Split (2)

train · 33.5k rows

patent_number stringlengths 0 9	section stringclasses 4 values	raw_text stringlengths 0 954k
039986934	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to safety systems for nuclear reactors. More specifically, this invention is directed to the prediction of internal reactor conditions commensurate with maintaining the integrity of the fuel element cladding. Accordingly, the general objects of the present invention are to provide novel and improved apparatus and methods of such character. 2. Description of the Prior Art The performance of a nuclear reactor, like that of many other energy conversion devices, is limited by the temperature which component materials will tolerate without failure. In the case of a reactor with a core comprising an assemblage of fuel assemblies which in turn consist of an array of fuel rods or pins, the upper limit of temperature is imposed by the fuel rod or fuel pin cladding material employed. In order to adequately protect the reactor core against excessive temperatures, it is necessary to examine the temperature of the "hottest" fuel pin or the hottest coolant channel between adjacent fuel pins of the core since demage will first occur in the hottest fuel pin. Thus, the hottest pin or channel becomes the limiting pin or channel for the reactor core. As is well known, heat is generated in a reactor by the fission process in the fuel material. The fission process, however, produces not only heat but radioacitve isotopes which are potentially harmful and which must be prevented from escaping to the environment. To this end, the fuel is clad with a material which retains the fission products. In order to prevent clad overheating, in the interest of precluding the release of the fission products which occur on clad damage or failure, a coolant is circulated through the reactor core. Heat transferred to the circulating coolant from the fuel elements is extracted therefrom in the form of usable energy downstream of the reactor core in a steam generator. Thus, for example, in a pressurized water reactor system the water flowing through the core is kept under pressure and is pumped on the tube side of a steam generator where its heat is transferred to the water on the shell side of the generator. The water on the shell side of the steam generator is under lower pressure and thus thermal energy transfer causes the secondary water to boil and the stream so generated is employed to drive a turbine. To summarize, in the design and operation of a nuclear reactor, the basic objective of removing heat from the fuel must be obtained without allowing the temperature of the fuel cladding of the limiting fuel pin to rise to such a degree that the clad will fail. As the coolant circulates through the reactor core heat will be transferred thereto either through sub-cooled convection, often referred to as film conduction, or through nucleate boiling. Nucleate boiling occurs at higher levels of heat flux and is the preferred mode of operation since it permits more energy to be transferred to the coolant thereby permitting the reactor to be operated at a higher level of efficiency. Nucleate boiling is characterized by the formation of steam bubbles at nucleation sites on the heat transfer surfaces. These bubbles break away from the surface and are carried into the main coolant stream. If the bulk coolant enthalpy is below saturation, the steam bubbles collapse with no net vapor formation in the channel. This phenomenon is called sub-cooled boiling or local boiling. If the bulk fluid enthalpy is at or above the enthalpy of saturated liquid, the steam bubbles do not collapse and the coolant is said to be in bulk boiling. If the heat flux is increased to a sufficiently high value, the bubbles formed on the heat transfer surface during nucleate boiling are formed at such a high rate that they can not be carried away as rapidly as they are formed. The bubbles then tend to coalesce on the heat transfer surface and form a vapor blanket or film. This film imposes a high resistance to heat transfer and the temperature drop across the film can become very large even though there is no further increase in heat flux. This transition from nucleate boiling to film boiling is called "departure from nucleate boiling", hereinafter referred to as DNB, and the value of the heat flux at which DNB occurs is called the "DNB heat flux" in a pressurized water reactor and the "critical heat flux" in a boiling water reactor. Similarly, if the quantity of steam per coolant volume becomes too great a condition known as "excessive void fraction" may occur. Excessive void fraction may result in flow instabilities or a decrease in the heat transfer coefficient from the cladding to the coolant. Since clad damage is likely to occur because of a decrease in heat transfer coefficient and the accompanying higher clad temperature which may result when DNB or excessive void fraction occurs, the onset of these conditions must be sensed or predicted and corrective action in the form of a reduction in fission rate promptly instituted. Restated, in reactor operation DNB must be prevented since the concurrent reduction in clad strength as temperature increases can lead to a clad failure because of the external coolant pressure or because of the internal fission gas pressures in the fuel rod. One way of monitoring DNB in a reactor is to generate an index or correlation which indicates the reactor condition with respect to the probability of the occurrence of DNB. For a theoretical discussion of the prediction of the onset of DNB, reference may be had to the article "Prediction Of DNB For An Axially Non-Uniform Heat Flux Distribution" by L. S. Tong which appeared in the Journal Of Nuclear Energy, 21:241, 1967. The ratio of the heat flux necessary to achieve DNB at specific local coolant conditions to the actual local heat flux is known in the art as the departure from nucleate boiling ratio (DNBR) or the critical heat flux ratio. The two correlations, DNBR and critical heat flux ratio, are based upon slightly differing statistical derivations such that the critical values of DNBR and critical heat flux ratio are defined to be 1.3 and 1 respectively. These are the statistically established limiting values above which DNB has a very small probability of occurring. As employed herein, in the interest of facilitating understanding of the invention, DNBR will be used to describe both correlations. Thus, for the purposes of this discussion and description, DNBR shall mean both the Tong W-3 correlation for departure from nucleate boiling ratio and the critical heat flux ratio correlation. It is known that DNB and excessive coolant void fraction occur as functions of the reactor operating parameters of heat flux or power distribution, primary coolant mass flow rate, primary coolant pressure and primary coolant temperature. In order to prevent an excessive coolant void fraction or DNB, also called "burn-out" or "boiling crisis", reactor protective systems must be designed to insure that reactor operation is rapidly curtailed, a condition known in the art as "reactor trip" or "reactor scram", before the combination of conditions commensurate with DNB or excessive coolant void fraction can exist. Departure from nucleate boiling and DNB ratio may be expressed for one fuel pin or channel as: EQU DNBR = f [ Q, T.sub.C, P, W, F.sub.r, F.sub.2 (Z), EQU T.sub.AZ ] (1) where Q = core power in percent of full power PA1 T.sub.C = coolant inlet temperature PA1 P = primary or reactor coolant system pressure PA1 W = coolant mass flow rate PA1 F.sub.r = integral radial peaking factor PA1 F.sub.z (Z) = axial power distribution in the pin which has the integral radial power peaking factor PA1 T.sub.AZ = azimuthal tilt magnitude (the azimuthal component of power distribution) which is a measure of side to side xenon tilt. In computing DNBR, core power in percent of full power may be determined in a manner similar to that disclosed in U.S. Pat. No. 3,752,735 entitled "Instrumentation for Nuclear Reactor" and assigned to the assignee of the present invention. Integral radial power peaking factor is defined as the maximum ratio of power generated in any fuel pin in the core to the average fuel pin power in the absence of aximuthal flux tilt. Axial power distribution is defined for each fuel pin as a curve of local pin power density versus axial distance up the pin divided by the total power generated in the pin. Solutions to the problem of protective system design assume that primary coolant mass flow rate, integral radial peaking factor and azimuthal tilt magnitude are maintained within predetermined limits during numerous events which necessitate a reactor trip to prevent the DNBR or coolant void fraction limits from being exceeded. Prior art approaches to protective system design have also assumed that the axial distribution of power in the reactor core was maintained within the limits of its normal operating envelope. For a full disclosure of a prior art thermal margin protection system based on the preceding assumptions, reference may be had to U.S. Pat. No. 3,791,922 entitled "Thermal Margin for a Nuclear Reactor Protection System" which is assigned to the same assignee as the present invention. U.S. Pat. No. 3,791,922 contains a detailed discussion of the means by which the locus of points at which a DNB or excessive coolant void fraction thermal limit will occur and the disclosure of said copending application is incorporated herein by reference. Heretofore the prior art, including the technique and apparatus of referenced U.S. Pat. No. 3,791,922 has maintained core protection through means and methods which have been unduly conservative and thus have sacrificed plant operating margins. The assumption that certain operational parameters, and particularly axial power distribution, were either constants held at their design values or were variables which varied only within their allowed envelopes, has precluded reactor operation at power levels approaching the optimum for the existing conditions. The economic penalty imposed by unduly conservative safety system design is particularly apparent in the case of very large and high power reactors. SUMMARY OF THE INVENTION The present invention overcomes the above briefly discussed deficiencies of the prior art by providing a novel and improved thermal margin warning and control apparatus and method for use in a nuclear steam supply system. The present invention is characterized by the fact that it permits a nuclear reactor to be operated at higher and thus more efficient power levels than possible with previous techniques and controls of similar character. In accordance with the present invention "reactor trip" is programmed primarily as a function of core primary coolant pressure. Accurate core primary coolant pressure, reactor inlet or "cold leg" temperature and core power signals are obtained or calculated and are employed in a calculation of the core thermal limit locus. A plot of the core thermal limits represents a locus of points at which 1.3 DNBR or void fraction limits occur for various conditions of coolant pressure, coolant temperature and core power. Thus, considering a protective system having a plurality of redundant channels, the present invention contemplates the generation of accurate signals commensurate with primary coolant cold leg temperature, corrected for stratification, and core power for each channel. These signals are supplied as the inputs to circuitry which calculates a variable thermal margin set point signal. This thermal margin set point or primary coolant pressure trip point signal corresponds to the minimum reactor coolant pressure which may be tolerated in the interest of safely avoiding the void fraction and DNB thermal limits for the existing conditions of primary coolant cold leg temperature and core power. The circuitry which calculates the pressure trip point signal also adjusts a selected signal commensurate with core power for the effects of both radial and axial peaking factor; the invention thus including an axial peaking factor function generator which receives an input commensurate with the axial offset or power distribution in the core. Also in accordance with the invention, an accurate measure of core power is insured by auctioneering a first core power signal, as calculated as a function of measured neutron flux, with a second core power signal, as calculated as a function of coolant temperature rise between the upstream and downstream sides of the reactor core. The auctioneering of two measures of core power is an added safety feature. A further novel feature of the present invention is the calculation of a signal commensurate with the primary coolant system pressure at which temperature saturation of the coolant will occur. This saturation pressure signal, prior to delivery as an input to an alarm and/or trip control, is auctioneered with the calculated primary coolant pressure trip point signal and with a further signal commensurate with the minimum permissible primary coolant pressure. Another feature of the present invention is the utilization of accurate core power and cold leg temperature input signals. As noted above, the core power signal is generated by auctioneering two separate measurements of power and thereafter compensating the selected measure of power for axial and radial peaking factor. The cold leg temperature signal is corrected for stratification. Since the input signals to the computation circuitry for each channel of the present thermal margin control are corrected prior to utilization, the function generators for each channel of the invention are permitted to have the same coefficients or constraints. This, in turn, permits these coefficients to be set up prior to plant operation and facilitates simple switchability for various coolant pump flow configurations; the pump or flow selector switch being ganged to and thus simultaneously selecting the proper compensation factors for biasing selected input signals and for adjusting function generators in the calculation circuitry.
054882290	claims	1. A high resolution, deep UV beam photolithography system comprising a deep UV radiation source for generating a beam of deep ultraviolet radiation along a path, mask receiving structure in said path, a first optical system in said path for homogenizing and shaping the deep UV energy in said path; and a second optical system in said path for directing radiation energy onto the surface of a substrate to be processed, said second optical system including large area mirror structure having a numerical aperture of at least 0.3 and a plurality of refractive elements disposed between said mask receiving structure and said substrate for compensating (reducing) image curvature introduced into the system by said large area mirror structure, said second optical system providing a focal point outside any one of said refractive elements. 2. The system of claim 1 wherein all of the refractive elements in said second optical system are of fused silica. 3. The system of claim 1 wherein said deep UV radiation source is a laser of wavelength in the 150-250 nanometer range. 4. The system of claim i wherein said large area mirror structure includes a first mirror that is disposed on the system axis and a second mirror of concave spherical configuration with an aperture portion disposed on said beam path for passing a beam of radiation to said first mirror. 5. The system of claim 4 wherein each of said mirrors is mounted on a refractive lens component and includes a clear region on said beam path. 6. The system of claim 1 wherein said system is a microlithography system with a numerical aperture of about 0.6. 7. The system of claim 1 wherein said second optical system includes a plurality of lens elements (42-50) and first and second lens-mirror combinations (54, 56; 60, 62) that have the following dimensional values: 8. The system of claim 1 and further including optics for allowing an operator to view the imaging process in focus at a visible wavelength while substrate processing at an ultraviolet wavelength is in focus and is in progress. 9. The system of claim 1 wherein said refractive elements provide field flattening improvement of at least five times. 10. The system of claim 9 wherein all of the refractive elements in said second optical system are of fused silica. 11. The system of claim 9 wherein said deep UV radiation source is a laser of wavelength in the 150-250 nanometer range. 12. The system of claim 9 wherein said large area mirror structure includes a first mirror that is disposed on the system axis and a second mirror of concave spherical configuration with an aperture portion disposed on said beam path for passing a beam of radiation to said first mirror. 13. The system of claim 12 wherein said second mirror is mounted on a refractive lens component and includes a clear region on said beam path. 14. The system of claim 13 wherein said second optical system includes a plurality of lens elements (42-50) and first and second lens-mirror combinations (54, 56; 60, 62) that have the following dimensional values: 15. The system of claim 1 and further including optics for allowing an operator to view the imaging process in focus at a visible wavelength while substrate processing at an ultraviolet wavelength is in focus and is in progress. 16. For use in a deep ultraviolet microlithography system a reflective imaging system comprising first and second mirrors, at least fifty percent of the magnification or imaging power on the fast speed end of the system being provided by said mirrors, and field flattening and aberration compensation structure including an array of lens elements, said array of lens elements all being formed from the same refractive material type and providing a focal point outside of said array of lens elements, comprising a first plurality of lens elements disposed at a first predetermined position along an optical path of said imaging system for providing aberration compensation, a second lens element disposed at a second predetermined position along said optical path subsequent to said first lens element, said second lens element being operative to act in conjunction with said mirrors to provide field flattening, and a supplemental lens element disposed at a third predetermined position along said optical path for providing color compensation. 17. The system of claim 16 wherein said same refractive material type is fused silica. 18. The system of claim 16 wherein said imaging system and said compensation structure includes a plurality of lens elements (42-50) and first and second lens-mirror combinations (54, 56; 60, 62) that have the following dimensional values: 19. The system of claim 17 wherein each of said first and second mirrors is mounted on refractive lens components.
039768880	claims	1. A method of producing approximately 14 MeV neutrons from fissionable material including U.sup.235 and a gas mixture including deuterium and tritium gas in about equal proportions by volume comprising: passing said gas mixture over and in contact with said fissionable material; exposing said fissionable material to a thermal neutron flux in order to fission a portion thereof resulting in energetic fission fragments which, in turn, transfer energy to said deuterium and tritium, producing approximately 14 MeV neutrons by the reactions t(d,n).sup.4 He and d(t,n).sup.4 He. 2. The method of claim 1 wherein said approximately 14 MeV neutrons are received within a sample material for subsequent analysis. 3. The method of claim 1 wherein said gas mixture is circulated within a closed loop in contact with said fissionable material at 10 to 100 atmospheres pressure and is cooled to remove heat generated within said fissionable material. 4. The method of claim 1 wherein said thermal neutron flux is in excess of 10.sup.15 neutrons/cm.sup.2 -sec and said 14 MeV neutron flux produced therefrom is in excess of 3.5 .times. 10.sup.11 neutrons/cm.sup.2. 5. A materials testing device for exposing a sample to neutrons of about 14 MeV in order to determine the suitability of said samples in controlled thermonuclear fission applications, said device comprising a vessel filled with a mixture of deuterium-tritium gas and adapted to be exposed to and penetrated by a flux of thermal neutrons; a plurality of foils including fissionable material enclosed within said vessel; means for supporting said sample within said vessel; and means for cooling said foils to remove heat released by the fission of said fissionable material. 6. The device of claim 5 wherein said foils are supported in spaced-apart layers with said gas mixture between said layers, each of said foils being of not more than 25 microns in thickness and spaced at least 3 millimeters apart. 7. The device of claim 5 wherein said plurality of foils are concentric cylinders of uranium including a major portion of U.sup.235, and wherein said means for supporting said sample is axially positioned in respect to said cylinders. 8. The device of claim 5 wherein said housing is filled with an approximately 50 volume percent deuterium and 50 volume percent tritium at a total pressure of 10 to 100 atmospheres. 9. The device of claim 5 wherein said vessel is positioned within the core of a nuclear reactor at a location adapted to sustain a flux of thermal neutrons in excess of 10.sup.15 neutrons/cm.sup.2 -sec. 10. The device of claim 5 wherein said means for cooling said foils comprises a closed conduit loop connected from one to the opposite end portion of said vessel, said loop including means for circulating said deuterium-tritium gas mixture through said vessel, and a heat exchange apparatus adapted to pass a flow of coolant, said heat exchange apparatus connected within said loop to permit said gas mixture to flow therethrough in indirect heat exchange relation with said coolant flow.
041359747	abstract	A structural support system for the core of a nuclear reactor which achieves relatively restricted clearances at operating conditions and yet allows sufficient clearance between fuel assemblies at refueling temperatures. Axially displaced spacer pads having variable between pad spacing and a temperature compensated radial restraint system are utilized to maintain clearances between the fuel elements. The core support plates are constructed of metals specially chosen such that differential thermal expansion produces positive restraint at operating temperatures.
	description	This application claims the benefit of U.S. Provisional Patent Application No. 63/041,722, filed Jun. 19, 2020, entitled “DIRECT LATTICE ENERGY CONVERSION DEVICE,” the content of which is fully incorporated by reference herein. This invention relates to a lattice energy conversion (LEC) device that was found to be capable of self-sustaining the conversion of energy in a lattice structure of some specially prepared materials or of materials within the lattice structure into ionizing radiation and electrical energy without requiring the use of materials that are considered to be naturally radioactive. There is a long recognized need for a MEANS and method to produce reliable and continuous “green” or CO2 emission free electrical energy that does not involve the burning of fossil fuels as well as other carbon based materials. Some approaches include nuclear, hydroelectric, geothermal, photovoltaic, and wind farms. However, each of these options has its own drawbacks. In particular, nuclear power requires the use of radioactive materials and produces hazardous radioactive waste. Hydroelectric and geothermal are limited to specific locations. Photovoltaic systems, without a means of energy storage, only supply power when the sun is shining. Wind farms, without a means of energy storage, only supply power when the wind is blowing and are known to create low frequency noise and be hazardous to birds. Known devices that convert thermal energy into electrical energy without using radioactive materials include thermoelectric generators (TEGs) that rely on the Seebeck effect or thermopiles that employ multiple thermocouples and thermionic converters that use thermionic electron emission in a vacuum where the temperature of the electron emitter may be as high as 700° C. or greater. Such devices require a temperature difference between a heat source and a heat sink. In general, these thermal to electrical energy devices only produce a small amount of electrical energy which has limited their applications. Some methods for direct energy conversion involve the use of radioactive materials. One approach is the Direct Charge method wherein the particles or ions emitted by radioactive decay transport their charge to an electrode which may be comprised of a simple metallic electrode or solid state energy conversion devices such as alpha voltaic or beta voltaic devices. This atomic Direct Charge method operates primarily as a current source. A second approach is the contact potential difference (CPD) method which utilizes the ions emitted by radioactive materials to ionize a gas wherein the gaseous ions are collected by electrodes or electrode structures which may be comprised of materials of different electrochemical properties or work functions. Although these two approaches have been known for nearly 100 years, their use has been limited in part due to the requirement for radioactive materials and the small amount of energy produced. The metal-hydrogen (M-H) system, Fukai (The Metal-Hydrogen System Second Edition, Y. Fukai, Springer Series in Materials Science, 2005), and the palladium-hydrogen (Pd—H) system Lewis, (The palladium-hydrogen system, 1967 Academic Press) have been studied for more than 150 years. In 1863, Sainte-Claire Deville and L. Troost reported that hydrogen diffused rapidly through homogeneous plates of fused iron and platinum. These surprising results led Thomas Graham, Master of the Royal Mint, to conduct a similar series of experiments with palladium. Three years later, in 1866, Graham was the first to report the high rate at which hydrogen would diffuse through heated palladium. In 1958, Darling (Platinum Metals Rev., 1958, 2, (1), 16 “The Diffusion of Hydrogen through Palladium” A. S. Darling, Ph.D., A. M. I. Mech. E.) reported that the permeability of hydrogen in Pd is greatly increased if the hydrogen gas is flowing, rather than static, over the surface of Pd. In his book on page 225, Fukai points out the importance of vacancies including super-abundant vacancies that are formed in the process of “electrodeposition of metals from aqueous solutions.” Likewise, the ionization of gases by ionizing radiation and the resulting conduction of electricity by the ionized gas is a complicated phenomenon that has been studied since the latter part of the 19th century. J. J. Thomson and E. Rutherford published some of their original work in 1896 titled “The passage of Electricity through Gases exposed to Röntgen Rays” Phil. Mag. S, 5, 42 (1896). A definitive publication that describes the conduction of electricity by gases over a wide range of pressures and temperatures is the two volume 3P Edition treatise by Noble laureates Sir J. J. Thomson, (physics 1906) and his son G. P. Thomson (physics 1937) entitled Conduction of Electricity Through Gases, 3P Edition, Volume 1 1928, Volume 11, 1933. K. K. Darrow (Electrical Phenomena in Gases, 1932 Williams & Wilkins Company) discussed the importance of the diffusion of ions to the measurement of the current density per unit area. This research forms the basis to analyze the performance of a lattice energy conversion device with the objective of both understanding the phenomenon and of optimizing its performance in order to realize a practical application. The Lattice Energy Conversion device or Lattice Energy Converter (LEC) cell described below builds on the knowledge of the metal hydrogen system involving hydrogen host metals such as iron, nickel, and palladium, and the knowledge of the conduction of electricity through a gas to produce a new and novel energy conversion device that produces ionizing radiation which results in the production of ions and electrical energy. Such a LEC cell offers the potential to meet the need for reliable continuous “green” or CO2 emission free electrical energy that does not involve the burning of fossil fuels as well as other carbon based materials. Moreover, a LEC cell does not require the use of naturally radioactive materials. The LEC embodiments include self-initiating and self-sustaining devices that convert the energy in a specially prepared hydrogen host material lattice that contains or is occluded by atoms of hydrogen or deuterium into ionizing radiation and electrical energy. Additionally, LEC embodiments operate over a wide range of temperatures without the requirement of a supply of external electrical energy and wherein the flux of ionizing radiation and the resulting ionization of the gas increase with temperature. U.S. Pat. No. 9,472,812 issued Oct. 18, 2016 describes “an electron collector located within said interior volume and proximate to said ionizing material for receiving electrons from said ionizing material;” and “an insulator material located within said interior volume positioned between said ionizing material and said ion collector” where the “Insulator=Non-electrically conductive materials positioned between the anode and cathode to prevent electrons from flowing therebetween while preferably allowing the gas or ionized gas within the cell to pass from (through and/or around the insulator) the anode to the cathode; . . . .” Nevertheless, there are several significant differences between the patented Electric Energy Cell referred to above and the lattice energy conversion (LEC) device implementations of our invention, wherein ionizing radiation is produced and converted into electricity without the requirement for layers of semi-conductor and/or insulating materials between the ionizing material or the inclusion of materials to prevent electrons from flowing while allowing the ionized gas to pass. In addition, the LEC cells described below have demonstrated the ability to produce ionizing radiation even when the working electrode is not part of a physical electrical circuit such as a wire. U.S. Pat. No. 10,841,989 issued Nov. 17, 2020 describes a “GASEOUS-PHASE IONIZING RADIATION GENERATOR” for the “ . . . generation of ionizing radiation in an electrically controllable manner . . . .” Our invention is an improvement of the patented Gaseous-Phase Ionizing Radiation Generator referred to above in that the LEC cells disclosed below have demonstrated the capability to self-initiate and self-sustain the production of ionizing radiation and the production of electrical potential and current in the absence of an external source of electrical potential or current. Disclosed herein are Lattice Energy Converter (LEC) cells that convert energy such as the thermal and/or the vibrational energy as well as other energy in a lattice structure, or of the material contained within the lattice structure of one or more working electrodes, into other forms of energy such as ionizing radiation and/or electricity without the requirement to use naturally radioactive materials. The “active” element of a LEC device consists of one or more working electrodes comprised in whole or in part of specially prepared hydrogen host material from the metal hydrogen system such as iron, nickel, and palladium. When the lattice structure of the hydrogen host material is occluded with hydrogen, the LEC cell will self-initiate the production of ionizing radiation. When the specially prepared hydrogen host material is in fluidic contact with a gas or vapor comprised in whole or in part of hydrogen, the hydrogen in the gas will diffuse into, be occluded, and diffuse out or be ejected out of the lattice structure of the hydrogen host material so as to cause the LEC cell to self-initiate and self-sustain the production of ionizing radiation. By including one or more counter electrodes or electrode structures in addition to an active working electrode, the ionizing radiation or the ions thereby produced by the LEC cell can be collected as electrical energy. For purposes of the disclosure below, in addition to standard scientific definitions, the following definitions also apply. Active material or active electrode: An electrode comprised of materials, that are not required to be naturally radioactive, that spontaneously produces and/or emits one or more forms of electromagnetic and/or particulate ionizing radiation when it is occluded with hydrogen. An active material or electrode may be comprised of nanoparticles or microparticles, clusters of nanoparticles or microparticles, deposited materials or bulk materials that are occluded with hydrogen or isotopes of hydrogen wherein the energy of the lattice structure in combination with the hydrogen or deuterium that is occluded in the lattice structure of the hydrogen host material leads to the production of ionizing radiation. The active material or hydrogen host material of the working electrode may be physically connected to other electrodes such as with a wire or as part of a physical electric circuit or it may be connected to the other electrodes only by the ionizing radiation and/or the ions in the gas. Cell: Unless otherwise defined, a “cell” refers to a Lattice Energy Conversion (LEC) device and/or its physical implementations. Cell current: Cell current, ICell or ILEC is the totality of the currents produced by the flux of cell radiation during its operation and is comprised of a radiation current IRadiation, an internal shunt current IShunt, and an external load current ILoad, where IRadiation=IShunt+ILoad Contact potential, contact potential difference (CPD), or Volta potential: Contact potential difference or Volta potential is the voltage difference in work functions between different materials or different surface conditions. Contact potential also refers to a device wherein positive and negative gaseous ions preferentially migrate to electrodes comprised of materials of different work functions. Counter electrodes: Counter electrodes may form a pair with other counter electrodes or with the working electrode to intercept or collect the charge from the ionizing radiation as well as the gas ions. A LEC device may contain multiple counter electrodes that may include materials with different work functions. Counter electrodes may also participate in the production of ionizing radiation via the photoelectric effect wherein electromagnetic radiation from the working electrode causes energetic electrons to be ejected from the counter electrode which may also ionize the gas. A counter electrode may be a solid material such as a sheet or rod or it may be a screen or a grid of wires. Counter electrodes also may be comprised of voltaic devices or other devices that produce electricity when interacting with particles, ions, or electromagnetic radiation. Electrode structure: An electrode or combination of electrodes that may be electrically interconnected and may include perforations, apertures, or open areas such as but not limited to a mesh, screen, comb, grid, or perforated plates for the passage of a gas and/or radiation. Fluidic contact: As used herein, fluidic contact includes contact between an electrode and a gas including molecules, atoms, or ions contained within the gas. If the gas contains hydrogen, it will diffuse into, be occluded, and diffuse out or be ejected out of the hydrogen host material. Flux: The rate of flow of a fluid or gas, radiant or ionizing energy, or particles across a given area. Hydrogen: As used herein, hydrogen includes hydrogen gas, its atoms, and ions as well as the isotopes and ions thereof such as deuterium and deuterium ions. Hydrogen host materials: Hydrogen host materials include materials and alloys of materials that may form a metal hydride when they are in fluidic contact with a gas containing hydrogen by well-established processes known as diffusion, loading, charging, or hydrogenation of hydrogen into the hydrogen host material wherein the hydrogen is occluded interstitially within the lattice structure of the hydrogen host material, within vacancies, within super-abundant vacancies, intergranularly, or within crystal dislocations, defects, and cracks. Hydrogen also will diffuse, deload or dehydrogenate out of the hydrogen host material. (“Molecular Dynamics Studies of Fundamental Bulk Properties of Palladium Hydrides for Hydrogen Storage,” X. W. Zhou et. al. Journal of Physical Chemistry C, Oct. 18, 2016). A few examples of hydrogen host materials include iron, palladium, nickel, titanium and alloys and combinations of these materials and others such as PdAg and NiTiNOL (NiTi). Hydrogen host materials may also include materials into which hydrogen diffuses but does not form a metal hydride at normal temperatures and pressures. (“Diffusion in Solids, Fundamentals, Methods, Materials, Diffusion-Controlled Processes,” H. Mehrer, 2007). Hydrogen host materials may include bulk and/or deposited materials, sponge-like forms such as iron sponge, palladium black and nickel black, as well as nanoparticles and microparticles and clusters of nanoparticles and microparticles of hydrogen host materials. The use of the term specially prepared hydrogen host materials includes materials with lattice features such as vacancies, super-abundant vacancies, cracks and other material defects and wherein the hydrogen host material is occluded with hydrogen such that it is capable of producing ionizing radiation. Ion-Ion plasma: In ion-ion plasmas, negative ions replace electrons as the primary negative charge carriers. In the absence of a significant number of electrons, ion-ion plasmas may behave quite differently compared to conventional electron-ion plasmas. An ion-ion plasma may be produced by energetic electrons passing through the gas. Ionizing radiation: Ionizing radiation includes radiation that has sufficient energy to produce ions by detaching electrons from atoms or molecules, thereby ionizing them. Ionizing radiation may include energetic subatomic particles, energetic electrons, ions, or atoms and electromagnetic radiation such as UV, gamma and x-rays or Rttntgen rays. Vapor: A vapor includes a fluid that may be a gas, a mixture of gases and/or a mixture of two phases such as a gas and a liquid. Voltaic device: A voltaic device is composed of materials that produce an electrical current or potential in an external circuit when impacted by ions or particles or illuminated by electromagnetic waves. Examples include alphavoltaic, betavoltaic, and photovoltaic devices. Work Function: “The electron work function Φ is a measure of the minimum energy to extract an electron from the surface of a solid” e.g., Φ: Pd polycr(yastal) 5.22 eV, Zn polyer 3.63 eV (https://public.wsu.edu/˜pchemlab/documents/Work-functionvalues.pdf.). The work function of a material may change due to changes at the surface of the material such as those caused by oxidation and the interaction of ionizing radiation or ions with the surface. Working electrode or material: As used herein, the term “working electrode” or “specially prepared working electrode” refers to the electrode as well as the hydrogen host material that converts the energy in the lattice and/or the energy in the material occluded within the lattice of the hydrogen host material into spontaneous ionizing radiation. The specially prepared working electrode or material is comprised in whole or in part of hydrogen host material with a lattice structure that may include one or more of vacancies, super-abundant vacancies and defects or cracks, and is occluded with hydrogen or deuterium. The working electrode may be composites or alloys of materials including hydrogen host materials where the atomic hydrogen atoms are occluded, stored, modified, ejected, or consumed. The working electrode or material may be comprised of individual small particles such as nanoparticles or microparticles, groups, clusters of or assemblies of particles such as palladium black, palladium sponge, bulk palladium, iron sponge, or electrodeposited or codeposited iron from an aqueous solution of FeCl2. A working electrode or material becomes “active” when it is producing one or more forms of ionizing radiation. The working electrode or material may be either the anode or cathode of an electrical circuit depending on the direction of the flow of the electrons or neither the anode nor the cathode of an electrical circuit and does not need to be physically connected, such as by a wire, to other components of an electrical circuit. Lattice Energy Converter (LEC): An energy conversion device that converts energy such as the thermal and/or vibrational energy as well as other energy in the lattice or of the material contained within the lattice of one or more working electrodes into other forms of energy such as ionizing radiation and/or energetic ions without requiring materials that are naturally radioactive. The “active” element of a LEC device consists of one or more working electrodes comprised in whole or in part of specially prepared hydrogen host material such as but not limited to palladium or alloys of palladium that are occluded with hydrogen or deuterium and wherein vacancies, including superabundant vacancies and other defects such as those that are produced during codeposition of palladium from an aqueous solution, those produced by continuous and prolonged electrolysis, and those produced by heating and cooling the hydrogen host material. As it relates to this invention, when the lattice structure of a specially prepared hydrogen host material is occluded with hydrogen, one or more forms of ionizing radiation are produced wherein the ionizing radiation has sufficient energy to transport a charge and/or ionize a gas that is in fluidic contact with the hydrogen host material. When the specially prepared hydrogen host material is in fluidic contact with a gas or vapor comprised in whole or in part of hydrogen, the LEC device will self-initiate and self-sustain the production of ionizing radiation. Experimental results have shown that the specially prepared hydrogen host material that is in fluidic contact with air which has less than one part per million of hydrogen is sufficient to produce measurable ionizing radiation at normal room temperatures. In addition to the active working electrode or electrodes, a LEC device may include one or more additional counter electrodes or electrode structures comprised of materials such as voltaic devices or materials to collect the radiation flux or the ions that are produced. Counter electrodes also may participate in the production of ionizing radiation via the photoelectric effect wherein electromagnetic radiation from the working electrode causes energetic electrons to be ejected from the counter electrode and these electrons can contribute to the ionization of the gas. Additionally, counter electrodes or electrode structures may be comprised of materials with different electrical properties or work functions that will preferentially collect the ionized gas ions between the electrodes or between the electrodes and ground in order to produce a voltage between the electrodes or a current in an external load connected between the electrodes. For some applications, a LEC device also may require a means to confine and maintain the gas or vapor in fluidic contact with the hydrogen host material such as a sealable vessel wherein the vessel may have ports and valves to inject and control the pressure of the gas or vapor to control the flux of ionizing radiation and electrical feedthroughs for the passage of electrical signals into and out of the vessel. A LEC device has multiple implementations and applications for the ionizing radiation such as but not limited to medical applications, sterilization of surfaces and foods, space propulsion, and the production of electricity. Analysis of experimental results indicates that in some embodiments, the LEC is operating like a current source. This is similar to the Direct Charge effect in nuclear batteries wherein radioactive decay such as energetic alpha or beta particles that transport charge to a receiving electrode. Experimental results also indicate that the gas ions produced by the ionizing radiation will preferentially drift under the influence of an electric field such as that which may be produced by different work functions or diffuse under the influence of a concentration gradient and deposit their charge on electrodes comprised of materials with different work function where they will produce a voltage between the electrodes and a current through a load impedance that is connected between the electrodes. A unique feature of the LEC disclosed herein is that it produces a wide range of experimental results without the requirement for materials that are naturally radioactive. Several LEC embodiments have been constructed and tested including: the use of a gas or vapor comprised of air which contains a small amount of hydrogen and gases or vapors comprised primarily of hydrogen or deuterium gas; the use of gas pressures between approximately 500 Torr and 3 bar; the use of different hydrogen host lattice materials; changes in the preparation of the hydrogen host lattice structure to include vacancies and other defects; changes to cell dimensions and geometries such as cylindrical, flat plate, and other configurations; increased or reduced separation distance between the electrodes, as well as additional electrodes and electrode structures comprised of materials such as copper and zinc which have different electrical properties or work functions. LEC embodiments have been demonstrated wherein the active working electrode is physically connected such as with a wire through a resistive load impedance to the counter electrodes. Other LEC embodiments will be explained wherein the active hydrogen host material of the working electrode is not physically connected, for example without a wire, to the electrical load or to the other electrodes and only needs to be in fluidic contact with the gas or vapor containing hydrogen to produce self-sustained ionizing radiation. Analysis of experimental results further indicate that some LEC device embodiments behave primarily as a current source while other LEC device embodiments behave primarily as a voltage source. In both cases, experimental evidence indicates that the flux of ionizing radiation increases with the temperature of the LEC device and its hydrogen host material. Experimental analysis also suggests that the flux of ionizing radiation and its conversion to electricity involves multiple physical and electrical phenomena including some concurrently competing phenomena. These effects will be more fully illustrated and described when referring to the drawings. Critical components of the LEC device include a specially prepared working electrode comprised in whole or in part of a hydrogen host material lattice structure that is occluded with hydrogen or deuterium and is in fluidic contact with a gas or vapor comprised in whole or in part of at least one of hydrogen, deuterium, their ions, or a combination thereof wherein the hydrogen or deuterium can diffuse into, be occluded and diffuse out of the hydrogen host material. In order to produce at least one of a voltage or a current, one or more counter electrodes may be required. For self-sustained production of ionizing radiation, a means or vessel to confine the gas or vapor in fluidic contact with the hydrogen host material may be required. For some embodiments, additional features may be included such as ports, valves, electrical feedthroughs, additional electrodes, or electrode structures, a heater or source of heat, as well as a source of magnetic field and other stimuli. As shown in the drawings, embodiments can also include a vessel comprised of electrodes that are separated by an electrically insulating material that also confines the gas in fluidic contact with the electrodes. Multiple experiments have demonstrated the production of ionizing radiation. In the absence of a gas or vapor containing hydrogen or deuterium in fluidic contact with the hydrogen host material, the flux of the ionizing radiation appears to monotonically decay over a few days. In order to self-sustain the production of ionizing radiation, the hydrogen host material must be in fluidic contact with a gas or vapor wherein hydrogen or deuterium is available to diffuse into the hydrogen host material to maintain the production of ionizing radiation. One possible mechanism for the production of ionizing radiation to ionize the gas is that the working electrode may eject particles or ions that have a charge and sufficient energy to ionize the gas and, depending on cell geometry, can transport a charge to a counter electrode. Another mechanism for the production of ionizing radiation to ionize the gas occurs when the working electrode emits electromagnetic radiation such as gamma radiation and/or UV radiation that interacts with a counter electrode to produce energetic electrons via the photoelectric effect and the energetic electrons ionize the gas. Experimental evidence also indicates that the flux and/or energy of the ionizing radiation increases with temperature. Experimental evidence indicates that vacancies, super-abundant vacancies and other defects in the lattice structure of the hydrogen host material aid the production of ionizing radiation wherein lattice dynamics, which may include nonlinear effects, combine to produce the conditions required to produce ionizing radiation from the hydrogen host material. Multiple protocols such as but not limited to the codeposition of both palladium and deuterium from an aqueous electrolyte comprised of palladium chloride and lithium chloride in a solution of D2O are described in U.S. Pat. No. 8,419,919. Another protocol that uses a solution of palladium chloride and lithium chloride in an aqueous solution of H2O to codeposit multiple layers of palladium and hydrogen is described in U.S. Pat. No. 10,841,989. This protocol has been used to conduct most of the experiments described herein. Experimental evidence also indicates that removing the electrode from the plating solution after several hours of codepositing Pd—H or Pd-D and allowing it to dry for several hours as well as heating the electrode to 350-450° C. for 10 to 30 minutes and cooling the electrode in the presence of normal atmosphere or hydrogen or deuterium gas as part of the preparation procedure may be beneficial. Another protocol to produce an active working electrode utilizing codeposition of iron from an aqueous solution of Ferrous Chloride, (FeCl2-4H2O) proved to be successful. Additional deposition protocols to prepare the hydrogen host materials such as but not limited to plasma discharge, ion implantation, and self-heating/cooling in gas by passing current have demonstrated the ability to produce ionizing radiation. For the purpose of promoting an understanding