector, in the plane parallel to the diffraction plane, so that the reflected X-rays that have been reflected at different flat reflective surfaces reach different points on the X-ray detector respectively;allowing the X-ray parallel beam to be incident on the sample; anddetecting different diffracted X-rays, which have been reflected at the mirror and have different diffraction angles, distinctly and simultaneously. 12. The X-ray diffraction method according to claim 11, wherein the respective centers of the flat reflective surfaces are located, in the plane parallel to the diffraction plane, on an equiangular spiral having a center that is located on a surface of the sample. 13. The X-ray diffraction method according to claim 11, wherein a center of at least one of the flat reflective surfaces is shifted, in the plane parallel to the diffraction plane, from a point on an equiangular spiral having a center that is located on a surface of the sample.
053902190	abstract	A device for trapping migrating bodies within the steam generator or secondary circuit of a nuclear installation is constituted by grids (6) placed between the upper part of the tube casing (8) and the pressure casing (7) of the steam generator. The meshes of the grids are so dimensioned as to prevent the passage of objects liable to jam between the tubes of the tube bundle of the primary circuit.
	claims	1. A fuel assembly for a pressurized water nuclear reactor including a plurality of elongated nuclear fuel rods having an extended axial length, at least a lowermost grid supporting said fuel rods in an organized array and having unoccupied spaces defined therein adapted to allow flow of fluid coolant therethrough and past said fuel rods when said fuel assembly is installed in the nuclear reactor and a plurality of guide thimbles extending along said fuel rods through and supporting said grid, a debris filter bottom nozzle disposed below said grid, below lower ends of said fuel rods, supporting said guide thimbles and adapted to allow flow of fluid coolant into said fuel assembly, said debris filter bottom nozzle comprising a substantially horizontal plate extending substantially transverse to the axis of the fuel rods and having an upper face directed toward said lowermost grid, said upper face of said plate having defined therethrough at least two different hole designs, the first hole design being a plurality of holes receiving lower ends of said guide thimbles where they are supported by said plate and the second hole design being a plurality of flow through holes extending completely through said plate for the passage of coolant fluid from a lower face of said plate to the upper face of said plate, each of said coolant flow through holes extending substantially in the axial direction of said fuel rods, in fluid communication with said unoccupied spaces, and in the extended direction at least some of said coolant flow through holes having a profile substantially of a venturi with flaring at both ends, wherein the flaring at the lower face of said plate comprises a series of a plurality of concentric countersinks of different included angles and depths into the coolant flow through hole. 2. The nuclear fuel assembly of claim 1 wherein said coolant flow through holes having a profile substantially of a venturi have an inlet end in the lower face of said plate and an outlet end in the upper face of said plate wherein the venturi is substantially formed by the concentric countersinks of different included angles and depths into the coolant flow through hole in said inlet and a chamfer in said outlet end. 3. The nuclear fuel assembly of claim 1 wherein the inlet chamfers approximates a curved surface. 4. The nuclear fuel assembly of claim 3 wherein the chamfers have the following dimensions and angles relative to a flow axis of the flow through hole where Chamfer A is the chamfer closest to the inlet, Chamfer B is the chamfer adjacent Chamfer A and Chamfer C is at the outlet of the flow through holesNominalMaximumMinimumAngleLength (in.)Length (in.)Length (in.)Chamfer A35° ± 3°0.0170.0390.012(0.043 cm)(0.099 cm)(0.030 cm)Chamfer B15° ± 3°0.0390.0570.010(0.099 cm)(0.145 cm)(0.025 cm)Chamfer C10° ± 3°0.0850.1420.059(0.361 cm)(0.361 cm) (1.397 cm). 5. The nuclear fuel assembly of claim 3 wherein the chamfers have the following relative dimensions and angles with regard to a flow axis of the flow through hole where Chamfer A is the chamfer closest to the inlet, Chamfer B is the chamfer adjacent Chamfer A and Chamfer C is at the outlet of the flow through holes and L/T is the length of the chamfer divided by the thickness of the plateChamfer L/TAngleMaximumMinimumChamfer A2.33 × B0.0710.020Chamfer B15° +/− 3°0.1040.017Chamfer C0.67 × B0.2580.101. 6. The nuclear fuel assembly of claim 1 wherein substantially every coolant flow through hole not associated with a guide thimble has the venturi profile in the extended direction. 7. The nuclear fuel assembly of claim 1 including support means adapted to support said fuel assembly when installed in the nuclear reactor with said plate fixed at its periphery on said support means. 8. The nuclear fuel assembly of claim 1 wherein the coolant flow through holes have a substantially circular cross-section. 9. The nuclear fuel assembly of claim 8 wherein the coolant flow through holes have a 0.190+/−0.008 inch (0.48+/−0.02 cm) or less diameter at their narrowest cross-section. 10. The nuclear fuel assembly of claim 8 wherein the through coolant flow through holes are packed in a density of about 16 per square inch. 11. A debris filter bottom nozzle for a pressurized water nuclear reactor fuel assembly having a plurality of elongated nuclear fuel rods having an extended axial length, at least a lowermost grid supporting said fuel rods in an organized array and having unoccupied spaces defined therein adapted to allow flow of fluid coolant therethrough and past said fuel rods when said fuel assembly is installed in the nuclear reactor, a plurality of guide thimbles extending along said fuel rods through and supporting said grid, said debris filter bottom nozzle designed to be disposed below said grid, below lower ends of said fuel rods, to support said guide thimbles and adapted to allow flow of fluid coolant into said fuel assembly, said debris filter bottom nozzle comprising a substantially horizontal plate extending substantially transverse to the axis of the fuel rods and having an upper face to be directed toward said lowermost grid, said upper face of said plate having defined therethrough at least two different hole designs, the first hole design being a plurality of holes for receiving lower ends of said guide thimbles where they are to be supported by said plate and the second hole design being a plurality of flow through holes extending completely through said plate for the passage of coolant fluid from a lower face of said plate to the upper face of said plate, each of said coolant flow through holes when incorporated in said fuel assembly, extending substantially in the axial direction of said fuel rods, in fluid communication with said unoccupied spaces, and in the extended direction at least some of said coolant flow through holes having a profile substantially of a venturi with flaring at both ends, wherein the flaring at the lower face of said plate comprises a series of a plurality of straight, discrete, adjacent chamfers with each adjacent chamfer at a different angle than another adjacent chamfer relative to the axial direction of said fuel rods. 12. A fuel assembly for a pressurized water nuclear reactor including a plurality of elongated nuclear fuel rods having an extended axial length, at least a lowermost grid supporting said fuel rods in an organized array and having unoccupied spaces defined therein adapted to allow flow of fluid coolant therethrough and past said fuel rods when said fuel assembly is installed in the nuclear reactor, a plurality of guide thimbles extending along said fuel rods through and supporting said grid, a debris filter bottom nozzle disposed below said grid, below lower ends of said fuel rods, supporting said guide thimbles and adapted to allow flow of fluid coolant into said fuel assembly, said debris filter bottom nozzle comprising a substantially horizontal plate extending substantially transverse to the axis of the fuel rods and having an upper face directed toward said lowermost grid, said upper face of said plate having defined therethrough at least two different hole designs, the first hole design being a plurality of holes receiving lower ends of said guide thimbles where they are supported by said plate, the second hole design being a plurality of flow through holes extending completely through said plate for the passage of coolant fluid from a lower face of said plate to the upper face of said plate, each of said coolant flow through holes extending substantially in the axial direction of said fuel rods, in fluid communication with said unoccupied spaces, and at least some of said coolant flow through holes having a discrete, double chamfered inlet with each adjacent chamfer of the double chamfered inlet at a different angle than the other adjacent chamfer relative to the axial direction of said fuel rods. 13. The nuclear fuel assembly of claim 12 wherein the double chamfered inlet approximates a curved surface. 14. The nuclear fuel assembly of claim 12 wherein all of the coolant flow through holes not associated with a guide thimble include the double chamfered. 15. The nuclear fuel assembly of claim 12 wherein the chamfers have the following dimensions and angles relative to a flow axis of the flow through hole where Chamfer A is the chamfer closest to an inlet of the flow through hole and Chamfer B is the chamfer adjacent Chamfer A, spaced from the inletNominalMaximumMinimumAngleLength (in.)Length (in.)Length (in.)Chamfer A35° ± 3°0.0170.0390.012(0.043 cm)(0.099 cm)(0.030 cm)Chamfer B15° ± 3°0.0390.0570.010(0.099 cm)(0.145 cm) (0.025 cm). 16. The nuclear fuel assembly of claim 12 wherein the chamfers have the following relative dimensions and angles with regard to a flow axis of the flow through hole where Chamfer A is the chamfer closest to the inlet, Chamfer B is the chamfer adjacent Chamfer A and L/T is the length of the chamfer divided by the thickness of the plateChamfer L/TAngleMaximumMinimumChamfer A2.33 × B0.0710.020Chamfer B15° +/− 3°0.1040.017.
	summary
	abstract	An exposure apparatus includes a loading device, a first energy-producing device, and a second energy-producing device. The loading device comprises a plurality of supporting elements, supporting a panel. The first and second energy producing devices are disposed above and below the loading device, respectively.
	description	This is a continuation application of copending application Ser. No. 13/981,425, having a §371 date of Oct. 7, 2013, which is a national stage filing based on PCT International Application No. PCT/JP2011/074335, filed on Oct. 21, 2011. The copending application Ser. No. 13/981,425 is incorporated by reference herein in its entirety. The present invention relates to a scintillator plate for converting radiation transmitted by an object, into scintillation light. The conventionally known technologies for detection of X-ray images include a direct conversion method which is a method of detecting charge produced by radiation incident into a detector, thereby to directly detect the radiation, and an indirect conversion method which is a method of converting the radiation into light by means of a radiation conversion member such as a scintillator material and detecting the light by a detector. A scintillator plate with a fluorescent panel having a phosphor layer formed on a substrate is disclosed as a scintillator used in apparatus employing the aforementioned indirect conversion method (cf. Patent Literature 1 below), Patent Literature 1: Japanese Patent Application Laid-open No. 2007-139604 In the case of the conventional scintillator plate as described above, however, since the substrate is present on one side of the phosphor layer, it was difficult to observe the scintillation light emitted from both of a radiation entrance surface and a back surface behind it. Namely, it is hard to observe the scintillation light generated on the back side of the phosphor layer by radiation in a relatively high energy band. Even if we can successfully observe the scintillation light emitted from the back surface side of the scintillator plate, the scintillation light generated on the entrance surface side of the scintillator plate will also be transmitted by the scintillator plate and emitted from the back surface side thereof. Therefore, the conventional technologies failed to separately observe the scintillation light generated on the entrance surface side of the phosphor layer by radiation in a relatively low energy band and the scintillation light generated on the back surface side of the phosphor layer by radiation in a relatively high energy band, and therefore they tended to have an insufficient energy separation capability of observed radiation. The present invention has been accomplished in view of the above-described problem and it is an object of the present invention to provide a scintillator plate enabling observation of scintillation light emitted from a radiation entrance surface and a back surface behind it, thereby enabling acquisition of radiation detection images with a high energy separation capability, In order to solve the above problem, a scintillator plate according to one aspect of the present invention is a scintillator plate which is a member of a flat plate shape to emit scintillation light according to incidence of radiation transmitted by an object and which is used in an image acquisition device to condense and image the scintillation light, the scintillator plate comprising: a partition member of a planar shape which transmits radiation; a first wavelength conversion member of a fiat plate shape which is arranged on one surface of the partition member and which converts the radiation into scintillation light; and a second wavelength conversion member of a fiat plate shape which is arranged on the other surface of the partition member and which converts the radiation into scintillation light. In this scintillator plate, the two wavelength conversion members of the flat plate shape to convert the radiation into scintillation light are arranged on both sides of the partition member of the planar shape which transmits the radiation; therefore, one wavelength conversion member converts the radiation transmitted by the object, into scintillation light and the other wavelength conversion member converts the radiation transmitted by the one wavelength conversion member and the partition member, into scintillation light. At this time, the existence of the partition member makes the scintillation light beams generated respectively by the two wavelength conversion members, easier to be emitted from the respective surfaces of the two wavelength conversion members on the opposite sides with respect to the partition member. As a result, when this scintillator plate is used in the image acquisition device to condense and image the scintillation light beams emitted from the two surfaces of the scintillator plate, it can efficiently separate the high-energy radiation image and the low-energy radiation image. The present invention enables observation of the scintillation light beams emitted from the radiation entrance surface and the back surface behind it, thereby enabling acquisition of radiation detection images with a high energy separation capability. Preferred embodiments of the scintillator plate according to the present invention will be described below in detail with reference to the drawings. Identical or equivalent portions will be denoted by the same reference signs in the description of the drawings, without redundant description. It is noted that each drawing is prepared by way of illustration only and is depicted so as to emphasize each part as object of description in particular. For this reason, the dimensional ratios of respective members in the drawings are not always coincident with actual ones. FIG. 1 is a front view showing a schematic configuration of a scintillator plate 1 according to a preferred embodiment of the present invention. As shown in the same drawing, the scintillator plate 1 is a member that converts radiation such as X-rays transmitted by an object, into scintillation light, and is configured so that two scintillators 3, 4 of a flat plate shape are arranged in contact with two surfaces of a partition plate (partition member) 2 of a planar shape. The scintillators 3, 4 are wavelength conversion members that generate scintillation light according to incidence of radiation, materials of which are selected depending upon energy bands of radiation to be detected and thicknesses of which are also set to appropriate values depending upon the energy bands of radiation to be detected, in the range of several μm to several mm. For example, the materials of the scintillators 3, 4 to be used herein are selected from Gd2O2S:Tb, Gd2O2S:Pr, CsI:Tl, CdWO4, CaWO4, Gd2SiO5:Ce, Lu0.4Gd1.6SiO5, Bi4Ge3O12, Lu2SiO5:Ce, Y2SiO5, YAlO3:Ce, Y2O2S:Tb, YTaO4:Tm, and so on. The two scintillators 3, 4 may be made of the same material or of different materials. When they are made of different materials, they are set to have different conversion efficiencies for wavelengths of radiation. For example, the materials of the scintillators 3, 4 can be any one of combinations such as Gd2O2S:Tb and CsI:Tl, Gd2O2S:Tb and CdWO4, or, CsI:Tl and CdWO4. The two scintillators 3, 4 may be formed in the same thickness or in different thicknesses. When they are formed in different thicknesses, it becomes feasible to adjust sensitivities to radiation transmitted by the two scintillators 3, 4 and response characteristics to wavelengths relative to each other. For example, the thickness of the scintillator 3 can be set in the range of several μm to 300 μm and the thickness of the scintillator 4 can be set in the range of 150 μm to several mm to be thicker than the scintillator 3. The partition plate 2 is a member of a planar shape in the thickness of 0.5 μm to 5 mm for supporting the scintillators 3, 4, which has two planes 2a, 2b in contact with the two scintillators 3, 4, respectively, and which has a property of transmitting radiation as an object to be detected, and blocking scintillation light generated by the scintillators 3, 4. This partition plate 2 to be used herein is, for example, a carbon plate, a glass plate member such as an FOP (Fiber Optic Plate), an aluminum plate, a beryllium plate, a metal plate member of titanium, gold, silver, iron, or the like, or a resin plate member such as a plastic plate. The scintillator plate 1 of the above configuration is manufactured by joining plate members on which the respective scintillators 3, 4 are arranged, to each other on the side opposite to the scintillator plates 3, 4. In this case, the scintillator plate can be manufactured with relative ease. The scintillator plate 1 may also be manufactured by placing the scintillators 3, 4 respectively on both sides of the partition plate 2 of a single layer structure. The below will describe a configuration of a radiation image acquisition device for acquiring a radiation image of an object A, e.g., an electronic component such as a semiconductor device, or a foodstuff, using the scintillator plate 1 of the present embodiment. FIG. 2 is a schematic configuration diagram of the radiation image acquisition device 11 using the scintillator plate 1. As shown in the same drawing, the radiation image acquisition device 11 is provided with a radiation source 12 which emits radiation such as white X-rays toward the object A, the scintillator plate 1 which generates scintillation light according to incidence of the radiation transmitted by the object A after emitted from the radiation source 12, a front observation photodetector 13 which condenses and images the scintillation light emitted from the radiation-incidence-side detection surface 1a of the scintillator plate 1, and a back observation photodetector 14 which condenses and images the scintillation light emitted from the detection surface 1b being the surface opposite to the detection surface 1a. The scintillator plate 1 is arranged in a state in which the detection surface 1a of the scintillator 3 faces the object A. Namely, the scintillator plate 1 is so arranged that the surface 1a of the scintillator 3 opposite to the partition plate 2 is opposed to the front observation photodetector 13 and that the surface 1b of the scintillator 4 opposite to the partition plate 2 is opposed to the back observation photodetector 14. These radiation source 12, scintillator plate 1, front observation photodetector 13, and back observation photodetector 14 are housed in a housing not shown and fixed in the housing. The front observation photodetector 13 (which will be referred to hereinafter as “front detector 13”) is an imaging device of the indirect conversion method that images the scintillation light emitted from the scintillator plate 1, on the detection surface 1a side of the scintillator plate 1, to acquire a radiation transmission image of relatively low energy of the object A. The front detector 13 is a detector of a lens coupling type having a condensing lens unit 13a for condensing the scintillation light emitted from the detection surface 1a of the scintillator plate 1, and an imaging unit 13b for imaging the scintillation light condensed by the condensing lens unit 13a. The condensing lens unit 13a condenses the scintillation light in a field 15 including a predetermined range on the detection surface 1a. The imaging unit lab to be used herein is, for example, a CMOS sensor, a CCD sensor, or the like. The back observation photodetector 14 (which will be referred to hereinafter as “back detector 14”) is an imaging device of the indirect conversion method that images the scintillation light emitted from the scintillator plate 1, on the detection surface 1b side of the scintillator plate 1, to acquire a radiation transmission image of relatively high energy of the object A. The back detector 14 is a detector of the lens coupling type having a condensing lens unit 14a for condensing the scintillation light emitted from the detection surface 1b of the scintillator plate 1, and an imaging unit 14h for imaging the scintillation light condensed by the condensing lens unit 14a, and thus it has the same configuration as the aforementioned front detector 13. The condensing lens unit 14a condenses the scintillation light in a field 16 including a predetermined range on the detection surface 1b. Furthermore, the radiation image acquisition device 11 is provided with a timing control unit 17 for controlling imaging timing at the front detector 13 and at the back detector 14, an image processing device 18 for receiving input image signals output from the front detector 13 and from the back detector 14 and executing a predetermined processing procedure such as image processing based on each of the input image signals, and a display device 19 for receiving an input image signal output from the image processing device 18 and displaying a radiation image. The image processing herein can be, for example, an inter-image operation to create a differential image or an addition image between the input relatively-low-energy image and relatively-high-energy image. The timing control unit 17 