of this invention, several embodiments are included in the drawings to demonstrate some of the functions, features, and implementations of the LEC as well as selected experimental data and supporting analysis. It is recognized that the ionizing radiation produced by a LEC device can be substituted for the ionizing radiation produced by radioactive materials in many applications such as the nuclear or atomic battery designs described by Ohmart in U.S. Pat. No. 2,696,564; Flannery in U.S. Pat. No. 1,217,739; Linder in U.S. Pat. No. 2,517,120; Brown in U.S. Pat. No. 5,087,533, and others. It will nevertheless be understood that no limitation of the scope of this invention is intended by the selected embodiments. Any alterations and further modifications in the described embodiments such as different working electrode alloys and hydrogen host materials, different electrode preparations such as sputtering and other deposition techniques as well as other metallurgical processes, different cell geometries and configurations, as well as any further applications of the concepts of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. Referring now to the drawings, FIG. 1 illustrates a first experimental embodiment for a Lattice Energy Converter (LEC) cell 100. Components included in the LEC cell 100 are a gas or vapor 112 comprised in whole or in part of at least one of hydrogen or deuterium or a combination thereof, a specially prepared and active working electrode 101 comprised in part of a hydrogen host material, an outer counter electrode 103 comprised of a brass or galvanized pipe nipple in combination with bushings 104 at opposite ends of the counter electrode 103, a valve 105 and a gas tight electrically insulating epoxy 106 form a vessel to confine the gas or vapor 112. An electrical conductor 120 passes through the gas tight electrically insulating epoxy 106 to make electrical contact with the working electrode 101 via a threaded connection 102. The working electrode 101 is centered within the counter electrode 103 by loose fitting O-rings 107 at opposite ends of the working electrode 101 so as to prevent physical electrical contact between the inner working electrode 101 and the outer counter electrode 103 while also allowing the gas or vapor 112 to pass so as to maintain the gas or vapor in fluidic contact with the working electrode 101. After assembly, the LEC cell 100 is evacuated and refilled with hydrogen or deuterium gas at pressures from 500 Torr to 3 bar. A digital volt meter (DVM) 110 with approximately 10 MΩ input impedance is connected by a conductor 114 to the counter electrode 103 and by conductors 116 and 120 to the working electrode 101 measured 109.8 mV that is spontaneously produced and self-sustaining between the electrodes 101 and 103 in the LEC cell 100 and wherein the voltage increased with increased temperature. A variable load impedance resistor 118 is connected in parallel with the DVM 110 to measure the LEC voltage and calculate the current output under various controlled load conditions. The LEC cell configuration of FIG. 1 also demonstrated the ability to produce a voltage and current in the presence of normal atmosphere which contains a small amount of hydrogen. Not shown in FIG. 1 is an optional external source of heat such as solar radiation, waste or low grade heat to increase the thermal energy of the working electrode and thereby increase the flux of ionizing radiation. Also not shown is an optional magnet or source of magnetic field to influence the lattice dynamics of the working electrode and the properties of the occluded hydrogen such as its spin alignment and orientation. A magnetic field can also influence the motion of ions within a gas. It should be recognized that the addition of an electric field can influence both the occlusion of hydrogen and the motion of ionized particles and thereby alter the flux of ionizing radiation and the resulting voltage and current. Typical dimensions for the LEC cell 100 shown in FIG. 1 are an inner working electrode 101 comprised of a ⅛ inch brass pipe nipple that is approximately 4 inches long which has been plated on its outer surface with a silver or nickel flash plating using a commercial plating solution followed by Palladium-hydrogen (Pd—H) codeposition from an aqueous solution of PdCl2 and LiCl. The outside diameter (od) of the ⅛ inch pipe nipple is 1.028 cm resulting in a circumference of ˜3.23 cm. Typically a ˜8 to 9 cm length of the nipple is codeposited resulting in ˜26 to 29 cm2 of covered surface area. The outer counter electrode 103 is a ⅜ inch pipe nipple that is approximately 5 inches long with a ˜1.26 cm inside diameter (id) which provides a separation distance between the inner and outer electrodes of approximately 1.1 mm. This separation distance was selected in order to minimize the recombination of the ions in the gas 112 between the electrodes 101 and 103. Tests were conducted using both brass and galvanized (zinc) pipe nipples, which have different work functions, for the outer electrode 103. Experimental procedures include tests with the temperature being relatively constant and tests with the LEC cell 100 placed in a temperature controlled chamber to obtain data over a range of temperatures. Voltage is measured with the DVM 110 initially set on the millivolt scale so the instrument input resistance is ˜1000 MΩ connected in parallel with the variable load resistor 118 connected between electrical instrumentation conductors 114 and 116 which are respectively connected to the outer electrode 103 and the wire 120 that is connected to the active working electrode 101. When the measured voltage drives the DVM into overload on the millivolt scale, the DVM is switched to the volt scale which has an input resistance of ˜10 MΩ. Current flowing through the variable load resistor 118 is calculated using Ohm's law. DVM output is recorded by way of an optical coupling to a computer (not shown) with a sample rate of approximately 2 samples per second. FIG. 2 shows an alternative experimental LEC cell embodiment 200 similar to that shown in FIG. 1. In this embodiment, the inner specially prepared working electrode with hydrogen host material 201 is comprised of a ¼ inch diameter Cu tube approximately 4 inch long that is plated on the outer surface with a silver or nickel flash followed by a codeposition of Pd—H hydrogen host material 202 from an aqueous solution. It is connected to a manifold 241 that includes a compound pressure gauge 251 and a valve 253 by a coupling 245. The working electrode 201 before codeposition has an outside diameter of 0.635 cm and a circumference of ˜1.99 cm. Typically ˜8-9 cm length of the Pd—H hydrogen host material 202 is codeposited, resulting in ˜16-18 cm2 of covered surface area. The vessel, also the counter electrode 221 is a ¾ inch by 5 inch long brass pipe nipple with a ˜2 cm inside diameter. Tests also have been conducted wherein the outer electrode is a ¾ inch galvanized (zinc) pipe nipple which provides materials with a different work function than that of a brass nipple. Typical separation distance between the inner 201 and outer 221 electrodes is approximately 6 mm. The gas 211 is confined by the assembly comprised of the counter electrode 221, an end cap 222, a bushing 223, and nylon PTFE, or high temperature epoxy 231 to provide a pressure seal and electrically insulate the inner working electrode 201 and outer 221 electrodes. Ionizing radiation 227 is spontaneously emitted from the inner or active hydrogen host material 202 of the working electrode 201 that produces positive 225 and negative 226 gaseous ions in the gas 211 between the inner and outer electrodes 201 and 221. Experimental procedures include tests with the temperature being relatively constant and tests with the cell placed in a temperature controlled chamber to obtain data over a range of temperatures. Voltage is measured across a variable load resistor 271 connected between the outer electrode 221 and the working electrode 201 via the manifold 241 and coupling 245, in parallel with a DVM 261 that is initially set on the millivolt scale so the instrument input resistance is ˜1000 MΩ. When the measured voltage drives the DVM into overload on the millivolt scale, it is switched to the volt scale which has an input resistance of ˜10 MΩ. Current through the variable load resistor 271 is calculated using Ohm's law. DVM output is recorded by way of an optical coupling with a sample rate of 2 samples per second. FIG. 3 shows plots of the spontaneous voltage and temperature as a LEC cell is being heated as a function of time. The plots indicate that the voltage increases approximately monotonically with temperature as the temperature is increased from approximately room temperature to 185° C. As shown, this LEC cell was only producing about 0.01 mV at room temperature and over 525 mV at 185° C. FIG. 4 shows the LEC voltage that is produced during a load test on a LEC cell with a working electrode comprised of a ⅛ inch by 4 inch long brass pipe nipple that was codeposited with palladium and a ⅜ inch by 5 inch galvanized pipe nipple outer or counter electrode when the variable load resistor is changed in ˜20% steps from a high value of 1.0 Ml to a low value of ˜220Ω. The time between steps is typically between 10 to 15 seconds in order to minimize atomic hydrogen (1H1+) or atomic deuterium (2H1+) deloading from the hydrogen host material of the working electrode. Some deloading of the occluded gas in the working electrode occurred as evidenced by the shape of the voltage rise-time required after the completion of the load test. The temperature during this test was constant at an ambient temperature of ˜294 K. This data is used to characterize the performance of the LEC cell as shown in FIG. 5. FIG. 5 shows a combined plot of measured LEC voltages and calculated currents through the load resistor as a function of load resistance at three different temperatures of 80° C., 140° C., and 185° C. with no external electrical energy being supplied to the cell. The upper traces plot the measured spontaneous LEC voltage versus resistance and the lower traces plot the calculated LEC load current and shunt current for the respective temperatures. LEC load current is calculated using Ohm's law. For low values of load resistance, the voltage increases in proportion to the increase in load resistance resulting in approximately constant current as plotted. Such behavior is indicative that the LEC cell is operating as a constant current source, which may also indicate the presence of diffusing ions and/or particulate radiation flux. This constant current behavior is also shown in the lower or current traces for low values of load resistance. At higher values of the load resistance, LEC cell voltage is no longer proportional to load resistance. This is shown in the load current traces as a decrease in load current for higher values of the load resistance and an increase in the internal shunt current. It may be noted that the reduction in load current is greatest for the higher temperatures where the LEC voltage is greater. This behavior is characteristic of a shunt impedance internal to the cell. The shunt current reduces the current available to the external load resistance. The value of the shunt conductance, (G=1/R) and thus the shunt cell current is a function of LEC cell voltage, wherein IRadiation=ILoad+IShunt. FIG. 6 shows a combined phenomenological model and physical electrical equivalent circuit representation of a LEC cell 601 based on the Norton equivalent circuit for a linear two-terminal electrical circuit. The approximately constant electrical current shown in FIG. 5 is modeled by a current source 603 where the magnitude of the ionizating radiation induced current 609 could be due to the direct charge and/or the diffusion of gaseous ions and may be designated IRadiation. The shunting of the load current is represented as a variable voltage shunt impedance, ZC 615, in parallel with the variable load impedance ZL 621 and is likely due to the drift of ions produced by the ionizing radiation. The IShunt current 617 that is shunted through shunt impedance ZC 615 may be designated as IShunt (i.e., the internal shunt current of the cell 601). The CCell physical capacitance 619 of the LEC cell configuration is represented as a shunt capacitance also in parallel with the load impedance Zt 621. The load current 625 may be designated as ILoad which satisfies the condition that the direct current (DC) component of the load current is ILoad=IRadiation−IShunt. The possibility that the working electrode and the counter electrode could have different electrical properties or work functions is shown in the schematic by the thickened electrical conductors labeled Working Electrode Work Function 607 and Counter Electrode Work Function 605. The polarity of the LEC voltage may be either positive (+) or negative (−) but is shown for the counter electrode as “+” 627 and for the working electrode as “−” 629 for the direction of the current shown. The polarity would be reversed if the source of the IRadiation is caused by the diffusion of negative ions. The positive gas ions 613 and negative gas ions 611 drift between the electrodes under the influence of the electric field strength determined by the LEC voltage, physical separation of the electrodes, as well as the space charge in the gas due the presence of the ions. Although not explicitly shown in the equivalent circuit, the radiation current 609, IRadiation is shown to be a function of Kelvin temperature, TK, since the spontaneous LEC currents were measured to be different at different cell temperatures as shown in FIG. 5. FIG. 7 is a plot of the spontaneous electrical power versus load resistance at three temperatures that is calculated from the data shown in FIG. 5. It may be noted that the power is the greater at higher temperatures. What is more, there is an optimal load impedance to maximize the power which occurs before the internal shunt current term dominates the conduction. FIG. 8 shows an Arrhenius plot of the data from FIG. 5 wherein the logarithm of the maximum current at the three temperatures is the ordinate axis versus reciprocal (inverse) cell temperature in Kelvin as the abscissa axis. The slope of the line is determined by the activation energy in eV divided by Boltzmann's constant in eV per Kelvin. The approximately straight line plot for higher temperatures between 80° C. and 185° C. (I/K=0.002833 and 0.002183) indicate that the current and thus the radiation flux are approximately exponential with inverse Kelvin temperature. It is also important to note that for most metals, the number of vacancies including superabundant vacancies increase exponentially to the inverse of the Kelvin temperature. This behavior strongly supports the importance of specially prepared hydrogen host lattice material procedures such as codeposition and other known processes that produce vacancies including super-abundant vacancies to establish a high initial number of vacancies which will further increase approximately exponentially with inverse temperature. FIG. 9 is a plot of the shunt current versus LEC voltage for a temperature of 185° C. as shown in FIG. 5. Sir J. J. Thomson predicted that the current in a gas should initially increase linearly with voltage. Subsequently, K. K. Darrow showed that the current and voltage would not go to zero simultaneously due to the diffusion of the ions in the gas at low voltage. Both of these predictions are displayed in this plot. FIG. 10 is a simplified cross-section view of an experimental LEC cell 1000 that includes alternating counter electrodes of Cu 1009 and Zn 1007 which have different work functions. The active working electrode 1003 is positioned at the center of the vessel 1001, and deuterium gas 1005 at approximately ambient pressure fills the vessel. The vessel 1001 for this cell 1000 is a glass jar which was selected to provide a longer ionization path distance between the ionization source of the working electrode 1003 and the fin-shaped electrodes 1009 and 1007 in order to exploit the ion diffusion, the Volta potential or contact potential difference phenomena, and to position the fin electrodes where most of the ionization occurs. Two sizes of glass jar vessels have been used; one allowing a 3% inch max diameter fin electrode configuration and the other with a wide mouth that allows about a 4 inch diameter fin electrode configuration. Several multiple-fin cell designs have been constructed and tested including six Cu fins 1009 and six Zn fins 1007 in alternating positions and also with two longer adjacent Cu fins alternating with two longer adjacent Zn fins. With the Cu fins connected together and the Zn fins connected together, the voltage is measured with a DVM 1013 connected between the Cu and Zn fin structures with a variable load resistor 1011 connected in parallel with the DVM. Another DVM 1015 is connected between the Cu fin structure 1009 and the active working electrode 1003 with a 5 MΩ load resistance 1017 connected in parallel with the DVM. FIG. 11 is a plot of data from the LEC fin cell 1000 of FIG. 10 which shows the cell temperature and the voltages measured between the Cu fins to the specially prepared codeposited Pd—H working electrode filled with deuterium gas. The Volta voltage or contact potential difference voltage is measured between the Cu and Zn fin structures. These results clearly show the presence of ion diffusion, or Volta or contact potential difference phenomena. Also, the voltage produced between the fin structures is a result of the ionized gas between the fins. A physical connection, such as a wire, between the fins and the working electrode is not required for a voltage and/or a current to be produced between the fin electrodes. Multiple experiments have demonstrated that the active working electrode will produce ionizing radiation without a physical connection to the other LEC cell electrodes, to ground, or to an external power supply. FIG. 12 shows a combined phenomenological physical and electrical LEC cell diagram 1201 represented by a Thévenin equivalent circuit of a two-terminal electrical device. For this cell's equivalent circuit 1201, VContactPotentialDifference or Volta potential 1211 and the internal cell impedance ZC 1220 represent the two-terminal electrical processes between the fins. The contact potential difference due to the dissimilar work functions of the finned electrodes 1251 and 1261 is represented by the Thévenin voltage source VCPD 1211. The capacitance of the cell 1201 is represented by CCell 1231. The Thévenin internal cell impedance is represented by ZC 1220, and the cell current is represented by ICell 1221 which connect the voltage source 1211 to the external load impedance ZL 1270. Thus, to maximize power, the external load impedance ZL 1270 should be equal to the internal cell impedance ZC 1220. The voltage source VCPD 1211 is approximately equal to the difference in the work functions of the electrodes 1251 and 1261 but diminished by the output voltage VLEC. The amount of current, ILoad 1271, that the cell 1201 can deliver to the external load impedance ZL 1270 depends upon a combination of the number of ions in the ion-ion plasma 1241, the electric field within the gas produced by the diffusion of the ions or the different work functions, the surface area of the fin electrode structure, the effective separation between the fins, and the magnitude of the load impedance Z 1270. FIG. 13 illustrates the ability of a LEC cell 1300 to produce a voltage between two counter electrodes 1303 and 1313 that are separated by an electrically insulating coupling 1330 where the working electrode 1301 is positioned midway between the counter electrodes and not physically connected to the counter electrodes or to ground. A bushing 1304 connects one counter electrode 1303 to a valve 1305 to allow for the evacuation of the LEC cell and its refilling with hydrogen gas 1312. The working electrode 1301 is positioned, and is separated by loose fitting O rings 1307, within the counter electrodes 1303 and 1313. The working electrode is attached to a threaded set screw 1302 which is connected to a wire 1320 that passes through a bushing 1319 that includes an electrically insulating material 1306 to provide a gas seal. A digital volt meter 1310 displays the voltage produced when connected by wires 1314 and 1316 between the two counter electrodes 1303 and 1313. A variable load resistor 1311 is connected between the wires 1314 and 1316 in order to characterize the performance of the cell 1300. As shown, the cell produced a self-sustained voltage of 150.5 mV after initial cell assembly. After several months of continuous operation through a 10 MΩ load, it was found that the LEC cell 1300 continued to produce approximately 125 mV. This cell embodiment illustrates the design and implementation flexibility for LEC devices. FIG. 14 illustrates an embodiment for a LEC cell 1400 to ionize a gas 1440 that is flowing between the specially prepared working electrode 1410 and a counter electrode 1415. This working electrode 1410 was prepared with a hydrogen host material lattice structure that is configured in the form of a tube. The tube 1410 in this embodiment consists of a woven wire mesh screen with a 0.075 mm hole size and 80 μm wire diameter super fine 304L stainless steel allowing a 34% open area that is rolled around and epoxied to a ⅛ inch brass pipe nipple 1450 at one end and a plug 1455 at the other end. The stainless steel wire mesh is initially plated with a nickel flash using a commercial Watts plating solution and then codeposited with palladium from an aqueous solution as previously described. The buildup of codeposited Pd—H will fill small openings in the screen to produce a solid layer of Pd—H on the outer surface of the tube. When a gas or vapor 1420 containing hydrogen or deuterium flows into the tube 1410, the hydrogen or deuterium diffuses into the specially prepared working electrode hydrogen host material from the inside so that, as the hydrogen host material becomes occluded, it produces ionizing radiation 1460. As the hydrogen diffuses through the hydrogen host material to the outer surface, ionizing radiation 1460 is produced which produces ions 1465 in the gas 1440. The gas 1440 to be ionized, which may be a mixture of gases that are selected for the specific application, flows between the working electrode 1410 and the counter electrode 1415 where the ionizing radiation 1460 ionizes the gas 1440 and produces positive and negative ions 1465. The ionized gas 1440 exits the cell and can be used for applications such as medical applications, killing bacteria, sterilizing surfaces that may have bacteria, and for food irradiation to improve the safety and extend the shelf life of foods by reducing or eliminating microorganisms and insects. FIG. 15 illustrates an alternative embodiment of a LEC cell 1500 designed to take advantage of an increase in the permeability of palladium by hydrogen of approximately 2 orders of magnitude when a combination of increased temperature and circulation of hydrogen is used. (“The Diffusion of Hydrogen through—Palladium” A. S. Darling, Platinum Metals Rev., 1958, 2, (1), 16-22) The working electrode 1510 is similar to the working electrode 1410 shown in FIG. 14 and includes a plug 1513 at one end and a ⅛ inch by 1 inch pipe nipple 1512 at the other end. The counter electrode 1515 is a ¾ inch pipe nipple approximately 5 inches long. Electrically insulating bushings 1530 provide a gas seal between the counter electrode 1515 and the ⅛ inch by 1 inch pipe nipple 1512 at one end that is attached to the working electrode 1510 and to a ⅛ inch by 1 inch pipe nipple 1511 at the other end of the counter electrode 1515. Hydrogen gas 1520 is pumped or blown into the interior of the working electrode 1510 through the nipple 1512 where it diffuses into, is occluded in the palladium, and produces ionizing radiation and ions 1525 in the space between the working electrode 1510 and the counter electrode 1515. Tubing and fittings 1550 and a pump or blower 1540 and the nipples 1511 and 1512 provide a means to recirculate the hydrogen gas 1520. An optional heater 1590 provides a source of heat to heat the hydrogen gas. Ionizing radiation is produced by the working electrode 1510 to provide a voltage and current between the working electrode 1510 and the counter electrode 1515. This voltage is measured by a digital volt meter 1580 connected by respective conductors 1570 and 1575 to the counter electrode 1515 and the working electrode 1510 via the nipple 1512 in parallel with a variable load resistor 1560. FIG. 16 illustrates a cross-section view of a rectangular box shaped LEC device 1600 including a vessel comprised in part of non-conducting non-permeable material 1620 and in part of an electrically conductive hydrogen non-permeable barrier material 1605 that has been codeposited on the inside with hydrogen host material 1610 to form the working electrodes. Additional working electrodes and one or more optional counter electrodes, not shown, may be installed between the working electrodes 1610 to increase the number of ions produced. For this embodiment, the gas 1630 containing hydrogen is introduced through a port 1635 in the non-conducting material 1620 at the end of the cell 1600 where the working electrode hydrogen host material 1610 produces ionizing radiation 1640 to produce ions 1645 in the gas 1630. The ionized gas flows between the fins of an electrode structure which is comprised of interdigitated electrodes 1650 and 1651. Alternating electrodes 1650 and 1651 may have different work functions and are electrically connected together by wires 1660 and 1661. As the ionized gas flows between the interdigitated electrodes, the positive and negative ions in the gas are preferentially attracted to the electrodes where the ions deposit their charge, producing a voltage across and a current through an external load 1670 that is measured by a digital volt meter 1675. The gas 1630 is recirculated via an external loop (not shown) and reintroduced through a port 1635 into the cell 1600. FIG. 17 illustrates an alternate electrode configuration to that shown in FIG. 16 having one or more electrode structures comprised of two foils or sheets 1710 and 1720 of conductive metal such as copper or zinc with an electrically insulating material 1715 located between them. Several of these electrode structures can be used to replace the electrodes illustrated in FIG. 16. A magnetic field, B 1755 is created, such as by two magnets 1730, that is orthogonal to the direction of the gas containing ions 1740 that is flowing with velocity v 1750 between the electrode structures. As shown, the magnetic field B 1755 creates a v×B force wherein positive ions go up and negative ions go down and where the ions are collected by the respective electrodes. Multiple electrodes 1710 and 1720 are electrically connected together, not shown, and connected to an external load with the voltage measured with a digital volt meter, not shown. In the presence of the magnetic field B 1755 as shown, the electrodes 1710 and 1720 do not need to have different work functions. FIG. 18 is a plot of the load current, shunt current, and power in a load resistance versus the logarithm of load resistance for the LEC cell 100 shown in FIG. 1 with the exception that the hydrogen host material is now codeposited iron from an aqueous solution of FeCl2. 4H2O rather than palladium, and the gas in the cell is now air at atmospheric pressure which only contains approximately 0.5 parts per million of hydrogen. For this embodiment, a ⅛ in by 4 inch “black iron” pipe nipple is cleaned to remove any protective coating and placed as the cathode in a plating bath consisting of 0.1 molar FeCl2.4H2O in an aqueous solution at room temperature. A platinum anode is used for the codeposition process. In this embodiment, codeposition of the iron started for 30 minutes at a current of approximately 50 μA/cm2 which was then increased to approximately 100 μA/cm2 for an additional approximately 30 minutes. The current was then increased to approximately 2 mA/cm2 for times ranging from 4 hours to one day. The working electrode was then removed from the plating bath and the aqueous plating bath was allowed to drip off before the working electrode was inserted it into a ¾ inch brass pipe nipple counter electrode, making sure that the working electrode is not in physical or direct electrical contact with the counter electrode. The data plotted in FIG. 18 was recorded using a digital volt meter having a 10 MΩ internal impedance in parallel with a resistor box with 24 resistance settings between 1 MΩ and 10Ω. The plot of FIG. 18 shows characteristics similar to the characteristics of a codeposited palladium-hydrogen host material plotted in FIG. 5. The working electrode also can be placed into a cell such as that described in FIG. 1 where the gas is hydrogen rather than air. The use of iron or alloys of iron as the hydrogen host material has significant cost and availability benefits over the use of other materials such as palladium. In addition, the use of air rather than hydrogen gas may be beneficial for some applications. FIG. 19 is a plot of a self-sustaining LEC cell 100 as shown in in FIG. 1 that reversed polarity three times over a time period of four days that included times when the cell was thermally cycled from approximately 24° C. to as high as 165° C. and times where the current changed when the temperature was relatively constant at room temperature. As shown, the voltage was initially approximately −0.1 volts at 24° C. and increased to approximately +0.05 volts as the temperature in the LEC cell increased to 165° C. When the temperature in the LEC cell cooled to 24° C., the voltage remained slightly positive but then dropped to −0.06 volts. From there, it gradually increased to +0.02 volts while the temperature remained at 24° C. On the third day, a short temperature increase caused the voltage to increase from approximately +0.02 to +0.04 volts at which time the temperature began to cool. As shown, six load tests were conducted during this time. The resulting cell behavior illustrates the multiple complex phenomena that may be involved in the production of ionizing radiation, ions, and electricity. In addition to temperature, other possible phenomena that could contribute to this behavior include a change in the work functions of the electrodes due to changes in the surfaces as a result of hydrogen loading and reloading, ions impacting the electrodes, and non-linear processes. (“Chemical and structural components of work function changes in the process of palladium hydride formation within thin Pd film,” R. Dus, R. Nowakowski, E. Nowicka, Journal of Alloys and Compounds Volumes 404-406, 8 Dec. 2005, Pages 284-287).
	claims	1. A variable focal length x-ray anti-scatter grid comprising: a plurality of pliable radiation absorbent members geometrically arranged relative to one another to absorb scattered radiation; and inter-space material between said radiation absorbing members, said grid is configured to flex along a first axis and a second axis, thereby allowing interim adjustment of an effective focal length of said grid to accommodate different x-ray procedures. 2. A variable focal length x-ray anti-scatter grid in accordance with claim 1 wherein said plurality of radiation absorbent members are integrally formed. claim 1 3. A variable focal length x-ray anti-scatter grid in accordance with claim 1 wherein said inter-space material is air. claim 1 4. A variable focal length x-ray anti-scatter grid in accordance with claim 1 wherein said radiation absorbent members are focused for convergence with an x-ray source. claim 1 5. A variable focal length x-ray anti-scatter grid comprising: a plurality of integrally formed injection molded pliable radiation absorbent members geometrically arranged relative to one another to absorb scattered radiation; and inter-space material between said radiation absorbing members. 6. A variable focal length x-ray anti-scatter grid comprising: a plurality of pliable radiation absorbent members geometrically arranged relative to one another to absorb scattered radiation, said radiation absorbent members fabricated from a loaded thermoplastic mix; and inter-space material between said radiation absorbing members. 7. An x-ray anti-scatter grid comprising: an integrally formed geometric grid structure defining a plurality of spaces; and an inter-space material located in said spaces, said grid and said inter-space material configured to flex along at least one axis, thereby allowing interim adjustment of an effective focal length of said grid to accommodate different x-ray procedures. 8. An x-ray anti-scatter grid in accordance with claim 7 wherein said grid structure is injection molded. claim 7 9. An x-ray anti-scatter grid in accordance with claim 7 wherein said grid structure is fabricated from a loaded thermoplastic material. claim 7 10. An x-ray anti-scatter grid in accordance with claim 9 wherein said thermoplastic material is a tungsten-thermoplastic mix. claim 9 11. An x-ray anti-scatter grid in accordance with claim 7 wherein said inter-space material is air. claim 7 12. An x-ray anti-scatter grid in accordance with claim 7 wherein said grid structure comprises a cross-grid. claim 7 13. An x-ray anti-scatter grid in accordance with claim 12 wherein said grid and said inter-space material is configured to flex along at least a second axis. claim 12 14. A method of improving x-ray image contrast with a variable length x-ray anti-scatter grid for use with an x-ray source emitting direct x-rays, said x-ray anti-scatter grid including an integrally formed geometric grid structure defining a plurality of spaces and an inter-space material located in the spaces, the x-ray anti-scatter grid focused along at least one axis at a first focal length for a first x-ray procedure, said method comprising the steps of: selecting a second focal length for use in a second x-ray procedure; flexing the integrally formed anti-scatter grid structure along the at least one axis until the second focal length is obtained; and positioning the anti-scatter grid between the x-ray source and the x-ray detector at the second focal length so that the anti-scatter grid absorbs radiation that is non-coincident with the direct rays of the x-ray source. 15. A method in accordance with claim 14 wherein the grid and inter-space material are configured to flex along a second axis, said method further comprising the step of flexing the anti-scatter grid along the second axis to form a substantially spherical grid. claim 14
	description	1. Technical Field Methods for manufacturing semiconductor devices which include partial implantation techniques are disclosed. 2. Description of the Related Art Generally, methods for manufacturing semiconductor memory devices, such as dynamic random access memory (DRAM), consist of several unit processes. The unit processes include deposition, etching, and implantation processes, etc., and are conventionally performed on a wafer-by-wafer basis. However, uniform process results are difficult to achieve. For example, uniform thicknesses of the stacked layers and etching ratios and uniform density of ions as throughout the area of the wafer are difficult to obtain because it is impossible to accurately control the large number of variables associated with the unit processes. Therefore, it can be said that process errors due to unpredictable or inaccurately controlled process variables are an inherent aspect of semiconductor device manufacturing. As expected, process errors ultimately deteriorate the characteristics of semiconductor devices to be manufactured. As an example, transistors often fail to maintain a uniform threshold voltage throughout the wafer. Even if the threshold voltage is adjusted to be uniform throughout the wafer via the implementation of an ion implantation process prior to forming a gate stack, the threshold voltage can become non-uniform during subsequent processes, resulting in uneven distribution of the threshold voltage throughout the wafer. In a subsequent formation of a gate insulation layer, an oxide layer as the gate insulation layer is formed in a non-uniform thickness throughout the wafer. This makes it impossible to achieve a uniform threshold voltage distribution throughout the wafer even if the ion implantation process is performed to impart the wafer with a uniform threshold voltage. Further, when source/drain regions having lightly doped drain (LDD) structures are formed, low-density ions are first implanted after formation of the gate stack, forming source/drain extension regions. Subsequently, a gate spacer is formed at the side wall of the gate stack, and then, high-density ions are implanted to form deep source/drain regions. However, there are problems in that the oxide layer and nitride layer of the gate spacer are stacked at a non-uniform thickness throughout the wafer, and that it is impossible to achieve a uniform etching ratio even when using an etch-back process. Thus, the gate spacer exhibits an uneven thickness on the wafer. When the gate spacer is used as an ion implantation mask to form the deep source/drain regions, furthermore, it inevitably adversely affects the threshold voltage in parts of the wafer. To solve the uneven distribution problem of the threshold voltage caused by non-uniform process results described above, a partial implantation method has been proposed. The partial implantation method is a method of implanting ions, that act as impurities, namely, dopant providing a threshold voltage adjustment, into respective regions of a wafer at varying densities in consideration of variations in the threshold voltage in subsequent processes. FIG. 1 is a diagram illustrating a conventional partial implantation method. A wafer 100 is divided into a plurality of regions according to the density of dopant ions to be implanted thereto. More specifically, based on a boundary line 110 crossing the center thereof, the wafer 100 is divided into an upper region 120 at the upper side of the boundary line 110 and a lower region 130 at the lower side of the boundary line 110. Here, it should be understood that the terms “upper” and “lower” are used for easy explanation of the wafer structure with reference to FIG. 1, and are not intended to limit the positional relationship therebetween. It will be understood that the wafer may be divided into three or more regions as occasion demands. Ions having different densities, in consideration of the threshold voltage variation in subsequent processes, are implanted to the respective divided regions, namely, the upper and lower regions 120 and 130. For example, when it is expected that the threshold voltage of the upper region 120 will be lowered during subsequent processes, dopant ions are implanted at a relatively lower density than the normal density of ions that are implanted in a general implantation process by approximately 5%, thereby increasing the threshold voltage of the upper region 120. Conversely, when it is expected that the threshold voltage of the lower region 130 will be increased during subsequent processes, dopant ions are implanted at a relatively higher density than the normal density by approximately 5%, thereby lowering the threshold voltage of the lower region 130. This enables both the upper and lower regions 120 and 130 of the wafer 100 to achieve a uniform threshold voltage distribution in spite of such a threshold voltage variation in subsequent processes. FIG. 2 is a graph illustrating the density distribution of dopant ions implanted by the conventional partial implantation method. The abscissa of the graph represents the length of the wafer 100 measured along the line II-II′ that intersects the boundary line 110 of the wafer 100. The origin of the abscissa indicates one point on the perimeter of the circular wafer 100, and the right end of the abscissa indicates the opposite point on the perimeter of the wafer 100 that is shown as a flat zone in FIG. 1. Further, a dashed line 110a indicates the boundary line 110 of FIG. 1. A region at the left side of the dashed line 110a indicates the upper region 120 of the wafer 100, and a region at the right side of the dashed line 100a indicates the lower region 130 of the wafer 100. The ordinate of the graph represents a therma-wave (TW) signal, which is proportional to the density of the dopant ions implanted in a wafer. Thus, the density distribution of the dopant ions implanted in the wafer 100 can be recognized by measuring the therma-wave signal. From the description as stated above with reference to FIG. 1, it can be clearly understood that the density of the dopant ions implanted in the upper region 120 of the wafer 100 is relatively low and the density of the dopant ions implanted in the lower region 130 of the wafer 100 is relatively high. Although the conventional partial implantation method as stated above can eliminate the non-uniformity of the threshold voltage throughout the respective regions of the wafer to some extent, it has a limitation when adjusting the density of dopant ions at a boundary line between the respective regions. That is, it is difficult to adjust the density of dopant ions in the vicinity of the boundary line 110 of the wafer 100 shown in FIG. 1. As is clearly illustrated in the graph of FIG. 2, the density of the dopant ions is not constant in the vicinity of the boundary line 110, but increases gradually from the upper region 120 to the lower region 130. The slope of the density is represented as a dotted line 200 in the vicinity of the dashed line 110a of the graph of FIG. 2 corresponding to the boundary line 110 of the wafer 100. The dotted line 200 is determined based solely upon the density of dopant ions implanted in the wafer 100, and cannot be freely adjusted. As will be easily understood, the slope of the dotted line 200 should be high in the vicinity of the boundary line 110 in order to achieve a wide difference between the characteristics of transistors in the respective regions divided by the boundary line 110. Conversely, when it is desired to narrow the differences between the characteristics of the transistors, the slope of the dotted line 200 should be low in the vicinity of the boundary line 110. However, the conventional partial implantation method cannot provide free adjustment of the slope of the dotted line 200, namely, the density of the dopant ions. In view of the above problems, a partial implantation method is disclosed which can allow free adjustment in the density distribution of the dopant ions implanted in the vicinity of a boundary line, which can divide a wafer into a plurality of regions in correspondence to the physical characteristics of the semiconductor devices being manufactured. A disclosed partial implantation method to implant dopant ions at different densities into a plurality of regions, including first and second regions defined in a wafer by means of a boundary line, comprises: defining a first implantation zone that is a remaining part of the first region except for a specific part of the first region close to the boundary line, a second implantation zone that is the remaining part of the second region except for a specific part of the second region close to the boundary line, and a third implantation zone that is the remaining part of the wafer except for the first and second implantation zones; and implanting the dopant ions at a first density into the first implantation zone, at a second density different from the first density into the second implantation zone, and at a third density that is a middle value between the first and second densities into the third implantation zone. Preferably, the first implantation zone may have an area corresponding to less than half or more preferably about 98% of the area of the first region. Preferably, the second implantation zone may have an area corresponding to less than half or more preferably about 98% of the area of the second region. Preferably, the first density of the dopant ions implanted in the first implantation zone may be lower than the third density of the dopant ions implanted in the third implantation zone, and the second density of the dopant ions implanted in the second implantation zone may be higher than the third density of the dopant ions implanted in the third implantation zone. Preferably, the first density may be lower than the third density by about 5%, and the second density may be higher than the third density by about 5%. Preferably, the boundary line between the first and second regions may be formed to vertically or horizontally bisect the wafer. Preferably, the boundary line between the first and second regions may be formed to divide the wafer into a center region and a peripheral region. Another disclosed partial implantation method to implant dopant ions at different densities into a center region and a peripheral region defined in a wafer by means of a circular boundary line, comprises: defining a first region at the upper side of a horizontal line as a tangent line of the circular boundary line and a second region at the lower side of the horizontal line; implanting dopant ions at a first density into a first implantation zone that is the remaining part of the first region except for a specific part of the first region close to the horizontal line, at a second density different from the first density into a second implantation zone that is the remaining part of the second region except for a specific part of the second region close to the horizontal line, and at a third density that is a middle value between the first and second densities into a third implantation zone that is the remaining part of the wafer except for the first and second implantation zones; and repeatedly implanting the ions while intermittently rotating the wafer within an angular range of 360°. Preferably, the repeated implanting of the ions while intermittently rotating the wafer may be performed until the wafer is rotated beyond at least the angular range of 360°. Preferably, the wafer may be intermittently rotated by an angle less than 180° during the implantation of the dopant ions. Preferably, the first implantation zone may have an area corresponding to about 98% of the area of the first region. Preferably, the second implantation zone may have an area corresponding to about 98% of the area of the second region. Preferably, the first density of the dopant ions implanted in the first implantation zone may be lower than the third density of the dopant ions implanted in the third implantation zone, and the second density of the dopant ions implanted in the second implantation zone may be higher than the third density of the dopant ions implanted in the third implantation zone. Preferably, the first density may be lower than the third density by about 5%, and the second density may be higher than the third density by about 5%. Another partial implantation method to implant dopant ions at different densities into a plurality of regions, including first and second regions defined in a wafer by means of a boundary line, comprises: defining a first implantation zone occupying part of the first region and a specific part of the second region close to the boundary line, and a second implantation zone equal to the second region; and implanting dopant ions at a first density into the first implantation zone, and at a second density different from the first density into the second implantation zone. Preferably, the first implantation zone may have an area corresponding to about 110% of the area of the first region. Preferably, the first density of the dopant ions implanted in the first implantation zone may be lower than the second density of the dopant ions implanted in the second implantation zone. Preferably, the first density may be lower than the second density by about 5%. Preferably, the first density of the dopant ions implanted in the first implantation zone may be higher than the second density of the dopant ions implanted in the second implantation zone. Preferably, the first density may be higher than the second density by about 5%. Another partial implantation method to implant dopant ions at different densities into a center region and a peripheral region defined in a wafer by means of a circular boundary line, comprises: defining a first region at the upper side of a horizontal line as a tangent line of the circular boundary line and a second region at the lower side of the horizontal line; defining a first implantation zone occupying part of the first region and a specific part of the second region close to the boundary line, and a second implantation zone equal to the second region; implanting dopant ions at a first density into the first implantation zone, and at a second density different from the first density into the second implantation zone; and repeatedly implanting the ions while intermittently rotating the wafer within an angular range of 360°. Preferably, the repeated implanting of the ions while intermittently rotating the wafer may be performed until the wafer is rotated beyond at least the angular range of 360°. Preferably, the wafer may be intermittently rotated by an angle less than 180° during the implantation of the dopant ions. Preferably, the first implantation zone may have an area corresponding to about 110% of the area of the first region. Preferably, the first density of the dopant ions implanted in the first implantation zone may be lower than the second density of the dopant ions implanted in the second implantation zone. Preferably, the first density of the dopant ions implanted in the first implantation zone may be higher than the second density of the dopant ions implanted in the second implantation zone. In the following description, it should be understood that the terms “upper” and “lower” are used for easy explanation of the wafer structure with reference to the accompanying drawings, and are not intended to limit positional relationship therebetween. FIG. 3 is a diagram explaining a partial implantation method according to a first disclosed method. A wafer 300 is divided into a plurality of regions according to the density of dopant ions to be implanted thereto. More specifically, based on a boundary line 310 crossing the center thereof, the wafer 300 is divided into a first region 320 at the upper side of the boundary line 310 and a second region 330 at the lower side of the boundary line 310. Of course, it will be naturally understood that the present embodiment bisects the wafer 300 into the first and second regions 320 and 330 based on the boundary line 310 crossing the center of the wafer 300, but it is only for exemplary, and the boundary line 310 is displaceable upward or downward as occasion demands. Alternatively, the boundary line 310 may extend in a vertical direction rather than a horizontal direction shown in FIG. 1, or may be inclined obliquely. After the wafer 300 is divided into the first and second regions 320 and 330, a first implantation zone 350 is defined in part of the first region 320. The first implantation zone 350 has an area determined by the density distribution of dopant ions implanted in a specific part of the first region 320 close to the boundary line 310. In the present embodiment, the area of the first implantation zone 350 is approximately 98% of the area of the first region 320. Here, the remaining area of the first region 320 corresponds to the specific part close to the boundary line 310. More specifically, based on dashed line 340 located above the boundary line 310, the first region 320 is divided into a zone close to the boundary line 310 at the lower side of dashed line 340, and a zone spaced apart from the boundary line 310 at the upper side of the dashed line 340. The zone, spaced apart from the boundary line 310 at the upper side of the dashed line 340, is used as the first implantation zone 350. Similarly, a second implantation zone 370 is defined in part of the second region 330. The second implantation zone 370 has an area determined by the density distribution of dopant ions implanted in a specific part of the second region 330 close to the boundary line 310. In the present embodiment, the area of the second implantation zone 370 is approximately 98% of the area of the second region 330. Here, the remaining area of the second region 330 corresponds to the specific part close to the boundary line 310. More specifically, based on dashed line 360 located at the lower side of the boundary line 310, the second region 330 is divided into a zone close to the boundary line 310 at the upper side of dashed line 360, and a zone spaced apart from boundary line 310 at the lower side of dotted line 360. The zone, spaced apart from the boundary line 310 at the lower side of dashed line 360, is used as the second implantation zone 370. The remaining part of the wafer 300 close to the boundary line 310 except for the first and second implantation zones 350 and 370 defines a third implantation zone 380. That is, the third implantation zone 380 extends from the boundary line 310 by predetermined distances in the first and second regions 320 and 330. After the first and second implantation zones 350 and 370, that are defined by excluding the specific parts close to the boundary line 310, and the third implantation zone 380, as the excluded part, are defined based on the boundary line 310, an ion implantation process for threshold voltage adjustment is performed on the first, second and third implantation zones 350, 370 and 380 by means of an ion implantation mask. Conventionally, the ion implantation process is sequentially performed on the first, second and third implantation zones 350, 370 and 380. In the present embodiment, dopant ions are implanted in the third implantation zone 380 at a normal density, while dopant ions are implanted in the first and second implantation zones 350 and 370 at different densities lower and higher than the normal density, respectively. Here, the normal density of the dopant ions implanted in the third implantation zone 380 corresponds to a density of the dopant ions to be implanted in the case of a general implantation process rather than a partial implantation. As an example of the ion implantation process for threshold voltage adjustment, when it is desired to increase the threshold voltage of the first region 320 beyond a predetermined level and to lower a threshold voltage of the second region 330 below a predetermined level, it is necessary for the first region 320 to compensate for the lowering of the threshold voltage thereof in subsequent processes, while it is necessary for the second region 330 to compensate for the increase of the threshold voltage thereof in the subsequent processes. For this, the density of the dopant ions implanted in the first implantation zone 350 must be lower than the normal density of the dopant ions implanted in the third implantation zone 380. Conversely, the density of the dopant ions implanted in the second implantation zone 370 must be higher than the normal density of the dopant ions implanted in the third implantation zone 380. More specifically, although the density of dopant ions to be implanted may be varied depending on the desired threshold voltage value, the density of dopant ions to be implanted in the first implantation zone 350 is determined to be lower than the density of the dopant-ions to be implanted in the third implantation zone 380 by approximately 5%, while the density of the dopant ions to be implanted in the second implantation zone 370 is determined to be higher than the density of the dopant ions to be implanted in the third implantation zone 380 by approximately 5%. By performing the ion implantation process using a partial implantation method described above, the density distribution of the dopant ions in the vicinity of the boundary line 310 can be adjusted by varying at least one of the areas of the first and second implantation zones 350 and 370. FIG. 4 is a graph illustrating the density distribution of dopant ions implanted by the partial implantation method according to the first disclosed method. The abscissa of the graph represents the length of the wafer 300 measured along a line that intersects the boundary line 310 of the wafer 300. A zero value at the center of the abscissa corresponds to the boundary line 310 of the wafer 300, and the left and right sides of the zero value indicate the first and second regions 320 and 330 of the wafer 300, respectively. The ordinate of the graph represents a therma-wave (TW) signal, which is proportional to the density of the dopant ions implanted in the wafer 300. As shown in FIG. 4, as a result of implanting the dopant ions using the partial implantation method of FIG. 3, it can be found that the density of the dopant ions in the vicinity of the boundary line 310 of the wafer 300 rapidly varies as compared to a conventional partial implantation method shown in FIG. 2. That is, the slope of a dotted line 400, that represents the density distribution of the dopant ions in the vicinity of the boundary line 310, is high. The slope of the dotted line 400 can be adjusted by varying at least one of the areas of the first and second implantation zones 350 and 370. For example, when it is desired to increase the slope of the dotted line 400, at least one of the areas of the first and second implantation zones 350 and 370 is increased by displacing at least one of the dashed lines 340 and 360, that define borders of the first and second implantation zones 350 and 370, toward the boundary line 310. Conversely, when it is desired to decrease the slope of the dotted line 400, at least one of the areas of the first and second implantation zones 350 and 370 is reduced by displacing at least one of the dashed lines 340 and 360 far away from the boundary line 310. FIG. 5 is a diagram explaining an alternative partial implantation method of the first disclosed method. In contrast to the disclosed method described with reference to FIG. 3, a wafer 300a is divided into first and second regions based on a circular boundary line 310a. That is, the first region is a center region of the wafer 300a inside the circular boundary line 310a, and the second region is a peripheral region of the wafer 300a outside the circular boundary line 310a. In this case, a first implantation zone 350a is defined inside a circular dashed line 340a displaced inward by a predetermined distance from the boundary line 310a, and a second implantation zone 370a is defined outside a circular dashed line 360a displaced outward by a predetermined distance from the boundary line 310a. A zone between the first and second implantation zones 350a and 370a is a third implantation zone 380a. Except for the above difference, the alternative embodiment described above is similar to the first embodiment of FIG. 3, and thus a detailed description thereof will be omitted for conciseness. FIGS. 6a to 6d are diagrams explaining a partial implantation method according to a second disclosed method. The partial implantation method involves implantation of ions several times while rotating a wafer 600. First, the wafer 600 is divided into a plurality of regions according to the density of the dopant ions to be implanted thereto. In the present embodiment, the wafer 600 is divided into first and second regions based on a circular boundary line 610. The first region of the wafer 600 is a peripheral region 620 outside the boundary line 610, and the second region of the wafer 600 is a center region 630 inside the boundary line 610. Next, the wafer 600 is oriented to a standard position. The standard position is that shown in FIG. 6, wherein a flat zone 601 of the wafer 600 is at the lowermost position of the wafer. In such an orientation, a first implantation zone 650 is defined at the upper side of a first dashed line 640 that is displaced upward from a standard dashed line 610a as a tangent line of the circular boundary line 610 by a predetermined distance parallel thereto. The area of the first implantation zone 650 can be determined to be approximately 98% of the area of a region at the upper side of the first dashed line 640. Similarly, a second implantation zone 670 is defined at the lower side of a second dashed line 660 that is displaced downward from the standard dashed line 610a as the tangent line of the circular boundary line 610 by a predetermined distance in parallel. The area of the second implantation zone 670 can also be determined to be approximately 98% of the area of a region at the lower side of the second dashed line 660. In this case, the remaining part of the wafer 600 close to the standard dashed line 610a except for the first and second implantation zones 650 and 670 defines a third implantation zone 680. That is, the third implantation zone 680 extends from the standard dashed line 610a by predetermined distances in the first and second regions 640. After the first, second and third implantation zones 650, 670 and 680 are defined, a primary ion implantation process for threshold voltage adjustment is sequentially performed on the first, second, and third implantation zones 650, 670, and 680 by means of an ion implantation mask. In this case, dopant ions are implanted in the third implantation zone 680 at a normal density, while dopant ions are implanted in the first and second implantation zones 650 and 670 at different densities higher and lower than the normal density, respectively. Here, the normal density of the ions implanted in the third implantation zone 680 corresponds to the density of dopant ions to be implanted in the case of a general implantation process rather than the partial implantation process. As an example of the ion implantation process for threshold voltage adjustment, when it is desired to increase a threshold voltage of the first region 620 beyond a predetermined level and to lower a threshold voltage of the second region 630 below a predetermined level, it is necessary for the first region 620 to compensate for the lowering of the threshold voltage thereof in subsequent processes, while it is necessary for the second region 630 to compensate for the increase of the threshold voltage thereof in the subsequent processes. For this, the density of the dopant ions implanted in the first implantation zone 650 must be lower than the normal density of the dopant ions implanted in the third implantation zone 680. Conversely, the density of the dopant ions implanted in the second implantation zone 670 must be higher than the normal density of the dopant ions implanted in the third implantation zone 680. More specifically, although the density of dopant ions to be implanted may be varied depending on the desired threshold voltage value, the density of the dopant ions to be implanted in the first implantation zone 650 is determined to be lower than the density of the dopant ions to be implanted in the third implantation zone 680 by approximately 5%, while the density of the dopant ions to be implanted in the second implantation zone 670 is determined to be higher than the density of the dopant ions to be implanted in the third implantation zone 680 by approximately 5%. Referring to FIG. 6b, after completing the primary ion implantation process, the wafer 600 is rotated 90° clockwise (designated by arrow r2 on FIG. 6b and r1 in FIG. 6a), causing the flat zone 601 to be at the leftmost position of the wafer 600. In such an orientation, a secondary ion implantation process is performed under the same process conditions as the primary ion implantation process. That is, dopant ions are sequentially implanted in the first, second, and third implantation zones 650, 670 and 680. The density of the dopant ions to be implanted in the first implantation zone 650 is determined to be lower than the normal density of the dopant ions to be implanted in the third implantation zone 680 by approximately 5%, while the density of the dopant ions to be implanted in the second implantation zone 670 is determined to be higher than the normal density of the dopant ions to be implanted in the third implantation zone 680 by approximately 5%. Referring to FIG. 6c, after completing the secondary ion implantation process, the wafer 600 is rotated 90° clockwise (designated by arrow r2 of FIG. 6b), causing the flat zone 601 to be at the uppermost position of the wafer 600. In such an orientation, a tertiary ion implantation process is performed under the same process conditions as the primary and secondary ion implantation processes. Referring to FIG. 6d, after completing the tertiary ion implantation process, the wafer 600 is rotated 90° clockwise (designated by arrow r3 of FIG. 6c), causing the flat zone 601 to be at the rightmost position of the wafer 600. In such an orientation, a quaternary ion implantation process is performed under the same process conditions as the primary, secondary, and tertiary ion implantation processes. After completing the quaternary ion implantation process, the wafer 600 is rotated 90° clockwise (designated by arrow r4 of FIG. 6d), causing the flat zone 601 to return to the original lowermost position of the wafer 600. It should be understood that the primary to quaternary ion implantation processes may be performed by repeatedly revolving the wafer 600, although the present embodiment has described the wafer 600 as being rotated by only an angular range of 360°. Further, instead of intermittently rotating the wafer 600 at an interval of 90°, the wafer 600 may be rotated less than 90° or between 90° and 180°. Correspondingly, it is natural that the number of ion implantation processes increases or decreases in proportion to the rotating angle of the wafer 600. FIG. 7 is a graph illustrating the density distribution of dopant ions implanted by the partial implantation method according to the second disclosed method. It will be understood that the density of the dopant ions implanted in the first region 620 of the wafer 600 is higher than the density of the dopant ions implanted in the second region 630 of the wafer 600. The slope of dotted lines 700, that represents the density distribution of dopant ions at an interface between the first and second regions 620 and 630, namely, in the vicinity of the boundary line 610, is determined depending on the way in which the first and second implantation zones 650 and 670 are defined, namely, distances from the standard dashed line 610a to the first and second dashed lines 640 and 660. The shorter the distance between the first or second dashed lines 640 or 660 and the standard dashed line 610a the higher the slope of the dotted lines 700. Conversely, the farther the distance between the first or second dashed lines 640 or 660 and the standard dashed line 610a, the lower the slope of the dotted lines 700. FIG. 8 is a diagram explaining a partial implantation method according to a third disclosed method. A wafer 800 is divided into a plurality of regions according to the density of the dopant ions to be implanted thereto. More specifically, based on a boundary line 810 crossing the center thereof, the wafer 800 is divided into a first region 820 at the upper side of the boundary line 810 and a second region 830 at the lower side of the boundary line 810. A first implantation zone 850 occupies part of the first region 820 and a specific part of the second region 830 close to the boundary line 810. The border of the first implantation zone 850 is indicated by dashed line 840. The area of the first implantation zone 850 is determined depending on the density distribution of the dopant ions in the vicinity of the boundary line 810. In the present embodiment, the area of the first implantation zone 850 is determined to be approximately 110% of the area of the first region 820. A second implantation zone 860 has an area equal to that of the second region 830. Consequently, part of the first implantation zone 850 is overlapped with part of the second implantation zone 860, thereby producing an overlapped zone 855. The overlapped zone 855 is positioned in the second region 830 close to the boundary line 810. After the first and second implantation zones 850 and 870 are defined, dopant ions are first implanted in the first implantation zone 850 by means of an ion implantation mask, and subsequently, dopant ions are implanted into the second implantation zone 860. As a result, the ions are implanted dually into the overlapped zone 855 of the first and second implantation zones 850 and 860. In this case, the density of the dopant ions implanted in the first implantation zone 850 is lower than the density of the dopant ions implanted in the second implantation zone 860. In the present embodiment, such a density difference between the dopant ions implanted in the first and second implantation zones 850 and 860 is approximately 5%. FIG. 9 is a graph illustrating the density distribution of the dopant ions implanted by the partial implantation method according to the third disclosed method. It will be understood that the density of dopant ions implanted in the first region 820 is lower than that of the second region 830. Further, the slope of a dotted line 900, that represents the density distribution of the dopant ions in the vicinity of the boundary line 810, is relatively low because the ion implantation process is performed in a state wherein the first and second regions 820 and 830 overlap in the vicinity of the boundary line 810. When it is desired to lower the slope of the dotted line 900, it is desirable to increase the area of the overlapped zone 855 of the first and second implantation zones 850 and 860. FIG. 10 is a diagram explaining an alternative partial implantation method according to the third disclosed method. A wafer 1000 is divided into a plurality of regions according to the density of dopant ions to be implanted thereto. More specifically, based on a boundary line 1010 crossing the center thereof, the wafer 1000 is divided into a first region 1020 at the upper side of the boundary line 1010 and a second region 1030 at the lower side of the boundary line 1010. A first implantation zone 1050 has an area equal to that of the first region 1020. A second implantation zone 1060 occupies part of the second region 1030 and a specific part of the first region 1020 close to the boundary line 1010. The border of the second implantation zone 1060 is indicated by dashed line 1040. The area of the second implantation zone 1060 is determined depending on the density distribution of dopant ions in the vicinity of the boundary line 1010. In the present embodiment, the area of the second implantation zone 1060 is determined to be approximately 110% of the area of the second region 1030. Consequently, part of the second implantation zone 1060 is overlapped with part of the first implantation zone 1050, thereby producing an overlapped zone 1055. The overlapped zone 1055 is positioned in the first region 1020 close to the boundary line 1010. After the first and second implantation zones 1050 and 1060 are defined, dopant ions are first implanted in the first implantation zone 1050 by means of an ion implantation mask, and subsequently, dopant ions are implanted into the second implantation zone 1060. As a result, the ions are implanted dually in the overlapped zone 1055 of the first and second implantation zones 1050 and 1060. In this case, the density of the dopant ions implanted in the first implantation zone 1050 is lower than the density of the dopant ions implanted in the second implantation zone 1060. In the present embodiment, such a density difference between the dopant ions implanted in the first and second implantation zones 1050 and 1060 is approximately 5%. The density distribution of the dopant ions, obtained by performing the ion implantation process using the partial implantation method described above, is similar to that shown in the graph of FIG. 9. FIG. 11 is a graph explaining the adjustment of density distribution in the vicinity of the boundary line according to the third disclosed method. The density distribution of dopant ions in the vicinity of the boundary line of the wafer can be adjusted to provide a dotted line 1101 having a lowest slope, a dotted line 1102 having an intermediate slope, and a dotted line 1.103 having a highest slope. The slope of the dotted line 1102 can be adjusted by varying the area of the overlapped zone of the first and second implantation zones. The larger the area of the overlapped zone of the first and second implantation zones, the lower the slope of the dotted line that represents the density distribution of dopant ions. The dotted line 1101 of the lowest slope is obtained when the first and second implantation zones overlap by a large area, while the dotted line 1103 of the highest slope is obtained when the first and second implantation zones overlap by a small area. FIGS. 12a to 12d are diagrams explaining a partial implantation method according to a fourth disclosed method. The partial implantation method according to the fourth disclosed method involves a plurality of ion implantation processes during rotation of a wafer 1200 similar to the previously described second embodiment. In the present embodiment, the wafer 1200 is divided into a plurality of regions according to the density of dopant ions to be implanted thereto. That is, based on a circular boundary line 1210, the wafer 1200 is divided into first and second regions. The first region of the wafer 1200 is a peripheral region 1020 outside the circular boundary line 1210, and the second region of the wafer 1200 is a center region 1230 inside the circular boundary line 1210. Next, the wafer 1200 is oriented with a flat zone 1201 at the lowermost position thereof. In such an orientation, a first implantation zone 1250 is defined at the upper side of a dashed line 1240, that is displaced downward from a standard dashed line 1210a as a tangent line of the circular boundary line 1210 by a predetermined distance in parallel thereto. A second implantation zone 1260 is defined at the lower side of the standard dashed line 1210a. After the first and second implantation zones 1250 and 1260 are defined, a primary ion implantation process for threshold voltage adjustment is performed in the first and second implantation zones 1250 and 1260 by means of an ion implantation mask. The primary ion implantation process is divided into an ion implantation step associated with the first implantation zone 1250 and an ion implantation step associated with the second implantation zone 1260. To the first and second implantation zones 1250 and 1260 are implanted dopant ions with different densities. The density of dopant ions to be implanted in the first implantation zone 1250 is determined to be lower than the density of the dopant ions to be implanted in the second implantation zone 1260. More specifically, although the density of dopant ions to be implanted may be varied depending on the desired threshold voltage value, the density difference of the dopant ions implanted in the first and second implantation zones 1250 and 1260 is approximately 5%. Referring to FIG. 12b, after completing the primary ion implantation process, the wafer 1200 is rotated 90° clockwise (designated by arrow r1 of FIG. 12a), causing the flat zone 1201 to be the leftmost position of the wafer 1200. In such an orientation, a secondary ion implantation process is performed under the same process conditions as the primary ion implantation process. That is, the dopant ions are implanted into the first and second implantation zones 1250 and 1260 so that the density of the dopant ions implanted in the first implantation zone 1250 is lower than the density of the dopant ions implanted in the second implantation zone 1260 by approximately 5%. Referring to FIG. 12c, after completing the secondary ion implantation process, the wafer 1200 is rotated 90° clockwise (designated by arrow r2 of FIG. 12b), causing the flat zone 1201 to be the uppermost position of the wafer 1200. In such an orientation, a tertiary ion implantation process is performed under the same process conditions as the primary and secondary ion implantation processes. Referring to FIG. 12d, after completing the tertiary ion implantation process, the wafer 1200 is rotated 90° clockwise (designated by arrow r3 of FIG. 12c), causing the flat zone 1201 to be the rightmost position of the wafer 1200. In such an orientation, a quaternary ion implantation process is performed under the same process conditions as the primary, secondary and tertiary ion implantation processes. After completing the quaternary ion implantation process, the wafer 1200 is rotated 90° clockwise (designated by arrow r4 of FIG. 12d), causing the flat zone 1201 to return to its original lowermost position. It should be understood that the primary to quaternary ion implantation processes may be performed by repeatedly revolving the wafer 1200, although the present embodiment has described the wafer 1200 as being rotated by only an angular range of 360°. Further, instead of intermittently rotating the wafer 1200 at an interval of 90°, the wafer 600 may be rotated less than 90° or between 90° and 180°. Correspondingly, it is natural that the number of the ion implantation processes increases or decreases in proportion to the rotating angle of the wafer 1200. FIG. 13 is a graph illustrating the density distribution of dopant ions implanted by the partial implantation method according to the fourth disclosed method. Along with FIGS. 12a to 12d, it can be understood that the density of the dopant ions in the first region 1220 of the wafer 1200 is higher than the density of dopant ions in the second region 1230. The slope of dotted lines 1300, that represents the density distribution of dopant ions at an interface between the first and second regions 1220 and 1230, namely, in the vicinity of the boundary line 1210, is determined depending on the way in which the first and second implantation zones 1250 and 1260 are defined, and a distance between the standard dashed line 1210a and the dashed line 1240, namely, the area of the overlapped region of the first and second implantation zones 1250 and 1260. The smaller the area of the overlapped region of the first and second implantation zones 1250 and 1260, the higher the slope of the dotted lines 1300. Conversely, the larger the area of the overlapped region of the first and second implantation zones 1250 and 1260, the lower the slope of the dotted lines 1300. FIGS. 14a to 14d are diagrams explaining an alternative partial implantation method of the fourth disclosed method. The partial implantation method according to the fourth disclosed method is similar to that described with reference to FIGS. 12a to 12d, except for the way in which first and second implantation zones 1450 and 1460 are defined. More specifically, based on a circular boundary line 1410, a wafer 1400 is divided into a first region 1420 that is a peripheral region outside the boundary line 1410, and a second region 1430 that is a center region inside the boundary line 1410. Next, the wafer 1400 is oriented with a flat zone 1401 at the lowermost position thereof. In such an orientation, a first implantation zone 1450 is defined at the upper side of a standard dashed line 1440 as a tangent line of the circular boundary line 1410. A second implantation zone 1460 is defined at the lower side of a dashed line 1410a that is displaced upward from standard dashed line 1440 as the tangent line of the circular boundary line 1410 by a predetermined distance in parallel thereto. After the first and second implantation zones 1450 and 1460 are defined, a primary ion implantation process for threshold voltage adjustment is performed on the first and second implantation zones 1450 and 1460 by means of an ion implantation mask. The primary ion implantation process is divided into an ion implantation step associated with the first implantation zone 1450 and an ion implantation step associated with the second implantation zone 1460. Ions are implanted into the first and second implantation zones 1450 and 1460 at different densities. That is, the density of dopant ions to be implanted in the first implantation zone 1450 is determined to be lower than the density of dopant ions to be implanted in the second implantation zone 1460. More specifically, although the density of dopant ions to be implanted may be varied depending upon the desired threshold voltage value, the density difference of dopant ions implanted in the first and second implantation zones 1450 and 1460 is approximately 5%. Referring to FIG. 14b, after completing the primary ion implantation process, the wafer 1400 is rotated 90° clockwise (designated by arrow r1 of FIG. 14a), causing its flat zone 1401 to be at the leftmost position of the wafer 1400. In such an orientation, a secondary ion implantation process is performed under the same process conditions as the primary ion implantation process. That is, dopant ions are implanted into the first and second implantation zones 1450 and 1460 so that the density of dopant ions to be implanted in the first implantation zone 1450 is lower than the density of dopant ions to be implanted in the second implantation zone 1460 by approximately 5%. Referring to FIG. 14c, after completing the secondary ion implantation process, the wafer 1400 is rotated 90° clockwise (designated by arrow r2 of FIG. 14b), causing the flat zone 1401 to be at the uppermost position of the wafer 1400. In such an orientation, a tertiary ion implantation process is performed under the same process conditions as the primary and secondary ion implantation processes. Referring to FIG. 14d, after completing the tertiary ion implantation process, the wafer 1400 is rotated 90° clockwise (designated by arrow r3 of FIG. 14c), causing the flat zone 1401 to be in the rightmost position of the wafer 1400. In such an orientation, a quaternary ion implantation process is performed under the same process conditions as the primary, secondary, and tertiary ion implantation processes. After completing the quaternary ion implantation process, the wafer 1400 is rotated 90° clockwise (designated by arrow r4 of FIG. 14d), causing the flat zone 1401 to return to its original lowermost position. It should be understood that the primary to quaternary ion implantation processes may be performed while repeatedly revolving the wafer 1400, although the present embodiment has described the wafer 1400 as being rotated by only an angular range of 360°. Further, instead of intermittently rotating the wafer 1400 by an interval of 90°, the wafer 600 may be rotated less than 90° or between 90° and 180°. Correspondingly, it is natural that the number of the ion implantation processes increases or decreases in proportion to the rotating angle of the wafer 1400. The density distribution of the dopant ions, obtained by performing the ion implantation process using the partial implantation method described above, is similar to that shown in the graph of FIG. 9. As apparent from the above description, the disclosed methods provide a partial implantation method for manufacturing semiconductor devices which comprises the steps of dividing a wafer into a plurality of regions according to the density of dopant ions to be implanted thereto, defining a plurality of ion implantation zones in the respective regions of the wafer so that they are spaced apart from a boundary line of the respective regions or overlap each other, and performing ion implantation processes on the respective ion implantation zones, thereby enabling the adjustment of a slope that represents the density distribution of dopant ions in the vicinity of the boundary line between the respective regions of the wafer. Although the preferred methods have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of this disclosure and the accompanying claims.
	abstract	A chiller's performance tester includes two flowrate sensors, four temperature sensors, one current sensor, one voltage sensor, all sensors being externally connectable, and an enclosure in which a thermal energy calculation IC board, an electrical power calculation IC board, and a programmable logic controller are arranged. The enclosure has a front side to which a man-machine interface panel that displays measurement readings and provides function-related operations is mounted. The enclosure has a back side to which a socket-carrying panel that is connectable to cables of the sensors is mounted. Readings of flowrate, temperature, current, and voltage are transmitted to the programmable logic controller in which software is executed to compile and integrate these signals to be further transmitted to a computer for subsequent analysis and monitoring. Test of a water chiller is made simple and cost, man power, and working hours are saved.
	abstract	A multi-column electron beam exposure apparatus includes: a plurality of column cells; a wafer stage including an electron-beam-property detecting unit for measuring an electron beam property; and a controller for measuring beam properties of electron beams used in all the column cells by using the electron-beam-property detecting unit, and for adjusting the electron beams of the respective column cells so that the properties of the electron beams used in the column cells may be approximately identical. The electron beam property may be any of a beam position, a beam intensity, and a beam shape of the electron beam to be emitted. The electron-beam-property detecting unit may be a chip for calibration with a reference mark formed thereon or a Faraday cup.
052290670	description	Referring now in detail to FIGS. 1-4 of the drawing, there is seen a reactor tank 1 which is surrounded by a double tank 2 and stands in a reactor cavern 3, which has cooling surfaces 4 on the inner surface thereof. The double tank 2 includes a plurality of rings 2a and a base 2b. A supporting plate 7 is disposed on the double tank 2 and is connected at sides thereof to an outer conduit 8. A grid plate 9 is disposed on the supporting plate 7 and includes two perforated plates 9a and 9b which are connected by pipe nozzles 10. The pipe nozzles 10 transfer the weight of core assemblies 11 to the supporting plate 7. As is best seen in FIG. 4, a base 5 of the cavern 1 is constructed as a supporting platform 6 and bears the double tank 2, the reactor tank 1, the supporting plate 7, the grid plate 9 and the core assemblies 11, which are centered one on top of the other. Not shown in the drawings are sliding materials of a different metal which are disposed between planar bearing surfaces of the superposed parts, in order to permit different movements of neighboring parts at differing temperatures. A reactor core 12, which is only diagrammatically shown in FIG. 1 but is shown in more detail in FIG. 4, is surrounded all around by a multipart metal shield 13, which in turn is surrounded by an inner conduit 14 and is lockably connected to a shaft 15 above the core. The conduit 14 is extended in the upward direction by a stack 23, which is initially surrounded by a plurality of electromagnetic pumps including an active part 16 and a passive part 17, and above them by a heat exchanger 18 as part of a non-illustrated secondary circuit. This secondary circuit transports reactor heat to a steam circuit for supplying steam turbo-generators. The heat exchanger 18 may be made up of a single annular tube bundle or of a plurality of parallel connected partial tube bundles. Not shown, but likewise possible, is also the use of mechanical pumps, having pump shafts being led between the partial tube bundles of the heat exchanger 18 upward to a drive motor through a ring cover 21. In an upper region, the shaft 15, the stack 23 and an inner jacket of the heat exchanger 18 have small holes 19, which are initially evenly distributed over the circumference. Above that, the shaft 15 has larger slits 20. Hot sodium rising from the reactor core 12 can flow to the heat exchanger 18 through the larger slits 20 as well as through the holes 19. The heat exchanger 18 is fastened together with the active part 16 of the electromagnetic pumps to the ring cover 21, which can be installed independently of the instrumentation cover 22, because the latter is supported by the shaft 15. As is seen in FIG. 4, the shaft 15 connects a shield 25 to the instrumentation cover 22 and contains both a linkage 24 for the automatic control and shutdown and leads for the instrumentation of the reactor core 12. The instrumentation cover 22 is sealed off from the ring cover 21 by inflatable seals in such a way as to permit an axial movement of the components against one another. The seals are not shown herein but are usual in the case of liquid metal cooled nuclear reactors. Disposed above the inflatable seals is a lifting and turning apparatus for the cover 22. The lifting and turning apparatus, which is required when changing core assemblies, is likewise known in the field of nuclear reactors and is therefore not shown herein. FIG. 4 uses the same designations as in FIGS. 1 to 3 to show how the base 2b, the reactor tank 1, the supporting plate 7 and the grid plate 9 are superposed in a centered manner on the supporting platform 6 at the base 5 of the reactor cavern 3. In this case too, the sliding materials that were already mentioned above are not shown in detail. The reactor core 12, including the core assemblies 11, is first of all surrounded by the multipart metal shield 13, which in turn is surrounded by the conduit 14 that is also shielded. The shaft 15 and the additional axial shield 25 above the core assemblies 11 rest on the shield 13. This shield 25 has vertical clearances 26 for the passage of coolant, for receiving the linkage 24 and various core instrumentation means and for changing the core assemblies 11. FIG. 5 shows a reinforced point of contact between a ring 2a and the base 2b, which are held together by remotely operable bolts 30. Centering means 31 are provided on the inside. In the area of contact between the ring 2a and the base 2b there are two sealing rings 32, which may be metal O-rings, that are disposed in corresponding grooves. Between the sealing rings 32, a vertical test bore 33 leads to a horizontal bore 34 and then through an angle piece 35 to a test line 36, with which the seal can be monitored from the outside. As indicated in FIG. 6, a driver bit 37 for driving the bolt 30 is remotely advanced towards the bolt 30 by a remote control unit 38. In the case of normal operation, the hot sodium flows out of the reactor core 12 upward through the shaft 15 and through the holes 19 or slits 20 to the heat exchanger 18, while giving off its heat to the outside by means of the non-illustrated secondary coolant circuit. The cooled sodium which is in a delivery gap of the electromagnetic pumps formed by the active part 16 and the passive part 17, is thereupon forced downward, where it is actually between an inner wall surface of the conduit 8 and an outer wall surface of the conduit 14, to the grid plate 9, from where it is conducted in the usual manner through slits in the pipe nozzles 10 into the lower end of the core assemblies 11, in order to take up their heat. In the event of a failure of the pumps, the sodium flows in the same way by natural circulation, while it likewise gives off its heat to the outside by means of the secondary coolant circuit. If the latter should fail, the heat is given off through the tank 1 and the double tank 2 to the cooling surfaces 4 or to a circulating gas in the reactor cavern 3. For example, the double tank 2, including a plurality of the rings 2a and the base 2b, may have a diameter of 5 m, a wall thickness of 150 mm and be formed of a spheroidal cast iron GGG according to DIN 1693. Considerable amounts of heat can be accumulated in this wall and given off to the cooling surfaces 4 with a time delay. In comparison with the usual heat accumulation in concrete, much higher temperatures can be allowed. In order to change the core assemblies, a changing machine, which is known per se, is moved over the cover 22. The machine takes the spent core assemblies 11 directly out of the reactor core 12 and inserts fresh core assemblies. In order to do so, the already previously mentioned lifting and turning apparatus, which can be removed for the purposes of inspection or exchange, vertically raises the instrumentation cover 22 with shaft 15 and the shield 25 and turns it until an opening, which is not illustrated in the figures, is positioned over the core assembly to be changed. Subsequently, the desired core assembly is drawn into a flask and sealed off from the outside. If it becomes necessary to repair heat exchangers or pumps, a special component changing flask is moved over the ring cover 21. Through the use of the flask, the annular heat exchanger 18, with the active parts 16 of the electromagnetic pumps fastened thereto, can be exchanged, in a likewise inerted and sealed-off atmosphere. Changing flasks of this type are known and are usual for inspecting or exchanging heat exchangers and pumps in the case of liquid metal cooled nuclear power plants mentioned initially above. The dimensions of the modular reactor according to the invention, and in particular the relatively small diameter of about 5 m, allows the shaft 15 or the parts 7, 8, 9, 10, 13, 14, 17 and 23 surrounding the nuclear core, or even an entire reactor tank 1 and the individual rings 2a as well as the base 2b of the double tank, to also be exchanged in this way. According to the modular principle mentioned above, the other modular reactors of this same nuclear power plant are kept in operation during such repairs, as well as during the changing of core assemblies, so that a high availability of the nuclear power plant is ensured. According to the repair concept described above, quick and inexpensive disposal, with minimum possible radiation exposure for the environment and personnel, at the end of the service life of a reactor, is also ensured.
046831169	abstract	A nuclear reactor in which control rods are inserted in the thimbles of only certain of the fuel assemblies (which may be called controlled assemblies) in the core and the remainder of the assemblies (which may be called non-controlled assemblies) are provided with hollow structural members containing burnable poison which form these non-controlled assemblies into integrated units. The hollow structural members are formed with end plugs welded to the lower end and are open at the top. The end plug of each member is secured to the bottom nozzle of the non-controlled fuel assembly. A skeleton is formed of the bottom nozzle, the structural members secured to it and a plurality of grids spaced along the structural members. A bulge tool is then inserted in each hollow member and it is on each side of each grid. Neutron absorbers are then inserted in each hollow member and an upper end plug is welded to it. The fuel rods are then inserted in the assembly and the upper end plugs are secured to the top nozzle.. Typically, there are 24 thimbles in a controlled assembly but not all thimble locations in a non-controlled assembly contain neutron-absorber structural members. Typically, there are eight structural members in a non-controlled assembly. In the other positions there are fuel rods. In reactors where there are water displacement control rods which extend over several assemblies, the so-called non-controlled assemblies may have the necessary thimbles for the water displacement rods.
046631178	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 and IA a nuclear reactor fuel assembly has multiple (typically 271) fuel pins 10 located in a hexagonal tubular wrapper 11 and stabilised by a series of spaced grids 12 (only one of which is indicated) and relative to which the pins 10 are slidable as a result of differential thermal expansion effects. The wrapper has an internal support cage 13 with upturned parts 14 which engage the walls 15 of unit cells 16 at the periphery of grid 12, the whole of the grid also being formed of unit cells, although not essentially. In FIG. 1 one corner of the wrapper 11 is shown. This corner is free of the cage 13 and it is observed (in distinction from previous designs) that a fuel pin lOA is accommodated in the corner position. The fuel pins are located in the unit cells of the grid by dimples 18. The cage 13 is made up from six vertical limbs 20 integral with top and bottom collars. In FIG. 2 one limb 20 of the cage 13 is shown. This also shows the upturned parts 14 and one displaced peripheral unit cell 16 for locating between two upturned parts 14. The cell 16 has tabs 21 which are used for spot welding the unit cell to the upturned parts. In FIG. 3 a limb 20 of the cage is shown but with only one upturned part 14. A single peripheral unit cell 16 with tabs 21 is "exploded" from the upturned part 14. Spot welds 22 for joining tabs 21 and upturned parts 14 are indicated. Access for welding electrodes impose no problems and the welds formed have a good strength to tensile loads. In FIG. 4 the lowermost grid 12 of the fuel assembly is shown spot welded 42 at its unit cells 16 to a bottom hold down grid 40 which is affixed within the wrapper 11, the lower ends of the fuel pins being anchored to the hold down grid 40. The limbs 20 of the cage 13 terminate at line 41 above which they are welded to tabs 21 of the cells of the lowermost grid 12. It will be noted that the only point of anchorage of the cage to the wrapper is at the lower end of the latter, ie. a position where the neutron flux is comparitively low and hence where irradiation embrittlement of the wrapper material is not a significant problem. In FIG. 5 a peripheral unit cell 50 (which may replace cells 16 of FIG. 3) has a cut-away part 51 which effectively produces a pair of joining tabs 52 at which welds 53 can be made to upturned parts 54. A dimple 55 (of which there are three) is shown in the cell wall to locate a fuel pin in the cell. The length dimension of the cell 50 is chosen to be the same as the depth of the grid in which it is located. This cell 50 allows use of existing grid welding equipment to weld the cell 50 to the upstands 54. FIGS. 6-8 are concerned with a modified form of cage structure. In this embodiment, the limbs 20 of the cage are formed with elastically yieldable formations 60 which are arranged to bear against the internal faces of the wrapper and provide sprung lateral support for the cage within the wrapper. Thus, as shown, the formations 60 may comprise pressed indentations extending longitudinally of the side limb 20 adjacent the edges thereof. The limbs 20 are also provided with flanges 62 at their edges for facilitating spot welding at the junctions between each corner cell 64 and the adjacent edge cells 16 each side thereof. As described previously, the edge cells 16 are provided with joining tabs 21 which are spot-welded at 22 to the upturned parts 14. At the corner/edge cell junctions, the edge cell and corner cell joining tabs 21A, 66 are of differing lengths so that one tab projects beyond the other and overlaps with the flange 52. This arrangement allows the spot welds 22A between the joining tabs 21A, 66 and the spot welds 68 between the joining tab 21A and flange 62 to be made through only double rather than triple thicknesses of material. A similar double thickness arrangement may be adopted between adjacent edge cells by producing them with different length joining tabs and by modifying the upturned parts 14 so that these only overlap the longer joining tabs. This is illustrated in FIG. 8A in which, it will be noted, the upturned parts 14 are interrupted so that the shorter sides of the edge cells can fit between the upper and lower parts 14A, 14B whereas the longer sides of the edge cells overlap the parts 14A, 14B. Thus, each longer joining tab 80 is spot welded at 82 to a respective part 14A or 14B whilst the shorter tab 84 is spot welded at 86 to the adjacent longer tab 80. In each of the embodiments described above it will be seen that the parts 14 of each side limb 20 project inwardly of the wrapper and into the cellular structure of the grids without encroaching on the open cross-sections of the cells. Although not shown in the drawings, those zones of the side limbs 20 extending between the sets of upturned parts 14 may be formed with strengthening ribs. FIG. 9 illustrates another modification in which a two-part cage structure is employed: a lower cage including side limbs 20A and an upper cage including side limbs 20B. The lower cage is secured to the wrapper 11 by bottom support hold down grid 40 whereas the upper cage is secured by a support structure 70 located beneath a mixer pin support grid 72. The lower and upper cages are affixed to the wrapper at only their lower and upper ends respectively and are separated by a gap 74 for allowing differential expansion of the cages. In addition the gap provides a convenient location at which the wrapper 11 can be cut during subsequent dismantling of the sub-assembly for the purpose of reprocessing the irradiated fuel.
	summary
	abstract	One embodiment of the present invention provides a system that tests the motion performance of an electronic display system, wherein the electronic display system includes a display, graphics processing software, graphics processing circuitry, and an interface coupling the display and the graphics processing circuitry. The system starts by receiving a request to measure an amount of distortion of an object in motion. In response to the request, the system measures the amount of distortion of the object in motion. In a variation on this embodiment, measuring the amount of distortion of the object in motion involves placing a ruler on a boundary of the object where the distortion occurs, increasing the width of the ruler until it covers the distortion, and then measuring the width to determine the size of the distortion.