and the image processing device 18 are composed of a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), input/output interfaces, and so one The display device 19 to be used herein is a well-known display. The timing control unit 17 and the image processing device 18 may, be configured as a program executed by a single computer or as respective units provided individually. The radiation source 12 is arranged so that the optical axis X of radiation makes a predetermined angle θ (0°<θ<90°) with respect to a normal B to the detection surface 1a of the scintillator plate 1. Namely, the radiation source 12 is located at a position where it faces the object A and the detection surface 1a and is set of the normal B to the detection surface 1a. The normal B here is a straight line extending normally to the detection surface 1a from a certain point on the detection surface 1a. The front detector 13 is arranged so that the optical axis of the incorporated condensing lens unit 13a is perpendicular to the detection surface 1a, so as to be able to image the scintillation light emitted from the detection surface 1a of the scintillator plate 1. In this configuration, the optical axis of the condensing lens unit 13a is coincident with the normal B to the detection surface 1a. Namely, the front detector 13 faces the detection surface 1a and is arranged on the normal B to the detection surface 1a. This condensing lens unit 13a condenses the scintillation light emitted in the direction of the normal B from the detection surface 1a, toward the imaging unit 13b. As described above, the front detector 13 is arranged of the optical axis X of the radiation source 12, Namely, the front detector 13 is arranged so as to be located apart from a radiation emission region (region where a radiation beam 20 exists) from the radiation source 12. This arrangement prevents the front detector 13 from being exposed to the radiation from the radiation source 12 and prevents a direct conversion signal of radiation from being produced inside the front detector 13 to generate noise. Furthermore, the back detector 14 is arranged so that the optical axis of the incorporated condensing lens unit 14a is perpendicular to the detection surface 1b, so as to be able to in the scintillation light emitted from the detection surface 1b of the scintillator plate 1. In this configuration, the optical axis of the condensing lens unit 14a is coincident with a normal C to the detection surface 1b. Namely, the back detector 14 faces the detection surface 1b and is arranged on the normal C to the detection surface 1b. The normal C here is a straight line extending normally to the detection surface 1b from a certain point on the detection surface 1b. In the radiation image acquisition device 11, the normal C is coincident with the normal B. The condensing lens unit 14a condenses the scintillation light emitted in the direction of the normal C from the detection surface 1b, toward the imaging unit 14b. The following will describe the operation of the radiation image acquisition device 11 having the above-described configuration. First, X-rays are emitted from the radiation source 12 toward the object whereupon the scintillation light emitted from the detection surface 1a becomes light resulting mainly from conversion of low energy components of incident radiation. On the other hand, the scintillation light emitted from the detection surface 1b becomes light resulting mainly from conversion of high energy components of incident radiation. This is because the radiation in the low energy band is likely to be converted into the scintillation light on the detection surface 1a side inside the scintillator 3 of the scintillator plate 1, while the radiation in the high energy band is likely to pass through the scintillator 3 and the partition plate 2 of the scintillator plate 1 and to be converted into the scintillation light near the detection surface 1b inside the scintillator 4. In this connection, the scintillator 3 which faces the object A and converts the radiation in the relatively low energy band is preferably thicker than the scintillator 4 which converts the radiation in the relatively high energy band. In this case, the scintillator 3 is more likely to cut the radiation in the low energy band and the radiation in the higher energy band becomes more likely to be converted into scintillation light on the detection surface 1b side of the scintillator 4; therefore, energy separation of radiation images acquired by the front detector 13 and the back detector 14 is more improved. When the energy of the radiation source 12 is low overall, the thickness of the scintillator 3 can be decreased to enhance efficiency of conversion of lower energy and increase the transmittance of high-energy radiation, so as to increase the conversion efficiency in the scintillator 4, thereby enhancing the energy separation performance. On the other hand, when the energy of the radiation source 12 is high overall, the thickness of the scintillator 3 can be increased to facilitate conversion of radiation of low energy to middle energy in the scintillator 3 and change a ratio of cutting the radiation in the low energy band, so as to facilitate conversion of radiation in the high energy band in the scintillator 4, thereby improving the energy separation performance. The timing control unit 17 performs control to make the front detector 13 and the back detector 14 simultaneously carry out their respective imaging operations with the X-ray irradiation as described above. The dual imaging of radiation images of the object A on both of the front and back surfaces is executed based on timing control by the timing control unit 17. In this dual imaging, the front detector 13 acquires the radiation image in the relatively low energy band and the back detector 14 the radiation image in the relatively high energy band. This operation results in acquiring the radiation images in the different energy bands, thus realizing dual energy imaging. The functions of the front detector 13 and the back detector 14 will be specifically described in more detail; the front detector 13 detects a fluorescent image on the detection surface 1a side. The detection of the fluorescent image on the detection surface 1a side is characterized by little blur of fluorescence and high luminance of fluorescence. This is because the front observation is less affected by blur inside the scintillator plate 1 and by diffusion and self-absorption inside the scintillator plate 1. On the other hand, the back detector 14 detects a fluorescent image formed on the detection surface 1b side after travel in the thickness direction in the scintillator plate 1. Next, the front detector 13 and the back detector 14 output their respective image signals corresponding to the radiation images on the front and back surfaces, to the image processing device 18. When the image processing device 18 receives the respective input image signals from the front detector 13 and from the back detector 14, the image processing device 18 executes the predetermined processing based on the input image signals and outputs an image signal after the image processing to the display device 19. When the display device 19 receives the input image signal after the image processing from the image processing device 18, the display device 19 displays a radiation image according to the input image signal after the image processing. In the radiation image acquisition device 11, the radiation source 12 is arranged at the position off the normal B to the detection surface 1a and, the front detector 13 and the back detector 14 are arranged on the normals B and C, respectively; therefore, no detector shadow is cast on the radiation transmission images, so as to suppress generation of noise component and it causes no attenuation of radiation due to the detectors, thus preventing reduction of signal components. Furthermore, the front detector 13 and the back detector 14 are prevented from being exposed to the radiation and generation of noise is suppressed inside the front detector 13. As a consequence, the low-energy image and the high-energy image can be simultaneously acquired by one shot, so as to ensure simultaneity, reduce an exposure dose, decrease an imaging time, and avoid pixel shifts (misregistration). In addition, the front detector 13 and the back detector 14 both can acquire the radiation images without perspective, which facilitates the operation between the images on the detection surface 1a side and on the detection surface 1b side. It is noted herein that the above-described radiation image acquisition device 11 may be configured with change in positional relationship among the radiation source 12, the front detector 13, and the hack detector 14 as described below. Specifically, as shown in FIG. 3, the radiation source 12 may be arranged to face the object A and the detection surface 1a on the normal to the detection surface 1a and the front detector 13 may be arranged so that the optical axis B of the condensing lens unit 13a makes a predetermined angle θ1 (0°<θ1<90°) with respect to the normal to the detection surface 1a; that is, the front detector 13 may be arranged opposite to the detection surface 1a and off the normal to the detection surface 1a. In this case as well, no detector shadow is cast on the radiation transmission images, so as to suppress reduction of signal components. Furthermore, the front detector 13 is prevented from being exposed to the radiation and generation of noise is suppressed inside the front detector 13. In addition, the back detector 14 can acquire the radiation image without perspective, and the radiation image acquired by the front detector 13 can be corrected for perspective, using the radiation image acquired by the hack detector 14 as a reference image, which facilitates the operation between the images on the detection surface 1a side and on the detection surface 1b side. As shown in FIG. 4, the back detector 14 may be arranged so that the optical axis C of the condensing lens unit 14a makes a predetermined angle θ2 (0°<θ2<90°) with respect to the normal to the detection surface 1b; that is, the back detector 14 may be arranged opposite to the detection surface 1b and off the normal to the detection surface 1b. In this case, the back detector 14 is also prevented from being exposed to the radiation and generation of noise is suppressed inside the back detector 14. In addition, the front detector 13 and the back detector 14 can acquire the radiation images with the same perspective, which facilitates the operation between the images on the detection surface 1a side and on the detection surface 1b side. For more facilitating the inter-image operation, it is desirable to make the angle θ1 and the angle θ2 equal to each other. FIG. 5 is a schematic configuration diagram of another radiation image acquisition device 31 using the scintillator plate 1. The radiation image acquisition device 31 shown in the same drawing is a device that can acquire the low-energy image and the high-energy image by a single detector, and is provided with the radiation source 12, the scintillator plate 1 arranged so that the detection surface 1a thereof is approximately perpendicular to the emission direction of the radiation from the radiation source 12, a photodetector 34 which images light resulting from conversion by the scintillator plate 1, and an optical system 35 which guides the light resulting from the conversion by the scintillator plate 1, as radiation transmission images to the photodetector 34. This photodetector 34 is a detector of the indirect conversion method having a condensing lens unit 34a and an imaging unit 34b as the detectors 13, 14 in FIG. 2 are. The optical system 35 is composed of five mirrors 36a, 36b, 37a, 37b, and 38 as optical members to control optical paths of the scintillation light emitted from the scintillator plate 1, and a rotary drive mechanism 39, to rotate the mirror 38. The mirrors 36a, 36b in the optical system 35 are arranged on the detection surface 1a side of the scintillator plate 1 and guide the scintillation light L1 emitted from the detection surface 1a, to the mirror 38 arranged at a distant position along an extending direction of the detection surface 1a from the scintillator plate 1. The mirrors 37a, 37b in the optical system 35 are arranged on the detection surface 1b side of the scintillator plate 1 and guide the scintillation light L2 emitted from the detection surface 1b, to the mirror 38. The mirror 38 in the optical system 35 is arranged so that a normal to a reflective surface 38a thereof is approximately parallel to a plane including the optical paths of the scintillation light L1, L2. The mirror 38 is supported so as to be rotatable around an axis approximately perpendicular to the plane including the optical paths of the scintillation light L1, L2 by the rotary drive mechanism 39 incorporating a motor. The mirror 38 supported by the rotary drive mechanism 39 as described above selectively guides the scintillation light L1, L2 toward the photodetector 34 arranged further away along the extending direction of the detection surface 1a from the mirror 38. Namely, when the rotary drive mechanism 39 rotates the mirror 38 so as to make the reflective surface 38a face the mirror 36b (as indicated by a solid line in FIG. 1), the scintillation light L1 is reflected toward the condensing lens unit 34a of the photodetector 34. On the other hand, when the rotary drive mechanism 39 rotates the mirror 38 so as to make the reflective surface 38a face the mirror 37b (as indicated by a double-dashed chain line in FIG. 1), the scintillation light L2 is reflected toward the condensing lens unit 34a of the photodetector 34. Furthermore, the radiation image acquisition device 31 is provided with a rotation control unit 41 for controlling rotation of the rotary drive mechanism 39, a timing control unit 42 for controlling timing of selection of the scintillation light L1, L2 by the mirror 38 and timing of imaging of the photodetector 34, and the image processing device 18 for processing image signals output from the photodetector 34. In more detail, the rotation control unit 41 sends a control signal to the rotary drive mechanism 39 in accordance with a command signal from the timing control unit 42 to control an angle of rotation of the mirror 38. The timing control unit 42 sends a command signal to the rotation control unit 41 to change over the rotation angle of the mirror 38 so as to reflect the scintillation light L1 toward the photodetector 34, and at the same time, it sends a command signal to the photodetector 34 to image the scintillation light L1 in synchronism with the changeover of the mirror 38. Furthermore, the timing control unit 42 sends a command signal to the rotation control unit 41 to change over the rotation angle of the mirror 38 so as to reflect the scintillation light L2 toward the photodetector 34, and at the same time, it sends a command signal to the photodetector 34 to image the scintillation light L2 in synchronism with the changeover of the mirror 38. The image processing device 18 acquires two image signals obtained as the result of the imaging of the scintillation light L1, L2 from the photodetector 34 and processes those two image signals to generate radiation transmission image data about the object A. In the radiation image acquisition device 31 of this configuration, since the scintillation light beams L1, L2 emitted from the two surfaces of the scintillator plate 1 are guided via the optical system 35 to the photodetector 34, the photodetector 34 can be located apart from the radiation emission region. This arrangement prevents a shadow of the detector from being cast on the radiation projection images of the object A and also prevents the low-energy components of the radiation from being attenuated by the detector. There is also little direct conversion noise generated due to incidence of the radiation into the detector itself. Since the single detector can acquire the radiation transmission image of low energy components and the radiation transmission image of high energy components, it is easy to achieve downsizing of the device. The below will describe the operational effect of the scintillator plate 1 described above. Since in the scintillator plate 1 the two scintillators 3, 4 of the flat plate shape to convert radiation into scintillation light are arranged on both sides of the partition plate 2 of the planar shape which transmits the radiation, one scintillator 3 converts the radiation transmitted by the object A, into scintillation light and the other scintillator 4 converts the radiation after transmitted by the scintillator 3 and the partition plate 2, into scintillation light. At this time, the existence of the partition plate 2 makes the scintillation light beams generated in the two scintillators 3, 4, easier to be emitted from the surfaces 1a, 1b of the two scintillators 3, 4 on the opposite sides with respect to the partition plate 2. As a result, when this scintillator plate 1 is used in the radiation image acquisition device 11, 31 for condensing and imaging the scintillation light beams emitted from the two surfaces 1a, 1b of the scintillator plate 1, the high-energy radiation image and the low-energy radiation image can be efficiently separated. Since the partition plate 2 has the property of blocking scintillation light, it can securely prevent the scintillation light generated in one of the scintillators 3, 4 from entering the other of the scintillators 3, 4 and thus can enhance the energy separation capability of radiation images. When, the wavelength conversion members highly sensitive to radiation in different energy bands are used as the materials of the scintillator 3 and the scintillator 4, the energy separation capability of radiation images can be more enhanced. Furthermore, when the thickness of the scintillator 3 is made different from the thickness of the scintillator 4, the detection sensitivities of radiation images in the different energy bands can be adjusted to each other, so as to simplify the image processing such as level correction. It should be noted that the present invention is by no means intended to be limited to the foregoing embodiments. For example, like a scintillator plate 101 which is a modification example of the present invention shown in FIG. 6, a reflective surface 102a or 102b to reflect the scintillation light generated by the scintillator 3 or 4 may be formed on each or either one of two surfaces of a partition plate 102. Such reflective surface 102a, 102b is formed on each or either one of the two surfaces of the partition plate 102 by evaporating aluminum thereon, by bonding a thin film of aluminum thereto, by coating the surface with metal particles transmitting radiation, in the thickness of not more than 0.1 μm, or by applying a white paint thereto. The reflective surface 102a, 102b may be formed by making the partition plate 102 itself of an aluminum plate or the like and mirror-polishing each or either one of two surfaces thereof. Furthermore, the reflective surface 102a, 102b may be arranged on each or either one of the two surfaces of the partition plate 102 by first forming the reflective surface 102a, 102b on the surface of the scintillator 3, 4 and then joining the scintillators 3, 4 to the partition plate 102. The configuration as described above allows the scintillator plate to securely prevent the scintillation light generated in one of the scintillators 3, 4 from entering the other scintillator 3 or 4 and also allows the radiation image acquisition device 11, 31 to efficiently detect the scintillation light. This allows acquisition of radiation images with high contrast while enhancing the energy separation capability of radiation images. The partition plate 2 of the scintillator plate does not have to be limited to the one having the property of blocking the scintillation light generated in the scintillators 3, 4 but may be one having a filter function to block a partial wavelength region of the scintillation light. This configuration also allows the scintillator plate to efficiently separate the high-energy radiation image and the low-energy radiation image in desired ranges. Furthermore, the partition plate 2 is not limited to the one that transmits all the energy components of incident radiation, but may be one having a property of blocking radiation in a low energy region. In this case, incidence of the scintillation light generated by the radiation in the low energy region can be reduced in the scintillator 4 on the back side, which can further enhance the energy separation capability. Preferably, the partition member has the property of blocking the scintillation light. The provision of the partition plate of this type can securely prevent the scintillation light generated in one wavelength conversion member from entering the other wavelength conversion member and thus enhance the energy separation capability of radiation images. The partition plate is also preferably one wherein the reflective surface which reflects the scintillation light is formed. This configuration securely prevents the scintillation light generated in one wavelength conversion member from entering the other wavelength conversion member and enables efficient detection of the scintillation light by the image acquisition device. This makes it feasible to acquire the radiation images with high contrast while enhancing the energy separation capability of radiation images. Furthermore, the first wavelength conversion member and the second wavelength conversion member are preferably formed of different materials. In this case, the use of the wavelength conversion members highly sensitive to radiation in different energy bands can further enhance the energy separation capability of radiation images. Yet furthermore, the first wavelength conversion member and the second wavelength conversion member preferably have, different thicknesses. By adopting this configuration, it becomes feasible to adjust the detection sensitivities of radiation images in different energy bands to each other. The present invention is applicable to the use as the scintillator plate for converting radiation transmitted by an object into scintillation light and enables observation of scintillation light emitted from a radiation entrance surface and a hack surface behind it, thereby enabling acquisition of radiation detection images with a high energy separation capability. 1, 101 scintillator plate; 2, 102 partition plate; 2a, 2b arrangement surfaces; 3, 4 scintillators; 11, 31 radiation image acquisition device; 102a, 102b reflective surfaces; A object.
	abstract	A system for monitoring a state of a reactor core in a nuclear reactor may include an internal monitoring device located inside the reactor core, the internal monitoring device including one or more internal sensor arrays configured to take measurements of conditions of the reactor core at different vertical regions within the reactor core to generate internal measurement data; an external monitoring device located in the reactor structure outside the reactor core, the external monitoring device including one or more external sensor arrays configured to take measurements of conditions of the reactor core at positions outside the reactor core corresponding the plurality of different vertical regions within the reactor core to generate external measurement data, and a transmitter configured to wirelessly transmit the external measurement data; and a receiver station configured to determine a state of the reactor core based on the external and internal measurement data.