	summary
	summary
050858246	description	MODE(S) FOR CARRYING OUT THE INVENTION Illustrated in FIG. 1 is a refueling platform, or gantry, 10 including a conventional bridge 12 having a longitudinal axis Y and a transverse axis X. The bridge 12 is conventionally supported by a first, or left, end frame 14 and a second, or right, end frame 16 spaced longitudinally therefrom. The left end frame 14 is fixedly joined to a first, or left drive truck 18, and the right end frame is fixedly joined to a second, or right drive truck 20. The left and right drive trucks 18 and 20 are conventionally mounted on conventional guide rails 22 fixedly attached to a conventional concrete foundation 24. The platform 10 further includes a conventional trolley 26 conventionally slidably movable along the bridge longitudinal Y axis in both left and right directions. The platform 10 further includes a conventional main hoist 28 joined to the trolley 26 for longitudinal movement therewith and has a conventional, selectively retractable and extendable mast 30 with a conventional grapple 32 at the end thereof. The grapple 32 is conventionally connectable to a fuel bundle 34 disposed under water 36 contained in a pool 38. The main hoist 28 is conventionally effective for raising and lowering the fuel bundle 34 along a vertical axis Z within the pool 38. A controller 40 is provided for controlling operation of the left and right drive trucks 18 and 20 and their transverse position X along the guide rails 22, the longitudinal position Y of the trolley 26 along the bridge 12, and the vertical position Z of the mast 30, and therefore the fuel bundle 34. First and second means 42 and 44 are provided for driving the first and second drive trucks 18 and 20, respectively, along the guide rails 22. The first and second driving means 42 and 44 are preferably identical, although in alternate embodiments of the present invention, they may be different. As illustrated in FIGS. 2 and 3, the first driving means 42 includes a conventional electrical motor 46.sub.l connected to the controller 40 by a 30 conventional electrical line 48.sub.l which controls its operation. The motor 46.sub.l includes an output shaft 50.sub.l having one end connected to a first speed reducing transmission 52.sub.l. In this exemplary embodiment of the present invention, the first transmission 52.sub.l includes a pair of conventional speed reducing sprockets and chains having an input sprocket 54.sub.l joined to the motor output shaft 50.sub.l, and an output sprocket 56.sub.l conventionally fixedly attached to a first, or left driven wheel 58.sub.l of the left drive truck 18 for selectively moving the left drive truck 18 along the guide rail 22. As illustrated in FIG. 4, the second driving means 44 includes an identical electrical motor 46.sub.l, electrical lines 48.sub.r, output shaft 50.sub.r, second transmission 52.sub.r, input sprocket 54.sub.r, and output sprocket 56.sub.r. The sprocket 56.sub.r is fixedly attached to a second, or right driven wheel 58.sub.r of the right drive truck 20 for selectively moving the right drive truck 20 along the guide rail 22. Referring again to FIGS. 2 and 3, the motor output shaft 50.sub.l is also connected at its other end to a conventional electromechanical brake 62.sub.l which is conventionally connected to the controller 40 by an electrical line 64.sub.l for selectively engaging and releasing the brake 62.sub.l. Referring again to FIG. 4, the second driving means 44 similarly includes a conventional electromechanical brake 62r connected to the controller 40 by an electrical line 64r for selectively engaging and releasing the brake 62r. During operation of the bridge 12, the controller 40 separately operates the first and second driving means 42 and 44, which are independent from each other, for moving the left and right drive trucks 18 and 20 either in a forward direction (negative X direction) or in a reverse direction (positive X direction) along the guide rails 22 as shown in FIG. 1. The brakes 62.sub.l and 62.sub.r are conventionally engaged as required for slowing and stopping movement of the bridge 12 along the guide rails 22. As illustrated in FIG. 1, the trolley 26 is disposed left of a longitudinal center 66 of the bridge 12 and in this exemplary mode of operation with the bridge 12 being moved in the forward X direction a resultant resistance force F is imposed against the fuel bundle 34 and in turn against the mast 30, trolley 26 and bridge 12. This resistance force F generates a torque on the bridge 12 around the vertical Z axis which will tend to cause the left drive truck 18 to travel less than the right drive truck 20. As described above, due to inherent flexibility of the bridge 12, backlash in the transmissions 52.sub.l and 52.sub.r, and/or slippage of the left and right driven wheels 58.sub.l and 58.sub.r , for example, actual differential transverse travel between the left and right drive trucks 18 and 20 will occur. In order to substantially eliminate this differential transverse travel, or maintain this differential transverse travel to less than a predetermined maximum, the present invention further includes means for controlling the first and second driving means 42 and 44 as indicated generally at 68 in FIG. 5. As described above, the left and right driving means 42 and 44 are independent of each other and therefore are independently controlled. Within the platform controller 40, a conventional motion controller 40a is used for independently controlling the left and right motors 46.sub.l and 56.sub.r while providing coordination therebetween as described below. The motion controller 40a may be an independent dedicated central processing unit (CPU), or may be part of the platform controller 40. In order to translate the bridge 12 in either its forward or reverse transverse direction along the X axis, the operator actuates a conventional speed and direction throttle 70 which conventionally provides a velocity command signal V.sup.c through a conventional electrical line 72 joined to the motion controller 40a. The controller 40a conventionally provides left and right velocity command signals V.sub.l.sup.c and V.sub.r.sup.c, which are nominally or initially equal to the velocity command signal V.sup.c, which control operation of the left and right motors 46.sub.l and 46.sub.r. In an exemplary embodiment of the present invention, the left and right velocity command signals V.sub.l.sup.c and V.sub.r.sup.c each have values ranging from -10 volts to 0 to +10 volts for controlling the motors for variable speed outputs ranging from 0 to .+-.1,750 rpm for translating the bridge 12 in forward and reverse directions along the X axis from 0 to about 50 feet per minute (to about 15.2 meters per minute). The left and right velocity command signals V.sub.l.sup.c and V.sub.r.sup.c are low voltage low current signals which are preferably used to control conventional left and right DC power drives 74.sub.l and 74.sub.r which are connected to the controller 40a by conventional electrical lines 76.sub.l and 76.sub.r. A conventional AC power supply 78 is conventionally connected to the left and right DC drives 74.sub.l and 74.sub.r by electrical lines 80.sub.l and 80.sub.r. The left and right velocity command signals V.sub.l.sup.c and V.sub.r.sup.c conventionally control the left and right DC drives 74.sub.l and 74.sub.r which change the AC power from the power supply 78 to DC power of the required polarity and power which is channeled to the motors 46V.sub.l and 46.sub.r by the lines 48.sub.l and 48.sub.r, respectively. In practice, providing identical power to the left and right motors 46.sub.l and 46.sub.r does not necessarily result in equal travel of the left and right drive trucks 18 and 20. This is due to inherent differences in the left and right driving means 42 and 44, and more specifically to the flexibility of the bridge 12 itself, backlash inherent in the transmissions 52.sub.l and 52.sub.r joining the motors to the driven wheels 58.sub.l and 58.sub.r, and any slippage which may occur between the driven wheels 58.sub.l and 58.sub.r and the respective guide rails 22. In accordance with the present invention, the controlling means 68 is effective for maintaining differential transverse travel between the left and right drive trucks 18 and 20 to less than a predetermined maximum, and preferably substantially equal to zero, for obtaining substantially equal travel of the left and right drive trucks 18 and 20 to prevent unacceptable skewing therebetween. In addition to providing the left and right velocity command signals V.sub.l.sup.c and V.sub.r.sup.c to the left and right driving means 42 and 44, the controlling means 68 additionally combines a travel error signal T.sup.e with at least one of the left and right velocity command signals V.sub.l.sup.c and V.sub.r.sup.c for changing or adjusting velocity of a respective one of the left and right drive trucks 18 and 20 for maintaining differential transverse travel between the two drive trucks to less than the predetermined maximum. Referring to both FIGS. 5 and 6, the controlling means 68 preferably includes a closed-loop, or feedback first, or left, velocity control means 82.sub.l for controlling velocity of the left drive truck 18 by affecting or adjusting the left velocity command signal V.sub.l.sup.c with conventional feedback. Similarly, the controlling means 68 also includes a closed-loop, or feedback, second, or right velocity control means 82.sub.r for controlling velocity of the right drive truck 20 by affecting, or adjusting the right velocity command signal V.sub.r.sup.c with conventional feedback. Conventional first and second, or left and right, motor sensors or encoders 84.sub.l and 84.sub.r are used for providing first and second, or left and right, feedback signals indicative of measured outputs of the left and right motors 46.sub.l and 46.sub.r, respectively. The motor sensors 84.sub.l and 84.sub.r conventionally provide measured outputs of rotational position, or travel, velocity, and acceleration of the motor output shafts 50.sub.l and 50.sub.r, i.e. T.sub.l.sup.m, V.sub.l.sup.m, A.sub.l.sup.m for the left motor 46.sub.l, and T.sub.r.sup.m, V.sub.r.sup.m, A.sub.r.sup.m for the right motor 46.sub.r. The motor sensors 84.sub.l and 84.sub.r, which are additionally shown in FIGS. 2-4, are conventionally connected to the controller 40a by electrical lines 86.sub.l and 86.sub.r, respectively. Since the bridge 12 is being preferably controlled by its velocity, the left velocity control means, or loop, 82.sub.l as represented by its generic Laplace transforms in FIG. 6 is shown based on controlling its output velocity V.sub.l.sup.m. Similarly, the right velocity control means 82.sub.r, or loop, is also represented in FIG. 6 for controlling the right motor output velocity V.sub.r.sup.m. The left and right motor velocity signals measured by the sensors 84.sub.l and 84.sub.r, or feedback signals, are conventionally fed back to conventional means 88.sub.l and 88.sub.r for subtracting the velocity feedback signals from the respective velocity command signals in the motion controller 40a for providing first and second, or left and right velocity error signals V.sub.l.sup.e and V.sub.r.sup.e for controlling the motors 46.sub.l and 46.sub.r. As illustrated in FIG. 6, the left and right loops 82.sub.l and 82.sub.r are conventional and effected in the motion controller 40a for conventionally controlling the output velocities of the motors 46.sub.l and 46.sub.r. The motors 46.sub.l and 46.sub.r are represented schematically by their respective Laplace transforms G.sub.l.sup.m (S) and G.sub.r.sup.m (S) which preferably include their respective left and right DC drives 74.sub.l and 74.sub.r. Similarly, the motor sensors 84.sub.l and 84.sub.r are represented by their Laplace transforms H.sub.l.sup.m (S) and H.sub.r.sup.m. The left and right loops 82.sub.l and 82.sub.r are effective for controlling the output of the motors 46.sub.l and 46.sub.r in response to the respective velocity command signals V.sub.l.sup.c and V.sub.r.sup.c. In alternate embodiments of the present invention, the measured left and right motor angular position or travel T.sub.l.sup.m, T.sub.r.sup.m, and the accelerations A.sub.l.sup.m, A.sub.r.sup.m may also be used for more precisely controlling the velocity of the output shafts 50.sub.l , 50.sub.r. The output shafts 50.sub.l , 50.sub.r in turn power the left and right transmissions 52.sub.l and 52.sub.r which in turn rotate the driven wheels 58.sub.l and 58.sub.r. In accordance with the present invention, the controlling means 68 also includes an auxiliary closed-loop, or feedback, travel control means 90 indicated generally at 90 in FIGS. 5 and 6. The travel control means 90 is provided to automatically adjust the performance of the system represented by the left and right loops 82.sub.l and 82.sub.r which act independently of each other for controlling travel of the left and right drive trucks 18 and 20. The travel control means 90 is effective for sensing a difference in travel of the left and right drive trucks 18 and 20 and providing the travel error signal T.sup.e which is used for coordinating the operation of the left and right loops 82.sub.l and 82.sub.r for reducing and preferably substantially eliminating differential transverse travel between the left and right drive trucks 18 and 20 during all modes of operation including those with the trolley 26 being positioned at either left or right of the center 66. Accordingly, any skewing which would otherwise be introduced by the resistance force F may be substantially eliminated. Actual travel of the drive trucks 18, 20 may be measured by any conventional position sensors located between the respective drive trucks 18, 20 and the guide rails 22. For example, in the preferred embodiment of the present invention, first and second, or left and right travel sensors, or encoders 92.sub.l and 92.sub.r as illustrated schematically in FIG. 5, are disposed adjacent to left and right undriven wheels 94.sub.l and 94.sub.r of the left and right drive trucks 18 and 20. The left and right travel sensors 92.sub.l, 92.sub.r are also shown in FIGS. 1-4 and further include conventional electrical lines 96.sub.l and 96.sub.r, respectively, for providing first and second, or left and right feedback travel signals T.sub.l.sup.a and T.sub.r.sup.a indicative of the actual, or measured, transverse positions of the drive trucks 18, 20 along the guide rails 22. As indicated functionally in FIG. 6, the left and right transmissions 52.sub.l and 52.sub.r are effective for powering the driven wheels 58.sub.l and 58.sub.r which in turn move the drive trucks 18 and 20. The actual movement of the drive trucks 18 and 20 is measured by the travel sensors 92.sub.l and 92.sub.r which provide the actual positions of the drive trucks 18 and 20 as represented by the left and right travel signals T.sub.l.sup.a and T.sub.r.sup.a. In the exemplary embodiment illustrated, the travel sensors 92.sub.l and 92.sub.r measure rotational position of the undriven wheels 94.sub.l, 94.sub.r which is simply mathematically converted to translation of the drive trucks 18 and 20 along the guide rail 22 by multiplying the rotation of the drive wheels times the circumferential length thereof. The travel error signal T.sup.e is simply obtained by a conventional comparator, or subtractor 98 as shown in FIG. 6. In this exemplary embodiment, the position of the left drive truck 18a is subtracted from that of the right drive truck 20 with the travel error signal T.sup.e being equal to the right travel signal T.sub.r.sup.a minus the left travel signal T.sub.l.sup.a. Of course, any polarity convention may be used. The travel error signal T.sup.e is combined with at least one of the left and right velocity command signals V.sub.l.sup.c and V.sub.r.sup.c for changing, or adjusting, the velocity of a respective one of the left and right drive trucks 18, 20 for maintaining any differential transverse travel between the two drive trucks to less than the predetermined maximum, and in the preferred embodiment, substantially equal to zero. A conventional combiner 100, which may simply take the form of conventional software algorithms in the motion controller 40a, predeterminedly combines the travel error signal T.sup.e with the respective velocity command signals. In a preferred embodiment of the present invention, the combiner 100 is effective for subtracting the travel error signal T.sup.e from the velocity command signal V.sub.r.sup.c or V.sub.l.sup.c for decreasing below the nominal velocity Vhd c the velocity of the respective left or right truck 18, 20 which tends to, or in fact travels more than the other drive truck. For example, if the trolley 26 is positioned to the left of the center 66 as illustrated in FIG. 1, and the bridge 12 is being moved in its forward direction (negative X direction), the right drive truck 20 will, but for the present invention, travel substantially more than the left drive truck 18. Accordingly, the travel error signal T.sup.e will have a positive value and the combiner 100 will automatically provide the travel error signal T.sup.e to only the right loop 82.sub.r through a right comparator 102.sub.r, or in this case a subtractor, which subtracts the travel error signal T.sup.e from the velocity command signal V.sup.c being channeled to the right loop 82.sub.r. The right velocity command signal V.sub.r.sup.c will then have a value represented by the difference of the velocity command signal V.sup.c and the travel error signal T.sup.e which will then reduce the velocity of the right drive truck 20 to reduce the differential travel with the left drive truck 18. Similarly, if the trolley 26 were positioned to the right of the center 66 and the bridge 12 were being moved in its forward direction, the left drive truck 18 would tend to travel further relative to the right drive truck 20. In this case, the travel error signal T.sup.e in FIG. 6 would have a negative value since the difference between T.sub.r.sup.a and T.sub.l.sup.a would be negative, and the combiner 100 would then automatically channel the travel error signal solely to a conventional left comparator 102.sub.l, or in this case an adder, which would add the travel error signal T.sup.e to the velocity command signal V.sup.c. Since the travel error signal T.sup.e has a negative value it, in effect, will be subtracted from the velocity command signal V.sup.c thusly reducing the value of the left velocity command signal V.sub.l.sup.c provided to the left loop 82.sub.l. This in turn will then slow down the left drive truck 18 relative to the right drive truck 20 thus reducing and preferably eliminating skewing therebetween. Alternatively, the combiner 100 as illustrated in FIG. 6 may be used for adding the travel error signal T.sup.e for increasing the velocity of the respective drive truck 18, 20 which tends to or in fact travels less than the other drive truck. In this case, the path through the combiner 100 would simply be reversed from that shown with positive values of the travel error signal T.sup.e being channeled to the left comparator 102.sub.l instead of the right comparator 102.sub.r. Also in this situation, if the travel error signal had a negative value, the combiner 100 would then simply channel the travel error signal T.sup.e to the right comparator 102.sub.r instead of the left comparator 102.sub.l for increasing the velocity of the right drive truck 20. Yet in another embodiment of the present invention, the travel error signal could be both added to the velocity command signal V.sup.c channeled to the left loop 82.sub.l for increasing the velocity of the left drive truck 18 in a situation where it tends to travel less than the right drive truck 20, and subtracting the travel error signal T.sup.e from the velocity command signal V.sup.c channeled to the right loop 82.sub.r for decreasing the velocity of the right drive truck 20. In the situation wherein the left and right drive trucks 18 and 20 travel identical distances, the travel error signal T.sup.e will have a zero value, and the left and right velocity command signals V.sub.l.sup.c and V.sub.r.sup.c will be identical. For example, this may occur for an ideal platform 10, or for operation of the platform 10 with the trolley 26 being positioned at the center 66 so that a skewing torque is not imposed on the bridge 12. However, in practical operation of the platform 10, and in particular as the trolley 26 is positioned further and further away to either the left or right of the center 66, the force F acting on the mast 30 will tend to cause the bridge 12 to skew in the transverse 10 direction. Skewing of the bridge 12 is due in part to the inherent flexibility thereof as well as by inherent backlash between the motors 46.sub.l, 46.sub.r and the driven wheels 58.sub.l, 58.sub.r, and additionally by any slippage between the driven wheels 58.sub.l, 58.sub.r, and their respective guide rails 22. In order to more accurately control the relative movement between the left and right drive trucks 18 and 20, the travel control means 90 illustrated in FIG. 6 conventionally mathematically models the left and right transmissions 52.sub.l and 52.sub.r between the motors 46.sub.l, 46.sub.r and the driven wheels 58.sub.l, 58.sub.r, which is represented generically by the Laplace transforms G.sub.l.sup.t (S) and G.sub.r.sup.t (S). Furthermore, any slippage between the driven wheels 58.sub.l, 58.sub.r and the guide rails 22 may also be mathematically modeled in the respective Laplace transforms of the left and right transmissions G.sub.l.sup.t (S) and G.sub.r.sup.t (S). Flexibility of the bridge 12 is generally a linear phenomena, whereas backlash in the transmissions and slippage between the driven wheels and the guide rails are nonlinear conditions. However, the motion controller 40a may be conventionally programmed for mathematically modeling these effects in controlling the operation of the left and right drive trucks 18 and 20. The left and right Laplace transform representations G.sub.l.sup.t (S) and G.sub.r.sup.t (S) are each predetermined correction models which are indicative of at least one of the backlash, transverse flexibility, or slippage conditions described above. In a preferred embodiment of the present invention, these correction models include all three conditions in order to more fully control the operation of the left and right drive trucks 18, 20 for minimizing and preferably eliminating any differential transverse movement between the left and right drive trucks. In the preferred embodiment of the present invention, the refueling platform 10 is assembled on-site and then the motion controller 40a is systematically operated in all desired modes of operation of the platform 10 for initializing or calibrating all required constants in the correction models particular to each individually built platform 10. For example, the bridge 12 is initially operated in both its forward and reverse directions for determining any backlash, or lag between operation of the respective left and right motors 46.sub.l, 46.sub.r and travel of the left and right drive trucks 18 and 20 as measured by the travel sensors 92.sub.l, 92.sub.r. The motion controller 40a conventionally provides required mathematical calculations to quantify the lag characteristics between the left and right drive trucks 18 and 20 due to at least one of the backlash, bridge flexibility, and wheel slippage described above. For example, by operating the bridge in the forward direction, the motion controller 40a will observe a certain amount of lag, or backlash, between initiation of rotation of the motors 46.sub.l, 46.sub.r and movement of the drive trucks 18 and 20 as measured by the travel sensors 92.sub.l, 92.sub.r. Accordingly, this backlash characteristic is preferably introduced into the respective left and right mathematical representation i.e. G.sub.l.sup.t (S) and G.sub.r.sup.t (S), for more accurately controlling operation of the left and right drive trucks during normal operation of the platform 10. Similarly, the motion controller 40a may be operated for determining the relative flexibility between the left and right drive trucks, which characteristic may also be introduced into the transforms G.sub.l.sup.t (S) and G.sub.r.sup.t (S). And yet further, any slippage between a driven wheel and its respective guide rail may also be introduced into the transforms if desired. In the embodiment of the invention illustrated in FIGS. 1-4, the transmissions 52.sub.l, 52.sub.r comprise conventional chain and sprocket reduction drives. These drives inherently include a substantial amount of backlash, and therefore, compensating for such backlash in the respective transmission Laplace transforms will provide a substantial improvement in reducing differential transverse movement between the left and right drive trucks 18 and 20. Since several refueling platforms 10 including such chain and sprocket transmissions presently exist in the field, the present invention will allow a relatively simple retrofit of such refueling platforms for obtaining improved operation thereof and reduced cost. The present invention may also be applied to other types of refueling platforms including those having conventional gear transmissions as represented schematically by the left and right transmissions 52.sub.l, 52.sub.r in FIGS. 5 and 6. Referring again to FIGS. 5 and 6, the primary control of the left and right drive trucks 18, 20 is velocity as provided by the velocity command signal V.sup.c and the left and right loops 82.sub.l and 82.sub.r shown for controlling velocity. However, acceleration and deceleration signals from the motor sensors 84.sub.l and 84.sub.r as represented by the acceleration signals A.sub.l.sup.m and A.sub.r.sup.m may also be conventionally used, if desired in the travel control means 90. For example, relatively high values of acceleration and deceleration will tend to cause larger differential transverse movement between the left and right drive trucks 18, 20 when subjected to a bridge load unbalance. Accordingly, the motor acceleration signals A.sub.l.sup.m and A.sub.r.sup.m in addition to the measured acceleration signals of the left and right drive trucks 18 and 20 i.e. A.sub.l.sup.a and A.sub.r.sup.a may be conventionally introduced into the travel control means 90, and in particular in the respective Laplace transforms thereof for reducing the differential transverse movement between the left and right drive trucks. As the acceleration of the motors 46.sub.l, 46.sub.r increases, proportionately more correction will be required i.e. larger travel error signal T.sup.e, in anticipation of the increased differential transverse movement between the left and right drive trucks to prevent or reduce the occurrence thereof. Additionally, the measured velocity of the left and right drive trucks i.e. V.sub.l.sup.a and V.sub.r.sup.a as obtained from the travel sensors 92.sub.l, 92.sub.r may also be used in the travel means 90 as required. For example, if the bridge 12 is being operated at a constant speed, the travel control means 90 may be conventionally programmed to recognize this mode of operation and anticipate required corrections provided in the travel error signal T.sup.e in the event of, for example a relatively sudden stop of the bridge and rapid deceleration thereof. The motion controller 40a preferably includes all the required programs or algorithms for maintaining identical left and right drive truck tracking, or substantially equal travel thereof, during all foreseeable modes of operation of the bridge 12 including acceleration, deceleration, speed control, starting, stopping, in both the forward and reverse directions. From the teaching herein, the left and right loops 82.sub.l and 82.sub.r and the travel control means 90 illustrated in FIG. 6 may be conventionally incorporated into appropriate programs or algorithms in the motion controller 40a. For example, the commercially available DMC-700 Industrial Motion Controller available from Galil Motion Control, Incorporated of Palo Alto, Calif., may be used for the motion controller 40a of the present invention. While there have been described herein what are considered to be preferred embodiments of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein, and it is, therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention. Accordingly, what is desired to be secured by letters patent of the United States is the invention as defined and differentiated in the following claims:
050376039	abstract	A hand held tool for removing a hollow locking tube from a locking position in the upper end portion of a guide thimble includes an elongated hollow tubular assembly having a lower end portion insertable in the locking tube and an actuator assembly mounted through the tubular assembly for axial movement therealong and having a lower end portion for actuating a set of lifting members of the lower end portion of the tubular assembly to extend and retract their catch elements through and from apertures in the tubular assembly for engaging with and disengaging from a lower edge of the locking tube. The lower end portion of the tubular assembly includes a guide member composed of a hollow tubular element and a guide element interfitted with an open end of the tubular element and having a body portion projecting therefrom. The tubular element has the apertures through which the catch elements on the lifting members can be extended to engage the lower edge of the locking tube. The end of the tubular element and the body portion of the guide element have substantially the same outside diameter so as to provide a continuous smooth transition from the tubular element end to the guide element body portion for facilitating insertion of the guide and tubular elements of the guide member into the hollow locking tube without catching on an upper edge thereof at the transition of the guide member.
047298693	description	DESCRIPTION OF THE DISCLOSED EMBODIMENT FIG. 1 depicts a typical steam generator 10 for a nuclear power plant. The steam generator has tubes 12 which are typically 3/4 or 7/8 of an inch outside diameter with a 0.05 inch wall thickness. Each of the thousands of tubes is inserted into a hole in the tubesheet face or lower surface 16. Experience has shown that the tubes 12 are prone to deterioration. Accordingly, they must be inspected and when necessary taken out of service by plugging or repaired by sleeving, through their open ends at the tubesheet face 16. Servicing personnel gain access to this space by crawling through the manway 18 and standing in the primary head 20 which may typically prove an approximate five foot clearance. Since the primary head 20 is highly radioactive, time on this task in this area is very limited but can be extended if proper radiation shielding can be provided. FIG. 2 shows a modular radiation shielding panel 22 for use on the lower side 16 of the nuclear steam generator tubesheet 14. The modular lead shielding panel 22 is typically of rectangular or other simple plain geometric shape for both ease of manufacture and ease of use. Although steam generator tubesheets and tubes supported thereby vary in dimension, a typical modular tile might be 85/8" in length and 73/8" in width. Such a lead plate conveniently is 1" thick and has a 1" diameter hole located on an axis of symmetry therewith which bisects its longest dimension. This axis is labeled 4--4 in the various figures. An asymmetric axis 6--6 perpendicular to the axis of symmetry 4--4 and also passing through the center of the transverse hole 24, may typically be located 4 5/16" from the longitudinal edge of the imaginary rectangle of lead tile 22 which makes it equidistant from both the longitudinal edge 26 and the longitudinal edge 28 of the rectangle which defines the geometric shape of the lead plate 22. The location of the hole 24 is determined by the particular size and location of tubes 12 in the tubesheet and whether they are arranged in a square pitch or a triangular pitch. In the typical pattern illustrated, for example, the 73/8" width of the lead tile 22 will shield six openings width-wise, and with its 85/8" of length will shield seven holes length-wise on the tubesheet 14. The position of tubes along the symmetrical axis 4--4 is schematically shown in FIG. 4 in the form of broken-line half circles 12' and they are separated by the tubesheet material 16 ' of tubesheet 16 lying between them. The lead tiles are arranged with the hole 24 in the location as shown such that if a previously plugged tube is encountered where the hole 24 is intended to be aligned, a quick 180.degree. rotation permits the hole to be lined up with another tube 12. Because of the softness of the lead and its propensity to be dented or otherwise misshapen by external forces and impacts, the lead tile 22 is provided with a means for protecting it. The means for protecting the modular panels 22 of lead sheathing, is a sheath of material such as stainless steel, which is harder than lead, and which is easily decontaminated. In FIGS. 5 and 6, a sheath is illustrated in the form of a box-like structure 30 slightly larger than the lead panel 22. For example, in the dimensions given, the sheath may have an outer dimension of 71/2" width, by 83/4" length, with a hole center 34 located at the corner of a square 43/8" from the outside edge of the sheath 30 to the center of the hole. The inside height of the sheath would be approximately 5/8". The hole 34 of the sheath 30, and 36 of the top 32, will thus be in register with a transverse hole 24 of the lead tile 22 when placed in the sheath or box 30 with the top 32 thereon welded or otherwise secured in place. To complete the sheathing, the box 30, after having the lead insert placed therein and the top 32 welded to its sides 38 is provided with a tube 50 having a washer 52 welded at either end. Tube 50 is inserted through the holes 34 and 36, and hole 24 in register therewith, thus completing the sheathed tile or modular radiation shielding panel assembly. The modular radiation shielding system for use on the lower side of a nuclear steam generator tubesheet 14 to protect inspection and repair workers in the primary head 20 from radiation of the tubesheet 14 and tubes 12 that it secures preferably utilizes a particular fastening means 40. The fastening means 40 extends through the transverse openings 24, 34 and 36 in register, and a tube 12 aligned therewith, thereby releasably fastening the modular panel to the tube sheet face 16. The "Rapid Installation Tube Gripper" 40 can be rapidly attached inside the end of the tube 12 which is held by means of weld 42 in tubesheet 14. The tube engaging balls 44 are manipulated by means of a flange 46 secured to an internal sleeve in a manner fully disclosed in the previously referenced U.S. patent application Ser. No. 686,114 filed Dec. 24, 1984. It is sufficient for this disclosure to state that the locked and released positions of the balls 44 and tapered shaft 48 are maintained by the internal sleeve to which flange 46 is attached until the device 40 is inserted into or removed from the tube. It will be understood by those skilled in the art that upon the installation of a plurality of the modular radiation shielding panels according to the system described herein, there will be areas within particular tubes 12 which the rapid installation tube grippers 40 are filling which will not include any shielding from radiation. This is because there will be no lead between the workers under the lead shielding panel assemblies and the inside surface of the tube. To alleviate this condition and to further insure maximum shielding, the projecting tapered end 48 of the rapid installation tube gripper 40 can be lead filled, thus creating a lead finger portion which prevents radiation from the tube 12 "to shine" into the primary head 20, to any appreciable degree, from the otherwise unshielded tube containing the gripper 40. While the foregoing description is of a system to be installed on the lower surface of a tubesheet in a nuclear reactor steam generator, it is obvious that the invention can be used in many other applications that require lead shielding. The adaptability of the modular concept, both from a standpoint of ease of manual handling of the shielding assemblies, and from the standpoint of being able to be quickly installed and removed in various confined areas makes the modular radiation shielding system of the instant invention particularly useful whether provided in the disclosured embodiment or in equivalent structures.
	summary
	claims	1. A transfer device for transferring a given powder or a mixture of given powders, the transfer device comprising:a hopper configured to contain the given powder or the mixture of given powders, said hopper comprising a side wall and at least one discharge opening, said hopper having an axisymmetric shape and having a substantially vertical axis of revolution, said hopper being arranged such that the at least one discharge opening is located in a lower portion of said hopper; anda device configured to displace the hopper in rotation about an axis of revolution thereof, whereon the at least one discharge opening is located, said device including a control unit being configured such that the device configured to displace the hopper in rotation imposes a first moving phase on at least one movable portion of the side wall of the hopper, wherein an acceleration greater than or equal to a minimum acceleration configured to cause the given powder or the mixture of given powders to slide relative to the at least one movable portion is applied to the at least one movable portion,wherein the control unit is further configured such that the device configured to displace the hopper in rotation:repeats the first moving phase successively, separated by phases at constant speed, andperiodically inverts a direction of rotation of the at least one movable portion between two successive first moving phases. 2. The transfer device according to claim 1, wherein the minimum acceleration is greater than or equal to a product of a coefficient of static friction, of a force exerted by the given powder or the mixture of given powders on the side wall of the hopper, and of a radius of the hopper divided by a moment of inertia of the given powder or the mixture of given powders. 3. The transfer device according to claim 1, wherein the control unit is further configured such that the device configured to displace the hopper in rotation maintains, during a second phase after the first moving phase, movement in rotation of the at least one movable portion in a given direction of rotation. 4. The transfer device according to claim 3, wherein the control unit is further configured such that the device configured to displace the hopper in rotation displaces the at least one movable portion at a constant speed during the second phase. 5. The transfer device according to claim 1, wherein the periodically inverted direction of rotation between the two successive first moving phases imposes an oscillating rotating movement. 6. The transfer device according to claim 5, wherein the oscillating rotating movement has a frequency between 5 Hz and 50 Hz. 7. The transfer device according to claim 1, further comprising a dynamic sealing element disposed between the at least one movable portion and fixed portions of the transfer device. 8. The transfer device according to claim 1, wherein the hopper is a removable container. 9. A device for manufacturing nuclear fuel elements, comprising the transfer device according to claim 1, a press provided with a table wherein at least one mould is formed, and a device configured to compress the given powder or the mixture of given powders in the mould, with the at least one discharge opening of the hopper configured to be placed facing said mould during a filling phase of the mould and to be sealed off outside of the filling phase. 10. A method for transferring a given powder or a mixture of given powders that implements the transfer device according to claim 1, the method comprising:a) setting into rotation the at least one movable portion of the side wall of the hopper about the axis of revolution thereof, whereon the at least one discharge opening is located, with the acceleration greater than the minimum acceleration causing sliding of the given powder or the mixture of given powders with respect to the at least one movable portion of the side wall. 11. The method for transferring according to claim 10, wherein the minimum acceleration is greater than or equal to a product of a coefficient of static friction, of a force exerted by the given powder or the mixture of given powders on the side wall of the hopper, and of a radius of the hopper divided by a moment of inertia of the given powder or the mixture of given powders. 12. The method for transferring according to claim 10, further comprising a later step b) of maintaining a rotation movement of the at least one movable portion of the side wall in a given direction of rotation. 13. The method for transferring according to claim 12, wherein during the step b), the rotation movement is carried out at a constant speed. 14. The method for transferring according to claim 12, wherein step a) is repeated successively, separated by steps at a constant speed. 15. The method for transferring according to claim 14, wherein the given direction of rotation is periodically inverted between two successive steps a).
046577246	summary	BACKGROUND OF THE DISCLOSURE In logging procedures, a common mode of irradiation is bombardment of the formations adjacent to the borehole with neutrons generated by a pulsed neutron tube. A pulsed neutron tube is operated periodically to form the neutron flux for obtaining an output signal at a radiation detector located in the logging tool. The neutron generator and the circuitry associated with it must be operated at relatively high temperatures typically encountered in downhole conditions. These high temperatures cause thermal drift for transistorized circuitry. Accordingly, it is difficult to obtain a stable pulsed ion source high voltage supply for operation of the neutron generator which is capable of adjustment to form pulses at varying lengths and at different frequencies. It is desirable to operate the neutron generator at different times with different pulse rates and different pulse widths. Thus, the width of the pulses may vary by perhaps ten fold, and the pulse repetition rate of frequency may vary also by ten fold. The apparatus of this circuit is an ion source high voltage power supply capable of being pulsed at different pulse widths and different frequencies. The circuit disclosed herein is particularly deirable because it is temperature stable (transistor impedance increase with temperature constrains thermal runaway), an advantage over circuits utilizing bipolar output transistors. The change in temperature from ambient temperatures at the surface to temperatures encountered in deep wells initiates drift or even thermal runaway in bipolar transistors and hence renders such high voltage power supplies inoperative. Accordingly, this circuit is able to adjust over a range to provide wideband tuning of pulse width and frequency. Moreover, the circuit will operate at ambient temperatures and the high temperatures normally encountered in downhole conditions. For this reason, the pulsed neutron generator can then be operated at any desirable pattern for the neutron flux formed by the generator. One advantage of this apparatus is a wide range of tuning. That is, the device is able to form pulses of different widths. The width adjustment accommodates a large range of pulse widths; in fact, there is a wide range of pulse widths permitted in the circuit itself, and practicalities limit pulse width. Likewise, pulse frequency can be varied widely and is limited only by the practicalities of application. Another advantage of this device is the utilization of an interlocking system whereby a string of FETs connected between the high voltage output terminal and ground has FETs grouped into two groups. The two groups are switched with a timing sequence between the groups to thereby assure proper overlap. The overlap in timing protects the FET string against the unwanted circumstance where they might form a short between high voltage and ground, thereby burning up all the output transistors. Moreover, while several FETs are included in this string, control can be exerted by less than all of the transistors; that is, the control pulses are applied to less than all the output transistors and the remaining transistors are switched by a cascade switching sequence across the string. These and other advantages will be observed on a review of the disclosed high voltage power supply capable of forming pulses of any width at any frequency for a pulsed neutron generator source. While the apparatus has been described only briefly herein, a greater understanding thereof will be obtained on review of the detailed description of the preferred embodiment set forth below which apparatus accomplishes the objects described herein and has the advantages noted above as well as other advantages.
	description	This application is a continuation-in-part application of U.S. patent application Ser. No. 10/951,531 filed Sep. 28, 2004 now abandoned, which is incorporated herein by reference. The current invention relates to the determination of electrochemical corrosion potential for components in a nuclear power plant. More specifically, the current invention provides a device and method for determination of electrochemical corrosion potential for both zirconium fuel rods and various structural materials (of the nuclear plant system) at the reactor water temperature in a reactor coolant system for a nuclear power plant, wherein the electrochemical corrosion potential is determined through potential measurements remote from the fuel rod. Nuclear reactors, for example boiling water and pressurized water reactors, pass water through a reactor core which contains nuclear fuel. The passing of this water through the reactor core heats the water. The water is heated to either a hot liquid phase (pressurized water) or a combination of a hot liquid phase and a vapor phase (boiling water). The water and/or steam are transported through systems in the nuclear power plant, such as the reactor pressure vessel, steam separators, pressurizers and steam generators to transfer the heat energy generated by the nuclear reaction to other working systems. These piping systems and components transporting the fluid are made of various materials which may be susceptible to corrosion and irradiation induced or assisted stress corrosion cracking. Electrochemical corrosion potential (“ECP”) provides a guide to determining an amount of a oxidation/reduction reaction which occurs on a metal surface, for example on the surface of primary water coolant pipes. The oxidation/reduction reactions may depend, for example, on a dissolved oxygen concentration of water in a nuclear reactor, hydrogen concentration and/or hydrogen peroxide concentration obtained during water radiolysis. To decrease the electrochemical corrosion potential of these reactor coolant systems, the dissolved oxygen, and hydrogen peroxide concentrations of the water are kept as low as possible, preferably, to a level of about 25 parts per billion. This is performed, for example, by adding hydrogen to the system. Practically, however, maintaining dissolved oxygen, hydrogen and hydrogen peroxide concentrations at this low level is extremely difficult due to the changing water chemistry in the reactor coolant system. Electrochemical corrosion potential measurements are made in nuclear power stations to determine whether corrosive conditions are occurring in the station and whether stress corrosion cracking is likely to occur. In particular, if the electrochemical corrosion potential value is relatively low (i.e. below a threshold value), corrosion rate and/or stress corrosion crack growth rates are not significant. Above the threshold value, however, the possibility of stress corrosion cracking and/or the corrosion rate increases when electrochemical corrosion potential values increase. Measurements of electrochemical corrosion potential are made at a single point in the primary coolant system on the materials of interest such as in the weakest materials of internals. Existing electrochemical potential probes contain sensors that are typically a metal to metal oxide configuration which respond to oxygen concentrations in the reactor water. Existing systems used to measure electrochemical corrosion potential have many drawbacks. First, the probes used are fragile and are only operable for approximately three months as the sensors within the probes deteriorate from heat and radiation. As a consequence, the probes can only measure the electrochemical corrosion potential for less than 25% of the resident reactor core time precluding their usage around a nuclear reactor. Nuclear power plant operators' alternatives to alleviate this drawback are few. The nuclear power plant may be operated without monitoring corrosive conditions, however if the electrochemical corrosion potential is not measured for the entire fuel cycle, conditions may favor the formation of corrosion or stress corrosion cracking, thereby potentially damaging sensitive and expensive nuclear power plant systems. Alternatively, the nuclear reactor may be shut down and the electrochemical corrosion potential probes around the reactor are replaced. This alternative is economically unattractive due to the economics of a facility closure. The second drawback is that existing systems use a discrete measurement point probe for analysis. This type of system merely provides a spot measurement on an individual system. Existing systems cannot ascertain if the electrochemical corrosion potential is elevated in a part of the nuclear plant system not directly measured. The complex and changing materials through a nuclear power plant coolant system do not allow current systems to accurately measure electrochemical corrosion potential of systems relative to one another. As a consequence, certain systems or subsystems of the nuclear reactor are more prone to corrosion and stress corrosion cracking, as compared to others. Current systems do not allow the nuclear plant operator to compare data derived from measuring different systems, therefore attention is focused on the probe location. A true risk assessment analysis of the entire nuclear plant system is not performed. Current systems also do not determine an electrochemical corrosion potential for the zirconium clad fuel elements, as compared with the electrochemical corrosion potential measured for structural internals or piping materials. To date, current systems are limited to determining electrochemical corrosion potential of structural or piping members inside the reactor cooling systems. There is a need to provide an electrochemical corrosion potential measuring system that will allow for a determination of an electrochemical corrosion potential of the zirconium fuel rods during an entire fuel cycle of a nuclear power plant. There is a further need to provide an electrochemical corrosion potential measuring system that allows for replacement of a probe and its associated sensors at the end of its service life in a cost efficient manner. There is also a need to provide an electrochemical corrosion potential measuring system that will determine the electrochemical corrosion potential of various materials (which make up the nuclear plant system) at the same time to provide data to a nuclear plant operator as to which nuclear systems are at risk for corrosion relative to other nuclear systems. There is also a further need to provide an electrochemical corrosion potential measuring system that may be utilized to determine the amount of potential degradation of fuel rods during reactor operating conditions. It is therefore an objective of the present invention to provide an electrochemical corrosion potential measuring system that will allow for determining an electrochemical corrosion potential for both zirconium fuel rods and various structural materials (of the nuclear plant system) at the reactor water temperature during an entire fuel cycle of a nuclear power plant. It is also an objective of the present invention to provide an electrochemical corrosion potential measuring system that allows for replacement of a probe and its associated sensors at the end of the sensors' respective lifetime in a cost efficient manner. It is also an objective of the invention to provide an electrochemical corrosion potential measuring system that will allow for determination of electrochemical corrosion potential for several different structural materials of a nuclear power plant to provide data to a nuclear plant operator as to what nuclear systems are at risk for excessive corrosion or for stress corrosion cracking relative to other nuclear systems (based on the materials making up such systems). By measuring the electrochemical corrosion potential of several components throughout the nuclear power plant system, the components closely associated in material type and position would have a similar electrochemical corrosion. Therefore, determining which systems of a nuclear power plant are at risk for corrosion relative to other nuclear systems can be accomplished by comparing the electrochemical corrosion potential of a zirconium fuel rod to that of a zirconium structural element (such as a pipe or other structure), or a stainless steel structural element (such as a pipe or other structure), or some combination thereof. The material structural elements with the highest ECP values will be at the highest risk for corrosion relative to the other material structural elements with the lower ECP values. It is a still further objective of the present invention to determine the electrochemical corrosion potential of nuclear fuel rods at their operating temperature. The objectives of the present invention are achieved as illustrated and described. The invention provides a system for determining an electrochemical corrosion potential of a zirconium fuel rod, the system comprising at least two electrochemical sensors positioned either in a nuclear reactor or in a system adjacent to the nuclear reactor, wherein at least one of the at least two electrochemical sensors includes a heated zirconium electrode, and the at least two electrochemical sensors measure voltages proportional to an electrochemical corrosion potential for a surface that each of the at least two electrochemical sensors are installed upon. The system also includes a means for heating the zirconium electrode, and an arrangement configured to accept the voltages produced by the at least two electrochemical sensors, wherein the arrangement is configured to determine an electrochemical corrosion potential of a zirconium fuel rod based upon the voltages of the at least two electrochemical sensors. Preferably, the means for heating the zirconium electrode is a heating sleeve, and the zirconium electrode is heated thereby to a temperature which is approximately equal to that of the fuel rod surface temperature. The present invention also provides a method for determining an electrochemical corrosion potential of a zirconium fuel rod, the method comprising positioning at least two electrochemical corrosion sensors in either a nuclear reactor or in a system adjacent to the nuclear reactor, wherein at least one of the at least two electrochemical sensors includes a heated zirconium electrode, and producing a voltage between the at least two electrochemical corrosion sensors. The method also includes measuring a current induced by the voltage, and determining an electrochemical corrosion potential of a zirconium fuel rod based upon the current induced. Preferably, the heated zirconium electrode is heated to a temperature which is approximately equal to that of the fuel rod surface temperature. Typically, the fuel rod surface temperature is approximately 400° C. Referring to FIG. 1, an electrochemical corrosion potential analyzing system 10 for a pressurized water reactor is illustrated. Although shown in FIG. 1 as relating to pressurized water reactors, the system 10 is equally applicable to boiling water reactors (“BWR”), and thus the example embodiment which is illustrated should not be considered limiting. A nuclear reactor 12 contains nuclear fuel in the form of fuel assemblies 18. The fuel assemblies 18 are located in the reactor 12 such that under prescribed conditions, the nuclear fuel in the fuel assemblies 18 produces a nuclear chain reaction which consequently produces heat. The heat generated by the reaction is removed from the reactor 12 by water flowing in an attached reactor coolant system 13. The water flows in the reactor coolant system 13 from a reactor water inlet 14 into the nuclear reactor 12 and through the nuclear fuel assemblies 18. A reactor outlet 20 allows the warmed water from the reactor 12 to exit the reactor 12 for further processing. The warmed water proceeds out of the reactor outlet 20 and then passes by a pressurizer 22 which maintains pressure and shock control for the reactor coolant system 13. A vapor phase 58 is maintained in a top part of the pressurizer 22 by the actuation of a heater 26 controlled by a heater control unit 24. Water volume in the pressurizer 22 may be modified by adding reactor coolant from a pressurizer surge tank. The pressurizer 22 is connected to the reactor coolant system via a pressurizer surge line 30, which may be straight or bent, (e.g. S bend), through which the pressure and shock control is performed. The water traveling through reactor outlet 20 passes to the pressurizer through the reactor coolant system steam generator inlet 48. The warmed water passes through the steam generator 42 and transfers the heat to a separate body of water passing from the steam generator secondary inlet 44 to the steam generator secondary outlet 46. The water passing through the steam generator secondary inlet 44 to the steam generator secondary outlet 46 may be transformed to a vapor phase and subsequently passed through a turbine for electrical generating purposes, for example. The water passing through the steam generator 42 exits through a reactor coolant system steam generator outlet 50. The water then returns back through the reactor coolant system 13 to the nuclear reactor 12 by aid of the reactor coolant pump 52. If the control valve 34 allows the warmed water which exits the reactor outlet 20 to the residual heat removal inlet line 54, the warmed water then passes through a residual heat removal pump 36 with a connected heat exchanger 38. The heat of the warmed water may be transferred by a heat exchanger 38 to a separate body of water flowing through an inlet/outlet 40. The water passing through the residual heat removal pump 36 may then be returned to the remainder of the reactor coolant system 13 through a residual heat removal outlet line 56. Referring to FIG. 2, an electrochemical corrosion potential analyzing system for a backward pumped boiling water reactor is illustrated. A nuclear reactor 12 contains nuclear fuel in the form of fuel assemblies 18. The fuel assemblies 18 are located in the reactor 12 such that under prescribed conditions the nuclear fuel in the fuel assemblies 18 produces a nuclear chain reaction by emitting nuclear radiation and heat. The heat, generated by the reaction, is removed from the reactor 12 by boiling water and thus producing steam. The water, which is used for boiling, is transported into the reactor 12 via the feedwater pipe 60. The water may be forced through the fuel assemblies 18 by use of internal jet pumps 70. The water may be transformed into steam when passing through the fuel assemblies 18. The steam then passes through a steam separator 62 and steam dryer 64 to the main steam pipe 66, which leads the steam away from the reactor 12. An average temperature distribution of the water is achieved circulating the water through an external recirculation piping 13. The water is removed from the reactor 12 through a reactor outlet pipe 20. It is then transported through the recirculation pump 80 and is then transported back to the reactor through the reactor inlet pipe 14. Referring to FIGS. 1 and 2, probes 200,202 of the system 10 may be positioned at multiple locations in the reactor coolant system 13 and reactor 12 and in adjacent systems to measure electrochemical corrosion potential. For example, a system adjacent to the reactor 12 could be an autoclave situated in a bypass circuit (for example, a regenerative heat exchanger), such that reactor coolant could flow through the autoclave in the bypass circuit and the ECP could be measured therein. The probes 200,202 may be positioned in the reactor coolant inlet 14 and the reactor outlet 20 to measure electrochemical corrosion potential in areas close to the reactor 12. The probes 200,202 may also be positioned anywhere in the reactor coolant system 13 for example on zirconium material structures for measuring of the potential. As illustrated, the probes 200,202 may also be installed on the fuel assemblies 18, for example, at a bottom tie plate or nozzle of the assembly. Referring to FIG. 3, an expanded view of a nuclear fuel assembly 18 is illustrated. The nuclear fuel assembly 18 has fuel rods 104 which are comprised of cylindrical fuel elements of enriched uranium dioxide fuel. The enriched uranium dioxide fuel is sheathed in zirconium alloy metal in the form of a rod 104. The typical length of a fuel rod 104 may be, for example, 350 to 450 cm long. The individual fuel rods 104 are maintained in relative position by use of spacers 106 placed at intermediate positions from a fuel assembly top 110 to the fuel assembly bottom 112. Control rods 102 are configured to be inserted in between the fuel rods 104 to slow down the nuclear reaction occurring in the fuel assembly. During the nuclear reaction process, the zirconium clad may be susceptible to corrosion due to increased levels of dissolved oxygen for example. To accurately measure the susceptibility of the zirconium clad nuclear fuel rods to electrochemical corrosion, the electrochemical corrosion potential system 10 measures the electrochemical corrosion potential of areas inside or outside of the reactor core (and away from the zirconium fuel rods) but nearby enough to the nuclear fuel assemblies to provide a representative value of the electrochemical corrosion potential of the zirconium clad. Preferably, the probes 200,202 (including a heated zirconium electrode) are positioned outside of the reactor 12 where they are close enough to the reactor 12 such that the half-life of the predominant radiolysis products (e.g., hydrogen, oxygen, and/or hydrogen peroxide) is not exceeded when such products reach the probes 200, 202. That is, the probes 200,202 (and the heated zirconium electrode) are preferably located at a position within the reactor coolant system 13 where not less than half of the predominant radiolysis products are still present in the reactor coolant. Such a location of the probes 200,202 (and the heated zirconium electrode) allows for the exact conditions of the zirconium fuel rod to be more closely and accurately reproduced at the measurement position of the probes 200,202, thereby resulting in a more accurate and informative electrochemical corrosion potential measurement by the probes 200,202 (and the heated zirconium electrode). Probes which measure the electrochemical corrosion potential of discrete areas of the reactor coolant system 13 may be placed throughout the reactor coolant system 13 such as at the feedwater inlet 14 and reactor outlet 20 as described in the example embodiment above to allow plant operators to both individually determine the susceptibility of the individual components of the reactor components as well as an entire system overview. By measuring several components inside or outside of the reactor for the electrochemical corrosion potential, the components closely associated in material type and position would have a similar electrochemical corrosion. For this reason, in the example embodiment described, electrochemical corrosion probes may be placed on the feedwater inlet 14, of the nuclear reactor pressure vessel close to the reactor 12 yet far enough away from neutron flux and heat of the reactor 12. These probes can be configured such that each of the probes measures a voltage which maybe proportional to the electrochemical corrosion potential of the individual metallic components measured. The measured values may then be sent by leads or other arrangements to an arrangement 208, such as a potentiostat and/or computer, configured to receive such voltage inputs. The arrangement 208 may then average the values obtained on the entrance and exit of the reactor or any other location in the reactor or adjacent system to obtain an average value of electrochemical corrosion potential. The arrangement 208 may be located at a remote location from the reactor coolant system 13 to allow operators to monitor electrochemical corrosion potential outside of a radioactive environment. The electrochemical corrosion system 10 may have a probe with at least two sensors 200, 202 wherein at least one of the sensors has at least one zirconium electrode. In addition, at least one of the sensors may include an electrode comprising a material which corresponds to a structural element of a nuclear power plant besides the zirconium fuel rod. For example, an electrode may comprise stainless steel (such as a 300-series stainless steel), which may correspond to a structural element of the plant such as piping, etc. Thus, by measuring the electrochemical corrosion potential with the electrode comprising a material corresponding to a specific structural element, that structural element would have a similar electrochemical corrosion potential and its suseptiblity to corrosion could therefore be measured. At least one of the sensors 200,202 has a zirconium electrode such that the zirconium electrode closely matches the material constituents of the fuel rods' zirconium fuel cladding, thereby indicating a corrosion potential of the zirconium cladding material of the fuel elements relative to that of other structural members and piping of the reactor internals. Preferably, the zirconium electrode comprises zircaloy, which is frequently used as the fuel rod cladding material. Preferably, the zirconium electrode is heated to a temperature which is approximately equal to that of the fuel rod surface temperature. Typically, the fuel rod surface temperature will be between approximately 250-400° C., especially between approximately 296-400° C. The heating of the zirconium electrode may be achieved by any conventional means, such as by inserting a heating rod or element into the zirconium electrode. The heating rod or element should have a watt density representative of a nuclear fuel rod such that the zirconium electrode can be heated to a temperature which is approximately equal to that of the fuel rod surface temperature. By heating the zirconium electrode to that of the fuel rod surface temperature, the exact conditions of the zirconium fuel rod are more closely and accurately reproduced at the zirconium electrode, thereby resulting in more accurate and informative electrochemical corrosion potential measurements by the zirconium electrode. Thus, in comparison to any previously known electrodes and methods of use thereof, the heated zirconium electrode of the present invention provides a more accurate measurement of the susceptibility of the zirconium clad nuclear fuel rods to undergo electrochemical corrosion. The electrochemical corrosion potential measurements may be made by two differing methods. A sensor may provide data for determination of an electrochemical corrosion potential through the application of an external current to a sensor in the probe, wherein after a voltage is then measured between the sensor and a reference sensor. Alternatively, the electrochemical corrosion potential may be determined from data provided by a sensor which is potentiostatically controlled (voltage controlled) (i.e. a voltage differential is created between at least two sensors). A current is then measured between the two sensors. In the instance of a potentiostatically controlled probe with two sensors, the measured current may then be used to calculate a corrosion rate knowing the material type, the area sampled, and the approximate density of the material sampled for example. Referring to FIG. 4, a system 10 for measuring an electrochemical corrosion potential is illustrated. A first probe 200 and a second probe 202 are connected to an arrangement 208. The first probe 200 and the second probe 202 may have internal sensors used for measuring the electrochemical corrosion potential of the surface that the probes 200,202 are installed upon. The arrangement 208 is configured to at least one of establish a voltage differential to the individual first probe 200 and second probe 202 or apply a current to each of the first probe 200 and second probe 202 through respective first 204 and second 206 leads. Each of the first and second leads 204,206 may be placed such that the leads 204,206 are not subject to excessive heat conditions. Additionally, each of the probes 200, 202 connected to the arrangement 208 may be configured with a differing material zirconium alloy, such that a electrochemical corrosion potential for differing material types is determined. The leads 204 and 206 may also be positioned such that potential electrical interference from flowing current and/or voltage is minimized. The leads 204 and 206 extend between the arrangement 208 and the first probe 200 and second probe 202, respectively. The leads 204 and 206 may both send and receive current and/or voltages to and from the probes 200,202 and the arrangement 208. In an alternative configuration, the probes 200,202 may be configured such that transmission of data determined by the probes is performed through wireless technology. The arrangement 208 may be a potentiostat, as a non-limiting example. The arrangement 208 may also be connected to a computer 210 which may retain data from the probes 200,202. The computer 210 may obtain data from the probes 200,202 on a periodic basis or on a continual basis at the discretion of the operator. The computer 210 may retain the data from the probes 200,202 in a memory or may output the data to an attached printer 212, a data storage device 214 and/or a display device 216. Each of the arrangement 208, computer 210, printer 212, data storage device 214 and/or display device 216 may be located at a remote location from the reactor coolant system 13 in order to allow operators to monitor electrochemical corrosion potential outside of a radioactive environment. In addition, even if such components are not located at a remote location from the reactor coolant system 13, these components may be configured such that transmission of data between these components is performed through wireless technology (i.e., the data can be accessed remotely). The arrangement 208 and the computer 210 may be configured such that more than two probes are connected for data acquisition. The computer 210 may also calculate the amount of corrosive damage to the fuel rods 104 over time, given the calculation of the electrochemical corrosion potential and derived corrosion rate. By performing this calculation of anticipated damage amounts over time, reactor operators are provided with an assessment of acceptable safety margins for the nuclear fuel assembly 18 over time. This consequently allows the reactor operators sufficient time to plan reactor outages as well as predict what work will need to be accomplished during the reactor outage. The probes 200,202 and associated leads 204,206 may also be installed inside the nuclear reactor such that measurements may be accomplished close to the nuclear reactor fuel assemblies 18. If the probes 200,202 and associated leads 204,206 are installed internally in the reactor pressure vessel 12, the probes 200,202 and leads 204,206 may be designed such that they can withstand the anticipated neutron flux and heat conditions of the reactor 12. The leads 204,206 may be placed through an existing instrumentation penetration in nuclear pressure vessel 12, thereby allowing the system 10 to be installed in existing nuclear power stations without modification. The probes 200,202 may be installed on structural members inside the reactor pressure vessel 12 which contain zirconium alloys, thereby allowing measurements to be obtained. Alternatively, the probes 200,202 may be attached to identifiable sections of fuel assemblies 18, for example the ends of the fuel assemblies such as the external positions of the nozzle 108. The attachment of the probes 200,202 to the reactor 12 is accomplished such that foreign material from the probes 200,202 is excluded from the reactor water coolant stream under normal and accident conditions. In another example embodiment, a probe or individual sensors, for example two sensors, may be positioned internally in the reactor 12, while two sensors remain outside the reactor 12 to provide a reference reading. The measurements obtained by the sensors in the reactor 12 and outside the reactor 12 are then provided to an arrangement such as a potentiostat. The probes 200,202 may extend from a penetration in the bottom of the reactor pressure vessel 12, for example an Instrumentation Thimble penetration, and may be positioned on any lower structure of the reactor 12, for example, the lower core plate, the flow mixer plate or bottom support forging. The computer 210 may then take the data provided to the potentiostat 208 and calculate the electrochemical corrosion potential. The probes 200,202 may be configured such that they can be removed during in-vessel work during a reactor outage such that maintenance of the probes 200,202 does not severely economically impact the operation of the reactor. As previously described, in a preferred embodiment of the invention, a zirconium electrode is heated to a temperature which is approximately equal to that of the fuel rod surface temperature. In comparison to any previously known electrodes and methods of use thereof, the heated zirconium electrode of the present invention provides a more accurate measurement of the susceptibility of the zirconium clad nuclear fuel rods to undergo electrochemical corrosion. To show the more accurate measurement capabilities of the heated zirconium electrode of the present invention, tests were conducted in the laboratory setting. To simulate the situation in a typical nuclear power plant at the beginning of a fuel cycle (i.e. without impurities or crud deposits on surfaces), a laboratory recirculation loop was used, equipped with all of the necessary means to control water chemistry at inlet and outlet (e.g., conductivity, O2 level, H2 level, etc.). In addition, a controlled dosage pump was provided in the recirculation loop to provide for a specified impurity level, if needed. A heating rod inserted into the zircaloy fuel cladding was employed to create heated zirconium surfaces at 70 W/cm2, which is the typical heating level existing in BWR. Several electrodes were used to measure the ECP of the zircaloy fuel rods: a heated zircaloy electrode (heated to the fuel rod surface temperature), an unheated type 347 stainless steel electrode and an unheated zircaloy electrode. A platinum electrode was used to measure the redox potential of the electrolyte, and a high temperature Ag/AgCl electrode was used as a reference electrode. The assembly was installed in a recirculation 1-liter autoclave in order to simulate (at smaller scale) the recirculation autoclave which would be adjacent to the nuclear reactor (e.g., situated in immediate proximity of the outside of the reactor vessel), as shown in FIG. 6. The recirculation 1-liter autoclave was equipped with specially fitted cooling jackets 601, 602, 603 and 604 on the lid 611 of the autoclave for cooling the electrical penetration to the heated zircaloy electrode 606 (inside the zircaloy tube) and the high temperature Ag/AgCl reference electrode 607. The electrodes went through the autoclave lid 611 via openings 612. The temperature of the heated zircaloy electrode was measured in three different areas by three thermocouples 605a, 605b and 605c brought close to the surface of the heated zircaloy electrode by a dip tube attached to the autoclave lid 611. The dip tube had small steel ligaments welded to it to keep the thermocouples in immediate contact with the heated zircaloy electrode during the testing. Their position was such that the temperature measurement was performed in the middle of the heated area (by the middle thermocouple) where the ECP measurement was performed, and in the unheated areas (upper thermocouple and lower thermocouple). The distance between the middle thermocouple and the thermocouples in the unheated areas was equal and approximately 4 cm. The width of the heated area inside of the heated zircaloy electrode was 8 cm and was equally distributed around the position of the central thermocouple. As can be seen by this example of a heated zirconium electrode, only the ECP measurement portion of the zirconium electrode needs to be heated in accordance with the present invention (i.e., only that portion of the zirconium electrode which will be measuring the ECP needs to be heated, preferably to a temperature which is approximately equal to that of the fuel rod surface temperature (the rest of the zirconium electrode may also be heated, but it is not required)). Inside the recirculation 1-liter autoclave, the platinum electrode 609 for measurement of the redox potential was approximately equally distanced at a 2 cm distance from the heated zircaloy electrode 606, from the unheated 347 SS electrode 610 and from the unheated zircaloy electrode 608. The size of the surface areas of each of the electrodes is presented in Table 1. TABLE 1Surface Area of Electrodes usedin the recirculation 1-liter autoclaveElectrodeSurface Area (cm2)heated zircaloy electrode 48 cm2unheated zircaloy electrode 7 cm2unheated SS 347 electrode5.2 cm2high temperature reference electrodeN/A(Ag/AgCl)platinum electrode3.1 cm2 The relative distances of the electrodes to the high temperature Ag/AgCl reference electrode is presented in Table 2. TABLE 2Relative Distance of the Electrodesto the High Temperature Ag/AgCl Reference ElectrodeDistance to the High TemperatureElectrodeAg/AgCl Reference Electrode (cm)heated zircaloy electrode~1 cmunheated zircaloy electrode~2 cmunheated SS 347 electrode~1 cmplatinum electrodeN/A The corrosion potential measurements were performed under BWR pressure and temperature conditions (i.e., 288° C. fluid exit temperature, 86 bar, with a surface temperature of the heated zircaloy electrode of 296° C.). Furthermore, a number of different chemistry conditions were run during the testing: inert water conditions; hydrogen injection in three steps from 0.68 ppm to 1.6 ppm; oxygen injection in three steps from 2.2 ppm to 8 ppm; and methanol 2 ppm and oxygen 2 ppm in a close loop (without methanol refreshing). The measurements of the ECP by the different electrodes during the course of hydrogen injection are presented in FIG. 5. Curve A represents the ECP measured by a Pt electrode (vs. a standard hydrogen electrode (SHE)) which is at the temperature of the medium (i.e., the coolant water in the autoclave), curve B represents the ECP measured by the unheated zircaloy electrode (vs. SHE), curve C represents the ECP measured by the unheated SS347 electrode (vs. SHE), and curve D represents the ECP measured by the heated zircaloy electrode (vs. SHE) (heated to the fuel rod surface temperature). Curves E and F show the temperature of the medium and of the heated zircaloy electrode, respectively. The testing was run under three different water conditions: H2 level=0.8 ppm; H2 level=1.6 ppm; and inert water conditions. As can be seen from FIG. 5, when the temperature of the zircaloy electrode is increased (i.e., the zircaloy electrode is heated) to the temperature of the fuel rod surface (296° C.), and the H2 level in the coolant water is increased to 1.6 ppm (making corrosion more likely), the resulting ECP measured by the heated zircaloy electrode (curve D) is much higher than the ECP measured by the unheated electrode of the same material (curve B). In fact, curve D is approximately 100 E/mV higher than curve B in this area of the graph, which is a considerable difference in terms of corrosion rate. Thus, these results show that a heated zirconium electrode provides a much more accurate value of the ECP (for a zirconium fuel rod) than does an unheated zirconium electrode, thereby providing a much more informative indicator of whether corrosion is likely to occur. As can also be seen from FIG. 5, curve B (representing the ECP measured by the unheated zircaloy electrode) and curve C (representing the ECP measured by the unheated SS347 electrode) largely coincide with one another during the portion of the testing wherein the H2 level in the coolant water was increased to 1.6 ppm. This indicates that using either zirconium or stainless steel electrodes in an unheated condition produces very similar ECP results, such that neither seems to be more indicative of susceptibility to excessive corrosion or to stress corrosion cracking. The present invention provides an electrochemical corrosion potential system that allows for determination of an electrochemical corrosion potential for nuclear fuel rods during an entire fuel cycle of a nuclear power plant. The proximity of the placement of the probes to the fuel assemblies and the heating of the zirconium electrode allow for the calculation of electrochemical corrosion potential for the zirconium cladding of the fuel assemblies unachievable by other systems. Replacement and maintenance costs of the present invention allow the operators of the facility to accurately monitor the corrosion potential, while providing minimal economic impact on the facility. In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense.
	abstract	A method for predicting the location of stress corrosion cracking in a steel gas pipeline in which in-line stress corrosion cracking smart tool data, external low level metal loss data and soil characterization data are compiled to predict the location of stress corrosion cracking in a steel gas pipeline segment.
	description	This application is a continuation of Ser. No. 14/044,267 filed Oct. 2, 2013, which is a continuation of Ser. No. 12/409,572, filed Mar. 24, 2009, now U.S. Pat. No. 8,574,545, which is a continuation-in-part of and claims priority to International Patent Application No. PCT/CA2008/001916, filed Oct. 31, 2008, which claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Ser. No. 60/984,163, filed Oct. 31, 2007, the disclosures of which are incorporated herein by reference in their entirety. This invention is in the field of medicine and in particular diagnostics of neurological disorders. This invention includes a formulation comprising an aqueous solution of [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane, wherein the solution comprises a radioactive concentration of at least about 18 mCi/mL, and particularly about 20 mCi/mL or more. [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane is potentially useful as an aid to diagnosing Parkinson's Syndromes (PS). Without being bound by any particular theory, PS is believed to be characterized by the loss of dopamine-producing neurons in the brain. The loss of dopamine-producing neurons is believed to begin long before symptoms of the disease actually present. Symptoms of PS are often similar to many other movement disorders. Consequently, misdiagnosis rates are high, with some reports of up to 50% misdiagnosis in the early stages. There is currently no available test that can clearly identify Parkinson's Syndromes, especially in early cases. A diagnostic for early stage PS has long been sought. Without being bound by any particular theory, the dopamine transporter (DAT) is believed to play a significant role in physiological, pharmacological and pathological processes in the brain. The transport system is a primary mechanism for terminating the effects of synaptic dopamine, thereby contributing to the maintenance of homeostasis in dopamine systems. It has also been reported to be a principal target of cocaine in the brain. (Kennedy and Hanbauer, J. Neurochem. 1983, 41, 172 178; Shoemaker et al., Naunyn-Schmeideberg's Arch. Pharmacol. 1985, 329, 227 235; Reith et al., Biochem Pharmacol. 1986, 35, 1123 1129; Ritz et al., Science 1987, 237, 1219 1223; Madras et al., J. Pharmacol. Exp. Ther. 1989a, 251, 131 141; Bergman et al., J. Pharmacol. Exp. Ther. 1989, 251, 150 155; Madras and Kaufman, Synapse 1994, 18, 261 275). The brain grouping formed by the caudate nucleus and the putamen is called the striatum. It constitutes the major target for the cortical afferents of the basal ganglia. The striatum reportedly has the highest levels of dopamine terminals in the brain. A high density of DAT is localized on dopamine neurons in the striatum and appears to be a marker for a number of physiological and pathological states. For example, in Parkinson's Syndromes, dopamine is severely reduced and the depletion of DAT in the striatum has been an indicator for Parkinson's disease (Schoemaker et al., Naunyn-Schmeideberg's Arch. Pharmacol. 1985, 329, 227-235; Kaufman and Madras, Synapse 1991, 9, 43-49). Consequently, early or pre-symptomatic diagnosis of Parkinson's Syndromes can be achieved by the quantitative measurement of DAT depletion in the striatum. (Kaufman and Madras, Synapse 1991, 9, 43-49). Simple and noninvasive methods of monitoring the DAT are quite important. Depletion could be measured by a noninvasive means such as brain imaging using a scintillation camera system and a suitable imaging agent (Frost et al., Ann. Neurology 1993, 34, 423 431; Hantraye et al., Neuroreport 1992, 3, 265-268). If possible, imaging of the dopamine transporter would also enable the monitoring of progression of the disease and of reversal of the disease such as with therapies consisting of implants of dopamine neurons or drugs that retard progression of the disease. We believe that a radiopharmaceutical that binds to the DAT might provide important clinical information to assist in the diagnosis and treatment of these various disease states. The decay of the [123I] associated with the compound results in the release of a photon with an energy of 159 KeV. This photon easily (and relatively safely) passes through human tissues and bones and can be detected, often by using a radiation detector array in a Single Photon Emission Computed Tomography (SPECT) camera. With appropriate software an image of the site from which the radiation is emerging can be constructed. The image can be compared to images obtained from subjects without signs of Parkinson's Syndromes. A decrease in emmission is presumptive evidence of a loss of dopamine transporter neurons, and potentially a diagnosis of Parkinson's Syndromes. An effective imaging agent for the disorders described above will exhibit a specific binding affinity and selectivity for the transporter being targeted. In addition, for imaging agents based on radioactive emission, a minimum level of radioactivity is also pertinent. The level of radioactivity is expressed in three ways, specific activity, the concentration of radioactivity, and the total amount of radioactivity administered. In addition, to be a viable commercial product, the radiochemical yield must be reasonable. Specific activity, in this context, refers to the proportion of 2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane molecules that have 123I as opposed to 127I, the non-radioactive iodine isotope. In order to obtain the maximum amount of signal per bound radiochemical molecule, the radiochemical procedure needs to be free of non-radioactive sodium iodide. In radiolabeling 2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-tributyltin-E-allyl) nortropane with 123I-sodium iodide, the chemical amount of 123I is extremely small relative to the amounts found in ordinary chemical reactions. Special expertise and experience are generally required to achieve high-yield radio-labeling reaction conditions, and optimizing the conditions requires experimentation. In addition the optimization of the process is particularly expensive at large scale and requires special precautions due to the large amounts of radioactivity. The concentration of the radiochemical and its stability are key factors in the successful commercial viability of radio-chemicals. The radiochemical and chemical stability of each uniquely structured radio-labeled entity is unpredictable from the structure alone. Furthermore, the effect of additives meant to increase stability cannot be known in advance of experimental testing. In addition, for those compounds with short half-life isotopes such as the one discussed herein, the shelf life is usually directly related to the concentration of the product. So long as the compound is stable to the effects of the additional radiation, the shelf life can be extended by using a higher the concentration of the compound. In this regard, [123I]2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane may be more useful if it can be produced in sufficiently high concentrations such that it would still be emitting at suitable levels for a longer useful period of time. Periods for detectable emissions of one or two days, or longer, after creation are noted. In one aspect, the invention features a diagnostic formulation comprising an aqueous solution comprising [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane. In one embodiment the formulation comprises a radioactive concentration of at least about 18-20 mCi/mL. In another embodiment, the formulation exhibits radioactive concentration of at least about 1.6 mCi/mL at least about 51 hours post-creation. In yet another embodiment the formulation comprises a pH of less than about 7. In another embodiment the formulation comprises a radiochemical purity of at least about 95%. In another embodiment the formulation comprises a concentration of ethanol in a percentage of less than about 10%. In another embodiment the formulation is substantially carrier free. In another embodiment the formulation is substantially ascorbic acid free. In another aspect, the invention features a method of preparing [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane comprising the steps of: a) Preparing a precursor solution comprising 2β-Carbomethoxy-3β-(4-fluorophenyl)-N-(3-tributyltin-E-allyl) nortropane), ethanol, hydrogen peroxide, and phosphate buffer; b) Preparing a sodium [123I]-iodide solution comprising sodium [123I]-iodide and trifluoroacetic acid having a pH of less than about 2; and c) Heating a mixture of precursor solution and sodium [123I]-iodide solution at a temperature of about 80° C. for about 15 minutes. In another aspect, the invention features a method of preparing an aqueous solution of [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane comprising the steps of: eluting the [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane through a C18 preparative HPLC column with an eluent, wherein the eluent comprises about 15% (v/v) ethanol; and Collecting the product peak in sodium chloride in an acetic acid buffer; wherein the radioactive concentration of the resulting solution is at least about 23 mCi/mL. In another aspect, the invention features a product foamed by the process for producing [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. 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 invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. For commercial production, it is important to maximize radiolabel (e.g. 123I) incorporation into a final product as well as minimize the reaction time. It is also required for safety of use that the final product has radiochemical and chemical purity acceptable to national regulatory agencies. Furthermore, since neither of the initial reactants is stable at low pH but the iodination reaction is optimal at low pH, care is taken to employ a process whereby the reaction period under acidic conditions is minimized. The successful commercialization of the product is further enhanced if the shelf life/stability can be lengthened. One method by which this can be accomplished is by increasing the final product's radioactive concentration. Since a radiolabel such as 123I has a half life of only 13.2 hours, extending the shelf life by an additional day suggests that the initial level of radioactivity should be increased about four-fold. Increased concentrations of radioactivity potentially reduce the stability of the product because of direct effects of radiation on the compound and by indirect effects caused by the generation of highly reactive compounds, including highly reactive compounds, from water. A more useful compound is one with the highest concentration of radioactive compound(s) that maintains sufficient chemical and radiochemical stability for the duration of use. Definitions For convenience, certain terms employed in the specification, examples, and appended claims are collected here. Unless defined otherwise, 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 invention belongs. The initial definition provided for a group or term herein applies to that group or term throughout the present specification individually or as part of another group, unless otherwise indicated. The articles “a” and “an” are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element. The teem “or” is used herein to mean, and is used interchangeably with, the term “and/or,” unless context clearly indicates otherwise. The term “carrier” is used herein to mean a non-radioactive version of a compound. The term “radiochemical yield” is the percentage of radioactive compound incorporated into a final product. Tropane is a bicyclic tertiary amine compound C8H15N that is the parent compound of atropine, cocaine, and related alkaloids. Certain small organic molecules, some of which have high affinity and selectivity for the dopamine transporter (DAT), and are useful in the diagnosis of Parkinson's disease (PS). In one embodiment the tropane compound as disclosed in U.S. Pat. No. 5,493,026. In one embodiment, the tropane compound is [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane. It is believed that, when given intravenously, [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane (Altropane®, Alseres Pharmaceuticals, Inc. Hopkinton, Mass.) is able to penetrate the brain and bind to dopamine transport receptors. Other examples of imaging agents that target the dopamine transporter include [123I] N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane or Ioflupane (123I) (DaTSCAN™, Nycomed-Amersham, Piscataway, N.J.), PE2I (11C or 18F), (-)-2-β-Carbomethoxy-3-β-(4-fluorophenyl)tropane (β-CFT, WIN 35,428), (99mTc) 0-1505, and (99mTc)-Technepine. The above agents and other examples of useful DAT ligands include but are not limited to compounds disclosed in Fischman et al., 1998, Synapse, 29:125-41, Madras et al., 1996, Synapse 22:239-46; Meltzer et al., 1993, J. Med. Chem. 36:855-62; and Milius et al., 1990, J. Medicinal Chem. 34:1728-31, U.S. Pat. Nos. 5,493,026; 5,506,359; 5,770,180; 5,853,696; 5,948,933; 6,171,576; 6,548,041; 7,081,238; 6,180,083; 5,310,912; 5,439,666; 5,698,179; 5,750,089; 6,447,747; 6,537,522; 5,980,860; 6241963 and 6,180,083. In one aspect, the invention features a diagnostic formulation comprising an aqueous solution comprising [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane, optionally wherein the aqueous solution is substantially carrier-free and substantially ascorbic acid-free. In another embodiment, the aqueous solution is substantially radioprotectant-free. In one embodiment, the aqueous solution comprises a radioactive concentration of at least about 15 and 18, and about 20 mCi/mL or more. In another embodiment, the aqueous solution comprises a radioactive concentration of at least about 23 mCi/mL. In another embodiment, the aqueous solution comprises a radioactive concentration of at least about 1.6 mCi/mL at least about 50 hours post creation. In one embodiment, the aqueous solution has a radiochemical purity of at least about 95%, and particularly at least about 97%. In another embodiment, the aqueous solution comprises a concentration of ethanol in a percentage of less than about 10%, and less than about 5%, and further less than about 1%. In another embodiment, the aqueous solution is substantially ethanol-free. In another embodiment, the aqueous solution comprises a pH of less than about 7. In another embodiment, the aqueous solution comprises a pH of less than about 6. In another embodiment, the aqueous solution comprises a pH ranging from about 2.5 to about 4.5. In one embodiment, the [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane is stable for at least 48 hours. In another embodiment, the [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane is stable for at least about 60 hours. In another aspect, the invention features a process for producing [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane. In one embodiment the process comprises the reaction of 2β-Carbomethoxy-3β-(4-flurophenyl)-N-(3-tributyltin-E-allyl) nortropane and sodium [123I]-iodide. In another embodiment the process produces [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane in less than about 60 minutes, with greater than 95% radiochemical purity, a concentration of at least about 20 mCi/mL, a radiochemical yield of at least about 45% (and particularly at least about 65%, and at least about 75%.), without added carrier, and having a radiochemical and chemical stability sufficient for over about 50 hours, and particularly at least about 51 hours. In another aspect, the invention features a process for producing an aqueous solution of [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane. In one embodiment, the solution is produced using a process comprising purification using hydrophobic media that allows separation and concentration. In another embodiment, a Preparative HPLC purification. In one embodiment, the purification step is substantially free of a radiolysis inhibitor. In another embodiment, the purification step comprises the addition of a radiolysis inhibitor. In another embodiment, the purification step of the target compound is performed within 30 minutes. Any suitable preparative HPLC system may be used but note is made of an HPLC column comprising packing material particles having an 18 carbon chain (C18). Examples of C18 columns include but are not limited to XTerra® C18 Column, (Waters Corp., Milford, Mass., See U.S. Pat. No. 6,686,035), and μBondpak C18 Column (Waters Corp., Milford, Mass.). In one embodiment the process for producing [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane comprises the steps of: a) Heating a basic solution (pH at least about 11) of sodium [123I]-iodide to a range of about 70° C. to about 150° C. b) Separately combining 2β-Carbomethoxy-3β-(4-flurophenyl)-N-(3-tributyltin-E-allyl) nortropane in great molar excess (about 0.05 to about 0.5 mg) in ethanol, an oxidizing agent (e.g., H2O2), and a buffer (e.g. sodium phosphate) at about pH 2.5 to 3.0 c) Acidifying the heated sodium [123I]-iodide to a pH less than about 2 using an appropriate buffer (e.g. trifluoroacetic acid) and adding the mixture defined in step (b) d) Heating the mixture from (c) for about 20 minutes or less at a temperature ranging from about 70° C. to about 150° C. e) Neutralizing the pH (e.g., by adding base such as NaOH) and a reducing agent (e.g. sodium metabisulfite) f) Purifying the [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane reaction product using hydrophobic media that allows separation and concentration (with or without radiolysis inhibitors) of the target compound within about 30 min, and g) Diluting into an isotonic saline solution with acidic (less than about pH 7) buffer (e.g. phosphate) with or without radiolysis inhibitors (e.g. ascorbic acid) to a concentration of about 23 mCi/mL. h) Sterilizing by autoclaving if the formulation buffer is less than about pH 6 (optionally pH about 2.5 to about 4.5), Optionally the solution at pH about 2.5 to about 7.0 may be sterilized by filtration (note: any lower limitation on useful pH is a function of degree of injection discomfort and not due to chemical instability). In another aspect, the invention features a product formed by the process for producing [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane. In one embodiment the product foamed by the process of preparing a precursor solution comprising 2β-Carbomethoxy-3β-(4-fluorophenyl)-N-(3-tributyltin-E-allyl) nortropane, ethanol, hydrogen peroxide, and phosphate buffer; preparing a sodium [123I]-iodide solution comprising sodium [123I]-iodide and trifluoroacetic acid having a pH of less than about 2; heating a mixture of precursor solution and sodium [123I]-iodide solution at a temperature of about 80° C. for about 15 minutes; eluting the [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane through a C18 preparative HPLC column with an eluent, wherein the eluent comprises about 15% (v/v) ethanol; and collecting the product peak in sodium chloride in an acetic acid buffer. Sodium [123I]-iodide (4 Ci) in 0.1N NaOH was dispensed in a 10 mL vial and heated to about 80° C. Phosphate buffer, 0.80 mL 0.1 M, pH 2.5-3.0, was combined with 0.20 mL 30% hydrogen peroxide, and 0.50 mL of 1 mg/mL (in ethanol) 2β-Carbomethoxy-3β-(4-fluorophenyl)-N-(3-tributyltin-E-allyl) nortropane) to form a precursor containing mixture. The sodium [123I]-iodide solution was acidified (final pH <2) by the addition of Trifluoroacetic acid. The precursor-containing mixture was added to the acidified sodium [123I]-iodide solution. The mixture was heated at 80° C. for 15 minutes. After 15 minutes, 2 mL of sodium metabisulfite solution was added to stop the reaction (100 mg/mL in Sterile Water for Injection). One mL of a 100 mg/mL solution of Ascorbic Acid was added to the reaction mixture as a radioprotectant. The acidic reaction mixture is optionally neutralized with 500 μL of 5 N Sodium Hydroxide. After neutralization, the pH is >6. Neutralization may be optional if the subsequent HPLC system is not degraded too quickly by the low pH and oxidant. The reaction mixture of Example 1 was transferred to a preparative HPLC system (μBondpak® C18 Column from Waters Corp., Milford, Mass.). μBondpak Column Packing Material: C-18 Particle Size: 10 μm Length: 300 mm Diameter: 19 mm Column Volume: 85 mL[123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane was eluted using the following eluent system: isocratic elution buffer, 80% (v/v) ethanol, 20% ascorbic acid in sterile water for injection 20 g/L. The product peak was collected into a vessel containing sodium chloride injection (USP) in an acetic acid buffer pH 2.5 to 3.5. Due to carry over the final solution has about 3.8 to about 6.3% ethanol and about 0.2 to about 0.4 g/L ascorbic acid. The resulting radioactive concentration of [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane was about 5 mCi/mL of solution. The chromatographed mixture of Example 3 is adjusted by dilution with acetic acid buffer, pH 2.5 to 4.5, to produce an aqueous solution comprising 4 mCi/mL (at the time of production), [123I]-2β-carbomethoxy-3β-(4-flurophenyl)-N-(3-iodo-E-allyl) nortropane, 4% ethanol, 0.3 mg/mL ascorbic acid, 10 μM glacial acetic acid, sodium hydroxide buffer, pH 2.5-3.5, and 0.9% sodium chloride. It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.