	description	The present application is a continuation-in-part application which claims priority from all the following applications: U.S. patent application Ser. No. 12/697,322, filed Feb. 1, 2010, which is a divisional application of U.S. Ser. No. 11/087,844, filed Mar. 23, 2005, which claims priority from U.S. Provisional Application Ser. No. 60/555,600, filed Mar. 23, 2004, and Provisional Application Nos. 60/564,416, 60/564,417 and 60/564,469, each filed Apr. 22, 2004, the disclosures of all of which are incorporated herein by reference. 1. Field of the Invention The present invention generally relates to a zirconium based alloy usable for the formation of strips and tubing for use in nuclear fuel reactor assemblies. Specifically, the invention relates to new technology that improves the in-reactor corrosion and/or the in-reactor creep of Zr—Nb based alloys by an essential and critical final heat treatment. The invention was applied to Zr—Nb based alloys that were developed by alloying element additions and exhibit improved corrosion resistance in water based reactors under elevated temperatures. 2. Description of the Prior Art In the development of nuclear reactors, such as pressurized water reactors and boiling water reactors, fuel designs impose significantly increased demands on all of the fuel components, such as cladding, grids, guide tubes, and the like. Such components are conventionally fabricated from zirconium-based alloys commercially titled ZIRLO, corrosion resistant alloys that contain about 0.5-2.0 wt. % Nb; 0.9-1.5 wt. % Sn; and 0.09-0.11 wt. % of a third alloying element selected from Mo, V, Fe, Cr, Cu, Ni, or W, with the rest Zr, as taught in U.S. Pat. No. 4,649,023 (Sabol et al.). That patent also taught compositions containing up to about 0.25 wt. % of the third alloying element, but preferably about 0.1 wt %. Sabol et al., in “Development of a Cladding Alloy for High Burnup” Zirconium in the Nuclear Industry: Eighth International Symposium, L. F. Van Swan and C. M. Eucken, Eds., American Society for Testing and Materials, ASTM STP 1023, Philadelphia, 1989. pp. 227-244, reported improved properties of corrosion resistance for ZIRLO (0.99 wt. % Nb, 0.96 wt. % Sn, 0.10 wt. % Fe, remainder primarily zirconium) relative to Zircaloy-4. There have been increased demands on such nuclear core components, in the form of longer required residence times and higher coolant temperatures, both of which cause increase alloy corrosion. These increased demands have prompted the development of alloys that have improved corrosion and hydriding resistance, as well as adequate fabricability and mechanical properties. Further publications in this area include U.S. Pat. No. 5,940,464; 6,514,360 (Mardon et al. and Jeong et al.) and Reexamination Certificate U.S. Pat. No. 5,940,464 C1 (both Mardon et al.), and the paper “Advanced Cladding Material for PWR Application: AXIOM™”, Pan et al., Proceedings of 2010 LWR Fuel Performance/Top Fuel/WRFPM, Orlando, Fla. 09/26-29/2010 (“technical paper”). Mardon et al. taught zirconium alloy tubes for forming the whole or outer portion of a nuclear fuel cladding or assembly guide tube having a low tin composition: 0.8-1.8 wt. % Nb; 0.2-0.6 wt. % Sn, 0.02-0.4 wt. % Fe, with a carbon content of 30-180 ppm, a silicon content of 10-120 ppm and an oxygen content of 600-1800 ppm, with the rest Zr. Jeong et al. taught a niobium containing zirconium alloy for high burn-up nuclear fuel application containing Nb, Sn, Fe, Cr, Zr with possible addition of Cu. The Pan et al. “technical paper” lists Alloys listed as X1, X4, X5, X5A, but deliberately only very generally describes the actual composition weight percentages, being very vague in this regard. Pan et al. reports tensile strength, elongation and creep test data, and shows micrographs and in-reactor corrosion and oxide thickness data. Aqueous corrosion in zirconium alloys is a complex, multi-step process. Corrosion of the alloys in reactors is further complicated by the presence of an intense radiation field which may affect each step in the corrosion process. In the early stages of oxidation, a thin compact black oxide film develops that is protective and retards further oxidation. This dense layer of zirconia exhibits a tetragonal crystal structure which is normally stable at high pressure and temperature. As the oxidation proceeds, the compressive stresses in the oxide layer cannot be counterbalanced by the tensile stresses in the metallic substrate and the oxide undergoes a transition. Once this transition has occurred, only a portion of the oxide layer remains protective. The dense oxide layer is then renewed below the transformed oxide. A new dense oxide layer grows underneath the porous oxide. Corrosion in zirconium alloys is characterized by this repetitive process of growth and transition. Eventually, the process results in a relatively thick outer layer of non-protective, porous oxide. There have been a wide variety of studies on corrosion processes in zirconium alloys. These studies range from field measurements of oxide thickness on irradiated fuel rod cladding to detailed micro-characterization of oxides formed on zirconium alloys under well-controlled laboratory conditions. However, the in-reactor corrosion of zirconium alloys is an extremely complicated, multi-parameter process. No single theory has yet been able to completely define it. Corrosion is accelerated in the presence of lithium hydroxide. As pressurized water reactor (PWR) coolant contains lithium, acceleration of corrosion due to concentration of lithium in the oxide layer must be avoided. Several disclosures in U.S. Pat. Nos. 5,112,573 and 5,230,758 (both Foster et al.) taught an improved ZIRLO composition that was more economically produced and provided a more easily controlled composition while maintaining corrosion resistance similar to previous ZIRLO compositions. It contained 0.5-2.0 wt. % Nb; 0.7-1.5 wt. % Sn; 0.07-0.14 wt. % Fe and 0.03-0.14 wt. % of at least one of Ni and Cr, with the rest Zr. This alloy had a 520° C. high temperature steam weight gain at 15 days of no more than 633 mg/dm2. U.S. Pat. No. 4,938,920 to Garzarolli teaches a composition having 0-1 wt. % Nb; 0-0.8 wt. % Sn, and at least two metals selected from iron, chromium and vanadium. However, Garzarolli does not disclose an alloy that had both niobium and tin, only one or the other. Sabol et al. in “In-Reactor Corrosion Performance of ZIRLO and Zircaloy-4,” Zirconium in the Nuclear Industry: Tenth International Symposium, A. M. Garde and E. R. Bradley Eds., American Society for Testing and Materials, ASTM STP 1245, Philadelphia 1994, pp. 724-744, demonstrated that, in addition to improved corrosion performance, ZIRLO material also has greater dimensional stability (specifically, irradiation creep and irradiation growth) than Zircaloy-4. More recently, U.S. Pat. No. 5,560,790 (Nikulina et al.) taught zirconium-based materials having high tin contents where the microstructure contained Zr—Fe—Nb particles. The alloy composition contained: 0.5-1.5 wt. % Nb; 0.9-1.5 wt. % Sn; 0.3-0.6 wt. % Fe, with minor amounts of Cr, C, 0 and Si, with the rest Zr. While these modified zirconium based compositions are claimed to provide improved corrosion resistance as well as improved fabrication properties, economics have driven the operation of nuclear power plants to higher coolant temperatures, higher burn-ups, higher concentrations of lithium in the coolant, longer cycles, and longer in-core residence times that have resulted in increased corrosion duty for the cladding. Continuation of this trend as burn-ups approach and exceed 70,000 MWd/MTU will require further improvement in the corrosion properties of zirconium based alloys. The alloys of this invention provide such corrosion resistance. Another potential way to increase corrosion resistance is through the method of forming of the alloy itself. To form alloy elements into a tubing or strip, ingots are conventionally vacuum melted and beta quenched, and thereafter formed into an alloy through a gauntlet of reductions, intermediate anneals, and final anneals, wherein the intermediate anneal temperature is typically above 1105° F. for at least one of the intermediate anneals. In U.S. Pat. No. 4,649,023 to Sabol et al., the ingots are extruded into a tube after the beta quench, beta annealed, and thereafter alternatively cold worked in a pilger mill and intermediately annealed at least three times. While a broad range of intermediate anneal temperatures are disclosed, the first intermediate anneal temperature is preferably 1112° F., followed by a later intermediate anneal temperature of 1076° F. The beta annealing step preferably uses temperatures of about 1750° F. Foster et al., in U.S. Pat. No. 5,230,758, determined the formability and steam corrosion for intermediate anneal temperatures of 1100° F., 1250° F., and 1350° F. An increase in intermediate anneal temperature is associated with an increase in both formability and corrosion resistance. U.S. Pat. No. 5,887,045 to Mardon et al. discloses an alloy forming method having at least two intermediate annealing steps carried out between 1184° to 1400° F. Note that the prior art for corrosion improvement summarized above involves alloying element additions and different intermediate anneal temperatures, but, notably, not the final anneal heat treatment temperature. Rudling et al., in, “Corrosion Performance of Zircaloy-2 and Zircaloy-4 PWR Fuel Cladding,” Zirconium in the Nuclear Industry: Eight International Symposium, ASTM STP 1023, L. F. Van Swam and C. M. Eucken, eds. American Society for Testing and Materials, Philadelphia, 1989, pp. 213-226, reported that Zr-4 fuel rod cladding fabricated from the same ingot with final heat treatments of stress-relieved (SRA) and fully recrystallized (RXA) exhibited similar oxide thickness corrosion (see Table 1). TABLE 1Post irradiation oxide thickness of Zr-4cladding after 1-cycle of irradiation.Final Heat4 Rod Average of the MaximumTreatmentOxide Thickness (μm)SRA12 +/− 1RXA10 +/− 1 Foster et al., in U.S. Pat. No. 5,125,985, presents a straightforward method of controlling the creep by use of the final area reduction and intermediate anneal temperature. A decrease in final area reduction decreases creep, and an increase in intermediate anneal temperature decreases creep. In different applications, the in-reactor creep can be more important than in-reactor corrosion. One such example is fuel rods containing fuel pellets coated with ZrB2. ZrB2 is a neutron absorber. When neutrons are absorbed, He gas is released which increases the rod internal pressure. In this case, creep resistant cladding is necessary so that the fuel/cladding gap remains closed. A closed fuel/cladding gap ensures that the fuel temperatures do not increase due to the formation of a He gas gap between the fuel and cladding. The new technology presented below in the Summary of the Invention will show that either the cladding corrosion or the cladding in-reactor creep may be improved by the final heat treatment. A further issue in nuclear reactors is corrosion of welds utilized in a nuclear fuel assembly. In a typical fuel rod, nuclear fuel pellets are placed within the cladding, which is enclosed by end caps on either end of the cladding, such that the end caps are welded to the cladding. The weld connecting the end caps to the cladding, however, generally exhibits corrosion to an even greater extent than the cladding itself, usually by a factor of two over non-welded metal. Rapid corrosion of the weld creates an even greater safety risk than the corrosion of non-welded material, and its protection has previously been ignored. In addition, grids have many welds and the structural integrity depends on adequate weld corrosion resistance. Thus, there continually remains a vital need, even in this late stage of nuclear power development, for novel zirconium cladding alloys that exhibit improved corrosion resistance and improved in-reactor irradiation creep resistance over known alloys in the field, and improved welds for holding end caps on claddings and for joining grid straps that likewise exhibit increased corrosion resistance. And, as can be seen, these cladding art patents and papers provide an extremely compact art area, where only very minor changes have shown, after extended testing, major and dramatic improvements. Thus, minor improvements can easily establish patentability in this specific area. Accordingly, an object of the present invention is to provide Zr—Nb alloys with improved corrosion resistance and/or improved in-reactor irradiation creep resistance through the selection of a specific type combination of final heat treatment. New technology presented below in the Summary of the Invention, and elsewhere in the specification following, will show that the in-reactor corrosion is, in part, unexpectedly dependent on the specific type of final heat treatment. The Zr—Nb alloys of this invention have improved alloy chemistry, improved weld corrosion resistance, and improved method of formation of alloys having reduced intermediate anneal temperatures during formation of the alloys. The new technology showing the effect of an essential and critical final heat treatment (and the final microstructure) on the in-reactor corrosion of Zr—Nb—Sn—Fe type alloys is presented in FIGS. 1 and 2. FIG. 1 shows the in-reactor oxide thickness corrosion data for 0.77 weight % Sn ZIRLO irradiated for 1, 2 and 3 cycles in the Vogtle Unit 2 PWR. All of the cladding was fabricated from the same ingot and received identical processing except for the final heat treatment. The cladding was given 3 different final anneal heat treatments of stress relief annealed (“SRA”), partially recrystallized (“PRXA”) and fully recrystallized (“RXA”). The amount of recrystallization in the PRXA heat treatment was about 15-20%. A generic composition useful in this invention, to provide unexpected results in corrosion resistance and/or in-reactor irradiation creep resistance, is an alloy comprising: 0.2 to 1.5 weight percent niobium, 0.01 to 0.6 weight percent iron, and additional alloying elements selected from the group consisting of: 0.0 to 0.8 weight percent tin 0.0 to 0.5 weight percent chromium 0.0 to 0.3 weight percent copper 0.0 to 0.3 weight percent vanadium 0.0 to 0.1 weight percent nickel, with the balance at least 97 weight percent zirconium, including impurities, wherein said alloy is characterized in that it has improved corrosion resistance properties due to a final heat treatment selected from one of i) SRA or PRXA (15-20% RXA) providing low corrosion; or ii) RXA or PRXA (80-95% RXA) providing low creep rate. Impurities mean less than 60 ppm or 0.006 wt. %. Other more specific compositions are set forth in the specification and claims. Referring now to the drawings; FIG. 1 very importantly shows that the oxide thickness depends on the final heat treatment. FIG. 1 presents the corrosion of 0.77 Sn ZIRLO. All of the cladding was fabricated from the same ingot and received identical processing except for the final heat treatment. The cladding was given three final heat treatments of SRA, PRXA and RXA. The highest corrosion (highest oxide thickness) was exhibited by cladding with the RXA —fully recrystallized—final heat treatment. Significantly lower corrosion was exhibited by cladding with both SRA and PRXA (15% to 20%) final heat treatments. FIG. 2 very importantly shows the in-reactor oxide thickness corrosion data for Standard ZIRLO (1.02 weight % Sn) irradiated for 1, 2 and 3 cycles in the Vogtle Unit 2 PWR. All of the cladding was fabricated from the same ingot and received identical processing except for the final heat treatment. The cladding was given 2 different final anneal heat treatments of SRA and RXA. FIG. 2, very importantly, shows that the oxide thickness depends on the final heat treatment as exhibited by the 0.77 weight % Sn ZIRLO data in FIG. 1. The highest corrosion (highest oxide thickness) was exhibited by cladding with the RXA final heat treatment. Significantly lower corrosion was exhibited by cladding with the SRA final heat treatment. As discussed above, depending on the application, improved in-reactor creep resistance can be as important as improved corrosion resistance. The in-reactor creep is also dependent on the final heat treatment. FIG. 3, very importantly, presents the in-reactor steady state creep rate for 0.77 weight % Sn ZIRLO irradiated for 1, 2 and 3 cycles in the Vogtle Unit 2 PWR (see paragraph 13). FIG. 3 shows that the highest in-reactor creep resistance (that is, the lowest in-reactor creep rate) is exhibited by cladding with a RXA final heat treatment. The lowest in-reactor creep resistance (that is, the highest in-reactor creep rate) is exhibited by cladding with a SRA final heat treatment. Intermediate in-reactor creep resistance is exhibited by the PRXA final heat treatment. Thus, both SRA and PRXA are effective in this regard with RXA the best. Hence, the effect of final heat treatment on in-reactor creep is opposite that of in-reactor corrosion. As a result, the cladding may be optimized for either maximum improved in-reactor corrosion resistance with a SRA or PRXA (15-20% RXA) final heat treatment, or maximum improved in-reactor creep resistance with a final PRXA (80-95% RXA) or RXA heat treatment. In more substantial detail, each of these “terms,” RXA, PRXA, SRA, etc. is defined as: SRA means—heat treatment where the microstructure is stress-relief annealed. RXA means—heat treatment where the microstructure is fully recrystallized. PRXA (15-20% RXA) means—heat treatment where 15-20% of the microstructure is recrystallized and 80-85% of the microstructure is stress relief annealed. PRXA (80-95% RXA) means—heat treatment where 80-95% of the microstructure is recrystallized and 5-20% of the microstructure is stress relief annealed. Note that the above SRA, PRXA and RXA designations represent more detailed descriptions of the final heat treatment process methods. It should be clear that this art area is not an area in patent filing where broad conclusions are suggestive of improved alloys within broad ranges; where, for example, 0.4 to 1.5 weight percent niobium and 0.1 to 0.8 weight percent tin, should be considered taught or obvious in view of a teaching of 0.0 to 3.0 weight percent niobium and 0.1 to 3.5 weight percent tin. As shown in FIG. 4, standard Zirlo compared to compositions X4 and X5 shows the dramatic difference a few tenths of weight percent elements make in this area: Standard Zirlo: 0.5-2 wt % Nb; 0.9-1.5 wt. % Sn X4: 1 wt. % Nb; 0 wt. % Sn, etc. or X5: 0.7 wt. % Nb; 0.3 wt. % Sn, etc.; where these seemingly reduced and very important minor changes in component elements provide extraordinarily improved oxide thickness. Specifically, at a burnup of 70 GWd/MTU, the oxide thickness is reduced at least by a factor of 3.5. FIG. 4, very dramatically, illustrates at 75 GWd/MTU a range of oxide thickness of about 35-40 micrometer for alloy X1, and a range of about 16 to 26 micrometers for alloys X4 and X5, all showing critical improvements relative to standard ZIRLO. A further object of the present invention is to provide a zirconium based alloy for use in an elevated temperature environment of a nuclear reactor, the alloy having 0.2 to 1.5 weight percent niobium, 0.01 to 0.6 weight percent iron, and additional alloy elements selected from 0.0 to 0.8 weight percent tin, 0.0 to 0.5 weight percent chromium, 0.0 to 0.3 weight percent copper, 0.0 to 0.3 weight percent vanadium, 0.0 to 0.1 weight percent nickel, the remainder at least 97 weight percent zirconium, including impurities. Further descriptions of vastly improved alloys X1, X4 and X5 follow. Alloy X4: A further object of the present invention is to provide a zirconium based alloy (denoted as Alloy X4) for use in an elevated temperature environment of a nuclear reactor, the alloy having 0.6 to 1.5 weight percent niobium, 0.02 to 0.3 weight percent Cu, 0.01 to 0.1 weight percent iron, 0.15 to 0.35 weight percent chromium, the balance at least 97 weight percent zirconium, including impurities. Alloy X5: A further object of the present invention is to provide a zirconium based alloy (denoted as Alloy X5), the alloy having 0.2 to 1.5 weight percent niobium, 0.25 to 0.45 weight percent iron, 0.05 to 0.4 weight percent tin, 0.15 to 0.35 weight percent chromium, 0.01 to 0.1 weight percent nickel, the balance at least 97 weight percent zirconium, including impurities. Alloy X1: A further object of the invention is to provide a zirconium based alloy (denoted as Alloy X1), the alloy having 0.4 to 1.5 weight percent niobium, 0.05 to 0.4 weight percent tin, 0.01 to 0.1 weight percent iron, 0.02 to 0.3 weight percent copper, 0.12 to 0.3 weight percent vanadium, 0.0 to 0.5 weight percent chromium, the balance at least 97 weight percent zirconium, including impurities. Alloy X6: A further specific object of the invention is to provide a zirconium based alloy (denoted as Alloy X6 and referred to as “Optimized” ZIRLO), shown in FIG. 4, the alloy having 0.4 to 1.5 weight percent niobium, 0.1 to 0.8 weight percent tin, 0.01 to 0.6 weight percent iron, 0.0 to 0.5 weight percent chromium, the balance at least 97 weight percent zirconium, including impurities. This alloy is still vastly superior to standard ZIRLO. The final heat treatment of Alloy X1 is PRXA (−80% RXA), which is associated with maximum, improved (low) in-reactor creep resistance. In addition, note that the corrosion resistance of Alloy X1 is significantly increased relative to Standard ZIRLO, by a factor of 2.2 at a burn-up of 70 GWd/MTU (see FIG. 4), because of decreased Sn and the addition of Cu. Further, if the amount of RXA in the PRXA final heat treatment of Alloy X1 is decreased to about 15-20%, the corrosion resistance of Alloy X1 would be further improved. The final heat treatment of Alloy X4 is PRXA (−80% RXA) which is associated with maximum improved in-reactor creep resistance. At a burn-up of 70 GWd/MTU, the corrosion resistance of Alloy X4 is increased be a factor of about 3.5 (see FIG. 4) relative to Standard ZIRLO. Note that the corrosion resistance of Alloy X4 is significantly increased relative to Standard ZIRLO because of decreased Sn and the additions of Cu and Cr. In addition, if the amount of RXA in the PRXA final heat treatment of Alloy X4 is decreased to about 15-20% PRXA (15-20% RXA), the corrosion resistance of Alloy X4 would by further improved. The final heat treatment of Alloy X5 is PRXA (−50% RXA), which is considered to be intermediate between maximum improved in-reactor creep resistance and maximum improved in-reactor corrosion resistance. FIG. 4 shows that at a burn-up of 70 GWd/MTU, the corrosion resistance of Alloy X5 is increased be a factor of about 3.0 relative to Standard ZIRLO. Note that the corrosion resistance of Alloy X5 is significantly increased relative to Standard ZIRLO because of decreased Sn, increased Fe and the addition of Cr. A sequence of steps for forming a cladding, strip, tube or like object known in the art from an alloy of the present invention is shown in FIGS. 5A and 5B. To create tubing for cladding, as shown in FIG. 5A, compositional zirconium based alloys were fabricated from vacuum melted ingots or other like material known in the art. The ingots were preferably vacuum arc-melted from sponge zirconium with a specified amount of alloying elements. The ingots were then forged