042971691	summary	The present invention relates generally to the art of corrosion prevention in nuclear reactors and is more particularly concerned with novel boiling water reactor nuclear fuel compositions and with a new method involving the use of CuFe.sub.2 O.sub.4 or CuTiO.sub.3 or mixtures thereof to prevent embrittlement of nuclear fuel cladding by cadmium. CROSS REFERENCES This invention is related to those of my following two patent applications assigned to the assignee hereof and filed of even date herewith: Patent Application Ser. No. 700,736, filed June 29, 1976, entitled "Nuclear Fuel Assembly and Process" which discloses and claims the concept of preventing embrittlement of fuel cladding by chemically inerting fission product cadmium through the use of relatively small but effective amounts of gold, silver or palladium or mixtures thereof. Patent Application Ser. No. 700,735, filed June 29, 1976, entitled "Nuclear Fuel Assembly and Process" which discloses and claims the concept of preventing embrittlement of fuel cladding by chemically inerting fission product cadmium through the use of relatively small but effective amounts of V.sub.2 O.sub.4 or V.sub.2 O.sub.5 or mixtures thereof. BACKGROUND OF THE INVENTION Boiling water reactor nuclear fuel in suitable compacted form is usually enclosed in corrosion-resistant, non-reactive, heat-conductive containers or cladding which in assembly may take the form of rods, tubes or plates. A plurality of fuel elements of this kind are assembled in a fixed spaced relation in a coolant flow channel, and a number of these assemblies are combined to form a reactor core capable of a self-sustained fission reaction. The core is contained in a reactor vessel through which water as a coolant is run continuously. A prime necessity in the operation of a nuclear reactor is the containment of radioactive fission products. The cladding serves this purpose, preventing release of those products into the coolant and, in addition, preventing contact and chemical reaction between the nuclear fuel and the coolant. Common cladding materials include zirconium and its alloys, particularly Zircaloy-2 and Zircaloy-4. During operation of a nuclear powered reactor, a fissionable atom of U-233, U-235, Pu-239 or Pu-241 undergoes a nuclear disintegration producing an average of two fission products of lower atomic weight and great kinetic energy. Some of such fission products, including iodine and bromine, have been found or considered to have corrosive effects on the cladding. Thus, cladding failure resulting from such corrosion has been observed during operation of nuclear reactors over long periods of time. As disclosed and claimed in U.S. Pat. No. 3,826,754, assigned to the assignee hereof, certain additives can be incorporated in nuclear fuels to prevent corrosive attack on cladding by fission products. This result is achieved without offsetting disadvantage by chemical combination or association of the additives with deleterious fission products whereby those fission products are prevented from migrating in the nuclear fuel to reach the cladding. SUMMARY OF THE INVENTION This invention is based upon my discovery that cadmium, which is produced in only relatively small amounts in the fission of an atom of U-232, U-235, Pu-239, Pu-241 or the like has a markedly deleterious effect upon common nuclear fuel cladding materials. In particular, I have found that embrittlement of zirconium alloy cladding is caused by cadmium in the temperature range of 300.degree.-340.degree. C. Thus, such destructive attack occurs in the presence of solid cadmium at 300.degree. C., liquid cadmium at 340.degree. C. and cadmium dissolved in liquid cesium at any temperature in that range. Still further, the presence in nuclear fuel of the immobilizing additives of the prior art does not prevent or limit this embrittling effect of cadmium. This invention is additionally based upon my discovery that the chemical displacement compounds, copper ferrite and copper titanate, have the capability individually and in combination of reacting with cadmium under normal boiling water reactor operating conditions and thereby preventing embrittlement of nuclear fuel cladding by cadmium in liquid or solid form or in solution in liquid cesium. Further, I have found that these compounds may be admixed with a nuclear fuel as a simple additive or used as a component of a multifunctional fuel additive, or they may be applied as a coating on fuel pellets or on the cladding inside surface, or distributed as a layer between fuel pellets. However, in whatever form and manner the additive is used for this cadmium-inerting purpose, it should be proportioned to insure that there will not be a substantial amount of cadmium free to contact and embrittle the fuel cladding. Thus, 0.0025 to 0.025 weight percent CuTiO.sub.3 on the basis of the nuclear fuel material (preferably 0.0075 weight percent) and on the same basis 0.0033 to 0.033 weight percent CuFe.sub.2 O.sub.4 (preferably about 0.01 weight percent) should be used in accordance with this invention. It will be understood by those skilled in the art that this invention has both process and composition aspects, the new process comprising the step of providing in contact with nuclear fuel material an amount of CuFe.sub.2 O.sub.4 or CuTiO.sub.3 effective to prevent cadmium embrittlement of nuclear reactor structural components such as fuel cladding at reactor operating temperatures. In its composition-of-matter aspect, in general, this invention comprises an oxide composition nuclear fuel material in compacted pellet form containing an amount of CuFe.sub.2 O.sub.4, CuTiO.sub.3 or admixture thereof effective to immobilize cadmium resulting from the nuclear fission chain reactions of the fuel material by reacting with the cadmium and thereby prevent reaction of the cadmium with the metal of reactor nuclear fuel cladding under reactor operating conditions.
	claims	1. An apparatus comprising:a radiation absorption layer comprising an electrode;a counter configured to register a number of radiation particles absorbed by the radiation absorption layer;a controller configured to start a time delay from a time at which an absolute value of an electrical signal on the electrode equals or exceeds an absolute value of a first threshold;a comparator configured to compare the electrical signal to a second threshold;wherein the controller is configured to activate the comparator during the time delay;wherein the controller is configured to cause the number registered by the counter to change, if the comparator determines that the absolute value of the electrical signal equals or exceeds an absolute value of the second threshold. 2. The apparatus of claim 1, further comprising a capacitor module electrically connected to the electrode, wherein the capacitor module is configured to collect charge carriers from the electrode. 3. The apparatus of claim 1, wherein the controller is configured to activate the comparator at a beginning or expiration of the time delay. 4. The apparatus of claim 1, further comprising a meter, wherein the controller is configured to cause the meter to measure the electrical signal upon expiration of the time delay. 5. The apparatus of claim 4, wherein the controller is configured to determine an energy of the radiation particles based on a value of the electrical signal measured upon expiration of the time delay. 6. The apparatus of claim 1, wherein the controller is configured to connect the electrode to an electrical ground. 7. The apparatus of claim 1, wherein a rate of change of the electrical signal is substantially zero at expiration of the time delay. 8. The apparatus of claim 1, wherein a rate of change of the electrical signal is substantially non-zero at expiration of the time delay. 9. The apparatus of claim 1, wherein the radiation absorption layer comprises a diode. 10. The apparatus of claim 1, wherein the radiation absorption layer comprises silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. 11. The apparatus of claim 1, wherein the apparatus does not comprise a scintillator. 12. The apparatus of claim 1, wherein the apparatus comprises an array of pixels. 13. The apparatus of claim 1, wherein the radiation particles are photons. 14. The apparatus of claim 13, wherein the photons are X-ray photons. 15. The apparatus of claim 1, wherein the electrical signal is a voltage. 16. The apparatus of claim 1, further comprising another comparator configured to compare the electrical signal to the first threshold. 17. The apparatus of claim 1, wherein the controller is configured to deactivate the comparator at expiration of the time delay or at a time when the absolute value of the electrical signal equals or exceeds the absolute value of the second threshold, or a time in between. 18. A system comprising the apparatus of claim 1 and a radiation source, wherein the system is configured to perform radiography on human chest or abdomen. 19. A system comprising the apparatus of claim 1 and a radiation source, wherein the system is configured to perform radiography on human mouth. 20. A cargo scanning or non-intrusive inspection (NII) system, comprising the apparatus of claim 1 and a radiation source, wherein the cargo scanning or non-intrusive inspection (NII) system is configured to form an image using backscattered radiation. 21. A cargo scanning or non-intrusive inspection (NII) system, comprising the apparatus of claim 1 and a radiation source, wherein the cargo scanning or non-intrusive inspection (NII) system is configured to form an image using radiation transmitted through an object inspected. 22. A full-body scanner system comprising the apparatus of claim 1 and a radiation source. 23. A computed tomography (CT) system comprising the apparatus of claim 1 and a radiation source. 24. An electron microscope comprising the apparatus of claim 1, an electron source and an electronic optical system. 25. A system comprising the apparatus of claim 1, wherein the system is a radiation telescope, or a radiation microscopy, or wherein the system is configured to perform mammography, industrial defect detection, microradiography, casting inspection, weld inspection, or digital subtraction angiography. 26. A method comprising:starting a time delay from a time at which an absolute value of an electrical signal on an electrode of a radiation absorption layer equals or exceeds an absolute value of a first threshold;activating a circuit during the time delay, wherein the circuit is configured to compare the absolute value of the electrical signal to an absolute value of a second threshold;determining whether an absolute value of the electrical signal equals or exceeds an absolute value of the second threshold;changing a count of radiation particles incident on the radiation absorption layer in response to determination that the absolute value of the electrical signal equaling or exceeding the absolute value of the second threshold. 27. The method of claim 26, further comprising connecting the electrode to an electrical ground. 28. The method of claim 26, further comprising measuring the electrical signal upon expiration of the time delay. 29. The method of claim 26, further comprising determining an energy of the radiation particles based on a value of the electrical signal at expiration of the time delay. 30. The method of claim 26, wherein a rate of change of the electrical signal is substantially zero at expiration of the time delay. 31. The method of claim 26, wherein a rate of change of the electrical signal is substantially non-zero at expiration of the time delay. 32. The method of claim 26, wherein activating the circuit is at a beginning or expiration of the time delay. 33. The method of claim 26, further comprising deactivating the circuit at an expiration of the time delay or at a time when the absolute value of the electrical signal equals or exceeds the absolute value of the second threshold. 34. The method of claim 26, wherein the radiation particles are photons. 35. The method of claim 34, wherein the photons are X-ray photons. 36. The method of claim 26, wherein the electrical signal is a voltage.
	summary
	claims	1. A process for producing molybdenum-99, comprising:irradiating at least a portion of a zirconium target with alpha particles, thereby producing an irradiated target portion comprising molybdenum-99; andseparating the molybdenum-99 from other target species, wherein the irradiating and the separating occur simultaneously. 2. The process according to claim 1, wherein separating comprises chemical separation. 3. The process according to claim 1, wherein separating comprises mass difference separation. 4. The process according to claim 3, wherein the mass difference separation comprises plasma separation. 5. The process according to claim 1, wherein the irradiating at least a portion of the target includes exposing the target to an alpha particle beam having a flux of at least about 1016 α/(cm2)s. 6. The process according to claim 1, wherein the target comprises at least about 10% zirconium-96. 7. The process according to claim 1, further comprising purifying the molybdenum-99 to produce purified molybdenum-99. 8. The process according to claim 7, further comprising loading the purified molybdenum-99 onto an adsorbent column. 9. The process according to claim 8, further comprising allowing at least a portion of the purified molybdenum-99 to decay to technetium-99m. 10. The process according to claim 9, further comprising eluting the technetium-99m from the adsorbent column. 11. The process according to claim 1, further comprising producing technetium-99m from the molybdenum-99. 12. A process for producing molybdenum-99, comprising:irradiating a first location of a zirconium target with alpha particles, thereby producing first irradiated target material comprising molybdenum-99, while simultaneously removing second irradiated target material from a second location of the target. 13. The process according to claim 12, wherein removing comprises contacting the second irradiated target material with a solvent, thereby producing an irradiated target solution. 14. The process according to claim 13, wherein the solvent is aqua regia. 15. The process according to claim 14, further comprising adjusting the concentration of the irradiated target solution to a chloride molarity of from about 4 to about 8 and subjecting the solution to ion-exchange chromatography. 16. The process according to claim 14, further comprising evaporating the aqua regia, thereby yielding a residue comprising zirconium and molybdenum-99. 17. The process according to claim 16, further comprising contacting the residue with an alkaline solution to selectively dissolve molybdenum species. 18. The process according to claim 12, wherein removing the second irradiated target material from the target comprises sputtering. 19. The process according to claim 18, wherein sputtering employs a focused ion beam. 20. The process according to claim 12, wherein removing the second irradiated target material from the target comprises mechanical milling. 21. The process according to claim 12, wherein removing and irradiating are performed in a continuous process. 22. The process according to claim 12, wherein alpha particles are within an alpha beam, and further comprising optimizing an energy of the alpha beam using alpha transport theory so as to maximize the production of molybdenum-99 and minimize the production of other products. 23. The process according to claim 12, further comprising producing technetium-99m from the molybdenum-99. 24. A process for producing molybdenum-99, comprising:irradiating a zirconium target with alpha particles while contacting the irradiated target with a fluorinating agent; andcontinuously adjusting the target such that different portions of the target are irradiated by alpha particles and contacted with the fluorinating agent,wherein the continuously adjusting occurs while continuously removing at least some irradiated target material from the target. 25. The process according to claim 24, wherein contacting the irradiated target with the fluorinating agent produces fluoride species comprising MoF5, MoF6 or both. 26. The process according to claim 25, wherein the fluorinating agent comprises at least one of NF3 and HF. 27. The process according to claim 25, wherein contacting the irradiated target with the fluorinating agent comprises activating the fluorinating agent with microwave radiation. 28. The process according to claim 24, further comprising producing technetium-99m from the molybdenum-99. 29. A process for producing molybdenum-99, comprising:positioning a zirconium target such that a portion of the target is irradiated by alpha particles from an alpha particle source, thereby producing irradiated target material comprising molybdenum-99; andcontinuously adjusting the target, the alpha particle source, or both the target and the alpha particle source such that a different portion of the target is irradiated by alpha particles,wherein the continuously adjusting occurs while continuously removing at least some of the irradiated target material from the target. 30. The process according to claim 29, further comprising purifying molybdenum-99 from the irradiated target material. 31. The process according to claim 30, wherein purifying molybdenum-99 comprises ion-exchange chromatography. 32. The process according to claim 30, wherein purifying molybdenum-99 comprises selectively dissolving molybdenum-99 in a solvent. 33. The process according to claim 30, wherein purifying molybdenum-99 comprises forming a molybdenum fluoride. 34. The process according to claim 29, further comprising producing technetium-99m from the molybdenum-99. 35. The process according to claim 29, wherein the continuously adjusting comprises moving the target in a cyclical pattern such that the removing exposes non-irradiated target material that is subsequently irradiated by the alpha particles. 36. The process according to claim 35, wherein the target comprises a rotating disk. 37. The process according to claim 35, wherein the target comprises a thin strip circulating in a loop.
	abstract	An apparatus for manipulating or modifying electromagnetic waves or electromagnetic waves or a beam of particles, eg atoms, ions, molecules or charged particles, the apparatus comprising a micro or nano electrical conductor crossbar network having multiple cross-over junctions that define respective scattering points for electromagnetic waves or the particles of the beam. At least one structural parameter of the crossbar network is selectively tuneable to obtain a desired manipulation or modification of said wave or beam when incident on the network in a pre-determined directional electrical conductor crossbar network (10) configured as an atomic beam diffraction grating. The direction of wave propagation of the atomic beam is indicated by the arrow (15). The atomic beam is sufficiently slowed for it to exhibit wave behavior having a de Broglie wavelength of the order of magnitude of the lattice spacing of a lattice of scattering points (20) defined by crossbar network (10), and is thereby diffracted so as to form a diffraction pattern on downstream image plane (30). In this way, incident beam (15) is manipulated or modified by crossbar network (10) whereby the beam emerges from the network manipulated or modified with respect to incident beam (15).
	abstract	An equivalent phantom is used for an X-ray Talbot imaging apparatus which includes an X-ray source, a plurality of gratings and an X-ray detector. The apparatus captures at least a Moire image from which a differential phase image of an object is generated. The equivalent phantom includes a first substance having a first refractive index and a second substance having a second refractive index. A ratio of the first refractive index to the second refractive index is equal to a ratio of a refractive index of a soft tissue to a refractive index of a surrounding tissue. At least a part of a shape of one of the first and second substances is equal to a shape of a corresponding portion of the soft tissue.
045281297	summary	This invention pertains to processing dry or aqueous radioactive wastes and uranium mill tailings and any accompanying toxic and hazardous waste materials into a substantially stabilized, insoluble, impermeable, encapsulated and solidified form suitable for safe and ecologically-acceptable disposal. The present invention is a significant advancement and improvement in the field of the disposal of radioactive wastes and uranium mill tailings. Other inventions by the present inventor in the specifically non-related and generally collateral fields of oil sump and sewage disposal are described in U.S. Pat. No. 4,038,240, granted June 7, 1977; U.S. Pat. No. 4,079,003, granted Mar. 14, 1978; and U.S. Pat. No. 4,184,958, granted Jan. 22, 1980. A considerable volume of uranium tailings have been and are being produced from mining and milling of uranium ores. The uranium mill tailings, which may be stockpiled or impounded in liquid-covered retention ponds, are of considerable concern from a safety and ecological standpoint. Radon gas RN-222, during the mining and milling process, will continually be produced and emanated from the mill tailings unless radium-226 and thorium-230 is removed from the uranium ore. Because of the long half lives of the radioactive elements, radon gas will be produced for a considerable period of time. For this reason, it is preferred that the uranium tailings typically be submerged in liquid in retention ponds. The liquid cover on the pond inhibits or prevents the emission of radon gas. Direct exposure to radon gas poses an immediate health threat, generally in the form of cancer. Tailings retention ponds are a source of potential ground water contamination, and are exposed to contact by humans and wildlife. The liquid in the pond is either highly acidic or highly basic, depending upon the type of recovery process used in milling the uranium ore. In addition, the tailings liquid includes amounts of aluminum, ammonia, arsenic, calcium, carbonate, cadmium, chloride, copper, fluoride, iron, lead, manganese, mercury, molybdenum, selenium, sodium, sulfate, vanadium, zinc, natural uranium, radium-226, thorium-230, polonium-210 and bismuth-210, and total dissolved solids, including uranium ore (U.sub.3 O.sub.8). Many of the materials accompanying the radioactive elements are hazardous and ecologically undesirable. These hazardous materials may leach from the retention pond into the ground water supply and are a health risk to humans and wildlife. The principal objectives for disposing of uranium tailings have been to attempt to protect the ground water against contamination, to control the atmospheric emission of radon gas, and to isolate the tailings from man's environment, permanently, or for long time periods. However, there is no universally followed or successful practice for disposing of the uranium tailings. Indeed, population centers have grown up around or on top of exposed stockpiles of tailings, and the ground water has exhibited some radioactive contamination in some locations. Past practices for disposing of uranium tailings have included burying the tailings in deep trenches or in abandoned mine shafts. The ecological impact of such practices is uncertain. Attempts have been made to neutralize the acidic liquid being discharged into the tailings retention ponds to a pH which is not substantially acidic or basic by adding milk of lime and other forms of alkaline reagents. This type of neutralization could not be maintained, partially because of feed-mix variables and the intrusion of fresh water into the ponds from natural sources. Barium chloride processes have also been considered, but such processes are not effective in removing radium. An ion exchange process employing an organic resin specially compounded to collect ions from a solution of the uranium tailings has also been considered, but the success of this process depended on the freedom of the solution from excessive solids, which was impractical and uneconomical to achieve. Other partial techniques involve removing water from the tailings by solar evaporation, thermal evaporation or filtration. This procedure only addresses the liquid fraction of the overall disposal problem and does not address the disposal problem associated with the remaining solid materials. Attempts have been made to encapsulate large quantities of uranium tailings to prevent leaching of the wastes into the ground water and to resist the diffusion and emission of radon gasses into the atmosphere. Prior encapsulation techniques involved constructing a clay or synthetic liner or clay covering of large quantity of tailings. Asphalt, asphalt and neoprene emulsions, resinous adhesives, elastomeric polymers, mixtures of wax and tar and pitch, and other chemical compounds have been tried as coatings or liners. These materials have, however, proved ineffective because of cracking and deterioration caused by the highly acidic or basic nature of the tailings, the weather and natural expansion and contraction. Cracked, deteriorated covering and expanded liners have allowed the diffusion of radon gasses into the atmosphere and the intrusion of natural water and seepage of tailings solutions into the ground water. Excessive costs were required to maintain or replace the liners or coverings. None of the prior techniques for disposing of radioactive wastes and uranium tailings have succeeded in controlling and terminating the persistent emission of radon gas into the atmosphere, and in protecting the ground water from potential contamination. SUMMARY The present invention possesses the capabilities, among others, of substantially or totally encapsulating the radioactive wastes and accompanying chemical contaminants present in uranium mill tailings in a solid mass of rock-like material which is substantially impermeable to the emission of radon gas therefrom and which is substantially insoluble to the leaching or seepage of the radiological and hazardous organic chemical wastes into the ground water. The characteristics of the manufactured rock-like material allow it to be disposed of relatively safely and without substantial known ecologically damaging effects. The manufactured rock-like material need not be covered with liners, sealers, or the like, since the product inherently possesses the required characteristics for substantially isolating the radioactive wastes from the environment. As a further result of the practice of the present invention, it is possible to eliminate tailings retention ponds and stockpiles of tailings and return the land to safe ecological utilization. According to its broad aspects, the process of the present invention comprises absorbing soluble radioactive wastes in an absorbing agent, preferably clay, and thereafter cementing the absorbed wastes and absorbing agent into a final matrix product having a pH of at least 8.0 and which is substantially impermeable. Cementing is achieved by use of lime, and the lime also renders the soluble radioactive wastes insoluble by pH neutralization or adjustment. Any non-neutralized contaminants are nonetheless captively held in the final matrix product. The final matrix product changes to a limestone in which the wastes are encapsulated by contact with carbon dioxide. The final matrix product achieves a significant reduction in the emission of radioactive gasses and the leaching out of soluble contaminants, and the resistance to both leaching and emission are improved in the limestone. The final matrix product is in a state for acceptable disposal. A more complete and thorough understanding of the invention can be obtained by reference to the detailed description of its preferred embodiment and the accompanying drawing.
040640000	description	DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 there is shown generally a liquid metal cooled, fast spectrum reactor 10 comprising a reactor vessel 12 and a reactor vessel head 14 vertically disposed and supported within a concrete containment structure 16. The reactor vessel 12 houses a nuclear core 18 comprised of a plurality of fuel assemblies 20 arranged and supported in a fixed array by support structure (not shown), as is well known in the art. The fuel assemblies 20 are comprised of fuel pins within a shroud or housing that contains nuclear material for sustaining a nuclear chain reaction. The housings 22 of fuel assemblies 20, as is conventional, are each of a hexagonal cross-section. Interspersed within an array of hexagonally shaped fuel assemblies 20 and arranged in a regular pattern are a plurality of hexagonally shaped control assemblies 24. The control assemblies 24 are comprised of an elongated, hexagonally shaped housing 26 which forms an aperture at its upper end in the array, and control elements (not shown), such as rods of a neutron absorbing material, adapted for longitudinal movement therewithin. Drive means 28 and 30, supported on the reactor vessel head 14 and extending downward therethrough (to be described in greater detail below) are coupled to the control elements for effecting longitudinal movement thereof to control and regulate the nuclear chain reaction in the core 18. By way of the nuclear chain reaction, substantial amounts of heat are generated within the core 18 and conveyed to a primary coolant, such as for example liquid sodium, which is introduced into and removed from the reactor core 18 by coolant inlet and outlet conduits 32 and 34 respectively. The heated coolant may then be cooled by a heat exchange system (not shown) to generate steam which is passed to a turbine which drives an electric generator for the ultimate transformation of thermal energy into electrical energy. Generally, the reactor vessel head 14 serves to seal the reactor vessel 12 and provide biological shielding, thermal insulation and alignment between the nuclear core 18 an any interfacing system such as control, instrumentation, and core access systems. It is a general requirement that all penetration and/or leakage paths around and through the reactor vessel head 14 be sealed to prevent ingress of gases into the reactor vessel 12 which might react with the liquid metal coolant and egress therefrom of cover gas possibly contaminated by released fission products and nuclear radiation. The biological shielding and thermal insulation may comprise a series of shielding blocks 36 and reflector insulating plates 38 housed within a welded steel enclosure structure 40. For practical considerations related to safety and ease of manufacturing and construction of liquid metal cooled fast spectrum reactors 10, control of the reactor and refueling operations take place through the top of the reactor vessel 12. Additionally, it is desirable that instrumentation of fuel assemblies 20 for monitoring the behavior of the liquid coolant in a nuclear core 18 also take place through the reactor vessel head 14. Still further, as can be appreciated, symmetrical patterns of vessel head penetrations are desirable. A symmetrical control pattern permits more efficient and finer control of the reactor 10 while a symmetrical instrumentation pattern minimizes the complexity of mechanisms for locating the instruments in the fuel assemblies 20. Complicating achievement of the above noted desirable features is the fact that it is equally desirable to provide a core access system in which only a small portion or area of the core 18 is exposed for refueling at any one time. While some systems have been developed which accommodate a symmetrical control and instrumentation pattern and which provide for through the head, line of sight refueling (see for example U.S. application Ser. No. 537,283 filed Dec. 30, 1974 for "Control Rod and/or Instrument Tree Assembly" by Noyes et al and U.S. application Ser. No. 537,284 filed Dec. 30, 1974 for "Core Access System for Nuclear Reactors" by Dupen). Such systems are not always applicable nor can they be utilized in the manner described for all reactor designs. For example, the above mentioned pending U.S. Applications disclose a control and/or instrumentation scheme and core access system respectively for gas spectrum reactors which have cores comprised of relatively large hexagonally shaped assemblies. While such a system is theoretically applicable for smaller subassembly sizes, it is not easily adaptable because of physical restraints in regards to the size of components for use with relatively small size assemblies comprising the nuclear core. For example, with small sized assemblies, say on the order of 4 inches across the flat, the number of penetrations through the reactor vessel head per the instrumentation and control schemes disclosed in the above cited applications is greatly increased for a given area. This then presents problems with regard to the spacing between the control drive mechanisms supporting nozzles on the reactor vessel head which in turn presents problems with regard to the placing of rotational supporting bearings for rotatable access plugs between adjacent nozzles. Accordingly, different systems might be appropriate for a given nuclear reactor depending on the size of assemblies making up the core. It is to an alternative and improved instrumentation and control scheme and core access system that the present application and its companion application, entitled "Improved Core Access System" and filed on the same date as the present application are directed. It is to be noted, of course, that while the present invention as well as the inventions described in the other above mentioned co-pending applications have been designed for a particular application with a given size of fuel assembly, that the inventions may have application with regard to other size fuel assemblies. The core servicing apparatus of the present invention provides a symmetrical quite regular arrangement of core servicing elements with respect to the nuclear core so as to achieve the desirable advantages which result from such an arrangement. By servicing elements or means, it is meant that the means provides a service to the reactor. Customarily, this includes the services of monitoring, inspecting or controlling the nuclear core, although other services may also be performed. To carry out such conventional services, a servicing element may include for example a thermo-couple, an eddy current flow meter probe, a neutron detector, or a neutron absorption element. The symmetrical pattern afforded by the present invention, accordingly results in a regular pattern or arrangement of such elements and thereby provides for complete and adequate services for the core. As noted hereinabove, with respect to smaller size assemblies comprising the nuclear core, the problem of limiting the number of penetrations in the reactor vessel head becomes more acute. As noted in both the above mentioned co-pending applications, Ser. Nos. 537,283 and 537,284 it is desirable that servicing means be placed either in or with respect to every assembly of the nuclear core. With respect to each penetration through the reactor vessel head than it is desirable that the core servicing apparatus be placed in and extending through such penetrations to provide services to a large number of the assemblies and thus a large area of the nuclear core. To accomplish this, and still maintain a reduced penetration size, it is necessary or desirable that means be provided for laterally displacing the servicing means, which extend through the limited size penetration, outward with respect to the boundaries of that penetration. That is, it is desirable to pass the core servicing apparatus in a compacted position through a relatively small size penetration and then laterally expand or extend the apparatus from the compacted state. In this way a larger area of the core may be serviced through a limited sized penetration. Such an arrangement for providing lateral displacement of servicing means is complicated further when the size of the subassemblies is reduced, as a certain size must be maintained for the penetration in order to provide room for components which can't be reduced in size and which are necessary for other interfacing systems. Accordingly, the core servicing apparatus of the present invention includes a removable plug from which is supported and suspended the servicing element for the nuclear core. The removable plug in turn is supported within an opening provided in the reactor vessel head. Briefly stated, and to be described in greater hereinbelow, the core servicing apparatus comprises a plurality of support columns suspended from the plug, rigid support means laterally extending and supported by each of the support columns, and a plurality of servicing means which are in turn supported from the laterally extending rigid support means. Means are then provided for rotating the rigid support means and servicing means from a condensed position which lies totally within the coextensive boundaries of the plug opening, to an expanded position in which some of the rigid support means and servicing means lie outside of the coextensive boundaries of the plug. In this way a core area can be serviced by a removable plug in which the cross-sectional dimension of the plug is less than the cross-sectional area of the core which is serviced by the servicing means suspended from the plug. With such an arrangement then, in which servicing apparatus is supported from a plurality of removable plugs which are in turn supported by the reactor vessel head, direct line of sight through the head refueling can be accomplished as another aspect of the present invention. Such refueling involves replacing the removable plugs in the reactor vessel head with extension skirts and refueling plugs mounted on top of the reactor vessel head within the penetration vacated by the core servicing plug. Briefly stated, and to be described in greater detail hereinbelow, the skirt extension has laterally extending portions on which are supported rotational supporting bearings for the refueling plug. The reactor vessel head includes a large rotatable cover which overlies the entire core and which includes penetrations therethrough for the core servicing and refueling plugs. With such an arrangement in which the core servicing plugs are replaced with refueling plugs which are rotatable, the entire core can be serviced for refueling with a limited number of penetrations for the refueling plugs by proper rotation of the refueling plugs and of the vessel head large rotating cover. Such rotation can position the access penetration in the refueling plugs over each and every fuel assembly forming the core of the reactor. PLUG MOUNTED CORE SERVICING APPARATUS More specifically now, referring to FIG. 1 the reactor vessel head 14 includes a relatively large rotatable plug or cover 42 which is supported in an opening 44 in the reactor vessel head. This large rotatable cover 42 is virtually identical to that disclosed in co-pending application Ser. No. 537,284 with respect to its composition. Of course, the size or lateral dimension of the plug and the penetrations therethrough for the plug mounted core servicing apparatus are different. During reactor operation the large rotatable cover is stationarily supported on appropriate flanges 16 provided in the annular support ring 48 which defines the boundary of the large reactor vessel opening. As more fully described in co-pending application Ser. No. 537,284, the plug 42 is mounted for rotational movement by means of appropriate bearings 50 spaced about the periphery of the large cover and supported on the annular support ring 48. The capability for rotational movement is achieved by actuating hydraulic screw jacks 52 to raise the large cover off the support flanges and to place the load on the bearings. The large rotatable cover 42 includes a plurality of penetrations 54 therethrough, in which are supported the core servicing plugs 55. In the embodiments shown and described herein, eight of such penetrations are provided. As best shown in FIG. 5, the boundaries of these openings or penetrations through the large rotatable cover are defined by upwardly extending skirts 56 welded to the upper surface of the reactor vessel head about the penetrations. As with the large annular support ring for the large rotatable cover, the penetrations through the large cover include inwardly extending flanges 58 which serve to support the removable plugs of the core servicing apparatus during normal reactor operation. Also included along the upper surface of the large rotatable cover are a plurality of upwardly extending nozzles 60 welded to and spaced about the ligament between the penetrations 54 of the large rotatable cover. These nozzles are hollow and extend through the entire thickness of the large rotatable cover 42 and serve as a housing to support single core servicing apparatus to complete the core servicing or instrumentation and control of the nuclear core as will be described in more detail hereinbelow. As can be seen from FIGS. 1 and 5, the upwardly extending nozzles on the large rotatable cover are located between adjacent upwardly extending skirts 56 and extend a short distance above the upper elevation of these skirts. Each of the core servicing plugs 55 are of the same composition as the rest of the reactor vessel head, i.e., they include graphite blocks 62 and reflector insulating plates 64 within a welded steel enclosure 66. The lower end 68 of the plug 55 is of a reduced diameter to provide a flange 70 to rest on the flange 58 within the penetration in the large rotatable cover. Appropriate sealing means such as O ring type seals 72 are provided along the cylindrical surface of the plugs 55 so as to effectively mate and seal the plugs when mounted in the penetrations 54 of the large rotatable cover. As noted above, these plugs are stationarily supported and do not rotate, thus no rotational bearings are provided. In the preferred embodiment, each of the core servicing plugs 55 includes seven upwardly extending nozzles 74, 74', similar to those nozzles provided on the large rotatable cover 42. Within the nozzles there is provided a penetration 76 through the plug within which are supported a downwardly extending support column 78, 78' of the core servicing apparatus 80, 80' as will be described in detail below. There is one central nozzle somewhat larger in diameter than the remaining six nozzles which surround the central nozzle and are located near the periphery of the plugs 55. As with the arrangement disclosed in co-pending application Ser. No. 537,284, the size or lateral dimension of the core servicing apparatus support plug 55 is related to the size of specified interfitting groups of assemblies 82 formed in the nuclear core. Again as in the aforementioned application, these interfitting groups of assemblies 82 are designated potential control clusters and in the preferred embodiment comprise a central hexagonally shaped assembly and six surrounding hexagonally shaped assemblies contiguous with the center assembly (see FIGS. 4 and 6). The nozzles 74, 74' on each of the plugs 55 are located such that the center lines of two adjacent nozzles 74, 74' coincide with the center of two adjacent and interfitting potential control clusters 82. The specific size of each of the nozzles and thus the internal diameter of the nozzles and of the penetrations through the plug can and do vary depending on whether the nozzle is located at the periphery of the plug or located in the center of the plug as best shown in FIG. 5. Peripheral nozzles will hereinafter be designated by the reference number 74 and central nozzles by the number 74'. Also throughout the description, where like reference numerals are used, the number bearing a "prime" designation will be associated with a central core servicing assembly. This size difference is a result of the fact that the central and peripherally located core servicing assemblies service different numbers of fuel assemblies in the core. Accordingly, the diameter or lateral dimension of the small plugs 55 is somewhat greater than twice the distance between the centers of two adjacent and interfitting potential control clusters 82. In any event, however, it is less than four times the distance as the boundary of the plug must fall between two adjacent nozzles, one on the plug and one on the large rotatable cover. As noted above, there are two general types of core servicing assemblies, central instrumentation servicing assemblies 80' and peripheral instrumentation servicing assemblies 80. Each of the peripheral assemblies 80 service 10 of the fuel assemblies 20 found in the core and the central assemblies 80' service 19 of such fuel assemblies. With either type of servicing assembly 80, 80', there is provided a guide tube and instrument tree support column 84, 84', laterally extending support structure 86, 86', and servicing means 88 such as instrumentation for monitoring the flow and temperature of the liquid metal coolant or means for effecting longitudinal movement of control or neutron absorbing control elements. The servicing means 88, i.e., either the instrumentation or control element drive extensions are supported from the support column and have means extending upwardly within the guide tube and instrument tree support column to exit above the reactor vessel head. Each of the servicing means is rigidly laterally fixed with respect to the support column 84, 84' and in some of the assemblies, namely the peripheral servicing assemblies 80, means are provided for rotating servicing means about the center line or axis of the peripheral servicing assembly. As seen generally in FIG. 7, the laterally extending structure 86, 86' is fixed to a central support column 78, 78' which extends upwardly into and through the other guide tube and instrument tree column 84, 84' which terminates some distance above the nuclear core. In the case of instrumentation, the instrument probes 88, which typically comprise either a thermo-couple or a flow meter, are suspended from the ends of the support structure, 86, 86' in a fixed array with respect to the nuclear core 18 and with respect to the support column 84, 84'. Electrical leads 116 housed in a flexible conduit 92 connected to the instrument probes pass upwardly from the support structure 86, 86' and radially inward around the central support shaft 78, 78'. The leads then extend upward around the shaft into the guide tube and instrument tree 84, 84' and exit above the nozzles 74, 74' supported on the plug 55 through an electrical connector assembly 94. In case of control drive extensions, in the preferred embodiment the extensions extend downward within the central support shaft 78, 78' and enter into appropriate apertures in a control assembly which is in alignment with the axis of the servicing assembly. Of course, this means that the large rotatable cover and the servicing plugs must be maintained in a fixed position with respect to the core. This can be easily accomplished by the use of guide pins (not shown). More specifically now, turning first to a peripheral servicing assembly 80 as shown in greater detail in FIGS. 9-12, the peripheral assembly includes a vertically extending support column comprised of an outer cylindrical tubular member 84 and a concentrically positioned inner cylindrical tubular member 78 supported for longitudinal movement relative to the plug 55 within one of the peripheral nozzles 74 supported on the servicing plugs. Basically, the general arrangement and composition of the components of the support column 84 at the elevation of the reactor vessel head 14 is the same as the arrangement and composition of the components for the control rod and/or instrumentation assemblies of previously cited co-pending application Ser. No. 537,283, which application is hereby incorporated by reference. Accordingly, the detailed description of the arrangement will not be set forth herein. The outer guide tube 84 is supported within the upwardly extending nozzle 74 and extends downward through the thickness of the head to a position above the nuclear core 18. The outer guide tube 84 includes a laterally extending support flange 96 which, in the assembly's lowermost position, rests on the ledge 98 of the nozzle 74. Within the outer guide tube a central tube 100, concentric with the guide tube 84 extends the full length of the outer tube and downwardly below the termination of the outer tubes and is in alignment with and engages an assembly 20 of the nuclear core. For control type assemblies which includes control element drive extensions, the inner tube 100 houses and serves as a guide for the control element drive extension 102 which also extends downwardly from above the reactor vessel head 14 where it is connected to a drive mechanism, either a safety drive mechanism 28 or a shim type drive mechanism 30, and extends downwardly into a control assembly 24 where the actuator is then coupled to the control element (not shown). Spaced equally about the inner tubular member are a plurality of instrumentation pull tubes 