into a material and thereafter β-quenched. β-quenching is typically done by heating the material (also known as a billet) up to its β-temperature, between around 1273 to 1343K. The quenching generally consists of quickly cooling the material by water. The β-quench is followed by extrusion. Thereafter, the processing includes cold working the tube-shell by a plurality of cold reduction steps, alternating with a series of intermediate anneals at a set temperature. The cold reduction steps are preferably done on a pilger mill. The intermediate anneals are conducted at a temperature in the range of 960-1125° F. The material may be optionally re-β-quenched prior to the final and foamed into an article there-from. The final heat treatment discussed previously is also shown. For tubing, a more preferred sequence of events after extrusion includes initially cold reducing the material in a pilger mill, an intermediate anneal with a temperature of about 1030 to 1125° F., a second cold reducing step, a second intermediate anneal within a temperature range of about 1030° to 1070° F., a third cold reducing step, and a third intermediate anneal within a temperature range of about 1030° to 1070° F. The reducing step prior to the first intermediate anneal is a tube reduced extrusion (TREX), preferably reducing the tubing about 55%. Subsequent reductions preferably reduce the tube about 70-80%. Each reduction pass on the pilger mill is preferred to reduce the material being formed by at least 51%. The material then preferably goes through a final cold reduction. The material is then processed with a final anneal at temperatures from about 800-1300° F. To create strip, compositional zirconium based alloys were fabricated from vacuum melted ingots or other like material known in the art. The ingots were preferably arc-melted from sponge zirconium with a specified amount of alloying elements. The ingots were then forged into a material of rectangular cross-section and thereafter β-quenched. Thereafter, the processing as shown in FIG. 5B, includes a hot rolling step after the beta quench, cold working by one or a plurality of cold rolling and intermediate anneal steps, wherein the intermediate anneal temperature is conducted at a temperature from about 960-1105° F. The material then preferably goes through a final pass and anneal, wherein the final anneal temperature is in the range of about 800-1300° F. The final heat treatment discussed previously is also shown. A more preferred sequence to create the alloy strip includes an intermediate anneal temperature within a range of about 1030 to 1070° F. Further, the pass on the mill preferably reduces the material being formed by at least 40%. The corrosion resistance was found to improve with intermediate anneals also that were consistently in the range of 960-1105° F., most preferably around 1030-1070° F., as opposed to typical prior anneal temperatures that are above the 1105° F. for at least one of the temperature anneals. As shown in FIGS. 6-10, a series of preferred alloy embodiments of the present invention were tested for corrosion in a 680° F. water autoclave and measured for weight gain. Tubing material was fabricated from the preferred embodiments of alloys of the present invention, referenced as Alloys X1, X4, X5 and X6, and placed in the 680° F. water autoclave. Data were available for a period of 100 days. Corrosion resistance measured in 680° F. water autoclaves for long term exposure have previously been found to correlate to corrosion resistance data of like alloys placed in-reactor. The preferred composition of these embodiments, further discussed below, are shown in Table 2. The preferred ranges of the compositions are presented in Table 3. TABLE 2AlloyPreferred Composition, by weight percentageX1Zr—0.7Nb—0.3Sn—0.12Cu—0.18V—0.05FeX1Zr—1.0Nb—0.3Sn—0.12Cu—0.18V—0.05FeX1 + CrZr—0.7Nb—0.3Sn—0.12Cu—0.18V—0.05Fe—0.2CrX1 + CrZr—1.0Nb—0.3Sn—0.12Cu—0.18V—0.05Fe—0.2CrX4Zr—1.0Nb—0.05Fe—0.25Cr—0.08CuX5Zr—0.7Nb—0.3Sn—0.3Fe—0.25Cr—0.05NiX6Zr—1.0Nb—0.65Sn—0.1FeX6 + CrZr—1.0Nb—0.65Sn—0.1Fe—0.2Cr TABLE 3AlloyPreferred Composition Ranges, by weight percentageX1Zr; 0.4-1.5Nb; 0.05-0.4Sn; 0.01-0.1Fe; 0.02-0.3Cu;0.12-0.3VX1 − CrZr; 0.4-1.5Nb; 0.05-0.4Sn; 0.01-0.1Fe; 0.02-0.3Cu;0.12-0.3V; 0.05-0.5CrX4Zr; 0.6-1.5Nb; 0.01-0.1Fe; 0.02-0.3Cu; 0.15-0.35CrX5Zr; 0.2-1.5Nb; 0.05-0.4Sn; 0.25-0.45Fe; 0.15-0.35Cr;0.01-0.1NiX6Zr; 0.4-1.5Nb; 0.14-0.8Sn; 0.01-0.6FeX6 + CrZr; 0.4-1.5Nb; 0.1-0.8Sn; 0.01-0.6Fe; 0.05-0.5Cr In order to evaluate the effect of intermediate anneal temperature on corrosion/oxidation, tubing of Standard ZIRLO and Alloys X1, X4 and X5 were processed with intermediate anneal temperatures of 1030° and 1085° F. The alloys of the invention were tested for corrosion resistance by measuring the weight gain over a period of time, wherein the weight gain is mainly attributable to an increase of oxygen (the hydrogen pickup contribution to the weight gain is relatively small and may be neglected) that occurs during the corrosion process. In general, corrosion related weight gain starts quickly and then the rate decreases with increasing time. This initial corrosion/oxidation process is termed as pre-transition corrosion. After a period of time, the corrosion rate increases, approximately linearly with time. This corrosion/oxidation phase is termed post-transition or rapid corrosion. As would be expected, alloys with greater corrosion resistance have lower corrosion rates in the pre- and post-transition phases. FIGS. 6-10 present 680° F. water corrosion test data. As can be seen in FIGS. 6-10, the weight gain associated with tubing processed with 1030° F. intermediate anneal temperatures was less than for higher intermediate anneal temperatures. Further, the weight gains for Alloys X1, X4, X5 and X6 in FIGS. 7-10 were less than that of Standard ZIRLO in FIG. 6. Thus, as the modified alloy compositions and the lower intermediate anneal temperatures exhibit reduced weight gain, and reduced weight gain is correlated with increased corrosion resistance, increased corrosion resistance is directly correlated with the modified alloy compositions and the lower intermediate anneal temperature of the invention. The chemistry formulation of the alloys is correlated with increased corrosion resistance. All of the weight gains from the 680° F. water autoclave testing presented in FIGS. 6-10 are in the pre-transition phase. Although the improvement in the 680° F. water autoclave corrosion weight gain due to lowering of the intermediate anneal temperature appears to be small in view of FIGS. 6-10, the improvement of in-reactor corrosion resistance is expected to be higher than shown by the 680° F. water autoclave data because of in-reactor precipitation of second phase particles in these Zr—Nb alloys and a thermal feedback from a lower oxide conductivity due to lower oxide thickness. Such second phase particle precipitation only occurs in-reactor and not in autoclave testing. In order to evaluate the effect of intermediate anneal temperature in post-transition corrosion, an 800° F. steam autoclave test was performed, as shown in FIGS. 11-15. The test was performed for sufficient time to achieve post-transition corrosion. Post transition corrosion rates generally began after a weight gain of about 80 mg/dm2. Alloys X1, X4, X5 and Standard ZIRLO were processed using intermediate anneal temperatures of 1030° and 1085° F. Alloy X6 (Optimized Zirlo) tubing was processed using intermediate anneal temperatures of 1030° and 1105° F. The tubing was placed in an 800° F. steam autoclave for a period of about 110 days. FIGS. 11-15 show that the post-transition weight gains of the alloys processed at the intermediate anneal temperature of 1030° F. are less than for alloy materials processed at the higher temperatures of 1085° or 1105° F. Further, the weight gain for Alloys X1, X4, X5 and X6 (Optimized Zirlo) of FIGS. 12-15 are less than those of the prior disclosed Standard ZIRLO presented in FIG. 11. Thus, the low intermediate anneal temperatures provide substantial improvements over the prior art as it provides a significant advantage in safety, by protecting cladding or the grids from corrosion, in cost, as replacement of the fuel assemblies can be done less often, and through efficiency, as the less corroded cladding better transmits the energy of the fuel rod to the coolant. Standard ZIRLO strip was processed with intermediate anneal temperatures of 968° and 1112° F. The material was tested for corrosion resistance by measuring the weight gain over a period of time, wherein the weight gain is mainly attributable to an increase of oxygen (the hydrogen pickup contribution to the weight gain is relatively small and may be neglected) that occurs during the corrosion process. The low temperature strip was processed with an intermediate anneal temperature of 968° F. and a final anneal temperature of 1112° F. The standard strip was processed with an intermediate anneal temperature of 1112° F. and a final anneal temperature of 1157° F. FIG. 16 shows that the low temperature processed material exhibits significantly lower corrosion/oxidation than the higher temperature processed material. The zirconium alloys of the present invention provide improved corrosion resistance through the chemistry of new alloy combinations. The alloys are generally formed into cladding (to enclose fuel pellets) and strip (for spacing fuel rods) for use in a water based nuclear reactor. The alloys generally include 0.2 to 1.5 weight percent niobium, 0.01 to 0.6 weight percent iron, and additional alloying elements selected from the group consisting of 0.0 to 0.8 weight percent tin, 0.0 to 0.5 weight percent chromium, 0.0 to 0.3 weight percent copper, 0.0 to 0.3 weight percent vanadium and 0.01 to 0.1 weight percent nickel. The balances of the alloys are at least 97 weight percent zirconium, including impurities. Impurities may include about 900 to 1500 ppm of oxygen. A first embodiment of the present invention is a zirconium alloy having, by weight percent, about 0.4-1.5% Nb; 0.05-0.4% Sn, 0.01-0.1% Fe, 0.02-0.3% Cu, 0.12-0.3% V, 0.0-0.5% Cr and at least 97% Zr including impurities, hereinafter designated as Alloy X1. This embodiment, and all subsequent embodiments, should have no more than 0.50 wt. % additional other component elements, preferably no more than 0.30 wt. % additional other component elements, such as nickel, chromium, carbon, silicon, oxygen and the like, and with the remainder Zr. Chromium is an optional addition to Alloy X1. Wherein chromium is added to Alloy X1, the alloy is hereinafter designated as Alloy X1+Cr. Alloy X1 was fabricated into tubing and its corrosion rate was compared to that of a series of alloys likewise fabricated into tubing, including ZIRLO-type alloys and Zr—Nb compositions. The results are shown in FIG. 4. FIG. 4 shows that the in-reactor corrosion resistance of Alloy X1 is increased by a factor of 2.2 relative to Standard ZIRLO. The chemistry formulations of Alloy X1 provide substantial improvement over the prior art as it relates to corrosion resistance in a nuclear reactor. A second embodiment of the present invention is a zirconium alloy having, by weight percent, about, about 0.6-1.5% Nb; 0.01-0.1% Fe, 0.02-0.3% Cu, 0.15-0.35% Cr and at least 97% Zr, hereinafter designated as Alloy X4. FIG. 4 shows that the in-reactor corrosion resistance of Alloy X4 is increased by a factor of 3.5 relative to Standard ZIRLO. A preferred composition of Alloy X4 has weight percent ranges for the alloy with about 1.0% Nb, about 0.05% Fe, about 0.25% Cr, about 0.08% Cu, and at least 97% Zr. The preferred Alloy X4 was fabricated into tubing and its corrosion rate was compared with the corrosion rate of Standard ZIRLO. The chemistry formulations of Alloy X4, like Alloy X1, provides substantial improvements over the prior art as it relates to corrosion resistance in a nuclear reactor. A third embodiment of the present invention is a zirconium alloy having, by weight percent, about 0.2-1.5% Nb; 0.05-0.4% Sn, 0.25-0.45% Fe, 0.15-0.35% Cr, 0.01-0.1% Ni, and at least 97% Zr, hereinafter designated as Alloy X5. This composition should have no more than 0.5 wt. % additional other component elements, preferably no more than 0.3 wt. % additional other component elements, such as carbon, silicon, oxygen and the like, and with the remainder Zr. A preferred composition of Alloy X5 has weight percent values for the alloy with about 0.7% Nb; about 0.3% Sn, about 0.35% Fe, about 0.25% Cr, about 0.05% Ni, and at least 97% Zr. The preferred embodiment of Alloy X5 was fabricated into tubing and its corrosion rate was compared to that of a series of alloys likewise fabricated into tubing. FIG. 4 shows that the in-reactor corrosion resistance of Alloy X5 is increased by a factor of 3.0 relative to Standard ZIRLO. The chemistry formulations of Alloy X5 provide substantial improvement over the prior art as it relates to corrosion resistance in a nuclear reactor. Another embodiment of the invention is a low-tin ZIRLO alloy designated as Alloy X6 (“Optimized Zirlo”). FIG. 4 shows that the corrosion in-reactor resistance of Alloy X6 is increased by a factor of 1.5 relative to Standard ZIRLO. The reduction of tin increases the corrosion resistance. Tin, however, increases the in-reactor creep strength, and too small an amount of tin makes it difficult to maintain the desired creep strength of the alloy. Thus, the optimum tin of this alloy must balance these two factors. As a result, this embodiment is a low-tin alloy essentially containing, by weight percent, 0.4-1.5% Nb; 0.1-0.8% Sn, 0.01-0.6% Fe, and the balance at least 97% Zr, including impurities, hereinafter designated as Alloy X6. A preferred composition of Alloy X6 has weight percent ranges of about 1.0% Nb, about 0.65% Sn, about 0.1% Fe, and at least 97% Zr, including impurities. Tin may be decreased if other alloy elements are included to replace the strengthening effect of tin. A second preferred embodiment of Alloy X6 (“Optimized Zirlo”) has generally the same weight percentages plus 0.05-0.5% Cr, hereinafter designated as Alloy X6+Cr. A preferred embodiment of Alloy X6+Cr has about 1.0% Nb, about 0.65% Sn, about 0.1% Fe and about 0.2% Cr. Alloy X6 provides substantial improvements in comparison to Standard ZIRLO over the prior art as it relates to corrosion resistance in a nuclear reactor. Weld-Corrosion Resistance In a typical nuclear fuel assembly large numbers of fuel rods are included. In each fuel rod nuclear fuel pellets are placed within cladding tubes that are sealed by end caps such that the end caps are welded to the cladding. The end cap-cladding weld, however, is susceptible to corrosion to an even greater extent than the non-welded cladding itself, usually by a factor of two. Zirconium alloys that include chromium show increased weld corrosion resistance. Thus, the addition of chromium in a zirconium alloy includes substantial advancement over prior zirconium alloys that do not include chromium. Multiplicities of alloys were tested for their effect on weld corrosion, as shown in Table 4. Several alloys were tested for their effect on laser strip welds in a 680° F. water autoclave test for an 84 day period. Some of these alloys had chromium, while the other alloys did not include chromium except in unintentional trace amounts. Still other alloy tube welds were tested in the form of magnetic force welds in an 879-day 680° F. water autoclave test. Each weld specimen placed in the two autoclave tests contained the weld and about 0.25 inches of an end plug and tube on either side of the weld. Separate same length tube specimens without the weld were also included in the test. The weight gain data were collected on the weld and tube specimens. The ratio of the weld corrosion to the non-weld corrosion was determined either from the weight gain data or the metallographic oxide thickness measurements at different locations on the specimen. TABLE 4Weld/BaseCorrosionAlloy NameComposition by weight %RatioLASER STRIPWELDSStandard ZIRLOZr—0.95Nb—1.08Sn—0.11Fe2.07Zr—NbZr—1.03Nb2.307Low-Sn ZIRLOZr—1.06Nb—0.73Sn—0.27Fe1.71StandardZr—0.97Nb—0.99Sn—0.10Fe2.094ZIRLO/590° C.RXAAlloy AZr—0.31Nb—0.51Sn—0.35Fe—1.3330.23CrMAGNETIC FORCETUBE WELDSOptin Zr-4Zr—1.35Sn—0.22Fe—0.10Cr0.805Zr-4 + FeZr—1.28Sn—0.33Fe—0.09Cr0.944Zr—2PZr—1.29Sn—0.18Fe—0.07Ni—1.0080.10CrAlloy CZr—0.4Sn—0.5Fe—0.24Cr0.955Alloy EZr—0.4Nb—0.7Sn—0.45Fe—1.1680.03Ni—0.24Cr As shown in Table 4, the ratios of the zirconium alloys not having chromium had a weld to base metal corrosion ratio of 1.71 or greater. In contrast, the zirconium alloys containing chromium had a maximum ratio of 1.333 or lower. The chromium additions reduce the ratio of weld corrosion relative to that of the base metal. Thus, the addition of chromium significantly reduces weld corrosion, thereby increasing the safety, cost and efficiency of the nuclear fuel assembly. The differences in weld versus base metal corrosion may be explained by differences in vacancy concentration. The weld region is heated to high temperature during welding, and cools at a faster rate than the base material. In a typical increase of temperature, the vacancies in the metal increase exponentially with the temperature. A fraction of the atomic vacancies introduced during the temperature increase are quenched during the cooling of the weld and, as a result, the vacancy concentration is higher in the weld region. Thus, the vacancy concentration is higher in the weld than the heat affected regions of the non-weld region. Since waterside corrosion of zirconium alloys is postulated to occur by vacancy exchange with oxygen ions, increased vacancy concentration in the weld region can increase vacancy/oxygen exchange and thereby increase corrosion in the weld region if the vacancies are not pinned by an alloying element. This exchange will be reduced resulting in improvement of corrosion resistance of the weld. Due to a high solubility of chromium in beta zirconium (about 47% weight percent), chromium is an effective solid solution element to pin the vacancies in the beta phase and thereby decrease the corrosion enhancement due to oxygen ion exchange with supersaturated vacancies in the quenched weld region. While a full and complete description of the invention has been set forth in accordance with the dictates of the patent statutes, it should be understood that modifications can be resorted to without departing from the spirit hereof or the scope of the appended claims. For example, the time for the intermediate anneals can vary widely while still maintaining the spirit of the invention.
	claims	1. A pair of linear arrays of gamma thermometer (GT) sensors arranged in a nuclear reactor core, the pair comprising:a first linear array of GT sensors, wherein the GT sensors are arranged asymmetrically along a length of the first linear array;a second linear array of GT sensors, wherein the GT sensors are arranged asymmetrically along the second linear array and wherein the second linear array of GT sensors is asymmetrical with respect to the first linear array of GT sensors, andthe first linear array positioned in the reactor core at a first core location and the second instrument housing positioned at a second core location, wherein a line of symmetry of the core extends through a center of the core and the first core location is the same horizontal distance from the line of symmetry as the second core location and wherein the horizontal distance for the first core location is along a line perpendicular to the line of symmetry and the horizontal distance for the second core location is along another line perpendicular to the line of symmetry. 2. The pair of linear arrays as in claim 1 wherein a majority of the GT sensors in the second linear array are in a lower half of the second linear array and a majority of the GT sensors in the first linear array are in an upper half of the first linear array. 3. The pair as in claim 1 wherein the first core location and second core location are at opposites sides of the line of symmetry. 4. A method to collect and present data from gamma thermometer (GT) sensors indicative of a nuclear reactor core, the method comprising:forming a plurality linear GT arrays of GT sensors, wherein an axial positions of the GT sensors in each array is not predetermined prior to forming the array;determining the axial position of each of a plurality of GT sensors arranged in each of the linear GT arrays;storing the axial positions for each GT sensors in a data file associated with the linear GT array;accessing the data file for each of the linear GT arrays using a core monitor software;for each of the linear GT arrays, a determination is made using the core monitor software of the elevation in the core of each of the GT sensors based on the axial positions in the data file;positioning the linear GT arrays in the core;collect data regarding an operating condition of the core from the GT sensors for each linear GT array, andusing the collected data to generate a presentation of a core condition at various core elevations. 5. The method of claim 4 wherein the presentation is a 3-Dimensional (3D) graph of core power at various core nodal positions corresponding to the linear GT arrays. 6. The method of claim 4 further comprising:positioning each of the linear GT arrays in a separate instrument tube;positioning detectors for a Local Power Range Monitor (LPRM) in each of the instrument tubes;for each instrument tube, identifying a one of the GT sensors of the array adjacent each of the detectors, andcalibrating each of the detectors by interpolating signals from GT sensors proximate to each of the detectors. 7. The method of claim 4 wherein forming the plurality linear GT arrays includes placing the GT sensors in a metallic rod and extruding the rod with the GT sensors in the rod. 8. The method of claim 4 wherein positioning the linear GT arrays includes arranging a pair of the GT arrays at core locations at a same distance from a line of symmetry extending through a core axis, wherein the distance is along lines perpendicular to the line of symmetry. 9. The method of claim 8 further comprising applying GT data collected from one array of the pair of GT arrays as having been collected at the other array of the pair of GT arrays. 10. The method of claim 8 wherein at least two of the GT arrays are positioned at a common distance from a line of symmetry extending through an axis of the core, wherein the common distance is along lines perpendicular to the line of symmetry. 11. The method of claim 10 wherein the GT arrays include a first GT array and a second GT array, and the first GT array is at a first core location and the second GT array is at a second core location, wherein a line of symmetry of the core extends through a center of the core and the first core location is the same horizontal distance from the line of symmetry as the second core location and wherein the horizontal distance for the first core location is along a line perpendicular to the line of symmetry and the horizontal distance for the second core location is along another line perpendicular to the line of symmetry, and the method further comprises using data collected from the first GT array as being representative of a condition at the second core location. 12. The method of claim 4 wherein each of the linear GT arrays has at least four GT sensors, and at least one GT sensor is in close proximity to a LPRM. 13. The method of claim 4 wherein the GT sensors in each linear GT array are asymmetrically arranged along an axis of the array.
	description	The priority application number JP2019-082459, entitled “X-ray phase imaging apparatus”, filed on Apr. 24, 2019, and invented by Satoshi Sano, Koichi Tanabe, Yukihisa Wada, Satoshi Tokuda, Akira Horiba, and Naoki Morimoto, upon which this patent application is based is hereby incorporated by reference. The present invention relates to an X-ray phase imaging apparatus, and more particularly to an X-ray phase imaging apparatus for performing imaging while relatively moving a subject and an imaging system. Conventionally, an X-ray phase imaging apparatus for performing imaging while relatively moving a subject and an imaging system is known. Such an X-ray phase imaging apparatus is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2017-44603. The Japanese Unexamined Patent Application Publication No. 2017-44603 discloses a radiation image generation apparatus (X-ray phase imaging apparatus) equipped with an imaging system including an X-ray source, a plurality of gratings, and a detection unit, a transport unit, and an image generation unit. In the radiation image generation apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2017-44603, the X-ray source, the plurality of gratings, and the detection unit are arranged in this order along the optical axis direction of X-rays. The detection unit detects the X-rays emitted by the X-ray source and transmitted through the plurality of gratings. The image generation unit generates a phase-contrast image including an absorption image, a phase differential image, and a dark field image based on a plurality of images captured while moving the subject by the transport unit (while relatively moving the subject and the imaging system) along a predetermined direction (the direction of the grating pitch of the grating or the direction along which the grating extends) in a plane perpendicular to the optical axis direction. Note that the absorption image denotes an image obtained by imaging the difference in the absorption degree of X-rays due to a subject. Also, note that the phase differential image denotes an image obtained by imaging the phase shift of X-rays. Also, note that the dark field image denotes a visibility image obtained by a change in visibility based on small-angle scattering of an object. In the X-ray phase imaging apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2017-44603, by performing imaging while relatively moving a subject and an imaging system, even in cases where the size of the subject is larger than the size of the grating in the direction along which the subject and the imaging system are moved relatively (in the movement direction during imaging, the entire subject can be imaged. Therefore, in the X-ray phase imaging apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2017-44603, it becomes possible to reduce the size of the grating in the movement direction during imaging. However, in the X-ray phase imaging apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2017-44603, although the grating can be reduced in size in the movement direction during imaging, the grating needs to be increased in size in a direction perpendicular to the movement direction during imaging in a plane perpendicular to the optical axis direction so that the subject does not protrude from the grating when imaging a relatively large subject. Note that a grating used in a conventional X-ray phase imaging apparatus as disclosed in Japanese Unexamined Patent Application Publication No. 2017-44603 has a large aspect ratio (the height (depth) of the grating relative to the grating pitch), so it is difficult to accurately produce a single grating having a large area. Therefore, although not disclosed in Japanese Unexamined Patent Application Publication No. 2017-44603, in a conventional X-ray phase imaging apparatus as disclosed in Japanese Unexamined Patent Application Publication No. 2017-44603, when imaging a relatively large subject, it is conceivable to increase the area of the grating by arranging a plurality of gratings side by side in a direction perpendicular to the movement direction during imaging. As described above, when a plurality of gratings is arranged side by side, it is conceivable that the plurality of gratings is bonded to each other, but since the plurality of gratings is manufactured as separate members from each other, an unintended gap may be generated between the plurality of gratings adjacent to each other due to a manufacturing error. For example, in a configuration in which a subject and an imaging system are relatively moved in the grating pitch direction of the grating (in a direction perpendicular to a direction along which the grating extends), a gap is generated in which the gratings are discontinuous in a direction along which the plurality of gratings is adjacent to each other (a direction along which the grating extends). In this case, when performing imaging while relatively moving the subject and the imaging system, a portion where the subject hardly passes through the grating may simply occur. In addition, in a configuration in which a subject and an imaging system are relatively moved in a direction in which the grating extends (in a direction perpendicular to the grating pitch direction), a gap may be sometimes generated as a portion (a portion that does not function as a grating) having at least one of a pitch different from the grating pitch and an angle different from the angle of the grating pitch in a direction in which a plurality of gratings is adjacent to each other (in a grating pitch direction). Also in this case, when performing imaging while relatively moving the subject and the imaging system, the subject passes through a gap as a portion which does not function as a grating, so that a portion in which the subject hardly passes through the grating substantially occurs. In this manner, when a portion in which the subject hardly passes through the grating is generated, a portion where the subject cannot be imaged is generated. Therefore, as disclosed in the X-ray phase imaging apparatus of Japanese Unexamined Patent Application Publication No. 2017-44603, in a configuration in which imaging is performed while relatively moving a subject and an imaging system, when a plurality of gratings is arranged side by side in order to increase the area in a direction perpendicular to a direction along which the subject and the imaging system are relatively moved, there may be a problem that a portion where the subject cannot be imaged is generated because a portion in which the subject hardly passes through the grating is generated. The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an X-ray phase imaging apparatus capable of enlarging an area in a direction perpendicular to a direction in which a subject and an imaging system are relatively moved while suppressing occurrence of a portion where the subject cannot be imaged due to occurrence of a portion in which the subject hardly passes through the grating in a configuration in which imaging is performed while relatively moving the subject and the imaging system. In order to achieve the above object, an X-ray phase imaging apparatus according to one aspect of the present invention includes: an X-ray source; a detection unit configured to detect X-rays emitted from the X-ray source; a plurality of gratings arranged between the X-ray source and the detection unit to allow the X-rays emitted from the X-ray source to pass therethrough; a moving mechanism configured to move 1) a subject arranged between the X-ray source and the detection unit or 2) an imaging system composed of the X-ray source, the detection unit and the plurality of gratings, along a direction in which the plurality of gratings extend or along a direction in which the plurality of gratings are arranged in a grating pitch; and an image processing unit configured to generate a phase-contrast image based on a plurality of images acquired based on signals detected by the detection unit with the subject and the imaging system being relatively moved with respect to each other, wherein at least one of the plurality of gratings is composed of a plurality of grating portions arranged along a third direction perpendicular to a first direction in which the subject or the imaging system is moved by the moving mechanism and a second direction in which the X-ray source, the detection unit, and the plurality of gratings are arranged, and wherein the plurality of grating portions are arranged so that adjacent grating portions overlap when viewed in the first direction. According to the present invention, as described above, at least one of the plurality of gratings is composed of a plurality of grating portions arranged along a third direction perpendicular to a first direction in which a subject or an imaging system is moved by a moving mechanism and a second direction in which an X-ray source, a detection unit, and a plurality of gratings is arranged, and the plurality of grating portions are arranged such that adjacent grating portions overlap each other when viewed in the first direction. With this, in the grating composed of the plurality of grating portions, it is possible to suppress the occurrence of a portion in which the subject hardly passes through the grating in the third direction in which the plurality of grating portions are arranged side by side when performing imaging while relatively moving the subject and the imaging system in the first direction. As a result, in the configuration in which imaging is performed while relatively moving the subject and the imaging system, it is possible to increase an area in a direction perpendicular to a direction in which the subject and the imaging system are relatively moved while suppressing the occurrence of a portion in which the subject cannot be imaged due to the occurrence of a portion in which the subject hardly passes through the grating. Embodiments embodying the present invention will be explained with reference to the attached drawings. Configuration of X-ray Phase Imaging Apparatus With reference to FIG. 1 to FIG. 8, a configuration of an X-ray phase imaging apparatus 100 according to a first embodiment will be described. As shown in FIG. 1, the X-ray phase imaging apparatus 100 is a device for imaging an interior of a subject P by utilizing a Talbot effect. The X-ray phase imaging apparatus 100 is provided with an imaging system 10, a processing unit 21, a grating position adjustment mechanism 22, and a subject moving mechanism 23. The imaging system 10 is composed of an X-ray tube 11, a detection unit 12, and a plurality of gratings 30. The plurality of gratings 30 includes a first grating 31, a second grating 32, and a third grating 33. Note that the X-ray tube 11 is an example of the “X-ray source” recited in claims. Also, note that the subject moving mechanism 23 is an example of the “moving mechanism” recited in claims. In the X-ray phase imaging apparatus 100, the X-ray tube 11, the third grating 33, the first grating 31, the second grating 32, and the detection unit 12 are arranged in this order in the X-ray irradiation axis direction (in the optical axis direction, the Z-direction). That is, the first grating 31, the second grating 32, and the third grating 33 are arranged between the X-ray tube 11 and the detection unit 12. In this specification, note that the direction from the X-ray tube 11 toward the detection unit 12 is referred to as a Z2-direction, and the opposite direction is referred to as a Z1-direction. Also, note that the Z-direction is an example of the “second direction” recited in claims. In the first embodiment, the direction (A-direction) of the grating pitch D (see FIG. 2) of the plurality of gratings 30 and the direction (B-direction) in which the gratings 30 of the plurality of gratings 30 extend are referred to as an X-direction and a Y-direction, respectively. Also, in the first embodiment, note that the X-direction and the Y-direction are an example of the “first direction” and an example of the “third direction” recited in claims, respectively. The X-ray tube 11 is an X-ray generator capable of generating X-rays by applying a high voltage. The X-ray tube 11 is configured to emit generated X-rays in the Z2-direction. The X-rays emitted from the X-ray tube 11 passes through the first grating 31, the second grating 32, and the third grating 33 arranged between the X-ray tube 11 and the detection unit 12. The detection unit 12 detects the X-rays emitted from the X-ray tube 11 and converts the detected X-rays into electric signals. The detection unit 12 is, for example, an FPD (Flat Panel Detector). The detection unit 12 is composed of a plurality of conversion elements (not shown) and pixel electrodes (not shown) arranged on the plurality of conversion elements. The plurality of conversion elements and pixel electrodes are arranged side by side in the X-direction and Y-direction at predetermined pixel pitches. The detection signal (image signal) of the detection unit 12 is sent to an image processing unit 21b (described later) included in the processing unit 21. As shown in FIG. 2, the first grating 31 has slits 31a and X-ray phase change portions 31b arranged in the X-direction (A-direction) at predetermined periods (grating pitches) D1. The slits 31a and the X-ray phase change portion 31b are each formed to extend in the Y-direction (B-direction). The first grating 31 is a so-called phase grating. As shown in FIG. 1, the first grating 31 is arranged between the X-ray tube 11 and the second grating G2 and is provided to form a self-image (by a Talbot effect) by the X-rays emitted from the X-ray tube 11. Note that a Talbot effect means that when coherent X-rays pass through the first grating 31 in which the slits 31a are formed, an image (self-image) of the first grating 31 is formed at a predetermined distance (Talbot distance) apart from the first grating 31. As shown in FIG. 2, the second grating 32 has a plurality of X-ray transmission portions 32a and X-ray absorption portions 32b arranged in the X-direction (A-direction) at predetermined periods (grating pitches) D2. The X-ray transmission portion 32a and the X-ray absorption portion 32b are formed to extend in the Y-direction (B-direction). The second grating 32 is a so-called absorption grating. As shown in FIG. 1, the second grating 32 is arranged between the first grating 31 and the detection unit 12 and is configured to interfere with the self-image formed by the first grating 31. The second grating 32 is arranged at a position apart from the first grating 31 by a Talbot distance so as to make the self-image interfere with the second grating 32. As a result, in the X-ray phase imaging apparatus 100, the interference fringe (moiré fringe) 40 (see FIG. 8) generated by the interference of the self-image with the second grating 32 is detected as X-rays by the detection unit 12 arranged in the vicinity of of the second grating 32 on the downstream side (Z2 side). As shown in FIG. 2, the third grating 33 has a plurality of slits 33a and X-ray absorption portions 33b arranged in the X-direction (A-direction) at predetermined intervals (pitches) D3. The slits 33a and the X-ray absorption portions 33b are each formed to extend in the Y-direction (B-direction). As shown in FIG. 1, the third grating 33 is arranged between the X-ray tube 11 and the first grating 31 and is irradiated with X-rays emitted from the X-ray tube 11. The third grating 33 is arranged so that the X-ray which has passed through each slit 33a is used as a linear light source corresponding to the position of each slit 33a. That is, the third grating 33 is provided to enhance the coherence of the X-rays emitted from the X-ray tube 11. The processing unit 21 includes a control unit 21a and an image processing unit 21b. The control unit 21a is configured to generate a moiré fringe 40 (see FIG. 8) on the detection surface of the detection unit 12 by controlling the grating position adjustment mechanism 22 to adjust the position of the first grating 31. The control unit 21a is configured to control the subject moving mechanism 23 to move the position of the subject moving mechanism 23 in the X-direction with respect to the imaging system 10. The control unit 21a includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The image processing unit 21b is configured to generate an image such as a phase-contrast image 51 (see FIG. 4) based on a detection signal sent from the detection unit 12. The image processing unit 21b includes, for example, a processor such as a GPU (Graphics Processing Unit) and an FPGA (Field-Programmable Gate Array) configured for image-processing. As shown in FIG. 4, the phase-contrast image 51 includes an absorption image 51a, a phase differential image 51b, and a dark field image 51c. The absorption image 51a is an image based on a difference in the absorption degree of X-rays. The phase differential image 51b is an image based on a phase shift of X-rays. The dark field image 51c is an image based on a change in visibility due to a small angle scattering of an object. The dark field image 51c is also called a small angle scattering image. As shown in FIG. 3, the grating position adjustment mechanism 22 is configured to move the first grating 31 in the X-direction, the Y-direction, the Z-direction, the rotation direction Rz about the axis of the Z-direction, the rotation direction Rx about the axis of the X-direction, and the rotation direction Ry about the axis of the Y-direction. The grating position adjustment mechanism 22 includes an X-direction linear motion mechanism 22a, a Z-direction linear motion mechanism 22b, a Y-direction linear motion mechanism 22c, a linear motion mechanism connecting portion 22d, a stage support portion drive portion 22e, a stage support portion 22f, a stage drive portion 22g, and a stage 22h. The X-direction linear motion mechanism 22a, the Z-direction linear motion mechanism 22b, and the Y-direction linear motion mechanism 22c are configured to be movable in the X-direction, the Z-direction, and the Y-direction, respectively. The X-direction linear motion mechanism 22a, the Z-direction linear motion mechanism 22b, and the Y-direction linear motion mechanism 22c include, for example, a stepping motor. The grating position adjustment mechanism 22 is configured to move the first grating 31 in the X-direction, the Z-direction, and the Y-direction by the operation of the X-direction linear motion mechanism 22a, the Z-direction linear motion mechanism 22b, and the Y-direction linear motion mechanism 22c, respectively. The stage support portion 22f supports the stage 22h for mounting (or holding) the first grating 31 in the Z2-direction. The stage drive portion 22g is configured to reciprocate the stage 22h in the X-direction direction. The bottom portion of the stage 22h is formed in a convex curved surface shape toward the stage support portion 22f and is configured to rotate about the axis line (Ry-direction) of the Y-direction by being reciprocated in the X-direction. The stage support portion drive portion 22e is configured to reciprocate the stage support portion 22f in the Y-direction. Further, the linear motion mechanism connecting portion 22d is provided on the X-direction linear motion mechanism 22a so as to be rotatable about the axis line (Ry-direction) of the Z-direction. The bottom of the stage support portion 22f is formed in a convex curved surface shape toward the linear motion mechanism connecting portion 22d and is configured to be rotated about the axis line (Rz-direction) of the X-direction by being reciprocated in the Y-direction direction. The grating position adjustment mechanism 22 may have a mechanism for holding the first grating 31, such as e.g., a chucking mechanism and a hand mechanism. As shown in FIG. 1, the subject moving mechanism 23 is configured to mount or hold a subject P. The subject moving mechanism 23 is configured to move a subject P in the X-direction by the control of the control unit 21a in a state in which the subject P is placed on or held. That is, in the first embodiment, it is configured such that the imaging system 10 and the subject P can be relatively moved. Although FIG. 1 shows that the subject moving mechanism 23 moves between the first grating 31 and the second grating 32 in the X-direction, the subject moving mechanism 23 may move between the first grating 31 and the third grating 33 in the X-direction. With the above-described configuration, the X-ray phase imaging apparatus 100 is configured to generate a phase-contrast image 51 (see FIG. 4) based on images acquired by performing imaging while moving the subject P in the X-direction. The generation of the phase-contrast image 51 will be described in detail later. Here, in the first embodiment, as shown in FIG. 5, the first grating 31 and the second grating 32 are each composed of a plurality of grating portions 30c arranged side by side along the Y-direction. Specifically, the plurality of grating portions 30c is linearly arranged so as to be adjacent to each other along the Y-direction. For example, the plurality of grating portions 30c is fixed to a grating holding member (not shown) so as to be linearly arranged so as to be adjacent to each other along the Y-direction. As a result, the length L2 of the second grating 32 in the Y-direction is larger than the length L1 in the X-direction. Note that the relation between the length of the first grating 31 in the Y-direction and the length in the X-direction is the same. In the X-ray phase imaging apparatus 100, since the extending direction (B-direction) of the grating 30 coincides with the direction (Y-direction) in which the plurality of grating portions 30c are arranged side by side, the angles of the X-rays entering from the X-ray tube 11 are substantially equal in any of the plurality of grating portions 30c arranged side by side in the Y-direction. In the first embodiment, as shown in FIG. 6, the plurality of grating portions 30c are configured such that adjacent grating portions 30c overlap each other when viewed in the X-direction. More specifically, the plurality of grating portions 30c are configured such that adjacent grating portions 30c overlap each other when viewed in the X-direction so that at least the grating region 30d is included in the X-direction over the entire Y-direction. Note that in FIG. 6, only the second grating 32 is shown as an example of a grating 30 composed of a plurality of grating portions 30c, but the configuration of the first grating 31 is also the same. Specifically, each of the plurality of grating portions 30c is formed in a polygonal shape when viewed in the Z-direction. A plurality of parallelogram-shaped grating portions 30c is arranged side by side along the Y-direction, so that a gap region 30e sandwiched by the grating regions 30d is formed between the plurality of grating portions 30c. Note that in FIG. 7, an example is shown in which the spacing of the gap region 30e is larger than the grating pitch D2(D). The plurality of grating portions 30c is arranged so that the sides 30f of the plurality of grating portions 30c adjacent to each other in the Y-direction includes portions extending in a direction intersecting with the X-direction when viewed in the Z-direction. In the first embodiment, the entire sides 30f are arranged so as to extend in a direction intersecting with the X-direction. In addition, the plurality of grating portions 30c is arranged such that the sides 30f adjacent to each other in the Y-direction are substantially parallel to each other when viewed in the Z-direction. The sides 30f adjacent in the Y-direction extend linearly in a direction intersecting with the X-direction when viewed in the Z-direction. With the above-described configuration, each of the sides 30f of the plurality of grating portions 30c adjacent in the Y-direction is in a state of extending in a direction intersecting with the XZ-plane 90. As a result, the Y2 side of the grating portion 30c arranged on the Y1 side and the Y1 side of the grating portion 30c arranged on the Y2 side of the plurality of grating portions 30c adjacent in the Y-direction overlap when viewed in the X-direction. The angle at which the side 30f intersecting with the XZ-plane 90 is, for example, less than 45 degrees. In the first embodiment, the adjacent grating portions 30c overlap each other when viewed in the X-direction so that at least one period D4 (see FIG. 7) of the moiré fringe 40 (see FIG. 8) is included in the X-direction. More specifically, as shown in FIG. 8, the X-ray phase imaging apparatus 100 is configured to perform imaging while relatively moving the subject P and the imaging system 10 in a state in which a moiré fringe 40 is generated so that at least one period D4 is included in the X-direction in which the subject P and the imaging system 10 are relatively moved. Further, the X-ray phase imaging apparatus 100 is configured to generate the moiré fringe 40 substantially aligned in the X-direction when viewed in the Z-direction in any of the plurality of grating portions 30c arranged side by side along the Y-direction. This allows the subject P to pass through the moiré fringe 40 so as to include at least one period D4 in the X-direction, not only when (each portion of) the subject P moves on the line 91 that does not include the gap region 30e, but also when it moves on the line 92 that includes the gap region 30e when the subject P and the imaging system 10 are relatively moved in the X-direction. In the embodiment shown in FIG. 8, the moiré fringe 40 for approximately three periods is included in the X-direction on the line 91, and the moiré fringe 40 for approximately one period is included in the X-direction on the line 92. Generation of Phase-Contrast Image With referring to FIG. 9 to FIG. 15, the generation of a phase-contrast image 51 (see FIG. 4) in the X-ray phase imaging apparatus 100 according to the first embodiment will be described in detail. In the first embodiment, the image processing unit 21b is configured to generate a phase-contrast image 51 (see FIG. 4) on the basis of a plurality of images (subject images) 52 (see FIG. 9) acquired on the basis of signals detected by the detection unit 12 by performing imaging while moving the subject P in the X-direction (performing imaging while relatively moving the subject P and the imaging system 10). Specifically, as shown in FIG. 9, the X-ray phase imaging apparatus 100 is configured to perform imaging while moving the subject P in the X-direction in a state in which the moiré fringe 40 is generated. Note that in FIG. 9, a plurality of (six) subject images 52 captured at the first to sixth imaging positions are shown while linearly moving the subject P in the X-direction by the subject moving mechanism 23 (see FIG. 1). FIG. 9 shows a change in the position of the pixel 52a among the pixels obtained by imaging the subject P in the plurality of subject images 52. The control unit 21a (see FIG. 1) moves the subject P by a predetermined movement amount dt by inputting a command value relating to a movement amount for arranging the subject P at each imaging position to the subject moving mechanism 23 (see FIG. 1). For example, when the subject moving mechanism 23 includes a stepping motor as a driving source, the command value for the moving distance dt is the number of pulses inputted to the subject moving mechanism 23. Note that in the subject image 52 at the second imaging position of FIG. 9, the position of the subject P at the first imaging position is illustrated by a broken line in order to make it easier to grasp the moving distance dt of the subject P. As described above, by performing imaging while moving the subject P by the subject moving mechanism 23 (see FIG. 1), the moiré fringe 40 and the subject P can be relatively moved. As a result, the image processing unit 21b (see FIG. 1) can generate the phase-contrast image 51 (see FIG. 4) based on the subject images 52 captured at the respective imaging positions (first to sixth imaging positions). Note that in the first embodiment, it is configured such that the subject P is moved by the subject moving mechanism 23 by at least one period D4 of the moiré fringe 40. Here, when imaging is performed while moving the subject P with respect to the moiré fringe 40, unlike when imaging is performed by translating the grating, the phase value of the pixel in each image (the subject image 52) cannot be obtained directly. Therefore, in the first embodiment, the image processing unit 21b (see FIG. 1) is configured to generate a phase-contrast image 51 based on the pixel value of each pixel 52a in the plurality of subject images 52 and the phase information 41 (see FIG. 10) of the moiré fringe 40 generated in the plurality of subject images 52. Specifically, as shown in FIG. 10, in the X-ray phase imaging apparatus 100, the image processing unit 21b (see FIG. 1) is configured to acquire the phase information 41 of the moiré fringe 40. That is, the X-ray phase imaging apparatus 100 acquires the moiré fringe image 53 of each Step (translationally moved position) by translationally moving the first grating 31 (see FIG. 1) by the grating position adjustment mechanism 22 (see FIG. 1). The moiré fringe image 53 is an image of the moiré fringe 40 generated on the detecting surface of the detection unit 12 (see FIG. 1) by translationally moving the first grating 31, and is an image of a striped pattern with bright and dark pixel values of the moiré fringe 40. The image processing unit 21b (see FIG. 1) is configured to acquire the phase information 41 on the moiré fringe 40 based on each moiré fringe image 53. The phase information 41 on the moiré fringe 40 is an image of a striped pattern in which the change of the phase value of the moiré fringe 40 is repeated every one period D4. That is, the phase information 41 on the moiré fringe 40 is an image in which the change of the phase value of the moiré fringe 40 from −π to π is illustrated in a striped pattern. The phase information 41 of the moiré fringe 40 may be in the range of −π to π or in the range of 0 to 2π as long as the range is 2π. The image processing unit 21b (see FIG. 1) is configured to associate the pixel value of each pixel of the subject P in the plurality of subject images 52 with the phase value of the moiré fringe 40 in each pixel based on the plurality of subject images 52 acquired by performing imaging while relatively moving the subject P and the imaging system 10 and the phase information 41 of the moiré fringe 40 generated in the plurality of subject images 52. The image processing unit 21b is configured to generate the phase-contrast image 51 by performing the alignment of the pixels at the same position of the subject P in the plurality of subject images 52 based on the position information on the pixels at the same position of the subject P in the plurality of subject images 52 and the pixel value of each pixel associated with the phase value. In the X-ray phase imaging apparatus 100, the image processing unit 21b (see FIG. 1) is configured to create position calibration data and perform alignment of pixels at the same position of the subject P in the plurality of subject images 52 using the created position calibration data. Specifically, as shown in FIG. 11, the image processing unit 21b (see FIG. 1) is configured to generate position calibration data used for aligning pixels at the same position of the subject P in the plurality of subject images 52 (see FIG. 9) based on the plurality of position calibration images 54 captured while relatively moving the label M and the imaging system 10 (see FIG. 1). The label M may be