104 which are supported in guide tubes 106 at the upper end of the assemblies. The guide tubes 106 extend downwardly partially into the reactor vessel head 14 where they are in registry with appropriate bores 108 and shielding cylinders 110 which are provided along the thickness of the reactor vessel head. The shielding cylinders 110 are attached to the central tubular member 100 and thus the guide tube and instrument tree and accordingly move therewith during vertical movement of the assembly. As pointed out above, the shielding cylinders 110 have holes or bores 108 therethrough in alignment or registry with a mating guide tube 106 through which the pull tubes 104 extend downward to the termination of the outer tubular member 84 (see Number 112 FIG. 9). Within each of the pull tubes the electrical leads 92 connected to the instrumentation probes 88 extend upwardly and are packed with an appropriate shielding material such as powdered steel shot. At the upper ends of the guide tube, the pull tubes 104 are maintained in fixed and sealing relationship by means of an appropriate yoke 114 (see FIG. 10). The leads 116 from the pull tube extend upwardly therefrom within the outer guide tube 106 and nozzle 74 and exit from the assembly through an electrical connector assembly 94 mounted to the top of the nozzle 74. At the lower end of the outer tubular member 84 the electrical leads 116 are housed within a flexible conduit 92 which in turn is attached to the bottoms of the pull tubes 104 and extends downwardly along the outside of the inner tubular member or support column 78. Referring to FIGS. 9, 11 and 12, the conduits 92 are initially spaced equally about the inner tubular member 78 as they exit from the outer tubular member 84 and eventually near the lower end of the inner tubular member 78 are grouped around one-half or side thereof. Appropriate guides and clamps 118 are provided along the outer surface of the inner tubular member 78 to maintain the conduits 92 in a fixed position. The lower end 120 of the inner tubular member 78, which is of an enlarged size compared to the upper portion for the purpose of housing the control rod latch mechanisms, includes a spreader assembly 122 which is adapted to fit over the top end of the control rod receiving assembly 24. The spreader assembly 122 includes appropriate openings 124 for directing the liquid metal coolant, which flows upwardly around and through the assemblies, outwardly from the interior of the spreader 122. Extending laterally from the upper end of the spreader assembly 122 is the lateral support structure 86 comprised of a plurality of segments 128 located at various distances and at various angles from the enlarged lower section 120 of the inner tubular member. This lateral support structure includes a plurality of sockets 130 therein at the end of each arm 128 through which the flexible conduits 92 containing the instrument probe leads pass and are fixed so as to be supported in a generally vertical direction above the fuel assemblies 20 surrounding the control assemblies 24 which are to be serviced. As best seen in FIG. 9, when the spreader assembly 122 is engaged with a control assembly 24, the lateral support structure 86 is maintained in a fixed position several inches above the upper end of the fuel assemblies 120. This support structure 86 serves to tie the instrument probes 88 together in a fixed array which corresponds to the arrangement of fuel assemblies within the core; that is, the sockets 130 and accordingly the instrument probes are maintained in a fixed pattern such that when properly oriented they will lie directly above the centers of the fuel assemblies 20 surrounding the central assembly 24. As is seen in FIGS. 4 and 12, the fuel assemblies served by the instrument probes from a peripheral servicing assembly 80 comprise five (four if the central assembly is a control assembly) fuel assemblies of a potential control cluster plus five fuel assemblies from three adjacent interfitting potential control clusters. The assemblies serviced by a typical peripheral servicing assembly are identified by a star in FIG. 4 with the central potential control cluster and the three adjacent potential control clusters outlined in lines of heavy thickness. The significance of this pattern will be apparent as the description continues. As can be seen from FIG. 9, the instrument probes 88 are situated within guide rings 132 attached to the upwardly extending fins 134 of the fuel assemblies 20. The only difference between an instrument servicing assembly and a control servicing assembly lies in the fact that instrument servicing assemblies are provided with an instrumentation lead along the central axis in place of a control element drive extension. In such a configuration, the instrument lead is supported within the central tubular member 78 in an appropriate manner so as to extend vertically down therein and into the upper end of the fuel assembly 20 over which the spreader assembly 122 is situated. As pointed out above, in such a situation the peripheral assembly will serve ten fuel assemblies instead of the nine fuel assemblies plus one control assembly served by a control peripheral assembly. As has been noted hereinabove, the instrumentation probes or servicing means of a peripheral assembly 80 can be moved between a compacted state and an expanded or normal state. In the preferred embodiment, this displacement is accomplished by combined vertical and rotational movement of the instrumentation probes 88. Vertical movement of the peripheral assembly is accomplished in a manner similar to that utilized for the control rod and instrument assemblies of co-pending incorporated application Ser. No. 537,283. This involves the use of a control rod drive extension rod and an auxiliary drive unit which are temporarily removably secured to the upwardly extending nozzles 74 on the reactor vessel head 14 and which serve to replace control rod drive mechanisms and electrical connector assemblies. A further description of the process for raising the instrumentation and control servicing assemblies will be set forth hereinbelow. During vertical upward movement of the guide tube and instrument tree assembly (hereinafter GTIT) within the upwardly extending nozzles 74, an effective seal is maintained between these elements to prevent the egress of fission gases and contaminated cover gases from the reactor and ingress of oxygen or air into the reactor through the use of bellows type seals. In the preferred embodiment, these bellows type seals 136 are sealingly secured to the upwardly extending nozzles 74 and to the upper end of the GTIT outer tube 84. Depending on the extent of vertical travel which is desired, the bellows type seal may be attached to the outwardly extending flange from the GTIT and to the nozzle at its other end, so as to permit vertical movement while maintaining the seal. In the preferred embodiment, rotational movement of the instrument probes of peripheral assemblies is accomplished by means of a pin and slot arrangement at the upper elevation of the reactor vessel head. A plurality of pins 138 are provided along the inside wall of the upwardly extending instrumentation nozzle 74. As best seen in FIG. 17, these pins extend laterally inward and are adapted to engage and fit into appropriate slots 140 machined along the outer surface of the outer cylindrical tube 84 of the GTIT. These slots, which in the preferred embodiment comprise two slots located on diametrically opposite sides, extend along the length of the outer tube 84 and have a helical portion near the upper end thereof. The helical portion extends approximately half way around the tube in a gradual slope so that as the guide tube 84 and instrument tree is lowered within the nozzle 74 the pins 138 engaging the slots 140 serve to rotate the guide tube and instrument tree assembly 80 approximately 180.degree.. The slots 140 are arranged so that the full rotational movement of 180.degree. is achieved for the peripheral assemblies 80 near the lower end of vertical travel of the guide tube and instrument tree assembly. However, this rotational movement is completed when the instrument probes 88 are located a short distance above the nuclear core, so that the rotational movement will not cause interference between downwardly depending instrument probes and the upwardly extending fins 134 on the assemblies forming the nuclear core. Straight portions of the slot 140 are provided at both the upper and lower ends of the helical portion so that only longitudinal, vertical motion of the GTIT assembly and accordingly the instrument probes occurs when the pins engage these portions of the slots. Referring now to FIGS. 13-16, the general arrangement for a central servicing assembly 80' is similar to that of a peripheral servicing assembly 80 with appropriate changes so as to accommodate a greater number of instrumentation probes and deletion of the provision for rotational movement. As the servicing means of a central assembly always remains within the coextensive boundaries of the instrumentation plug 55, it is not necessary to provide for rotation or other displacement of the servicing means between compacted and extended positions to permit removal of the plug from which it is suspended and to permit servicing of a portion of the nuclear core. In the preferred embodiment, the central servicing assemblies 80' are designed to service 19 assemblies, comprising a 7 assembly potential control cluster 82 and 12 adjacent assemblies of surrounding and interfitting potential control clusters. This arrangement can best be seen in FIG. 16. As with the peripheral assembly, the central assembly 80' overlies and is in axial alignment with the center assembly of a potential control cluster. This central assembly may be either a control assembly 24 or a conventional fuel assembly requiring instrumentation. Depending upon which it is, a control element drive extension 102 or an instrumentation lead is provided within the central inner tubular member 78'. Again, the central inner tubular member 78' extends downward into the core 18 and engages through a spreader 122', the upper end of a central assembly. Also provided at the lower end of the central assembly and attached to the inner tubular member is a support structure 86' comprising an array of support arms 128' extending laterally outward therefrom and having appropriate sockets 130' into which instrumentation conduits 92 are received and supported. A socket overlies the center of each of the 18 assembly positions which surround and are closest to the central assembly. These 18 surrounding assemblies comprise the first two rows radially outward from the central assembly. The flexible conduits 92 within which the instrumentation leads 116 are housed are attached to the upper ends of the instrumentation probes 88 and extend upwardly and inwardly to be positioned about the outside surface of the inner central tubular member 78'. From there the instrumentation leads 116 extend upwardly into pull tubes 104' which are located in the annular space between the outer tubular member 84' and the inner central tubular member 78'. As seen in FIG. 14, the pull tubes 104 are arranged in two rows at different radial distances from the centerline of the assembly. The pull tubes 104 extend upwardly and terminate a short distance above the reactor vessel head where they are housed within and sealed within appropriately provided guide tubes, also arranged in two rows about the centerline of the assembly. Again, an appropriate bellows seal is provided which is attached to the upwardly extending nozzle 74' and also to the other guide tube 84' of the central instrument tree in order to provide sealing during vertical movement of the assembly. This arrangement is similar to that shown in FIG. 9 for a peripheral assembly and thus is not shown in a separate drawing. With the arrangement described above, the core of a liquid metal cooled fast breeder reactor, or at least a central portion thereof, can be fully instrumented, and a regular pattern of control obtained. As best seen in FIGS. 2, 4 and 6, the nuclear core is comprised of 469 assemblies, each assembly being 4 inches across the flats in the preferred embodiment. Eight core servicing plugs 55 are provided in a specified pattern shown in FIGS. 2 and 4. Each of these plugs is capable of servicing 79 assemblies if the preferred arrangements described hereinabove are utilized. As no open portions are provided in the nuclear core, it is necessary to provide additional instrumentation or control mechanisms at various positions between adjacent plugs. These are indicated in the figures by small individual nozzles 142 and guide tubes 144 respectively, which are supported over an assembly located between adjacent plugs 55. In accordance with the preferred embodiment, the assemblies over which these small nozzles and/or guide tubes are positioned are the central assemblies of potential control clusters and, accordingly, will be provided with either control rod drive mechanisms or instrumentation probes. In either case, the guide tube 144 which is supported within the nozzle 142 on the reactor vessel head extends all the way down into the core and engages the appropriate assembly with which it is aligned. Referring to FIG. 7, a control rod guide grid 146 is provided above the nuclear core having appropriate rings joined together to guide the guide tubes depending from the reactor vessel head for the smaller single servicing means and which provide lateral support therefore. The grids are open beneath the plugs so as not to provide any interference with regard to the assemblies thereof. A particular instrumentation and control pattern is disclosed in FIG. 2. As can be seen from FIG. 2, since each nozzle provided on the reactor vessel head overlies the central assembly of a potential control cluster, there are provided 7 safety control assemblies 148, 24 shim control assemblies 150, and 43 instrumented central assemblies 152. The control rods of a safety control assembly 7 are normally maintained during reactor operation in a raised position relative to the core to provide a safety margin for shutdown in the event of a reactor accident while the shim control rods provide the regulation of power output during normal reactor operation. The specific drive mechanisms and control rod extensions for such arrangements are adequately described in co-pending application Ser. No. 537,283, and as they are virtually identical in the preferred embodiment of the present invention, a description of these is not necessary. The remaining assemblies within the central portion of the core are provided with instrumentation probes such as described hereinabove. The pattern of these instrumentation probes with respect to the core is shown for the preferred embodiment in FIG. 4. As can be seen from FIG. 4, the central axis of the reactor vessel head coincides and is aligned with the center of the nuclear core (see reference number 153), and the central core servicing plug 55 (position shown in outline) is offset from the center. This arrangement of plugs having a concentric reactor vessel head and eccentric plug arrangement has been chosen in order to provide the requisite refueling coverage when refueling plugs and extension skirts replace the core servicing plugs 55 and rotation is permitted as will be described hereinbelow. While not all assemblies comprising the nuclear core are instrumented, the majority of the assemblies are. The three outermost rows of assemblies forming the core comprise the shielding and reflector assemblies and as such do not contain any nuclear fuel. The next three innermost rows comprise blanket region assemblies which contain nuclear fuel but which do not generate power. As can be seen from FIG. 4, all the assemblies in Rows 1-10 (counting from the center outward), the power generating portion of the nuclear core, are serviced by the plugs and single penetration servicing elements. Of the blanket assemblies, only 23 of the assemblies are serviced. While the concentric large plug and eccentric array of small plugs arrangement does not provide all the servicing of all the assemblies forming the active core, it does provide servicing for the major portion and presents no problems as a result of non-servicing (in particular not instrumenting) of some of the blanket region assemblies. An alternative arrangement which will provide complete servicing of all assemblies forming the active core is disclosed in FIG. 18. In this arrangement an eccentric large plug 42 is shown having a concentric array of small plugs 55. As can be seen from this figure, 7 plugs provide the requisite core servicing capability and are arranged concentrically with respect to the core; the reactor vessel head, however, is position eccentrically with respect to the core. In this arrangement the entire active core is provided with servicing elements and some other reflector and shielding assemblies also have instrumentation. While such an arrangement does provide for a better instrumentation coverage and thus servicing of the nuclear core, it is not preferred due to the increased cost in providing an eccentric reactor vessel head which will result in a larger vessel head and reactor vessel. In order to minimize and reduce the possibility of flow induced vibrations being set up in the guide tubes 78, 78' which support the instrument trees, a locking arrangement is employed to pin the 7 guide tubes in each plug together in a rigid structure. As best seen in FIGS. 6 and 7 and 16, the locking mechanism comprises a spider 154 which is welded to the central instrument tree guide tube 78' some distance above the lower end thereof. This spider arrangement is supplied with 12 spokes 156 which extend laterally outward therefrom and which are each furnished with an alignment pin 158 which extends downwardly at the extremity of the spokes. Appropriate collars 160 are fixed to each of the guide tubes 78 of the peripheral assemblies at an elevation above the lower end thereof. These collars 160 have mating holes or sockets 162 vertically arranged and oriented generally on the diametrically opposite side of the guide tube from the instrumentation probes 88 and support arms 86. The alignment pins 158 on the spider spokes 156 are adapted to engage and fit into the sockets 162 on the collars of the peripheral assemblies when the central assembly instrument tree is lowered into place in the core. Such an arrangement of locking insures that the peripheral assemblies 80 will be in correct alignment with respect to each other and with respect to the core assemblies and elements. The installation procedure for the plug mounted core instrumentation or servicing will now be described. Initially, 7 instrument tree assemblies 80, 80' mounted on each of the plugs 55 are maintained in a raised and compacted state and the plug 55 is lowered into position to rest on the appropriate flanges 70 within the opening 54 in the large rotatable cover 42. The arrangement and location of the instrument trees with the control rod drive extension 102 and instrument probes 88 is as shown in FIG. 8. The mechanism for maintaining the instrument trees in the raised position will be described hereafter. As can be seem from FIG. 8, the central instrument tree 80' is positioned the greatest distance above the nuclear core 18 and in the preferred embodiment this corresponds to a distance of approximately 53 inches. Directly beneath the central instrument tree 80' there are located a first set of three of the peripheral trees 80 in which the laterally extending support structure 86 and instrument probes have been rotated inwardly to lie completely beneath the plug and within the coextensive boundaries thereof as is evident upon viewing the lower end 68 of the plug in this figure. These three peripheral trees correspond to 3 alternately spaced trees and are located approximately 38 inches above the nuclear core. The lowermost set of instrument trees 80 correspond to the remaining three trees and are located approximately 25 inches above the nuclear core and are also in a compacted condensed state in which the lateral support structure 86 and probes are located totally within the coextensive boundaries of the plug. It is necessary to maintain these three elevations of instrument trees in order to fit all of the probes and support arms within the coextensive boundaries of the plug so as to permit insertion of the plugs through the penetration opening 54 in the reactor vessel head 14. Next the lowermost set of alternately spaced instrument trees are lowered with respect to the vessel head by appropriate means and, as this occurs, the guide pins 138 located within the nozzles 74 and engaging the camming slots 140 in the guide tubes 78 serve to rotate the laterally extending support structure 86 and instrument probes 88 approximately 180.degree. as the GTIT moves downward into the nuclear core wherein the instrument probes 88 are positioned within the guide rings 132 joining the upwardly extending fins 134 of several of the fuel assemblies forming the nuclear core. If these peripheral trees comprise control assemblies the control rod drive extension 102 is lowered within the control assembly is alignment with the center guide tube of the peripheral tree and engages a control rod such as shown in FIG. 7. The complete rotation of 180.degree. of course is achieved while the GTIT is totally above the nuclear core so as to prevent any interference between the instrument probes and the upper ends of the fuel assemblies. Next, the remaining three alternately spaced peripheral trees 80 are lowered, the guide pins, again, working in the cam slots to rotate the support structure 180.degree. to bring the probes 88 into alignment so that they may be lowered into engagement with the nuclear core. Finally, the central instrument tree 80' is lowered and the alignment pins 158 on the locking spider 154 slide into engagement with the appropriate holes 162 on the collars 160 of the peripheral trees 80 to lock the seven guide tubes together in a rigid structure. This is the position shown in FIG. 7. For refueling purposes, as will be described hereinbelow, it is necessary to completely remove the plug mounted instrumentation and core servicing assemblies from the reactor vessel head. In order to accomplish this removal, without interference, the trees must be stacked at three different levels such as shown in FIG. 8, this being the same arrangement shown for insertion of the plugs. Initially, the central tree 80' is raised approximately 53 inches to provide room underneath the plug for theperipheral trees 80, then three alternately spaced peripheral trees are raised approximately 38 inches and rotated inwardly by means of the pins engaging the camming slots and finally the three remaining peripheral trees are raised approximately 25 inches and also rotated inwardly to a compact state. Upon completion of these steps, all six of the peripheral instrument trees are within the coextensive plug boundaries and the plug may be removed from the reactor vessel head through the plug opening 54. Accomplishment of the raising and lowering of the instrument trees to permit insertion and removal of the plugs is accomplished in a manner similar to that described for the control rod and instrument tree assemblies of copending application Ser. No. 537,283. With the control rod drive mechanism 28 and electrical connector assemblies 94 removed from the nozzles 74, 74', 142 on the reactor vessel head 14, and on the plugs 55, an instrument tree drive extension lock 164 is mounted to the nozzle 74. As seen in schematic FIG. 21a and 21b, the instrument tree drive extension lock 164 includes an extension at its lower end and the lock assembly at its upper end. An instrument tree drive extension lock is needed for each of the instrument tree assemblies and accordingly for each plug nozzle. Two lock assemblies 166, 168 are associated with each of the drive extension locks. One lock 166 is adapted to be moved into locking engagement with a lock seat 169 on the guide tube end cap when the guide tube end cap, which holds the instrument pull tubes 104 and maintains them in their lowered position, and accordingly the guide tube and instrument tree, have been lifted vertically a sufficient distance for the lower end of the guide tube instrument tube to clear the core and be maintained at its appropriate elevation. The other lock 168 is positioned for locking engagement with another lock seat (not shown) in the control rod drive extension when the guide tube and instrument tree tube is raised as noted hereinabove and the drive rod extension is withdrawn upwardly to its fullest extend within the guide tube. This final configuration is depicted schematically in FIG. 21b. In order to raise the guide tube instrument tree to any control rod drive extension, an auxiliary instrument tree drive unit 170 is removably secured, such as by bolting, to the upper end of the drive extension rod. The auxiliary drive unit 170 contains one drive which substitutes for the conventional drive means to operate the drive rod extension and a second drive which vertically moves the guide tube and instrument tree tube. Because the auxiliary drive unit 170 is installed following a scram or a shutdown of the reactor and the drive rod extension is in its fully inserted position the drive for the rod extension must run down the fullest extent for engagement with the upper end of the rod extension and the connection is made by rotating the axis through an angle sufficient to couple the drive means with a breech block lock on the drive extension. The second drive of the auxiliary drive unit 170 is run down and rotated into engagement with the seat and the guide tube end lock cap and, upon actuation of the drive, serves to raise the guide tube instrument tree tube. The extension portion of the CDEL is necessary in order to raise the guide tube and instrument tree assembly the requisite distance in order to provide space beneath the plug for stacking of all the instrument trees. As the upwardly extending nozzles on the reactor vessel head are approximately 28 inches in height, different length drive extensions are provided, the length depending upon the desired final height of the guide tube and instrument tree assemblies to be raised. With the instrument tree assemblies maintained in their upper position by means of the drive extension locks, the auxiliary drives may be removed and the plug removed from the penetration in the reactor vessel head in a manner described hereinbelow in discussing the refueling scheme. It should be apparent there are other types of drive means and locking means which may be employed in order to raise and maintain the instrument trees in their raised and condensed position. REFUELING PLUG SYSTEM Rotating plug systems for providing core access in liquid metal cooled fast breeder reactors provide a convenient arrangement for exposing only a small area of the core at one time and for permitting line of sight through the head refueling, as is well known in the art. When nozzles are provided on the reactor vessel head for guiding and directing control elements and instrumentation probes into the nuclear core, penetrations for the rotating plug system are generally required to be located between the upwardly extending nozzles and between the penetrations through the head for such core servicing apparatus. When the nozzles for the core servicing apparatus on the reactor vessel head are arranged in a regular pattern, such as disclosed hereinabove with reference to the instrumentation system, a problem is created in having sufficient distance between adjacent nozzles within and without the rotating plugs for placement of rotational supporting bearings therebetween for supporting the rotating plugs for rotational movement in the penetrations in the reactor vessel head. This problem is further compounded where smaller assemblies make up the nuclear core since such smaller assemblies necessitate the nozzles being located closer together for a given pattern of control and instrumentation. Unless nozzle size can be made very small, it is not possible, or it is extremely difficult to place rotational supporting bearings between adjacent nozzles to provide the rotational support for the rotating plugs. The present invention overcomes such problems by providing a skirt extension 172 and a refueling plug 174 which are substituted for instrumentation supporting plugs in the reactor vessel head. The skirt extension and refueling plug are interchanged with the instrumentation and control supporting plugs in the reactor vessel head. The skirt extension and refueling plug are interchanged with the instrumentation and control supporting plugs when core access is desired such as when the reactor is shut down for refueling. The refueling plug 174 is provided with an opening 176 therethrough which is sized to permit passage of fuel assemblies therethrough or for any other purposes in which core access is necessary. To prevent the escape of fission gases and contaminated cover gas from the reactor and to prevent the ingress of air into the reactor, sealing means are provided as well as removable closure means for sealing the penetration openings and other leakage paths which may exist by virtue of the substitution of refueling plugs for instrumentation and core servicing plugs. Referring now specifically to FIGS. 19 and 20, the skirt extension or bearing supporting skirt 172 comprises a generally cylindrical member 178. The lower end of the bearing supporting skirt is provided with flanged portions 180 extending laterally outward therefrom which are adapted to mate with similar flange portions 182 on the upper end of the upwardly extending skirt 56 surrounding the penetration opening 54 in the reactor vessel head 14. The flange portions 180, 182 are arranged such that they interfit between adjacent upwardly extending individual nozzles 142 arranged about the periphery of the penetration opening as best seen in FIG. 19. Sealing means, such as a double O-ring type seal 184, are provided where the bearing supporting skirt 172 and the upwardly extending skirt 56 meet to provide a gas tight seal. The upper end of the bearing supporting skirt 172 is provided with an outwardly extending flange 186 about its circumference on which is supported the rotational bearings 188 of the refueling plug 174. The bearings are of the crossed-roller type in which the axis of rotation of the rollers 190 alternates about the circumference of the bearing 188. These rollers are captured between inner and outer races and this arrangement is in turn supported in position on the flange 186 of the upper end of the bearing supporting skirt 178 by means such as bolts 192 spaced about the circumference of the annular bearing and flange. Appropriate O-ring type seals 194 are provided along the interior surface of the bearing supporting skirt near its upper end for sealing the leakage path between the skirt 178 and the refueling plug 174. As can be seen from FIG. 20, the outwardly extending flange 186 at the upper end of the bearing supporting skirt 178 and thus the bearing 188 are positioned above the upper elevation of the upwardly extending individual nozzle 142 adjacent to the skirt 56 surrounding the penetration in the reactor vessel head. Also in the embodiment shown, this flange is above a control element drive extension box 196 mounted on the nozzle 142 which maintains the instrument or control rod drive extension in an elevated position to permit rotation of the large rotatable cover 42 without interference by the core servicing elements therein with the nuclear core. In the preferred embodiment the refueling plug 174 is comprised of a handling plug 198 and a floor valve 200 each of which have axial penetrations or bores 202, 204 respectively therethrough sized to permit the insertion and removal of fuel assemblies and control assemblies therethrough. More particularly, these bores are sized to permit insertion of a fuel handling machine which is capable of extending down into the nuclear core and into which fuel assemblies will be raised and maintained in a bath of sodium or other liquid metal coolants as it is removed from the reactor vessel. Such a fuel handling machine is similar to that disclosed in copending application Ser. No. 430,292 entitled, "Nuclear Fuel Handling Apparatus." The handling plug 198 comprises a large substantially solid circular plug made of a suitable material, such as steel, which is inserted into the penetration opening provided in the large rotatable cover and which replaces the instrumentation servicing plug. The handling plug 198 is provided with a flanged surface 206 near its upper end which is sized to permit the lower end of the plug to be inserted in the opening defined by the skirt 56 and which engages a mating flanged surface 208 in the opening in the vessel head to limit the penetration of the plug into the opening. Appropriate sealing means such as O-ring type seals 210 are provided near the upper end to provide a gas tight seal. When first installed in the reactor, a shield plug 212 is inserted within the circular opening 202 in the handling plug 198. The shield plug 212 effectively seals the penetration to prevent leakage of gases into or out of the reactor vessel 12. The floor valve 200 which comprises the other half of the refueling plug 174 includes a generally cylindrical lower portion 214 which is adapted to fit within the opening defined by bearing supporting skirt 56. Alignment pins 216 are provided on either the floor valve 200 or the handling plug 198 to ensure proper alignment of the two bores 202, 204 through the floor valve and the handling plug. A large ring gear 218 provided around the outer periphery of the floor valve 200 at about mid-elevation includes outwardly extending gear teeth adapted to be engaged by an appropriate drive mechanism for rotating the refueling plug 174 relative to the bearing supporting skirt 172. The drive mechanism, not shown, is similar to that described with reference to the small rotating plugs of U.S. application Ser. No. 537,284. Beneath the ring gear 218, there is provided along the outer surface of the floor valve an outwardly extending flange 220 which is adapted to engage and mate with the inner race of the bearing 188. In this way the floor valve 200 is supported on the bearing for rotational movement about its axis and about the axis of the penetration opening. Sealing means such as O-ring type seals 222 provided along the inner surface of the skirt extension 172 provide a gas tight seal between the extension and the floor valve. The valve portion 224 of the floor valve is positioned above the bearings and ring gear in the upper portion of the floor valve. During refueling, the upper surface 226 of the floor valve 200 interfaces with the refueling machine to form a hermetically sealed passage to transfer fuel assemblies from the reactor vessel. When the valve 224 is closed it provides a barrier of lead shielding for personnel protection. Basically, the floor valve is a heavily shielded gate valve. The valve disc 228 is tapered on its lower face to mate with a similarly tapered valve seat 230 provided in the body 231 of the upper portion of the floor valve. This configuration protects the O-ring lower sealing element 232 from damage when the disc is moved to close or open the passage. The valve body 231 is otherwise a hermetically sealed unit with connections provided for purging the body of the valve with clean argon or other similar gas. Movement of the valve disc 228 is achieved by a ball screw drive arrangement 234 mounted to the side of the floor valve and above the ring gear 218. The disc 228 is mounted on rails and rides on a series of ball bushings 236 and the ball screw drive arrangement 234 provides a motive force. The drive motor 238 is mounted outside of the valve body 231 and drives the ball screw shaft through a coupling 240. The shaft and motor are axially stationary and engage a ball nut 242 attached to the valve disc 228. Upon actuation of the motor the disc is caused to be inserted or retracted with the ball screw shaft 238 extending through a longitudinal cavity within the disc 228 when the valve is fully open. This arrangement is similar to that disclosed for the floor valve of co-pending application Ser. No. 430,292 with the exception that the penetration opening 204 in the floor valve is circular whereas in the co-pending application it was oval or obround. In order to provide the requisite refueling coverage (to be described in more detail hereinbelow) it is necessary that the floor valve 200 which is rotatably supported on the bearings 188, be attached to the handling plug 198 so that the two may rotate together. This is accomplished by a series of screw jacks 244 provided in the upper surface of the floor valve which extend downward therethrough and into appropriate sockets 246 in the handling plugs. Upon actuation or tightening of the screw jacks, the handling plug is raised off the flanged surface 182 provided on the upwardly extending skirt so as to be coupled and mate with the floor valve. In this way the two components of the refueling plug rotate as a unit. As can be appreciated, the bearing supporting skirt extension 172 is necessary with the core arrangement and nozzle arrangement on the reactor vessel head in order to place the bearings 188 in a location to permit rotation of the refueling plugs or whatever plug is provided inside of the skirt. In prior arrangements, enough space was available between adjacent nozzles on the rotating plug and on the reactor vessel head, however, with the extremely small fuel assemblies in the present configuration, this is not possible. Instead it is necessary to remove the drive mechanism and electrical connectors from the upwardly extending nozzles and to utilize the skirt extension so that the bearings will be supported above the nozzles. As can be seen from the drawings, the laterally extending lip 186 which supports the bearings 188 on the shirt extension 172 overlie at least a portion of some of the nozzles 142 which are adjacent to the upwardly extending skirt 56 surrounding the boundary of the penetration. In order to interchange the refueling plug and the plug mounted instrumentation assembly it is necessary to provide a special two-position handling cask 248 similar to that design employed to replace the instrument tree plug and the handling plug of co-pending application Ser. No. 537,283. This is schematically shown in FIGS. 22a through 22c. Initially, the core servicing means 88 are raised out of engagement with the core 18 so as to be free from the core in a manner as described hereinabove; i.e., the plug mounted core servicing apparatus are displaced from their expanded and lowered positions to their condensed and raised positions in which the instrumentation or other servicing means of the various trees are maintained in a stacked relationship completely within and beneath the plug boundaries. For the single core servicing means the control rod drive extension or instrumentation lead is raised a short distance out of engagement with the core and maintained in this raised position through use of appropriate drive extension locks. The auxiliary drives are then removed and the servicing means of both single and plug mounted instrumentation nozzles are maintained in a raised position by means of appropriate drive extensions. Next the two-position cask 248 is used to maintain the reactor cover gas and prevent release of fission products and secondly to shield the contaminated plugs. The handling cask 248 is mounted on the upwardly extending skirt 56 and the lower portion 249 extends upwardly to a distance above the drive extension locks on adjacent nozzles where it then expands to a larger size which is necessary in order to provide two chambers which are large enough to hold the core servicing plug 55 and the handling plug 198. The cask includes a lifting means for liftingly engaging the core servicing plug 55 and for moving it vertically up into one of the chambers of the cask. After the cask is positioned in sealing relationship on the upwardly extending skirt 56 the core servicing plug 55 is lifted into one of the chambers of the cask leaving the penetration 54 in the reactor vessel head 14 open. When the plug is entirely within the cask chamber it is moved laterally out of vertical alignment with the penetration opening and a second chamber of the cask moved into alignment therewith. This second chamber also includes an appropriate lifting and drive means which is engaged to the handling plug portion 198 of the refueling plug 174. The handling plug 198 is then lowered into the penetration opening 54 and allowed to rest on the inwardly protruding flange surfaces 206 of the upwardly extending skirt 56. When the handling plug is placed within the penetration opening, the shield plug 212 with appropriate seals is in place in the access opening 176 or bore therethrough. The handling cask 248 is then removed from the upwardly extending skirt 56; the bearing supporting skirt extension 172 is positioned in place and the floor valve 200 lowered to rest upon the bearings 188. Next, the screw jacks 244 on the upper surface of the floor valve 200 are actuated to engage the handling plug and raise it into engagement with the floor valve 200. While this is being done, the valve disc 228 of the floor valve 200 may be in either the closed or open position since the shield plug 212 is in place in the handling plug. After the floor valve 200 is properly installed, the valve disc 228 is opened and a second handling cask 250 (see FIG. 22c) is placed over the valve opening 204 and actuated to remove the shield plug 212 from the handling plug 198. Following this step the floor valve 200 is closed and the handling cask 250 containing the shield plug 212 is removed to a remote location. The refueling plug system is then in condition for operation. Upon proper rotation of the refueling plugs 174 and the large rotatable cover 42, the access port in the floor valve and handling plug may be placed over any desired core location. The next step in the refueling operation is to position the fuel handling machine, not shown, above the reactor access port by an appropriate means. Once aligned the entire machine is then coupled to the floor valve 200 and the passage between the floor valve and the handling machine purged with argon and checked for leak tightness to ensure that no air is permitted to enter the reactor. Such operations are similar to those described with respect to the fuel handling machine described in co-pending application Ser. No. 430,292. For operation with the floor valve 200 and handling plug 198 having a circular access opening 202, 204, the fuel handling machine of co-pending application Ser. No. 430,292 will have to be modified for proper operation. Such modifications are within the purview of persons skilled in the art and familiar with the description of fuel handling machine of the co-pending application Ser. No. 430,292. Replacement and installation of fuel assemblies may then be accomplished. With each of the plug mounted instrumentation schemes disclosed hereinabove with reference to the core servicing plugs 55 only four refueling plugs 174 are needed in order to adequately provide access directly over each assembly comprising the nuclear core. For the preferred plug mounted instrumentation scheme, shown in FIG. 4, in which the reactor vessel head 14 is concentrically positioned with respect to the nuclear core 18 and in which the array of instrumentation plugs 55 is eccentric with respect to the core in the reactor vessel head, the penetrations into which refueling plugs should be placed in order to provide access to the core over each assembly are depicted in FIG. 23 and are labled plugs A, B, C and D. FIG. 23 is a schematic representation of the reactor vessel head with the core 18 being shown in outline. The circles drawn about the center of the reactor vessel head represent the limit of reach of each of the refueling plugs A, B, C and D and accordingly depict the zones of the core which may be serviced by each of these plugs. That is, they depict the inner and outer boundaries of refueling coverage obtainable with each of the plugs A, B, C and D. As noted above, insertion and withdrawal of fuel assemblies is accomplished with the use of a fuel handling machine which enters through the access ports in the floor valve and the handling plugs to reach into the core and engage or release a fuel assembly. These access ports are indicated on the refueling plugs as circular portions a, b, c, d within the circles A, B, C, D respectively indicating the refueling plugs. The zones of the core served by each of the refueling plugs are indicated as circular or annular spaces and labled zone A, B, C or D respectively. As can be seen in FIG. 23, there is at least a small overlap of the core area which is served by each of the plugs. A similar schematic representation based on the plug arrangement shown in FIG. 18 and again indicating the refueling plugs as A, B, C and D is shown in FIG. 24. As with FIG. 23, each of the zones served by each of the refueling plugs A, B, C and D are labled and indicated as annular or circular rings. This refueling coverage corresponds to an eccentric reactor vessel head and a concentric array of plugs. With either of the refueling schemes depicted in FIGS. 23 and 24, the plug or plug penetrations not including refueling plugs may retain the core servicing plugs in place. The instrument trees attached and supported by these servicing plugs, of course, will necessarily have to be maintained in a raised and compacted position so as not to interfere with the core upon rotation of the large rotatable cover and the refueling plugs, and so as not to interfere with the fuel handling machine upon its insertion into the access port in the refueling plugs. SUMMARY Accordingly, there has been disclosed hereinabove a novel core servicing apparatus which is mounted to plugs which in turn are supported within penetrations of the reactor vessel head in order to provide servicing functions to the assemblies comprising the nuclear core of a liquid metal cooled fast breeder reactor. The core servicing apparatus includes a plurality of support columns suspended from a removable plug mounted in the reactor vessel head. Laterally extending rigid support arms are fixed to the support columns and a plurality of core servicing means are supported by and extend downwardly from the lateral support arms. Core servicing means are supported in a fixed array with respect to the support columns. Rotational motion means are provided for rotating and moving vertically the support columns to move the servicing means between condensed and expanded states. When in the condensed state, in the preferred embodiment, the servicing means of the plurality of support columns are maintained in stacked relationship in which the servicing means of one of the columns are supported vertically above and within the co-extensive boundaries of the plug above the servicing means of another of the support columns, the servicing means of all the support columns being maintained within the co-extensive boundaries of the plug. When in the expanded position, the servicing means of the support columns are maintained at the same vertical elevation. Also disclosed herein is a refueling arrangement for a liquid metal cooled fast breeder reactor of a type having a reactor vessel head on which are mounted upwardly extending nozzles in which are supported core servicing apparatus of the nuclear core. Some of the nozzles are mounted on removable stationary plugs. The refueling arrangement comprises a bearing supporting extension skirt and a refueling plug. The extension skirt is mounted upon an upwardly extending skirt surrounding the boundary of the penetration in the reactor vessel head provided for the core servicing plug and serves to support rotational bearings above the elevation of adjacent nozzles on the reactor vessel head. The refueling plug is rotatably supported on the rotational bearings of the bearing support extension skirt and is provided with an access port therethrough for providing refueling access to the core of the nuclear reactor. In the preferred embodiment the refueling plug comprises a handling plug supported within the upwardly extending skirt on the reactor vessel head and a floor valve having its bore in line with the bore of the handling plug and being supported on the rotational supporting bearings. The floor valve is coupled to the handling plug so that the two rotate together and the floor valve is provided with a closure means for sealingly closing the access port therethrough. The embodiments shown and described are merely illustrative of the present invention and changes may be made as well as modifications without departing from the scope of the present invention. What is thought to be protected here and is only that which is set forth in the appended claims.