anything as long as it absorbs X-rays. The label M includes, for example, a wire. FIG. 11 shows the position calibration image 54 captured at first to sixth imaging positions while moving the label M in the X-direction by the subject moving mechanism 23 (see FIG. 1). In addition, in the examples shown in FIG. 11, the movement amount dm of the label M is acquired by focusing on the pixel 54a among the pixels in which the label M is imaged. The position calibration data is created based on a command value relating to a movement amount inputted to the subject moving mechanism 23 when relatively moving the label M and the imaging system 10 by the subject moving mechanism 23 (see FIG. 1) and an actual movement amount dm of the label M in the position calibration image 54 when the label M and the imaging system 10 are relatively moved based on the command value. More specifically, the position calibration data is created by acquiring an approximate expression indicating the relation between the command value and the movement amount dm of the label M based on the position of the pixels at the same position of the label M in the plurality of position calibration images 54. Specifically, as shown in FIG. 12, the control unit 21a (see FIG. 1) obtains an approximate expression by linearly fitting the plots mp shown in the graph 61. FIG. 12 is a graph 61 in which the vertical axis represents the position of the label M in the position calibration image 54 and the horizontal axis represents command values when the label M is moved. Then, as shown in FIG. 13, the image processing unit 21b (see FIG. 1) acquires the position in each subject image 52 (see FIG. 9) of the pixel at the same position of the subject P using the position calibration data, and performs the alignment of the pixels in each subject image 52. FIG. 13 shows a subject image 55 in which the subject images 52 at the first to sixth imaging positions are aligned so that the subject P at the second imaging position is stationary. Further, in FIG. 13, since the whole of the subject Pin the X-direction is not reflected in the image captured by arranging the subject P at the first imaging position, a blank area E is generated in the subject image 55 after the alignment. That is, when attention is paid to the pixel 55a in the subject images 55 after the alignment, it is understood that the moiré fringe 40 is moved with respect to the pixel 55a. In addition, in the X-ray phase imaging apparatus 100, the image processing unit 21b (see FIG. 1) is configured to perform alignment using position calibration data also for the phase information 41 of the moiré fringe 40 in order to acquire the phase value of the moiré fringe 40 in each pixel of each subject image 55 after the alignment. More specifically, as shown in FIG. 14, the image processing unit 21b (see FIG. 1) is configured to align the position of the phase information 42 at each imaging position by performing the same converting process as that performed when converting into an image in which the subject P is still also for the phase information 42 of the moiré fringe 40. FIG. 14 shows the phase information 42 after the phase information 41 of the moiré fringe 40 shown in FIG. 10 is aligned using the position calibration data. In addition, in the example shown in FIG. 14, the position corresponding to the position of the pixel 55a of each subject image 55 after the alignment is illustrated by a point 55b. That is, the position of the pixel at each imaging position and the position of the phase value of the moiré fringe 40 in the phase information 42 after the alignment are associated with each other in a one-to-one relation. As shown in FIG. 15, the image processing unit 21b (see FIG. 1) acquires the intensity signal curve 62 of the pixel value in which the respective phase values of the pixels at the same position of the subject P in the plurality of subject images 55 and the respective pixel values are associated with each other in a one-to-one relation, using the respective subject images 56 after the alignment and the phase information 42. Note that in the intensity signal curve 62 shown in FIG. 15, the horizontal axis represents phase values, and the vertical axis represents pixel values. FIG. 15 shows an intensity signal curve 62 obtained by acquiring plots pb based on the pixel value in each pixel 55a of the plurality of subject images 55 and the phase value of each point 55b corresponding to the pixel 55a of the subject image 55 in the plurality of phase information 42 and fitting the plots pb with a sine wave. Note that the blank area E shown in FIG. 13 is not sampled in FIG. 15 because there is no phase information 42 of the moiré fringe 40. The image processing unit 21b is configured to generate the phase-contrast image 51 (see FIG. 4) based on the acquired intensity signal curve 62. Phase-contrast Image Generation Flow Next, with reference to FIG. 16, a flow of generating the phase-contrast image 51 (see FIG. 4) by the X-ray phase imaging apparatus 100 according to the first embodiment will be described. First, in Step S1, the image processing unit 21b acquires a plurality of position calibration images 54 while moving the label M to the first to sixth imaging positions by the subject moving mechanism 23 under the control of the control unit 21a. Next, in Step S2, the control unit 21a obtains an approximate expression based on the movement amount dm of the label M and the command value. The control unit 21a acquires the position calibration data based on the slope of the acquired approximate expression. Next, in Step S3, the image processing unit 21b acquires phase information 41 of the moiré fringe 40. Next, in Step S4, the image processing unit 21b acquires a plurality of subject images 52 while relatively moving the subject P and the imaging system 10 by the subject moving mechanism 23 under the control of the control unit 21a. Next, in Step S5, the image processing unit 21b performs alignment of pixels at the same position of the subject P in the plurality of subject images 52 and acquires a plurality of subject images 55. Next, in Step S6, the image processing unit 21b performs alignment of the phase information 41 and acquires a plurality of phase information 42. Next, in Step S7, the image processing unit 21b associates the pixel of the subject P in the plurality of subject images 55 with the phase value of the moiré fringe 40. Next, in Step S8, the image processing unit 21b generates the phase-contrast image 51 based on the intensity signal curve 62, and ends the process. It should be noted that either the acquisition processing of the position calibration data in Step S1 and Step S2 or the acquisition processing of the phase information 41 of the moiré fringe 40 in Step S3 may be performed first. That is, the acquisition processing of the position calibration data may be performed at any time as long as it is prior to the alignment of the pixels in the plurality of subject images 52. The acquisition processing of the phase information 41 of the moiré fringe 40 may be performed at any time prior to the process of aligning the phase information 42. In the device of the first embodiment, the following effects can be obtained. In the first embodiment, as described above, at least one of the plurality of gratings 30 (the first grating 31 and the second grating 32) is composed of the plurality of grating portions 30c arranged side by side along a third direction (Y-direction) perpendicular the first direction (X-direction) in which the subject P or the imaging system 10 is moved by the subject moving mechanism 23 and the second direction (Z-direction) in which the X-ray tube 11, the detection unit 12, and the plurality of gratings 30 are arranged, and the plurality of grating portions 30c are arranged such that adjacent grating portions 30c overlap each other when viewed in the first direction. As a result, it is possible to suppress the occurrence of a portion in which the subject P hardly passes through the grating 30 in the third direction in which the plurality of grating portions 30c is arranged side by side when performing imaging while relatively moving the subject P and the imaging system 10 in the first direction in the grating 30 (the first grating 31 and the second grating 32) composed of the plurality of grating portions 30c. As a result, in a configuration in which imaging is performed while relatively moving the subject P and the imaging system 10, it is possible to increase the area in a direction perpendicular to the direction (X-direction) in which the subject P and the imaging system 10 are relatively moved while suppressing the occurrence of a portion in which the subject P cannot be imaged due to the occurrence of a portion in which the subject hardly passes through the grating. Further, in the first embodiment, as described above, the image processing unit 21b is configured to generate the phase-contrast image 51 based on the pixel values of the respective pixels in the plurality of images and the phase information 41 of the moiré fringes 40 generated in the plurality of images (subject images 52), and the plurality of grating portions 30c are arranged so that adjacent grating portions 30c overlap each other when viewed in the first direction so that at least one period D4 of the moiré fringes 40 is included in the first direction (X-direction) over the entire third direction (Y-direction). As a result, since the subject P can pass (can be imaged) at least for one period D4 of the moiré fringe 40 over the entire third direction (Y-direction), it becomes possible to suppress the occurrence of a portion in which the phase-contrast image 51 based on the phase information 41 cannot be generated due to the occurrence of a portion in which the image of one period D4 of the moiré fringe 40 cannot be captured. Further, in the first embodiment, as described above, the gap region 30e sandwiched by the grating regions 30d is formed between the plurality of grating portions 30c arranged side by side along the third direction (Y-direction), and the plurality of grating portions 30c are arranged such that adjacent grating portions 30c overlap each other when viewed in the first direction so that at least the grating region 30d is included in the first direction (X-direction) over the entire third direction. Thereby, by arranging the plurality of grating portions 30c side by side along the third direction, even when the gap region 30e is formed between the plurality of grating portions 30c due to an error or the like at the time of manufacturing the grating, it is possible to reliably suppress the occurrence of the grating portion 30c in which the subject P hardly passes through in the third direction in which the plurality of grating portions 30c is arranged side by side. Therefore, it is possible to effectively suppress the generation of a portion where the subject P cannot be imaged. In the first embodiment, as described above, the plurality of grating portions 30c are formed in a polygonal shape as viewed in the second direction (Z-direction), and the adjacent sides 20f of the plurality of grating portions 30c arranged adjacent to each other along the third direction (Y-direction) are arranged so as to include the portion extending in a direction intersecting with the first direction (X-direction) as viewed in the second direction, whereby the adjacent grating portions 30c are configured to overlap as viewed in the first direction. With this, it is possible to easily make the adjacent grating portions 30c overlap each other when viewed in the first direction by the portion extending in a direction intersecting with the first direction when viewed in the second direction between the sides 20f of the plurality of grating portions 30c adjacent in the third direction. Further, since the plurality of grating portions 30c need not be arranged in two or more columns in the first direction as compared with the case in which the plurality of grating portions 30c is arranged in a zigzag shape as viewed in the second direction (Z-direction) in order to cause the adjacent grating portions 30c to overlap as viewed in the first direction, it is possible to suppress the grating 30 from becoming large in size in the first direction. Further, in the first embodiment, as described above, the plurality of grating portions 30c is arranged such that the sides 30f of the plurality of grating portions 30c adjacent in the third direction arranged adjacent to each other along the third direction (Y-direction) extend across the entire side 30f as viewed in the second direction (Z-direction) in a direction intersecting with the first direction (X-direction). This makes it possible to lengthen a portion extending in a direction intersecting with the first direction as compared with a case in which only a portion of the sides 30f of the plurality of grating portions 30c adjacent to each other in the third direction extends in a direction intersecting with the first direction as seen from the second direction, and therefore, it is possible to more easily make the adjacent grating portions 30c overlap as seen from the first direction. Further, in the first embodiment, as described above, the plurality of grating portions 30c is arranged such that the sides 30f adjacent in the third direction (Y-direction) are substantially parallel to each other when viewed in the second direction (Z-direction). With this, it is possible to suppress the occurrence of a relatively large gap between the sides 30f of the plurality of grating portions 30c adjacent to each other in the third direction as compared with the case in which the sides 30f adjacent to each other in the third direction are not substantially parallel. Therefore, it is possible to more easily make the sides 30f of the plurality of grating portions 30c adjacent to each other in the third direction overlap the grating portion 30c adjacent to each other when viewed in the first direction. With reference to FIG. 17 to FIG. 19, a second embodiment will be described. This second embodiment is different from the first embodiment which is configured to perform imaging while relatively moving the subject P and the imaging system 10 in the direction of the grating pitch D of the plurality of gratings 30. The second embodiment is configured to perform imaging while relatively moving the subject P and the imaging system 10 in the direction of the extension of the grating 230 of the plurality of gratings 230. Note that in the drawings, the same component as that of the first embodiment is denoted by the same reference symbol. As shown in FIG. 17, the X-ray phase imaging apparatus 200 according to the second embodiment of this embodiment is provided with a plurality of gratings 230. The plurality of gratings 230 includes a first grating 231, a second grating 232, and a third grating 233. As shown in FIG. 18, the first grating 231 and the second grating 232 are each composed of a plurality of grating portions 230c arranged side by side along the Y-direction. In the second embodiment, the grating pitch direction (A-direction) of the plurality of gratings 230 and the extending direction (B-direction) of the grating 230 of the plurality of gratings 230 are denoted as a Y-direction and an X-direction, respectively. Also note that, in the second embodiment, the Y-direction and the X-direction are examples of the “first direction” and the “third direction” recited in claims, respectively. As shown in FIG. 19, the plurality of grating portions 230c are arranged such that adjacent grating portions 230c overlap each other when viewed in the X-direction in the same manner as in the first embodiment. Specifically, a gap region 230e sandwiched between the grating regions 230d is formed between the plurality of grating portions 230c. In FIG. 19, an example is shown in which the spacing of the gap region 230e is larger than the grating pitch D2 (D). The plurality of grating portions 230c is arranged such that the sides 230f of the plurality of grating portions 230c adjacent to each other in the Y-direction extend in a direction intersecting with the X-direction over the entire side 230f as viewed in the Z-direction. Although only the second grating 232 is shown as an example of the grating 230 composed of a plurality of grating portions 230c, the configuration of the first grating 231 is the same. Here, in the second embodiment, as shown in FIG. 18, the first grating 231 and the second grating 232 each have a plurality of grating portions 230c arranged in an arc shape so as to have a convex arc shape toward the detection unit 12 side (Z2 side) when viewed in the X-direction. Specifically, in the X-ray phase imaging apparatus 200, the plurality of gratings 230 (the first grating 231, the second grating 232, and the third grating 233) is each configured to have a shape along an arc (not shown) centered on the X-ray tube 11. The first grating 231 and the second grating 232 are each composed of a plurality of grating portions 230c arranged along an arc so as to face the X-ray tube 11. That is, when viewed in the Z-direction, any portion of the grating 230 is arranged so as to face the X-ray tube 11. Note that, in the X-ray phase imaging apparatus 200, any portion of the grating 230 is arranged so as to extend in a direction intersecting with the X-direction over the entire side 230f when viewed in the Z-direction, and is arranged so that any portion of the plurality of grating portions 230c faces toward the X-ray tube 11, so that only cross-sectional portions of the plurality of grating portions 230c adjacent to each other in the Y-direction are opposed to each other (are positioned so as to be twisted with each other). In the X-ray phase imaging apparatus 200, the subject moving mechanism 23 is configured to move the subject P or the imaging system 10 along the direction (B-direction) in which the gratings of the plurality of gratings 230 extend. According to the above configuration, as shown in FIG. 19, in the X-ray phase imaging apparatus 200, in the same manner as in the X-ray phase imaging apparatus 100 according to the first embodiment, when the subject P and the imaging system 10 are relatively moved in the X-direction, it is possible to make the subject P pass through the moiré fringes 40 (see FIG. 8) so as to include at least one period D4 (see FIG. 8) in the X-direction not only when (each portion of) the subject P moves on the line 93 that does not include the gap region 230e but also when the subject P moves on the line 94 that includes the gap region 230e. The rest of the configuration of the X-ray phase imaging apparatus 200 according to the second embodiment is the same as that of the first embodiment. In the second embodiment, the following effects can be obtained. In the second embodiment, as described above, the subject moving mechanism 23 is configured to move the subject P or the imaging system 10 along the direction (B-direction) in which the gratings of the plurality of gratings 230 extend, and the plurality of grating portions 230c is arranged side by side along the arc such that at least one of the gratings 230 (the first grating 231 and the second grating 232) composed of the plurality of grating portions 230c has a convex arc shape on the detection unit 12 side (the Z2-side) as viewed in the first direction (X-direction). This makes it possible to suppress oblique incidence (oblique incidence) of X-rays in all of the plurality of grating portions 230c arranged side by side along the third direction (Y-direction) as compared with when the plurality of grating portions 230c is arranged substantially linearly as viewed in the first direction. As a result, in a third direction in which the grating 230 is increased in size by arranging the plurality of grating portions 230c side by side, it is possible to suppress the occurrence of a portion in which the X-ray dose passing through the grating 230 decreases due to oblique incidence of X-rays and to suppress the occurrence of a portion in which the X-ray dose required for image generation cannot be detected. The other effects of the second embodiment are the same as those of the first embodiment. With reference to FIG. 20 to FIG. 22, a third embodiment will be described. This third embodiment is different from the first embodiment in which the sides 30f of the plurality of grating portions 30c adjacent in the Y-direction are configured to include a portion extending in a direction intersecting with the X-direction when viewed in the Z-direction. The third embodiment is configured so that the plurality of grating portions 330c is arranged in a zigzag shape (staggered shape) when viewed in the Z-direction. Note that in the drawings, the same component as that of the first embodiment are denoted by the same reference symbol. As shown in FIG. 20, the X-ray phase imaging apparatus 300 according to the third embodiment of this embodiment is provided with a plurality of gratings 330. The plurality of gratings 330 includes a first grating 331 and a second grating 332. The first grating 331 and the second grating 332 are each composed of a plurality of grating portions 330c arranged side by side along the Y-direction. Here, in the third embodiment, as shown in FIG. 21, each of the first grating 331 and the second grating 332 is configured such that a plurality of grating portions 330c are arranged in a zigzag shape as viewed in the Z-direction, and thus, adjacent grating portions 330c overlap as viewed in the X-direction. More specifically, the plurality of grating portions 330c is arranged such that the grating portions 330c of columns C adjacent in the X-direction are offset from each other in the Y-direction in a state in which the columns C composed of the plurality of grating portions 330c arranged adjacent to each other along the Y-direction are arranged to form two columns along the X-direction. Specifically, the second grating 332 includes a plurality of columns C1 and C2 of the grating portions 330c arranged adjacent to each other along the Y-direction. Column C1 is arranged on the X1 side of the second grating 332 and column C2 is arranged on the X2 side of the grating 332. Each of the plurality of grating portions 330c has a rectangular shape (polygonal shape) when viewed in the Z-direction. In the columns C1 and C2, the plurality of grating portions 330c each having a rectangular shape is arranged side by side along the Y-direction, so that a gap region 330e sandwiched by the grating regions 330d is formed between the plurality of grating portions 330c in the Y-direction. The plurality of grating portions 330c is arranged such that the sides 330f adjacent to each other in the Y-direction are substantially parallel in the X-direction when viewed in the Z-direction. That is, the gap region 330e formed between the plurality of grating portions 330c adjacent to each other in the Y-direction is substantially parallel to the X-direction when viewed in the Z-direction. The columns C1 and C2 are arranged so as to be adjacent to each other along the X-direction when viewed in the Z-direction. The columns C1 and C2 are arranged so as to be adjacent to each other along the X-direction, so a gap region 330g is formed between the grating portions 330c adjacent to each other along the X-direction. The interval of the gap region 330g formed in the X-direction may be equal to or different from the interval of the gap region 330e formed in the Y-direction. In FIG. 21, an example is shown in which the interval of the gap region 330g is larger than that of the gap region 330e. In the columns C1 and C2, the grating portions 330c are arranged so as to be shifted in the Y-direction so that the gap regions 330e formed in the columns C1 and C2 do not overlap when viewed in the X-direction. In the X-ray phase imaging apparatus 300, the columns C1 and C2 are arranged to be shifted in the Y-direction by half the length (½ pitches) of the grating portion 330c. As a result, (the grating regions 330d of) the adjacent grating portions 330c overlap with each other when viewed in the X-direction. Note that in FIG. 21, only the second grating 332 is shown as an example of the grating 330 composed of a plurality of grating portions 330c, but the configuration of the first grating 331 is the same. With the above configuration, as shown in FIG. 22, in the X-ray phase imaging apparatus 300, in the same manner as in the X-ray phase imaging apparatus 100 according to the first embodiment, even when the subject P and the imaging system 10 are moved relative to each other in the X-direction, it is possible to make the subject P pass through the moiré fringe 40 (see FIG. 8) so as to include at least one period D4 (see FIG. 8) in the X-direction, not only when (each portion of) the subject P moves on the line 95 that does not include the gap region 330e but also when the subject P moves on the line 96 that includes the gap region 330e. The other configurations of the X-ray phase imaging apparatus 300 according to the third embodiment are the same as those of the first embodiment. In the third embodiment, the following effects can be obtained. In the third embodiment, as described above, the plurality of grating portions 330c are arranged such that the columns C composed of the plurality of grating portions 330c arranged adjacent to each other along the third direction (Y-direction) are arranged in at least two columns along the first direction (X-direction), and the grating portions 330c of the columns C adjacent in the first direction are arranged in the third direction to each other, so that the plurality of grating portions 330c is arranged in a zigzag manner as viewed in the second direction (Z-direction), whereby the adjacent grating portions 330c overlap each other as viewed in the first direction. As a result, it is possible to easily make the adjacent grating portions 330c overlap when viewed in the first direction by the plurality of grating portions 330c arranged in a zigzag shape when viewed in the second direction (Z-direction). The other effects of the third embodiment are the same as those of the first embodiment. With reference to FIG. 23 to FIG. 25, a fourth embodiment will be described. The fourth embodiment is configured to perform imaging while continuously moving the subject P, unlike the first embodiment configured to image the subject P at the first to sixth imaging positions. In the drawings, the same configuration portion as that of the first embodiment is denoted by the same reference symbol. As shown in FIG. 23, the X-ray phase imaging apparatus 400 according to the fourth embodiment is provided with a processing unit 421 and a subject moving mechanism 423. The processing unit 421 includes a control unit 421a and an image processing unit 421b. Note that the subject moving mechanism 423 is an example of the “moving mechanism” recited in claims. Here, in the fourth embodiment, the subject moving mechanism 423 is configured to continuously move the subject P along the direction (B-direction) of the grating pitch. In addition, the image processing unit 421b is configured to generate a phase-contrast image 51 (see FIG. 4) based on continuous images acquired by continuously performing imaging while continuously moving the subject P and the imaging system 10 relative to each other. Specifically, under the control of the control unit 421a, the subject moving mechanism 423 is configured to be continuously movable in the X-direction in a state in which the subject P is placed on or held. The image processing unit 421b is configured to generate the phase-contrast image 51 (see FIG. 4) based on the acquired continuous subject images 52 (see FIG. 9) to acquire the subject images 52 as a moving image continuously captured at predetermined frame rates (time intervals). As shown in FIG. 24, in the X-ray phase imaging apparatus 400, the subject images 52 (see FIG. 9) acquired as a moving image are aligned using position calibration data, and the phase information 41 is also aligned using position calibration data. Similarly to the first embodiment, the image processing unit 421b associates the pixel value of each pixel of the subject image 55 with the phase value of the moiré fringe 40 based on the pixel of each subject image 55 (see FIG. 13) after the alignment and the phase information 42 (see FIG. 14) after the alignment, and acquires the intensity signal curve 63 shown in FIG. 24. In the intensity signal curve 63, in the same manner as in the intensity signal curve 62 in the first embodiment, the horizontal axis represents phase values, and the vertical axis represents pixel values. In the same manner as in the first embodiment, the image processing unit 421b generates the phase-contrast image 51 (see FIG. 4) based on the intensity signal curve 63. Phase-Contrast Image Generation Flow Next, with reference to FIG. 25, a flow of generating the phase-contrast image 51 (see FIG. 4) by the X-ray phase imaging apparatus 400 according to the fourth embodiment will be described. First, in Step S1 to Step S3, the same process as that of the first embodiment is performed. Next, in Step S404, the control unit 421a acquires a plurality of subject images 52 while continuously moving the subject P by the subject moving mechanism 423. Next, in Step S5 to Step S7, the same process as that of the first embodiment is performed. Then, in Step S8, the image processing unit 421b generates a phase-contrast image 51 and ends the process. The other configurations of the X-ray phase imaging apparatus 400 according to the fourth embodiment are the same as those of the first embodiment. In the fourth embodiment, the following effects can be obtained. In the fourth embodiment, as described above, the subject moving mechanism 23 is configured to continuously move the subject P or the imaging system 10 along the direction (A-direction) in which the grating extends or along the direction (B-direction) of the grating pitch, and the image processing unit 21b is configured to generate the phase-contrast image 51 based on continuous images acquired by continuously performing imaging while continuously moving the subject P and the imaging system 10 relative to each other. As a result, by performing imaging at several points (for example, six points) of the imaging position, the phase-contrast image 51 can be generated based on a larger number of images (subject images) 52 as compared with the case in which a plurality of images (subject images) 52 is acquired, so that the image quality of the phase-contrast image 51 can be improved. The other effects of the fourth embodiment are the same as those of the first embodiment. It should be noted that the embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated by claims rather than by the above description of the embodiments and includes all modifications (modified examples) within the meaning and range equivalent to the claims. For example, in the first to fourth embodiments, an example is shown in which the X-ray phase imaging apparatus 100 (200, 300, 400) is configured to move the subject P and the imaging system 10 relatively by moving the subject P, but the present invention is not limited to this. In the present invention, in the same manner as in the X-ray phase imaging apparatus 500 according to the modified example of the first embodiment shown in FIG. 26, the X-ray phase imaging apparatus may be configured such that the subject P and the imaging system 10 are relatively moved by moving the imaging system 10. As shown in FIG. 26, the X-ray phase imaging apparatus 500 is provided with a processing unit 521 and an imaging system moving mechanism 523. The processing unit 521 includes a control unit 521a. The imaging system moving mechanism 523 is configured to mount or hold the imaging system 10. The imaging system moving mechanism 523 is configured so as to be able to move the imaging system 10 in the X-direction by the control of the control unit 521a in a state in which the imaging system 10 is mounted or held. Note that the imaging system moving mechanism 523 is an example of the “moving mechanism” recited in claims. In the first to fourth embodiments, an example is shown in which the first grating 31 (231, 331) and the second grating 32 (232, 332) are each composed of a plurality of grating portions 30c (230c, 330c) arranged side by side along the third direction (Y-direction), respectively, but the present invention is not limited to this. In the present invention, only one of the first grating and the second grating may be composed of a plurality of grating portions arranged side by side along the “third direction”. In addition, the third grating may be composed of a plurality of grating portions arranged side by side along the “third direction”. In the first to fourth embodiments, an example is shown in which the plurality of grating portions 30c (230c, 330c) are arranged such that adjacent grating portions 30c (230c, 330c) overlap each other when viewed in the first direction so that at least one period D4 of the moiré fringe 40 is included in the first direction (X-direction) over the entire third direction (Y-direction), but the present invention is not limited thereto. In the present invention, a plurality of grating portions may be configured such that a part which is less than one period of a moiré fringe in the “first direction” in the “third direction”. In this case, the subject needs to interpolate the information of the portion that has passed through the portion which is less than one period of the moiré fringe. Further, in the first to fourth embodiments, an example is shown in which the sides 30f (330f) of the plurality of grating portions 30c (230c, 330c) adjacent in the third direction (Y-direction) extend linearly in a direction intersecting with the first direction (X-direction) when viewed in the second direction (Z-direction), but the present invention is not limited to this example. In this embodiment, like in the second modified example shown in FIG. 27, it may be configured such that the sides of the plurality of grating portions adjacent in the “third direction” extend in a curved manner in a direction intersecting with the “first direction” when viewed in the “second direction”. It also may be configured such that adjacent sides of a plurality of grating portions adjacent in the “third direction” include a portion extending linearly in a direction intersecting with the “first direction” when viewed in the “second direction” and a portion extending curvilinearly. As shown in FIG. 27, the grating 630 is composed of a plurality of grating portions 630c arranged side by side along the Y-direction. A gap region 630e is formed between the plurality of grating portions 630c. The plurality of grating portions 630c extends in a curved shape such that the sides 630f of the plurality of grating portions 630c adjacent to each other in the Y-direction intersect with the X-direction when viewed in the Z-direction. In the first to fourth embodiments described above, an example is shown in which the sides 30f (330f) of the plurality of grating portions 30c (230c, 330c) adjacent in the third direction (Y-direction) are configured to extend across the entire sides 30f (330f) as viewed in the second direction (Z-direction) in a direction intersecting with the first direction (X-direction), but the present invention is not limited thereto. In the present invention, as in the third modified example shown in FIG. 28, the sides adjacent of the plurality of grating portions in the “third direction” may extend in a direction intersecting with the “first direction” in only a portion of the sides when viewed in the “second direction”. As shown in FIG. 28, the grating 730 is composed of a plurality of grating portions 730c arranged side by side along the Y-direction. A gap region 730e is formed between the plurality of grating portions 730c. The plurality of grating portions 730c includes a portion in which the sides 730f of the plurality of grating portions 730c adjacent to each other in the Y-direction extend linearly in a direction intersecting with the X-direction when viewed in the Z-direction and a portion in which the sides 730f extend linearly in a direction intersecting with the Y-direction. In the first to fourth embodiments, an example is shown in which the plurality of grating portions 30c (230c, 330c) is arranged such that the sides 30f (330f) adjacent in the third direction (Y-direction) are substantially parallel to each other when viewed in the second direction (Z-direction). However, the present invention is not limited to this. In the present invention, the plurality of grating portions may be configured such that the sides adjacent in the “third direction” include portions that are not substantially parallel to each other when viewed in the “second direction”. In the second embodiment, although an example is shown in which the plurality of gratings 230 are arranged along an arc shape centered on the X-ray tube 11, the present invention is not limited to this example. In the present invention, the plurality of gratings may be arranged along a shape other than a shape along a circular arc centered on the X-ray tube as long as they are configured to have an arc shape convex toward the detection unit when viewed from the X-ray tube. In the third embodiment, an example is shown in which the columns C composed of the plurality of grating portions 330c arranged adjacent to each other along the third direction (Y-direction) are arranged in two columns (columns C1 and C2) along the first direction (X-direction), and the columns C1 and C2 are arranged in the third direction (Y-direction) so as to be shifted by half (½) pitches) of the grating portion 330c, but the present invention is not limited to this. In this embodiment, as long as the gap regions formed in each of the two columns arranged along the “first direction” do not overlap when viewed in the “first direction”, it may be configured such that the columns arranged along the “first direction” are arranged so as to be offset from each other by a length other than half of the grating portion in the “third direction”. In the third embodiment, an example is shown in which the columns C composed of the plurality of grating portions 330c arranged adjacent to each other along the third direction (Y-direction) are arranged in two columns along the first direction (X-direction), but the present invention is not limited to this. In the present invention, it may be configured such that a plurality of grating portions columns arranged adjacent to each other along the “third direction” is arranged in three or more columns along the “first direction”. In the first to fourth embodiments, an example is shown in which the X-ray phase imaging apparatus 100 (200, 300, 400) is configured to adjust the position of the first grating 31 (231, 331) in order to generate the moiré fringe 40 on the detection surface of the detection unit 12, but the present invention is not limited to this. In the present invention, the X-ray phase imaging apparatus may be configured to move the second grating or the third grating to generate a moiré fringe on the sensing surface of the detection unit. In the first to fourth embodiments, an example is shown in which the X-ray phase imaging apparatus 100 (200, 300, 400) is configured to generate the moiré fringes 40 substantially aligned in the first direction (X-direction) when viewed in the second direction (Z-direction) in any of the plurality of grating portions 30c (230c, 330c) arranged side by side along the third direction (Y-direction), but the present invention is not limited to this. In the present invention, like the fourth modification shown in FIG. 29, the X-ray phase imaging apparatus may be configured to generate moiré fringes shifted in the “first direction” when viewed in the “second direction” between a plurality of grating portions arranged side by side along the “third direction”. In the first to fourth embodiments, an example is shown in which the X-ray phase imaging apparatus 100 (200, 300, 400) is configured to perform imaging while relatively moving the subject P and the imaging system 10 in a state in which the moiré fringe 40 is generated in the first direction (X-direction) in which the subject P and the imaging system 10 are relatively moved, the present invention is not limited to this. In the present invention, like the fifth modified example shown in FIG. 30, the X-ray phase imaging apparatus may be configured to move the subject and the imaging system relative to each other in a state in which the moiré fringe is generated in a direction (crossing direction) different from the “first direction” in which the subject and the imaging system are moved relative to each other. In the first to fourth embodiments, an example is shown in which the plurality of gratings 30 (230, 330) includes the third grating 33 (233) for enhancing the coherence of the X-rays emitted from the X-ray tube 11, but the present invention is not limited to this example. In the present invention, it may be configured such that the plurality of gratings does not include the third grating. In this case, it is desirable to use an X-ray tube which is high in coherence of X-rays emitted. In the first to fourth embodiments, an example is shown in which the first grating 31 (231, 331) is used as a phase grating for generating a self-image by a Talbot effect, but the present invention is not limited to this example. In the present invention, since it is enough that the self-image is a striped pattern, an absorption grating may be used instead of a phase grating as the first grating. When an absorption grating is used, a region (non-interferometer) in which a fringe pattern is simply generated due to an optical condition such as a distance and a region (interferometer) in which a self-image due to a Talbot effect occurs are generated. In the first to fourth embodiments described above, for convenience of explanation, the processes by the control unit 21a (421a) and the image processing unit 21b (421b) are described using a flowchart of a “flow-driven type”, but the present invention is not limited to this. In the present invention, the processes of the control unit and the image processing unit may be performed in an “event-driven type” in which the processes are performed on an event-by-event basis. In this case, the operation may be performed in a complete event-driven type or in a combination of event-driven and flow-driven. It will be appreciated by those skilled in the art that the exemplary embodiments described above are illustrative of the following aspects. Item 1 An X-ray phase imaging apparatus comprising: an X-ray source; a detection unit configured to detect X-rays emitted from the X-ray source; a plurality of gratings arranged between the X-ray source and the detection unit to allow the X-rays emitted from the X-ray source to pass therethrough; a moving mechanism configured to move 1) a subject arranged between the X-ray source and the detection unit, 2) or an imaging system composed of the X-ray source, the detection unit and the plurality of gratings, along a direction in which the plurality of gratings extend or along a direction in which the plurality of gratings are arranged in a grating pitch; and an image processing unit configured to generate a phase-contrast image based on a plurality of images acquired based on signals detected by the detection unit with the subject and the imaging system being relatively moved with respect to each other, wherein at least one of the plurality of gratings is composed of a plurality of grating portions arranged along a third direction perpendicular to a first direction in which the subject or the imaging system is moved by the moving mechanism and a second direction in which the X-ray source, the detection unit, and the plurality of gratings are arranged, and wherein the plurality of grating portions are arranged so that adjacent grating portions overlap when viewed in the first direction. Item 2 The X-ray phase imaging apparatus as recited in the aforementioned Item 1, wherein the image processing unit is configured to generate the phase-contrast image based on a pixel value of each pixel in the plurality of images and phase information on a moiré fringe generated in the plurality of images, and wherein the plurality of grating portions are arranged such that adjacent grating portions overlap when viewed in the first direction so that at least one period of the moiré fringe is included in the first direction throughout the third direction. Item 3 The X-ray phase imaging apparatus as recited in the aforementioned Item 1 or 2, wherein a gap region sandwiched by grating regions is formed between the plurality of grating portions arranged along the third direction, and wherein the plurality of grating portions are arranged such that adjacent grating portions overlap when viewed in the first direction so that at least the grating region is included in the first direction throughout the third direction. Item 4 The X-ray phase imaging apparatus as recited in any one of the aforementioned Items 1 to 3, wherein each of the plurality of grating portions have a polygonal shape when viewed in the second direction, and wherein sides of the plurality of grating portions arranged adjacent to each other along the third direction arranged in the third direction are arranged to include a portion extending in a direction intersecting with the first direction when viewed in the second direction, so that the grating portions adjacent to each other overlap when viewed in the first direction. Item 5 The X-ray phase imaging apparatus as recited in the aforementioned Item 4, wherein the plurality of grating portions are arranged such that sides of the plurality of grating portions adjacent to each other in the third direction arranged adjacent to each other in the third direction extend in a direction intersecting with the first direction over an entirety of the sides when viewed in the second direction. Item 6 The X-ray phase imaging apparatus as recited in the aforementioned Item 4 or 5, wherein the plurality of grating portions are arranged such that the sides of the plurality of grating portions adjacent in the third direction are substantially parallel to each other when viewed in the second direction Item 7 The X-ray phase imaging apparatus as recited in any one of the aforementioned Items 4 to 6, wherein the moving mechanism is configured to move the subject or the imaging system along a direction along which the gratings of the plurality of gratings extend, and wherein at least one of the gratings composed of the plurality of grating portions are arranged side by side along an arc having a convex arc shape toward a detection unit side when viewed in the first direction. Item 8 The X-ray phase imaging apparatus as recited in any one of the aforementioned Items 1 to 3, wherein in the plurality of grating portions, in a state in which columns composed of the plurality of grating portions arranged adjacent to each other in the third direction are arranged in at least two columns along the third direction, the grating portions of adjacent columns in the first direction are arranged offset in the third direction, so that the plurality of grating portions are arranged in a zigzag manner as viewed in the second direction, whereby the grating portions adjacent to each other overlap as viewed in the first direction. Item 9 The X-ray phase imaging apparatus as recited in any one of the aforementioned Items 1 to 8, wherein the moving mechanism is configured to continuously move the subject or the imaging system in 1) a direction along which the gratings extend or 2) along a direction of the grating pitch, and wherein the image processing unit is configured to generate the phase-contrast image based on continuous images acquired by continuously performing imaging with the subject and the imaging system being relatively moved with respect to each other.
	summary
046363351	description	DESCRIPTION OF THE PREFERRED EMBODIMENT Now the process of this invention and experimental results leading thereto will be described. A cation exchange resin has a polymer matrix comprising a copolymer of styrene ##STR1## with divinylbenzene ##STR2## has a crosslinked structure formed by bonding a sulfonic acid group (SO.sub.3 H) as an ion exchange group to the polymer matrix; has a three-dimensional structure; and is represented by the following structural formula: ##STR3## Further, its molecular formula is represented by (C.sub.16 H.sub.15 O.sub.3 S).sub.n. On the other hand, an anion exchange resin is prepared by bonding a quaternary ammonium group (NR.sub.3 OH) as an ion exchange group to the same polymer matrix as in the cation exchange resin; and is represented by the following structural formula: ##STR4## Further, its molecular formula is represented by (C.sub.20 H.sub.26 ON).sub.n. The bond energy of a bonding between the constituents of an ion exchange resin is illustrated. FIG. 1 shows a skeletal structure of a cation exchange resin, and the case of an anion exchange resin is basically the same except that the ion exchange group is different. Table 1 shows the bond energies of bondings 1, 2, 3 and 4 between the constituents in FIG. 1. TABLE 1 ______________________________________ Bond Bond- energy* ing Structure (kJ/mol) ______________________________________ 1 Ion exchange Quaternary ammonium group 246 groups (anion exchange resin) Sulfonic acid group 260 (cation exchange resin) 2, 3 Polymer Straight-chain moiety 330-370 4 matrix Benzene ring moiety 480 ______________________________________ *Bond energy values obtained from "Daiyukikagaku", Spec. Vol. 2, publishe by Asakurashoten, 1963, Ed. by Munio Kotake When an ion exchange resin is thermally decomposed, the ion exchange group with the lowest bond energy is first decomposed, then the chain moiety of the polymer matrix is decomposed, and finally the benzene ring moiety is decomposed. FIG. 2 shows the results of a thermogravimetric analysis (TGA) of an ion exchange resin using a differential calorimetric balance. In FIG. 2, weight loss due to the evaporation of water occuring at 70.degree. to 110.degree. C. is not shown. The solid line represents a thermal weight change of an anion exchange resin, and the broken line represents that of a cation exchange resin. Table 2 lists decomposition temperatures of the bondings shown in FIG. 2. TABLE 2 ______________________________________ Decomposition Structure temperature (.degree.C.) ______________________________________ Ion exchange Quaternary ammonium group 130-190 groups (anion exchange resin) Sulfonic acid group 200-300 (cation exchange resin) Polymer Straight chain moiety 350-400 matrix Benzene ring moiety 380-480 ______________________________________ According to Table 2, in case of an anion exchange resin, the quaternary ammonium group as an ion exchange group is first decomposed at 130.degree. to 190.degree. C., then the straight chain moiety at above 350.degree. C., and the benzene ring moiety at above 380.degree. C. In case of a cation exchange resin, the sulfonic acid group as an ion exchange group is decomposed at 200.degree. to 300.degree. C., and then the straight-chain and the benzene ring moieties are decomposed at the same temperatures required in the case of an anion exchange resin. Based on the above results, only the ion exchange group of an ion exchange resin is selectively decomposed in the first stage by carrying out low-temperature thermal decomposition at 350.degree. C. or below, and the nitrogen or sulfur contained only in the ion exchange group is converted in this stage into nitrogen compounds (NO.sub.x, NH.sub.3, etc.) or sulfides (SO.sub.x, H.sub.2 S, etc.), which are then disposed of by conventional techniques. Then the residue is reduced to below a few %, e.g. 3 to 10% in the second stage by carrying out the high-temperature thermal decomposition at above 350.degree. C. and completely decomposing the polymer matrix consisting of carbon and hydrogen. The exhaust gas generated in this stage consists of CO, CO.sub.2, H.sub.2, and the like and hence no particular exhaust gas disposal treatment is necessary. When an ion exchange resin is decomposed by dividing thermal decomposition into a plurality of stages including low-temperature and high-temperature thermal decomposition, the exhaust gas disposal can be markedly facilitated as compared with a case where the thermal decomposition is carried out in one stage at a high temperature of above 350.degree. C., e.g. from 350.degree. to 1000.degree. C. Namely, when the thermal decomposition is carried out in one stage, 1.42 m.sup.3 of exhaust gas is generated per kg of an ion exchange resin (a 2:1 mixture of cation exchange and anion exchange resins), and this gas contains only about 5% of sulfur oxides and nitrogen oxides (the sum of the both is 0.074 m.sup.3). On the other hand, in case of the two-stage thermal decomposition, low-temperature thermal decomposition is first carried out at 300.degree. C. or below and then the high-temperature thermal decomposition is carried out at above 350.degree. C., so that 0.074 m.sup.3 or sulfur oxides and nitrogen oxides are produced only in the first stage low-temperature thermal decomposition, and these gases are not produced in the second stage high-temperature thermal decomposition, though 1.34 m.sup.3 of CO.sub.2 and the like are produced. Because sulfur oxides and nitrogen oxides of which the discharge into the atmosphere is regulated and which require exhaust gas treatment such as desulfurization and denitrification are generated in small quantities only in the first stage low-temperature thermal decomposition, the volume of the exhaust gas to be treated extensively can be reduced to only 0.074 m.sup.3. On the other hand, when the thermal decomposition is carried out in one stage, the exhaust gas in a quantity of as large as 1.42 m.sup.3 must be disposed together with other various gases in order to dispose the above exhaust gases (sulfur oxides, nitrogen oxides) contained in a quantity of as low as 0.074 m.sup.3 (5%), and this inevitably leads to the use of a large-scale exhaust gas disposal equipment. Namely, it becomes possible to reduce the volume of exhaust gas which requires a careful exhaust gas disposal treatment to about 1/20 by carrying out the two-stage thermal decomposition of this invention. It is further possible to scavenge SO.sub.x which accounts for 2/3 of the exhaust gas generated during the low-temperature decomposition by adding a scavenger for sulfur oxides (SO.sub.x) formed during the low-temperature thermal decomposition and to thereby reduce the volume of the exhaust gas requiring a careful treatment to about 0.025 m.sup.3, i.e., 1/90 of the total volume of the exhaust gas. Transition metal oxides, such as manganese oxide (MnO.sub.2) and nickel oxide (NiO), and calcium salts are effective as the scavenger. Calcium oxide (CaO) is preferred from the viewpoint of cost and performance, though mixtures of such oxides are also effective. EXAMPLE 1 This invention will now be described in detail with reference to an example shown in FIG. 3. This example illustrates a volume reduction treatment comprising thermally decomposing an ion exchange resin discharged from a condensate demineralizer of a boiling water reactor. FIG. 3 shows an example of equipment for practicing this invention. The waste resin is in the form of slurry in order to discharge it from the condensate demineralizer by back-washing. The waste resin slurry is fed to a slurry tank 6 through a sluury transfer conduit 5. A predetermined amount of the waste resin in the slurry tank 6 is fed to a reaction vessel 7, heated to 350.degree. C. by a heater 8 in an inert gas atmosphere (for example, nitrogen gas) to effect thermal decomposition of the waste resin. By this thermal decomposition, only the ion exchange group undergoes decomposition, and sulfur oxides (SO.sub.x), sulfur compounds (H.sub.2 S, etc.), nitrogen oxides (NO.sub.x), nitrogen compounds (NH.sub.3, etc.) are generated in the gaseous form. These exhaust gases are scrubbed in an alkali scrubber 9 with an aqueous sodium hydroxide solution 10 and converted into an aqueous solution of the sodium salt 11. These compounds can be disposed by a chemical waste disposal unit in the area of an atomic power plant. Further, the moisture contained in the waste resin is generated in the form of steam, which is condensed in a condenser 12 and serves as recirculation water 13. The exhaust gas treated in the alkali scrubber 9 (consisting mainly of inert gas) is passed through a filter 14 and then discharged. The waste resin (only the polymer matrix) which has undergone the low-temperature thermal decomposition in the reaction vessel 8 is transferred to a reaction vessel 15 and heated to above 350.degree. C., i.e. 600.degree. C., by a heater 16 to effect thermal decomposition. By this high-temperature thermal decomposition of the waste resin the undecomposed polymer matrix undergoes decomposition and forms a stable inorganic residue, which is a substance extremely stable to storage and keeping. By this decomposition, carbon dioxide (CO.sub.2), carbon monoxide (CO), hydrogen (H.sub.2) and hydrocarbons (CH.sub.4, etc.) are formed. These gases are passed through a filter 17, burned in a flare stack 18, and discharged in the form of gas 19 such as CO.sub.2 or steam (H.sub.2 O). The residue after the decomposition consists mainly of silica (SiO.sub.2) or a crud (consisting mainly of iron oxides). And the radioactive components are contained in the residue as a oxides or sulfides. And the residue is stored in a tank 20. This is placed in a drum or the like and finally solidified with a solidifying agent such as cement or plastic. In carrying out decomposition in the reaction vessel 7, air can also be used as an atmosphere without any obstruction instead of inert gas. In FIG. 3, it is also possible that CaO as an SO.sub.x scavenger is added from a tank 21 to convert the formed SO.sub.x into CaSO.sub.4, which is then incorporated in the decomposition residue. In this case, the volume of the exhaust gas is reduced but the amount of the residue is somewhat increased. Further in carrying out decomposition in the reaction vessel 15, it is preferred to add an oxidizing agent 22 such as steam, air or oxygen gas for the purpose of improving the rate of decomposition. FIG. 4 illustrates the effect of the addition of an oxidizing agent. In the graph, about 25 to 30% of a residue is left even when the waste resin is heated to 1,000.degree. C. in case of a nitrogen atmosphere to which no oxidizing is added in the high-temperature thermal decomposition which is effected at above 350.degree. C. (represented by curve A). On the other hand, when steam is added as an oxidizing agent (represented by curve B), the amount of the residue is greatly reduced at above 600.degree. C., and reduced to below several % at above 700.degree. C. Further, when air is used as an oxidizing agent (represented by curve C), the weight is greatly reduced at above 400.degree. C. and the residue is reduced to several % at above 500.degree. C. Namely, when the high-temperature decomposition is carried out in the reaction vessel 15, it is preferred to carry out the decomposition at above 700.degree. C. in case of an inert gas atmosphere such as nitrogen gas, and at above 500.degree. C. in case of an air atmosphere. To minimize the amount of the residue, it is preferred to add an oxidizing agent such as steam or air. By this, it becomes possible to reduce the volume of the waste resin to 1/10. Oxygen gas is not preferred as an oxidizing agent because of a hazard of explosion. Although the low-temperature and the high-temperature thermal decompositions in this example are carried out in separate reaction vessels, it is also possible to carry out both decompositions in the same reaction vessel. Namely, the same effect as in the above example can be obtained by raising the temperature stepwise in two stages in the same reactor and switching the exhaust gas disposal equipment. Although this example is one of application to a boiling water reactor, this invention is also applicable to waste resins produced from the waste liquor purification system of radioactive substance handling equipment, such as a reactor purification system, or a primary coolant purification system of a pressurized water reactor. EXAMPLE 2 1 kg of an ion exchange resin containing adsorbed cobalt-60 was placed in a 20 l Inconel type reaction vessel and heated to subject it to the first stage low-temperature thermal decomposition at 350.degree. C. for 2 hours. Then, steam was added at a flow rate of 0.01 Nm.sup.3 /hour, and the waste resin was subjected to the second stage high-temperature thermal decomposition at 800.degree. C. As a result, about 30 g of ash was left as a residue in the reaction vessel. The exhaust gas generated in the first stage was passed through both a gas scrubbing bottle charged with 5 l of a 1 wt. % aqueous NaOH solution and high-performance filter, whereby the concentrations of SO.sub.x and NO.sub.x in the exhaust gas were each reduced to below 0.1 ppm and a decontamination factor of above 1,000 was obtained. Further, the exhaust gas generated in the second stage was passed through a ceramic filter and an HEPA filter, thereby giving a decontamination factor of about 1,000. When the waste resin contains adsorbed easily volatile radioactive substances such as cesium-137 or cesium-134 in carrying out the second stage high-temperature thermal decomposition in the twostage thermal decomposition as shown in Example 1, it is preferred to prevent the volatilization of the radioactive substances by adding a vitrifying material and fixing them within the network structure of glass. The vitrifying material can be glass frit consisting mainly of silica (SiO.sub.2) which is a usual glass component, and it is preferred to add about 20 wt. % of boron oxide (B.sub.2 O.sub.3) in order to carry out effectively the melting and solidification of glass during the thermal decomposition. EXAMPLE 3 1 kg of an ion exchange resin containing adsorbed cesium-137 was subjected to thermal decomposition in the same manner and the same conditions as in Example 2. In carrying out the second stage high-temperature thermal decomposition, 30 g of glass frit and 6 g of B.sub.2 O.sub.3 were added. The proportion of cesium-137 contained in the waste gas produced in the second stage was about 1% of that contained in the initial resin. Namely, 99% of cesium-137 was fixed in a residue (about 60 g). In the two-stage thermal decomposition in Example 1, it is also possible that the reaction residue after the first stage low-temperature thermal decomposition is ground, if necessary, to a desired particle size and the ground reaction residue is burned with diffusion flame to effect the high-temperature thermal decomposition. This method makes the exhaust gas disposal easier than with a method in which the residue is directly burned at once, because the exhaust gas contains no SO.sub.x and NO.sub.x. It is also possible to recover the heat of combustion during burning and utilize it as a heat source for the first stage low-temperature thermal decomposition. This improves the thermal efficiency.
055301746	description	SUMMARY OF THE INVENTION An object of the present invention is therefore to provide a method of producing a vitrified waste in which, even if the waste content of the vitrified waste is increased over the conventional level of 25%, the same leaching rate as that of the conventional vitrified waste is ensured without suffering from the yellow phase separation. The inventors have noted the fact that the precipitate formed in the high-level liquid waste is composed mainly of Mo and Zr and have attempted to vitrify a high-level liquid waste from which the precipitate has been removed by separation prior to vitrification with the use of the conventional raw glass materials. However, when the waste content of the vitrified waste is increased to as high as 45% , it has been impossible to suppress the yellow phase precipitation. Thus, the chemical composition of the employed raw glass material has widely been studied. As a result, it has been found that the employment of a raw glass material having a chemical composition wherein SiO.sub.2, B.sub.2 O.sub.3, Li.sub.2 O, ZnO and Al.sub.2 O.sub.3 as the glass components are contained in specific proportions enables not only suppression of the yellow phase separation but also retention of a given leaching rate even when the waste content of the vitrified waste is increased to as high as 45%. The present invention has been accomplished on the basis of the above finding. The method of vitrifying a high-level liquid waste according to the present invention comprises removing a precipitate composed mainly of Mo and Zr from a high-level liquid waste, mixing the resulting high-level liquid waste with a raw glass material having a chemical composition wherein the B.sub.2 O.sub.3 /SiO.sub.2, ZnO/Li.sub.2 O and Al.sub.2 O.sub.3 / Li.sub.2 O ratios are at least 0.41, at least 1.00 and at least 2.58, respectively, and melt-solidifying the mixture to thereby form a vitrified waste. Eighty-percent or more of Mo which is present in the high-level liquid waste and causes the yellow phase separation limiting the waste content of the vitrified waste is contained in the precipitate formed in the liquid waste. This precipitate contains Zr as well as Mo. In the present invention, therefore, the precipitate is removed from the high-level liquid waste by solid-liquid separation technique such as filtration prior to the vitrification. This enables removal of about 80% of Mo contained in the liquid waste. The high-level liquid waste having the precipitate removed by separation is mixed with the raw glass material in given proportions and melt-solidified in a glass melting furnace into a vitrified waste. Conventional melt-solidification conditions can be employed. In the present invention, however, the use of a raw glass material having a specific chemical composition enables the waste content of the vitrified waste to be increased to a value higher than the 25%, for example, about 45%. The chemical composition of the raw glass material to be used in the present invention is based on the conventional one of PF798 of Table 1 and involves the modification thereof. More specifically, the component SiO.sub.2 of the PF798 has been replaced within the range of 3.7 to 4.6% by B.sub.2 O.sub.3 effective in suppressing the phase separation, thereby raising the ratio of B.sub.2 O.sub.3 /SiO.sub.2 to 0.41 or higher. Further, the component Li.sub.2 O of the PF798 has been replaced within the range of 0 to 3.6% by ZnO, thereby raising the ratios of ZnO/Li.sub.2 O and Al.sub.2 O.sub.3 /Li.sub.2 O to at least 1.00 and at least 2.58, respectively, for improving the chemical durability of the vitrified waste. With respect to any vitrlfled waste produced with the use of a raw glass material having a chemical composition which does not satisfy the above requirements, an increase in the waste content to 45% leads to incapability of retaining the conventional level of leaching rate although no phase separation is observed by visual inspection. PREFERRED EMBODIMENTS OF THE INVENTION The present invention will now be described in detail with reference to the following Examples. High-Level Liquid Waste The chemical composition of the employed simulated high-level liquid waste SW-11NP is as specified in Table 2. The parenthesized values in the Table signify the replacement by another element. More precisely, the elements of the platinum group (Ru, Rh and Pd) were replaced by the lighter elements in the other period of the same group (Fe, Co and Ni), respectively. Pm was replaced by Nd whose atomic number is smaller than that of Pm by one, and actinide elements U, Np, Pu, Am and Cm were replaced by Ce. Therefore, the content of each of the above elements Fe, Co, Ni, Nd and Ce employed for replacement includes that of the element introduced for the replacement. Tc not listed in the Table was replaced by Mn, and the content of Mn includes that of the element introduced for replacing Tc. TABLE 2 ______________________________________ Chemical composition of simulated high-level liquid waste SW-11NP [unit: g/l] Oxide Content ______________________________________ Na.sub.2 O 30.4 P.sub.2 O.sub.5 0.901 Fe.sub.2 O.sub.3 8.453 Cr.sub.2 O.sub.3 0.73 NiO 1.76 Rb.sub.2 O 0.34 Cs.sub.2 O 2.269 SrO 0.91 BaO 1.49 ZrO.sub.2 4.448 MoO.sub.3 4.404 MnO.sub.2 1.139 RuO.sub.2 (2.249) Rh.sub.2 O.sub.3 (0.43) PdO (1.06) CoO 0.43 Ag.sub.2 O 0.04 CdO 0.06 SnO.sub.2 0.05 SeO.sub.2 0.06 TeO.sub.2 0.57 Y.sub.2 O.sub.3 0.55 La.sub.2 O.sub.3 1.29 CeO.sub.2 10.138 Pr.sub.6 O.sub.11 1.27 Nd.sub.2 O.sub.3 4.206 Pm.sub.2 O.sub.3 (0.04) Sm.sub.2 O.sub.3 0.889 Eu.sub.2 O.sub.3 0.14 Gd.sub.2 O.sub.3 0.07 UO.sub.3 NpO.sub.2 PuO.sub.2 (7.513) Am.sub.2 O.sub.3 Cm.sub.2 O.sub.3 ______________________________________ In the present invention, the precipitate composed mainly of Mo and Zr is removed from the high-level liquid waste before vitrification. Thus, simulated liquid waste SW-22 having the concentrations of MoO.sub.3 and ZrO.sub.2 each reduced to about 50% in the chemical composition of the above liquid waste SW-11NP was prepared with the assumption of removal of part of the precipitate (assuming removal of about 50% of each of Mo and Zr). Further, with the assumption of the case where the content of Mo in the precipitate was low depending on the change of the chemical composition of the precipitate present in the liquid waste, simulated liquid waste SW-22M was prepared which had the concentrations of MoO.sub.3 and ZrO.sub.2 reduced to about 75% (assuming removal of about 25% of Mo) and about 50% (assuming removal of about 50% of Zr), respectively, in the chemical composition of the above liquid waste SW-11NP. In the practical vitrification, each of the above simulated liquid wastes SW-22 and SW-22M was used. Raw Glass Material The type and chemical composition of each of the raw glass material employed in the Examples and Comparative Examples are specified in Table 3. The chemical composition of the raw glass material PF798 as a standard in Table 3 is one given in Table 1 which has been employed by Power Reactor and Nuclear Fuel Development Corporation. In the preparation of each raw glass material, the individual components were blended in a batch of 100 g. Each component was weighed in the form of an oxide, phosphate, carbonate, nitrate, sodium salt or chloride and mixed by milling in an alumina mortar. TABLE 3 ______________________________________ Chemical composition of raw glass material [unit: wt. %, total: 100 wt. %) Stand- ard Comp. Ex. Ex. component PF798 PF-A PF-B PF-C PF-D PF-E ______________________________________ SiO.sub.2 62.3 58.6 56.8 55.0 55.0 55.0 B.sub.2 O.sub.3 19.0 20.9 22.7 22.7 22.7 23.6 Al.sub.2 O.sub.3 6.7 8.5 8.5 10.3 10.3 9.4 CaO 4.0 4.0 4.0 4.0 4.0 4.0 ZnO 4.0 4.0 4.0 4.0 5.8 7.6 Li.sub.2 O 4.0 4.0 4.0 4.0 2.2 0.4 component ratio B.sub.2 O.sub.3 /SiO.sub.2 0.31 0.36 0.40 0.41 0.41 0.43 ZnO/Li.sub.2 O 1.00 1.00 1.00 1.00 2.64 19.00 Al.sub.2 O.sub.3 /Li.sub.2 O 1.68 2.13 2.13 2.58 4.68 23.50 ______________________________________ Production of Vitrified Waste Each of the simulated liquid wastes SW-22 and SW-22M was mixed with each of the raw glass materials having the chemical compositions as specified in Table 3, transferred into a platinum beaker and melted by means of an electric furnace. The melting temperature was set at 1100.degree. C. and each batch was heated for 2.5 hr after the charging thereof. The melt was agitated with a quartz rod thrice at intervals of 15 min starting 1 hr after the initiation of the heating. Subsequently, the melt was allowed to flow on a metal plate and to naturally cool in the air at room temperature. Thus, a vitrified waste having a waste content of 45% was prepared by the above procedure. In addition, a vitrified waste having a waste content of 25% was prepared with the use of the conventional raw glass material PF798 to provide a control for comparison of the properties. The chemical compositions of the resultant vitrified wastes are collectively given in Table 4. TABLE 4 __________________________________________________________________________ Chemical composition of vitrified waste [unit: wt. %] Content of Designation of chem. Waste raw glass compsn. of Chem. compsn. of glass component content material raw glass material SiO.sub.2 B.sub.2 O.sub.3 Li.sub.2 O CaO ZnO Al.sub.2 O.sub.3 __________________________________________________________________________ 25 75 PF798 46.72 14.25 3.00 3.00 3.00 5.03 45 55 PF798 34.27 10.45 2.20 2.20 2.20 3.69 PF-A 32.27 11.45 2.20 2.20 2.20 4.69 PF-B 31.27 12.45 2.20 2.20 2.20 4.69 PF-C 30.27 12.45 2.20 2.20 2.20 5.69 PF-D 30.27 12.45 1.20 2.20 3.20 5.69 PF-E 30.27 12.95 0.20 2.20 4.20 5.19 __________________________________________________________________________ Evaluation of Properties of Vitrified Waste The results of evaluation of each vitrified waste specimen with respect to the occurrence of yellow phase separation and leaching rate (total weight loss rate) are collectively given in Table 5. The measuring methods were as follows. Occurrence of yellow phase separation: visually inspected. Leaching rate: determined as follows. Each vitrified waste specimen was milled into 250 to 420 .mu.m particles. 1 g thereof was immersed in 50 ml of distilled water at 98.degree. C. for 24 hr and the resultant weight loss was measured. The total weight loss rate was calculated by dividing the above weight loss by the surface area of the specimen obtained by multiplying the specific surface area determined according to the B.E.T. method by 1 g as the specimen weight. When the total weight loss ratio is 4.times.10.sup.-4 kg/m.sup.2 d or less, the vitrified waste has been evaluated as being on a par in leaching rate with the conventional vitrified waste. TABLE 5 __________________________________________________________________________ Evaluation of properties of vitrified waste Designation of simulated liq. waste SW-22 simulated liq. waste SW-22M Content of glassifying MoO.sub.3 concn. Occurrence Total wt. MoO.sub.3 concn. Occurrence Total wt. Waste glassifying material of vitrified of phase loss ratio of vitrified of phase loss ratio content material compsn. waste separation (kg/m.sup.2 .multidot. d) waste separation (kg/m.sup.2 .multidot. d) __________________________________________________________________________ 25% 75% PF798 0.73% none 2.8 .times. 10.sup.-4 1.12% none 3.2 .times. 10.sup.-4 45% 55% PF798 1.62% found 5.2 .times. 10.sup.-4 2.50% found 4.3 .times. 10.sup.-4 PF-A none 3.5 .times. 10.sup.-4 none 4.6 .times. 10.sup.-4 PF-B none 4.2 .times. 10.sup.-4 none 6.1 .times. 10.sup.-4 PF-C none 3.1 .times. 10.sup.-4 none 3.8 .times. 10.sup.-4 PF-D none 2.8 .times. 10.sup.-4 none 3.6 .times. 10.sup.-4 PF-E none 2.5 .times. 10.sup.-4 none 1.7 .times. 10.sup.-4 __________________________________________________________________________ With respect to both the simulated liquid wastes SW-22 (about 50% of Mo removed from the liquid waste) and SW-22M (about 25% of Mo removed from the liquid waste), it is apparent from Table 5 that whenever any of the raw glass materials PF-C, PF-D and PF-E (Examples) having the given component ratios is used, there is no occurrence of yellow phase separation and the leaching rate can be held on a par with that of the conventional vitrified waste (standard) even if the waste content is increased to 45%. In contrast, the vitrified waste produced with the use of either of raw glass materials PF-A and PF-B (Comparative Examples) not having any given component ratio which has a waste content of 45% is inferior in leaching rate to the conventional vitrified waste although there is no yellow phase separation observed. As apparent from the foregoing description, according to the present invention, a vitrified waste in which, even if the waste content of the vitrified waste is increased over the conventional level of 25%, the same leaching rate as that of the conventional vitrified waste is ensured without suffering from yellow phase separation can be obtained by melt-solidifying a mixture of a high-level liquid waste having the precipitate removed therefrom and a raw glass material having a chemical composition wherein the B.sub.2 O.sub.3 /SiO.sub.2, ZnO/Li.sub.2 O and Al.sub.2 O.sub.3 /Li.sub.2 O ratios are at least 0.41, at least 1.00 and at least 2.58, respectively. Therefore, the present invention enables an effective volume-reduction of the vitrified waste in the vitrification of a high-level liquid waste.
	claims	1. A neutron absorbing apparatus for insertion into a fuel cell storage system, the apparatus comprising:a corner spine;a first wall and a second wall, each affixed to the corner spine to form a chevron shape, wherein each wall comprises:an absorption sheet comprising a metal matrix composite having neutron absorbing particulate reinforcement, the absorption sheet extending along a longitudinal axis from a top edge to a bottom edge and having a first planar surface and a second planar surface that extend between the top and bottom edges; anda guide sheet having a first surface and an opposite second surface, the guide sheet affixed to the absorption sheet so that the first surface of the guide sheet covers a portion of the first planar surface of the absorption sheet, the guide sheet extending longitudinally beyond the top edge of the absorption sheet, wherein the absorption sheet extends along the corner spine along a greater length than the guide sheet; andwherein at least one of the first and second walls comprises a cutout extending through the absorption sheet between the first and second planar surfaces from the top edge downwardly towards the bottom edge and a locking protuberance having a first portion coupled to the first surface of the guide sheet and a second portion obliquely angled relative to the first portion to extend from the first surface of the guide sheet and protrude into the cutout in the absorption sheet. 2. The apparatus of claim 1, wherein the locking protuberance is resiliently deflective by about 0.125 inch. 3. The apparatus of claim 1, wherein the locking protuberance protrudes past the second planar surface of the absorption sheet by between about 0.125 inch to 0.254 inch. 4. The apparatus of claim 1, wherein the locking protuberance comprises a tab. 5. The apparatus of claim 1, wherein the locking protuberance is formed from 301 stainless steel, tempered to 3/4 hard. 6. A neutron absorbing apparatus for insertion into a fuel cell storage system, the apparatus comprising:a corner spine; anda first wall and a second wall, each affixed to the corner spine to form a chevron shape, wherein each wall comprises:an absorption sheet affixed to the corner spine, the absorption sheet comprising a metal matrix composite having neutron absorbing particulate reinforcement; anda guide sheet affixed to the absorption sheet, the guide sheet extending over a top of the absorption sheet, andwherein at least one of the first wall and the second wall further comprises a locking protuberance having a first portion coupled to a first surface of the respective guide sheet and a second portion extending from the first surface of the respective guide sheet and terminating in a free end, the second portion of the locking protuberance protruding through an opening formed in the respective absorption sheet, a distance between the first surface of the respective guide sheet and the second portion of the locking protuberance continuously increasing from the first portion of the locking protuberance towards the free end of the second portion of the locking protuberance. 7. The apparatus of claim 6, wherein the guide sheet is affixed to and covers a fractional upper portion of the absorption sheet. 8. The apparatus of claim 6, wherein each locking protuberance comprises a tab. 9. The apparatus of claim 8, wherein the tab is formed from 301 stainless steel, tempered to 3/4 hard. 10. The apparatus of claim 6, wherein each locking protuberance is resiliently deflective by about 0.125 inch. 11. The apparatus of claim 6, wherein each locking protuberance protrudes past an outer surface of the absorption sheet by between about 0.125 inch to 0.254 inch. 12. The apparatus of claim 1, wherein for each of the first and second wall, the guide sheet comprises a planar portion and an extension portion, the extension portion being angled relative to the planar portion towards the absorption sheet, the planar portion affixed to the portion of the first planar surface of the absorption sheet and the extension portion extending over the top edge of the absorption sheet so that a longitudinal plane that includes the second planar surface of the absorption sheet intersects the extension portion of the guide sheet. 13. The apparatus of claim 1, wherein the corner spine and the guide sheets of the first and second walls are formed from a different material than the absorption sheets of the first and second walls. 14. The apparatus of claim 1, wherein the corner spine, the guide sheets of the first and second walls, and the absorption sheets of the first and second walls are formed as separate and distinct parts. 15. The apparatus of claim 6, wherein for each of the first and second wall, the absorption sheet comprises a top edge and a planar front surface extending along the corner spine, and the guide sheet is affixed to and covers the planar front surface within an upper portion of the absorption sheet and extends over the top edge of the absorption sheet. 16. The apparatus of claim 6, wherein the corner spine and the guide sheets of the first and second walls are formed from a different material than the absorption sheets of the first and second walls. 17. The apparatus of claim 6, wherein the corner spine, the guide sheets of the first and second walls, and the absorption sheets of the first and second walls are formed as separate and distinct parts.
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