044951477	summary	The invention relates to a heat-retarding closure system for pressure relief openings of partitions, especially of those in nuclear reactor buildings, in the area where the main coolant nozzles of the reactor pressure vessel penetrate the biological shield, with lightweight construction closure elements which can be pushed outwardly out of their anchors by an overpressure on the reactor side. It has become known through German Published, Prosecuted Application DE-AS No. 21 60 991 to use a closure system for pressure relief openings in the biological shield of a nuclear reactor pressure vessel, in which several shielding chambers filled with shielding material are provided in the biological shield which are spaced around the periphery of the reactor pressure vessel and are sealed gastightly to the outside by glass panes of a predetermined blowout pressure. A similar closure system is shown in German Published, Prosecuted Application DE-AS 27 19 923, in which the shielding elements closing the relief openings are formed of a lattice structure, the grid meshes of which are filled with granular shielding material. The grid structure is anchored in the opening of a partition by means of a frame, and the grid meshes are closed by sheet metal panels which are pushed out together with the granulate filling upon the occurrence of a given overpressure. The present invention also starts from lightweight-construction closure elements which can be pushed outwardly out of their anchors by overpressure from the reactor side. However, the closure elements are particularly heat-retarding. They are disposed especially in the area where the main coolant nozzles of the reactor pressure vessel penetrate the biological shield. In case of a postulated fracture (improbable per se) of a main coolant line, coolant would flow through a leak fixed in its size at a certain area, e.g. 200 cm.sup.2, between a double pipe and the main coolant nozzle into an annular space formed by the reactor pressure vessel and the biological shield. The overpressure built up thereby must be relieved in inherently safe fashion. Together with the outer supporting shield to which the supporting structure of the reactor pressure vessel is mounted and anchored, the biological inner shield forms the entire biological shield. However, the objective is not merely the relief of possibly occurring overpressure; in addition the nozzle space must be insulated against heat removed to the outside. The nozzle space insulation thus forms the separation of the area under compression from the annular gap which receives its geometry or shape from the supporting shield and the inner shield. It is accordingly an object of the invention to provide a heat-retarding closure system for pressure relief openings of partitions, especially in nuclear reactor buildings, which overcomes the hereinafore-mentioned disadvantages of the heretoforeknown devices of this general type, and through which a convection-tight closure of the pressure relief openings is made possible and which has the same effectiveness with regard to its heat retardation as the adjoining heat retarding system. Other requirements which the invention is intended to meet are the following: Blowout pressures for the closure system that are precisely determinable mathematically and experimentally; construction of the closure elements and closure system in a manner which makes cocking or canting within the pressure relief opening during the pushout process impossible; and finally, as lightweight a construction of the closure elements as possible which, when tripped, are pushed out of the pressure relief opening, in order to prevent damage to components of the environment. With the foregoing and other objects in view there is provided, in accordance with the invention, a heat retarding closure system for partitions having pressure relief openings formed therein especially in nuclear buildings where main coolant nozzles of a reactor pressure vessel penetrate a biological shield, comprising lightweight construction closure elements having a side facing the reactor and anchors for holding the closure elements, the closure elements being pushable out of the anchors by an overpressure in a given pressure difference direction on the reactor side, and an outer sealing blowout skin, the closure elements being in the form of heat-retarding cassette inserts having a front surface with a peripheral shearing edge formed thereon resting against the blowout skin, and the blowout skin having a given thickness in the given pressure difference direction enabling the cassette insert to shear off the blowout skin and be pushed out of the anchors or seat when a given permissible pressure difference is at least reached or exceeded. In accordance with another feature of the invention, the cassette insert contains retarding material in the form of mineral fibers. In accordance with a further feature of the invention, the cassette insert is formed of metal and includes layered and mutually spaced apart retarding foils in the interior thereof in the retarding direction for retarding pressure in the pressure difference direction, the foils forming retarding cells. In accordance with an added feature of the invention, the anchors are in the form of an expendable partition seat having an outside and an inside and being conically shaped from the inside to the outside or truncated pyramoidally shaped. In accordance with again another feature of the invention, the cassette insert has a partition area and the blowout skin is in the form of a glass blowout pane being clamped and sealed to the partition area. In accordance with again a further feature of the invention, the blowout skin is a metallic blowout foil. In accordance with again an added feature of the invention, the cassette insert includes a peripheral sheet metal envelope having a front surface and the shearing edge projects from the front surface of the envelope. In accordance with a concomitant feature of the invention, one of the foils is a front foil forming the shearing edge, the front foil having a doubly chamfered rim being substantially V-shaped and having a relatively greater thickness of its wall as a pressure foil than the others of the foils. The advantages achievable by the invention are to be seen primarily in that the cassette inserts are lightweight elements of high heat retarding ability, through which pressure relief openings are now made possible even in the nozzle space area, particularly in pressurized-water reactors. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a heat-retarding closure system for pressure relief openings of partitions, especially in nucler reactor buildings, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
	description	This application is a continuation-in-part of U.S. application Ser. No. 11/409,067, entitled “Method for Preventing Neurodegeneration,” filed Apr. 24, 2006, which makes reference to and claims the priority date of U.S. Provisional Patent Application Ser. No. 60/674,311, filed Apr. 25, 2005. The entire disclosure and contents of these two applications is incorporated herein by reference in their entirety. United States government may own rights to the present invention as work done in development of the invention described herein was funded in whole or in part by Federal Grant No. F32-Ey14515 from the National Institutes of Health. The present invention relates generally to a method for preventing neurodegeneration, and specifically to a method of preventing, e.g., protectively inhibiting neurodegeneration that occurs in the eye, particularly a condition known as glaucoma. The method of the invention also generally relates to the use of high-dose ionizing radiation, such as ionizing radiation including gamma radiation and x-ray radiation, beta and proton radiation, and bone marrow transfer, or both in the treatment of neurodegeneration, and particularly a form of neurodegeneration of the eye known as glaucoma, such as a hereditary form of glaucoma. The glaucomas are a group of complex neurodegenerative diseases. As a consequence of this neurodegeneration, glaucoma patients exhibit a loss of retinal ganglion cells (RGCs), characteristic changes in the visual field, and degeneration of the optic nerve (Ritch, R., et al. (1996)1, and Weinreb & Khaw, (2004)2. Glaucoma is traditionally viewed as a pressure-induced neurodegeneration, in which deleteriously high intraocular pressure (IOP) results in optic nerve damage over time. As a consequence, all major existing glaucoma therapeutics aim to lower IOP. However, many individuals who have high IOP for extended periods do not develop optic nerve and retinal damage, whereas others develop optic nerve damage despite normal IOP values (Heijl, A., et al. (2002)3, Collaborative Normal-Tension Glaucoma Study Group (1998)4. Thus, glaucoma is defined as a neurodegeneration and magnitude of IOP may not indicate current or future glaucoma status. Therefore, treatments that directly target the retina and optic nerve need to be developed. Mouse studies are very useful for studying mechanisms contributing to multifactorial diseases and for testing potential treatments; see John, S. W., et al. (1999)5. DBA/2J mice are a naturally occurring mouse model of glaucoma. DBA/2J mice develop an age-related form of hereditary glaucoma initiated by mutations in two genes, Tyrp1 and Gpnmb; see John, S. W. M., Smith, et al. (1998)6, Chang, B., et al. (1999)7, and Anderson, M. G., et al. (2002)8. Clinically, indications of DBA/2J glaucoma are first evident by a pigment-dispersing iris disease that involves melanosomal and inflammatory components. As dispersed pigment from the iris disease accumulates within the aqueous humor drainage sites, DBA/2J mice develop an elevated IOP, which progressively insults RGCs and the optic nerve. By 10 to 12 months, the majority of DBA/2J mice have severe glaucoma evident by massive RGC loss and optic nerve damage. Little is known about the mechanisms or molecular pathways that contribute to RGC degeneration in the glaucomas. As in other neurodegenerative diseases, the majority of effort has focused on apoptotic degeneration pathways; see Quigley, H. A. (1999)9, and Nickells, R. W. (2004)10. Recently, there has been recognition that distinct degenerative processes exist within different parts of a neuron, see Raff, M. C., et al. (2002)11. Bone marrow transplantation combined with radiation or chemotherapy is used in the field of clinical oncology where it is used for Non-Hodgkins Lymphoma, Hodgkins Disease, breast cancer, and some types of leukemia and testicular cancer. Intense immunosuppressive conditioning combined with autologous hematopoietic stem cell transplantation is reported to treat autoimmune diseases such as multiple sclerosis (MS) and lupus, see Robert A. Good (July 2000)12. The above review demonstrates a need continues to exist in the medical arts for more effective methods of treating and inhibiting the progression of neurodegeneration that accompanies the forms of glaucoma. The above and other long felt needs in the art are met in the present invention. According to a first broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to a head or eye area of a subject having a potential for developing glaucoma, to thereby protectively inhibit the eye of the subject against neurodegeneration caused by glaucoma, prior to the onset of any indication of glaucoma. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising radiation to an area of interest in an animal, wherein said radiation is administered in a neurodegeneration-inhibiting amount, and administering an effective amount of bone marrow cells. In some embodiments, the bone marrow is an autologous bone marrow sample. In other embodiments, the radiation is administered at the same time or before the bone marrow is administered. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to a head or eye area of a subject being a suspect of developing glaucoma manifestations, to thereby protectively inhibit the eye of the subject against neurodegeneration caused by glaucoma, prior to the onset of glaucoma. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to a head or eye area of a subject being a suspect of developing glaucoma manifestations, to thereby protectively inhibit the eye of the subject against neurodegeneration caused by glaucoma, prior to the onset of glaucoma and not requiring the need to reduce the IOP of the subject. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to a head or eye area of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation is delivered to the subject prior to an incision to the eye. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to an optic nerve head of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the optic nerve head. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to an optic nerve as it exits the eye of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the optic nerve as it exits the eye. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to a retina of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the retina. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to myelin junction region of the optic nerve of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the myelin junction region of the optic nerve. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to retina and optic nerve head of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the retina and optic nerve head. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to the optic nerve head and myelin junction region of the optic nerve of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the optic nerve head myelin junction region of the optic nerve. According to another broad aspect of the present invention, there is provided a method for treating, inhibiting and/or preventing neurodegeneration, comprising: administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to the retina, optic nerve head and myelin junction region of the optic nerve of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the retina, optic nerve head myelin junction region of the optic nerve. In some embodiments, the invention provides for a method that provides for the treatment of an area of an animal with radiation at other than over an entire body (whole body). For example, the area of the body to be treated may in some embodiments be the head area. In even more specific embodiments the head area is further defined as the eye area of the head. Even more specifically, the eye area may be further defined as the eye itself, the area may be further defined to the posterior section of the eye. In this manner, a treatment of radiation may be focused at the area of the body directly of interest for treatment, such as that area of the body that is afflicted with a degenerative disease or suspected to be afflicted with a condition of interest to be treated. This method also permits the ability to avoid radiation exposure to areas of the body that are not expected to be afflicted with a condition of interest to be treated. Among other advantages, this permits a reduction in dose inhomogeneity in the radiation treatment being administered to an animal. In addition, this procedure of administering the treatment of radiation to a specific area rather than the entire body of an animal will reduce and/or eliminate damage to healthy tissue that is not the target of the therapy. In some embodiments, the method provides for a treatment regimen comprising radiation that is gamma radiation. In some embodiments, the treatment regimen comprises a single dose of radiation. In some of these embodiments, the radiation is administered to an area of the body at an amount of radiation comprising from about 1 Gy to about 15 Gy, preferably in a range comprising from about 5 Gy to about 10 Gy. In other embodiments, the treatment regimen comprises more than a single dose of radiation, such as two approximately equal doses of radiation, or as multiple doses of radiation. In particular embodiments, the treatment regimen comprises two doses of radiation, particularly two approximately equal doses of radiation. In some of these embodiments, the dose regimen will comprise an initial and/or first dose of radiation comprising from about 5 Gy to about 7 Gy, and a subsequent and/or second dose of radiation comprising from about 5 Gy to about 7 Gy. In some embodiments, the dose regimen will comprise an initial and/or first dose of radiation comprising about 5 Gy and a subsequent and/or second dose of radiation comprising about 5 Gy. In other embodiments, the treatment regimen comprises multiple doses of radiation, given over an appropriate and/or prescribed period of time. In these embodiments, the treatment regimen may comprise a regimen in which radiation is administered in fractions and/or multiple treatments of radiation at doses in a range comprising about 1.0 Gy to about 5.0 Gy. In some embodiments, each of the multiple doses of radiation comprises a radiation dose comprising about 2.5 Gy. In some embodiments, the administration of the radiation is by brachytherapy, a procedure in which the radioactive material is sealed in needles, seeds, wires, or catheters. According to some embodiments, the brachytherapy delivery mode selected is placed in relatively close proximity to the area to be treated, such as the head, ocular or eye region. With bracheotherapy, the median dose of radiation that will be delivered to a specific area to be treated will be at a dose of about 1 Gy to about 15 Gy, preferably in the range of about 5 Gy to about 10 Gy. An alternative method is via external beam radiotherapy that will be delivered to specific area of treatment at a dose in a radiation range comprising about 1 Gy to about 15 Gy, or in a radiation range comprising about 5 Gy to about 10 Gy. With either or any of the particular treatment approaches presented herein, radiation is intended to be focused in the head and/or ocular region. In some embodiments, the invention provides for a method that is directed to a method of treating, inhibiting and/or preventing neurodegeneration of the eye. In some embodiments, the neurodegenerative condition of the eye is glaucoma, particularly age-related forms of glaucoma, including those associated with particular genetic profiles, including those that are characterized by the presence of and/or initiated by a mutation in the gene Tyrp1, Gpnmb, or a mutation in the Tyrp1 gene and the Gpnmb gene, such as in DBA/2J mice. According to yet another aspect of the present invention there is provided a method of characterizing pathways necessary for glaucoma induced retinal ganglion cell degeneration comprising treating an area of an animal, for example, an area of a DBA/2J mouse, with radiation. According to another aspect of the present invention, there is provided a method of characterizing a physiological and/or molecular event of interest associated with glaucoma induced retinal ganglion cell degeneration in an animal. In one embodiment, the method comprises measuring the particular physiological and/or molecular event of interest in an animal having glaucoma or with a predisposition to glaucoma both before and after treatment (or alternatively treated group vs. untreated group) with a neurodegeneration-inhibiting amount of radiation and/or bone marrow, and comparing said before and after measures of the physiological and/or molecular event of interest. In the method, differences may be identified between the before and after measurements (or alternatively treated group vs. untreated group) with of the physiological and/or molecular event of interest. By performing this kind of comparison, defined changes in measures of a specific physiological and/or molecular event of interest may be examined in order to further characterize the mechanism/s by which radiation and/or bone marrow treatment elicits a neurodegenerative protective effects in an animal having glaucoma or predisposed to induced retinal ganglion cell degeneration. According to another aspect of the present invention, there is provided a method of characterizing a physiological and/or molecular event of interest associated with the application of a neurodegeneration-inhibiting amount of radiation to glaucoma induced retinal ganglion cell degeneration in an animal. In one embodiment, the method comprises measuring the particular physiological and/or molecular event of interest in an animal having glaucoma or with a predisposition to glaucoma both before and after treatment (or alternatively treated group vs. untreated group) with a neurodegeneration-inhibiting amount of radiation and/or bone marrow, and comparing said before and after measures of the physiological and/or molecular event of interest. In the method, differences may be identified between the before and after measurements (or alternatively treated group vs. untreated group) with of the physiological and/or molecular event of interest. By performing this kind of comparison, defined changes in measures of a specific physiological and/or molecular event of interest may be examined in order to further characterize the mechanism/s by which radiation and/or bone marrow treatment elicits a neurodegenerative protective effects in an animal having or predisposed to glaucoma induced retinal ganglion cell degeneration. Alternatively, another embodiment of the method may comprise the use of this model to compare the herein described radiation and/or bone marrow treatment for glaucoma induced retinal ganglion cell degeneration, with other potential treatments and/or regimens of treatment. In this manner, physiological functions, molecular pathways, protein expression, cellular regulatory regulation or regulatory cell activity, and gene expression patterns, etc., may be compared and used to design comparable and/or alternative or supplementary treatment protocols for pressure-induced retinal ganglion cell degeneration and conditions related and/or associated therewith, such as glaucoma. By way of example, an animal model that may be used in these methods that develop pressure induced retinal ganglion cell degeneration is the DBA/2J mouse. The methods of the invention provide for the treatment, inhibition and/or prevention of a disease of interest in any animal, including a mouse, human, dog, cat, horse, rabbit or other domestic or non-domesticated animal of interest. In some embodiments, the animal to be treated is a human. The present invention provides a method for preventing, inhibiting and/or treating neurodegeneration in an animal having or likely to develop a neurodegenerative disease. By way of example, such a form of neurodegeneration is the neurodegeneration of the eye, including but not limited to inherited and/or age-related forms of glaucoma. In some embodiments, the animal is a mouse, horse, cat, dog, bird, or other animal, including a human. While glaucoma is the degenerative disease discussed in detail in the present application, the method is applicable to treat, inhibit, ameliorate, prevent, etc., other degenerative diseases. By way of example, these diseases include, but are not limited to, age-related macular degeneration (AMD), retinal degeneration, optic nerve atrophy, multiple sclerosis, diabetic retinopathy, Alzheimer's disease, Parkinson's disease, stroke, or other conditions following a transient ischemic event, etc. In some aspects, the present invention provides a method for treating, inhibiting, and/or preventing neurodegeneration comprising administering a treatment regimen comprising radiation in a neurodegeneration-inhibiting amount to an area of interest of an animal. In some embodiments, the form of neurodegeneration that is to be treated, inhibited and/or prevented is neurodegeneration of the eye. In a particular embodiment, the neurodegeneration of the eye is described as glaucoma, particularly age-related forms of glaucoma and/or hereditary forms of glaucoma. In some embodiments, the methods of the invention provide for administering a treatment regimen to an area of interest of an animal, such as the head area, particularly the eye area. In other embodiments, the methods of the invention provide for administering a treatment regimen to the whole body. In some embodiments, the method provides a method for treating, inhibiting, and/or preventing neurodegeneration comprising administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to the whole body of an animal, and an effective amount of bone marrow cells. In some embodiments, the neurodegeneration-inhibiting amount of radiation comprises a high-dose whole-body radiation. The radiation treatment may be administered before, after, or at the same time that the bone marrow cells are administered to the animal. In some embodiments, the method comprises a first step of administering radiation, and a subsequent step of injecting with bone marrow cells. The subsequent step may comprise any administering step that occurs after an initial step of administering radiation. Hence, the step of administering bone marrow cells may comprise, for example, a second, third, fourth and/or fifth step of the protocol. The sequence of steps in this regard is not critical where at least an initial and/or first step of administering radiation occurs. In some embodiments of the method, the animal will undergo a syngeneic bone marrow transfer. The term “syngeneic” is defined as a bone marrow sample that has been harvested for treatment which is of a genotype that is the same as that of the animal being treated. The bone marrow transplantation and/or treatment may be heterologous (harvested from an animal other than the animal being treated) or autologous (harvested from the animal being treated) relative to the animal receiving the bone marrow as defined in the practice of the present invention. By way of example, in humans, autologous bone marrow transplantation is preferred. The animal will preferably undergo autologous bone marrow transplantation which involves using the subject's own bone marrow. In this instance, the bone marrow is to be harvested prior to the administration of a first or initial treatment with radiation, such as a high-dose radiation, and this bone marrow is then re-administered to the animal in order to re-establish hematopoietic cell function after the administration of radiation. The hematopoietic stem cells for re-infusion into the subject preferably come from the subject's bone marrow. Alternatively, peripheral blood may also be used. In a preferred embodiment, a bone marrow treatment will be conditioned by the selective removal of T-cells prior to re-infusion into the animal being treated. By way of example, T-cells may be removed using techniques known by those of skill in the art, such as by using antibodies and cell sorting by flow cytometry prior to re-infusion. (Mackall C L, et al. (1997)15; Etienne Roux, et al. (1996)16; Champlin R., (1990)17; O'Reilly R J (1992)18; Martin P J, et al. (1985)19; Prentice, H. G., et al. (1982)20; Waldmann H, et al. (1984)21; Antin J H, et al. (1991)22; De Witte T, et al. (1986)23; Maraninchi D, et al. (1988)24; Soiffer R J, et al., (1992)25; Filipovich A H, et al. (1990)26; Wagner J E, et al. (1990)27; Herve P, et al., (1985)28). Techniques for treating humans with selected body section radiation treatment are known in the art. For example, brachytherapy is a focused radiation administration approach that provides for the delivery of a radiation dose to a desired area using radiation that has been sealed in needles, seeds, wires or catheters, and then being placed directly into or near the area of the body where delivery of the radiation is desired. (See L. Lumbroso-Le Rouic et al (2004)41). In the present invention, the method for preventing and treating neurodegenerative diseases includes whole body radiation, or irradiation of a part of the body, of an animal subject by irradiating the subject or subject area with either a single dose of about 10 Grays (Gy) administered to the midplane and about 8 Gy administered to the lungs or, alternately, in fractions of 12 Gy on three consecutive days and 9 Gy to the lungs prior to the bone marrow transplantation. Techniques for treating humans with whole body radiation are known for treating cancer and autoimmune diseases (Belkacemi Y, et al. (1998)29; Richard K. Burt, et al. (1998)30; Homing S J, et al. (1994)31). In one aspect, the invention provides a method that targets axonal and somal pathways of a neuron. The present methods are profoundly neuroprotective, and can completely prevent detectable glaucomatous degeneration of both the neuronal soma and axons. Because glaucoma observed in DBA/2J mice is known to affect axons and somas, treating an animal afflicted with glaucoma or an ocular degenerative disease like glaucoma, offers a powerful system for determining mechanisms of neurodegeneration and providing neuroprotective treatments. In some embodiments, the method of the present invention includes irradiating an animal with 1,000 Rads (10 Gy) of radiation in two equal doses. By way of example, the treatment with the radiation may be to the whole body, or instead focused at a desired body area, such as the head area or ocular (eye area). Subsequent to at least one radiation treatment, such as after a second radiation dose, the animal may also receive a bone marrow treatment. In some embodiments, the bone marrow treatment may comprise about 200 μl of i.v. injections (in the lateral tail vein) containing 5×106 T-cell depleted bone marrow cells. After treatment, IOP measurements of the mice are taken, the optic nerves are analyzed, axons are counted, and the retinas are analyzed. The complete details are set forth in the example below. It is found that the treated animals may still experience elevated IOP over time, but the treated animals do not experience optic nerve damage and do not develop glaucoma. Further, the method of the present invention prevents the loss of axons of the RGCs, the loss of somas of the RGCs, and the change in morphology of the somas in the animals. The treatment confers protection against neurodegeneration in animal of an age when RGC degeneration is usually very severe and essentially complete in the majority of untreated mice. The finding that optic nerve damage and the physical symptoms of glaucoma may be reduced without reducing IOP is unexpected. In yet another aspect, the invention provides for a method of selecting and screening candidate substance and/or treatments for degenerative diseases, particularly degenerative diseases of the eye, such as those that accompany the onset and progression of glaucoma. In some embodiments, the method comprises the use of a model for selecting glaucoma-associated neurodegenerative inhibiting agents in an animal, this model being a DBA/2J mouse. In some embodiments, the method comprises administering to an area of interest of a test animal having glaucoma-associated neurodegeneration an amount of a test agent, and measuring the amount of glaucoma-associated neurodegeneration in said animal to provide a potential neuroprotective activity test value; administering to an area of interest of a control animal having glaucoma-associated neurodegeneration an effective amount of radiation and measuring the amount of glaucoma-associated neurodegeneration in said animal to provide a control neuroprotective baseline value for a glaucoma-associated neuroprotective agent; comparing the test value to the control neuroprotective baseline value; and selecting a test agent or treatment regimen that demonstrates a test value of 50% or more of the control neuroprotective baseline value as a potential agent for inhibiting glaucoma-associated neurodegeneration. In some embodiments, treatment regimes or agents that provide 60%, 70%, 90% or essentially 100% of the neurodegenerative protective effect of the control neuroprotective baseline value may be selected as a candidate substance for the treatment of glaucoma-associated neurodegeneration. In some embodiments, the method involves protectively inhibiting glaucoma of an eye of a subject at the risk of developing a form of glaucoma (including hereditary forms) comprising administering a treatment regimen comprising administering x-ray radiation in a neurodegeneration-inhibiting amount to a head or eye area of a subject, to thereby protectively inhibit the eye of the subject against neurodegeneration caused by the form of glaucoma. In some embodiments, the method involves protectively inhibiting glaucoma of an eye of a subject having or predisposed to a hereditary form of glaucoma, comprising the following steps: administering x-ray radiation in a neurodegeneration-inhibiting amount to a head or eye area of a subject, to thereby protectively inhibit the eye of the subject against neurodegeneration caused by the hereditary form of glaucoma; and administering to the subject a volume of bone marrow cells. It is advantageous to define several terms before describing the invention. It should be appreciated that the following definitions are used throughout this application. Where the definition of terms departs from the commonly used meaning of the term, applicant intends to utilize the definitions provided below, unless specifically indicated. For purposes of the present invention, it should be noted that the singular forms, “a”, “an”, and “the” include reference to the plural unless the context as herein presented clearly indicates otherwise. For purposes of the present invention, the term “glaucoma” refers to a group of neurodegenerative diseases characterized by a specific pattern of retinal ganglion cell death and optic nerve atrophy, often associated with elevated intraocular pressure (IOP). The term glaucoma includes, but is not limited to: primary open angle glaucoma, normal pressure glaucoma, primary juvenile glaucoma, acute angle closure glaucoma, intermittent angle closure glaucoma, chronic angle closure glaucoma, primary congenital glaucoma, primary infantile glaucoma, and/or glaucoma associated with congenital anomalies. For purposes of the present invention, the term “age-related form of glaucoma” refers to forms of glaucoma associated with aging (including hereditary forms), in that the symptoms of glaucoma become manifest in the later years of the subject, for example, after about 40 or more years in the case of humans, or after about 5 or more months in the case of DBA/2J mice. For purposes of the present invention, the term “neurodegeneration” refers to the damage, loss and/or death of nerve cells. For purposes of the present invention, the term “neuroprotective” refers to guarding or protecting against a destructive or poisonous effect upon nerve tissue. For purposes of the present invention, the term “neurodegeneration-inhibiting amount” is an amount or dose regimen of radiation, specifically gamma irradiation and x-ray radiation, that is sufficient to elicit a reduction or inhibition of the amount, extent, severity or incidence of a detectable neurodegenerative physiological event in an animal, compared to the amount, extent, severity or incidence of a detectable neurodegenerative physiological event in an animal not having been treated with the same or similar amount or dose regimen of radiation. By way of example, such an amount to be administered to a targeted area of the body, such as the head or the eye region, would be in the range of about 1 to about 15 Gy, preferably in the range of about 5 to about 10 Gy, or given in fractions by repeated treatment in the range of about 1.0 Gy to about 5.0 Gy, preferably about 2.5 Gy. For purposes of the present invention, the term “x-ray radiation” refers to electromagnetic ionizing radiation having a wavelength in the range from about 0.01 to about 10 nanometers, and energies in the range of from about 120 eV to about 120 keV. In the human eye, x-ray radiation has a penetration depth of between 0 mm to at least 30 mm, depending on the energy utilized and the time of exposure provided. For the purpose of the present invention the penetration depth of x-ray radiation is controlled to allow for interaction of the x-rays with the posterior portion of the eye. For purposes of the present invention, the term “gamma radiation” refers to electromagnetic ionizing radiation having frequencies above 1019 Hz and therefore energies above 100 keV and wavelength less than 10 picometers, often smaller than an atom. Gamma radioactive decay photons commonly have energies of a few hundred KeV, and are almost always less than 10 MeV in energy. In the human eye, gamma radiation fully penetrates all soft tissues. For the purpose of the present invention the penetration depth of gamma radiation allows for interaction of gamma rays with at least the posterior portion of the eye and possibly extended portions of the optical nerve. For purposes of the present invention, the term “whole body radiation” refers to treatment regimes that deliver whole body radiation in the range of about 8 Gy to about 14 Gy up to a maximum of about 15 Gy, given in fractions in the range of about 1.0 Gy to about 5.0 Gy, preferably about 2.5 Gy. For purposes of the present invention, the term “radiation dose” as it is used when the radiation treatment is administered as part of a single dose regimen to a defined area of the body, such as the head area, or more particularly to the eye area, is a dose of radiation comprising a range of about 1 Gy to about 40 Gy, or in a range of about 5 Gy to about 10 Gy. In other, embodiments, the term “radiation dose”, as it is used when radiation treatment is administered in two approximately equal doses, the dose of radiation comprises an initial and/or first dose of radiation in a range of about 5 Gy to about 7 Gy, and a subsequent and/or second dose or doses of radiation in a range of about 5 Gy to about 7 Gy, or preferably two or more approximately equal doses of about 5 Gy. In other embodiments, the term “radiation dose”, as it is used when radiation treatment is administered in a multiple treatment regimen, is defined as a radiation dose comprising about 1.0 Gy to about 5.0 Gy, or preferably about 2.5 Gy and may be any combination of doses so long as the treatment regimen does not exceed 40 Gy. For purposes of the present invention, the term “rads” refers to a unit of absorbed dose of ionizing radiation equal to energy of 100 ergs per gram of irradiated material. For purposes of the present invention, the term “Gray” or “Gy” refers to the international system unit of radiation dose expressed in terms of absorbed energy per unit mass of tissue. The gray is the unit of absorbed dose and 1 gray=1 Joule/kilogram and also equals 100 rad. In embodiments involving administration of, for example, x-ray radiation, the radiation dose may be in the range of from about 1 Gy to about 15 Gy, for example, from about 5 Gy to about 10 Gy, such a from about 5 Gy to about 7 Gy. For purposes of the present invention, the term “cGy” refers to centigray. 1 cGy=1 rad. For purposes of the present invention, the term “protectively inhibiting” refers to a treatment which may prophylatically contribute to inhibiting, minimizing, reducing, preventing, etc., an underlying cause of a neurodegenerative disease. For purposes of the present invention, the term “protectively inhibiting glaucoma” refers to a treatment which may prophylatically contribute to inhibiting, minimizing, reducing, preventing, etc., an underlying cause of the glaucoma (e.g., neurodegeneration). For purposes of the present invention, the term “area of the body” refers to a portion or area of the body that does not include the entire body. By way of example, an area of the body is the head area, the eye area, or the face area, or any portion of these areas that include the eye or eyes of an animal. For purposes of the present invention, the term “syngeneic” refers to genetically identical or similar especially with respect to antigens or immunological reactions. For purposes of the present invention, the term “autologous” refers to something that is derived from the same individual. For purposes of the present invention, the term “hematopoietic” refers to forming blood or blood cells. For purposes of the present invention, the term “heterologous” refers to something that is derived from a different species, as a graft or transplant. For purposes of the present invention, the term “midplane” refers the mid point of the mouse body with the plane orientated at right angles to its spine to the pelvic plane of least dimensions. For purposes of the present invention, the term “DBA/2J mice” refers to a naturally occurring mouse model of glaucoma, wherein the mice develop an age-related form of hereditary glaucoma initiated by mutations in two genes, Tyrp1 and Gpnmb. For the purpose of this invention, the term “indication of glaucoma” means: an increase in IOP which if left unchecked will result in ocular damage, and/or an abnormal disc ratio. For the purpose of this invention, the term “onset of glaucoma or glaucoma manifestations” means ocular damage as a result or manifested by: an increase in IOP, visual field decline, and/or an abnormal disc ratio where ocular damage is present. The embodiments of method of the present invention provide a very reproducible and long-lasting neuroprotective treatment. Potential, non-mutually exclusive mechanisms for conferring the neuroprotective treatment of the present invention include neuronal preconditioning, altered immune responses, radiation-sensitive cell types, trophic factors, glial changes, and stem/precursor cells. In order to fully understand the teachings of the present invention, one must first understand the physical structure of the eye. Turning now to FIG. 8, a human eye 800 is illustrated. As may be seen, eye 800 comprises a cornea 802 which is disposed above an anterior chamber 804. Disposed below anterior chamber 804 is an iris 806 which covers pupil 808. Lens 810 is disposed below pupil 808 and is maintained in position by suspensory ligaments 812 and ciliary muscles 814. Zonular fibers 816 connect ciliary muscles 814 to ligaments 812. A posterior chamber 818 is defined by the borders of iris 806, muscle 814 and ligament 812. Eye 800 is encased in a sclera 820. A vascular layer of connective tissue, known as the choroid 822, is disposed between sclera 820 and retina 824. Retina 824 is a light sensitive tissue lining the inner surface of eye 800. As may be see, retina 824 is located in the posterior section of eye 800. A clear gel, known as the vitreous body 826, fills the space between retina 824 and lens 810. An optic disc or optic nerve head 828 connects retina 826 to optic nerve 830. Hyaloid canal 832 extends from optic disc 828 through vitreous humor 826 to lens 810. Blood is provided to eye 800 by retinal blood vessels 832 Finally, the fovea 834 is disposed in retina 824. In a typical human, eye 800 may be approximated by a spherical shape having a diameter in the range 23-29 mm. It should be understood that only a very small portion of eye 800 physically exposed to allow for treatment to be administered to the eye. In fact, one critical aspect of the teachings of the present invention is the use of methods for reaching the posterior section of the eye. For the purpose of the present application, the posterior portion of the eye is defined as retina 824, optic disc 828 optic nerve 830, the blood vessels located therein, and the myelin junction region of the optic nerve. In order to fully understand the teachings of the present invention, one must first understand the traditional diagnostic and treatment protocols used in the treatment of neurodegenerative disease such as glaucoma. Traditionally, this has involved first detecting the disease and then treating the disease when it is in an advanced state. The development of neurodegeneration in a patient may be divided into the following phases: 1) At risk or pre-glaucoma, 2) asymptomatic damage, 3) early glaucoma or moderate glaucoma, 4) symptomatic damage and advanced glaucoma, and 5) far advanced glaucoma. We will now discuss these phases of the disease with reference to the existing protocols for detection and treatment. During the first phase, at risk or pre-glaucoma, the primary technique utilized for assessing risk is family history. Recently, there have been significant developments in genetic testing for glaucoma. Additionally, the use of disc variation as a factor for detecting glaucoma may be utilized. In particular, research has shown that the disc ratio correlates positively with subsequent visual field decline. It has been found that the cup to disk ratio of 0.1 is average. If this ration exceeds 0.5, there is a strong correlation to the development of glaucoma. This test would be helpful if consistently conducted at the clinical level. Unfortunately, this test is not consistently utilized at this stage. Intraocular pressure (IOP) is the best known risk factor that may be modified and detected on clinical exam, A high or elevated IOP (>21 mmHg) is a risk factor for glaucoma. IOPs in 20 mmHg values are often present before glaucoma manifestation. This test would be helpful if consistently conducted at the clinical level. Unfortunately, this test is not consistently utilized at this stage, depending on the age of the patient. In particular, genes associated with glaucoma include, but are not limited to: GLC1A (1q24), GLC1B (2-cen-q13), GLC1C (3q21-q24), GLC1D (8q23), GLC1E (10p14-p15), GLC1F (7q35-q36), GLC3A (2p21 Cytochrome), P4501B1 (CYP1B1), and GLC3B (1p36.2-36.1). These genetic markers may be utilized in generic screens for determining the likelihood of developing glaucoma before the onset of the disease. Currently, there are no genetic tests being utilized in the at risk or pre-glaucoma phase. It should be appreciated that there is no existing treatment protocol for the at risk or pre-glaucoma stage. There is a very long pre-symptomatic phase of the disease during which early identification and treatment would benefit the sufferer. None of the above tests address this pre-symptomatic phase and no existing treatments are provided during this pre-symptomatic phase due to cost, potential side effects, and many will never develop glaucoma. Thus, deterioration occurs before treatment is initiated. The only clinical approach utilized in the at risk or pre-glaucoma stage is to monitor for deterioration. Thus, there is a need for the prophylactic treatment of neurodegeneration at this stage. One aspect of the present invention is to provide for a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to a head or eye area of a subject having a potential for developing glaucoma, to thereby protectively inhibit the eye of the subject against neurodegeneration caused by glaucoma, prior to the onset of any indication of glaucoma. This novel approach allows for the retardation and possibly for the prevention of glaucoma from manifesting later stages in the patient. The treatment regimen has not been utilized or even contemplated in the prior art treatment regimen. During the second phase, asymptomatic damage, the primary technique utilized for diagnosis is the serial study of the optic disk (disk ratios), nerve fiber layer, and angle. Once again, it should be appreciated that there is no existing treatment protocol for the asymptomatic damage stage. Even worse, damage is now physically manifest but has not presented any traditional symptoms associated with glaucoma. Unfortunately, since the damage has not noticeably affected visual field acuity, the patient is unlikely to seek medical attention. The only clinical approach utilized in the at risk or pre-glaucoma stage is to monitor for deterioration for those patients that have requested medical attention. Thus, there is a need for the prophylactic treatment of neurodegeneration at this stage. One aspect of the present invention is to provide for a treatment regimen comprising administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to a head or eye area of a subject being a suspect of developing glaucoma manifestations, to thereby protectively inhibit the eye of the subject against neurodegeneration caused by glaucoma, prior to the onset of glaucoma manifestations. During the third phase, early glaucoma or moderate glaucoma (i.e. where damage has occurred), the primary technique utilized for diagnosis is the serial study of the optic disc and visual field. At the clinical level, the manifestation of the presence or absence of visual field decline is utilized as a test to determine the onset of early glaucoma or moderate glaucoma. The primary drawback to this approach for detection is that damage has already occurred and the disease has manifested itself. Thus, this screen is a confirmatory screen for the existence of the disease. The only clinical approach utilized in the at risk or pre-glaucoma stage is to monitor for deterioration. Thus, there is a need for the treatment of neurodegeneration at this stage. One aspect of the present invention is to provide for a treatment regimen comprising administering a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to the eye of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with posterior portions of the eye. During the fourth and fifth phase, symptomatic damage and advanced glaucoma, and 5) far advanced glaucoma, the primary technique utilized for diagnosis is the use of intraocular pressure (IOP). There have been numerous studies which provide a correlation between elevated IOP and the onset of early to moderate glaucoma. Generally, when IOP is greater than 16 to 21 mm Hg, it may be an indicator of symptomatic damage and advanced glaucoma. When IOP is over 25 there is a very strong correlation to the development of far advanced glaucoma. This simplistic model has several disadvantages. First, an individual's, optic nerve has a level of IOP that it either can or cannot withstand. Thus, the range for IOP to be an indicator is highly variable by individual. In fact, many if not the majority of individuals with an elevated IOP never develop glaucoma, while other individuals develop glaucoma with IOPs at the normal population average of 16 mmHg. Second, by the time that high IOP is detected, significant damage may have already begun and the disease has already occurred. It should be appreciated the in many patients IOP is most likely high before damage occurs. The issue is high IOP is not typically symptomatic and so the patient does not know about it unless screened. Thus, IOP is often first detected when glaucoma is advanced. Some individuals do not have an eye exam until they already have a visual problem and so elevated IOP is detected when disease is advanced or already manifested. Thus, the use of IOP may be used as a risk factor but is not determinative of the onset of the disease. Other factors that have been utilized are the presence of myopia, family history, diabetes and systemic hypertension. During the fourth phase, treatments usually involve the reduction of IOP via non-invasive mechanisms. Generally, this stage of treatment involves hypertensive drops or medications to treat elevated IOP. Classes of IOP agents include, but are not limited to: cholinergic agents such as parasympathomimetics and miotics; aderenergic agents such as epinephrine compounds; agonists; beta blockers; oral and topical carbonic anhydrase inhibitors; and prostaglandin analogues. It should be appreciated that all of these techniques focus on the treatment of IOP and do not directly treat the existing glaucoma. Thus, these treatments have varying success, depending on the patients particular IOP sensitivity. Thus, there is a need for the treatment of neurodegeneration at this stage. One aspect of the present invention is to provide for a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to an optic nerve head of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the optic nerve head. In another embodiment of the invention, a treatment regimen is provided and comprises administering radiation in a neurodegeneration-inhibiting amount to an optic nerve as it exits the eye of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the optic nerve as it exits the eye. In another embodiment of the invention, a treatment regimen is provided and comprises administering radiation in a neurodegeneration-inhibiting amount to a retina of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the retina. In another embodiment of the invention, a treatment regimen is provided and comprises administering radiation in a neurodegeneration-inhibiting amount to myelin junctions of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation in a neurodegeneration-inhibiting amount interacts with the myelin junctions. During the fifth phase, treatments usually involve the reduction of IOP via invasive mechanisms. These mechanisms include the use of laser treatment and traditional surgery. Once again, all of these techniques focus on the treatment of IOP and do not directly treat the existing glaucoma. In addition, these techniques also have the added disadvantage of being highly invasive techniques with modify the eye structure by having an incision therein or thereon. These treatments have varying success, depending on the patients particular IOP sensitivity. As a follow-up to either laser or traditional surgery, the patient may be treated with beta radiation to reduce scarring. Of the three common types of radiation given off by radioactive materials, alpha, beta and gamma, beta radiation has the medium penetrating power and the medium ionizing power. Although the beta particles given off by different radioactive materials vary in energy, most beta particles can be stopped by a few millimeters of aluminum or other material. Being composed of charged particles, beta radiation is more strongly ionizing than gamma radiation. When passing through matter, a beta particle is decelerated by electromagnetic interactions and thus has a very low penetration depth. For example, beta radiation generated from a Sr source loses 50% of its energy after penetrating 1.5 mm of water, and the 106Ru source loses 50% of its energy after penetrating 2.4 mm. In the human eye, beta radiation has a penetration depth of between 0.0 mm and 4.6 mm for the doses utilized with the present invention. As stated above, beta radiation has a very limited depth penetration in the eye. Thus, its use is limited to the reduction of scarring at or near the surface of the eye. Because of this limited penetration, there is no interaction between the beta radiation and the posterior portion of the eye. There is a need for the treatment of neurodegeneration at this stage. One aspect of the present invention is to provide for a treatment regimen comprising administering radiation in a neurodegeneration-inhibiting amount to a head or eye area of a subject having glaucoma, to thereby further inhibit the eye of the subject against neurodegeneration caused by glaucoma, wherein radiation is delivered to the subject prior to an incision to the eye. Turning now to the teachings of the present invention, it has been found that the use of properly applied radiation may significantly effect neurodegeneration in mammals. We will now turn to the specific teachings of the present invention as discussed above. A system for providing x-ray radiation treatment to the eye region is illustrated in FIG. 6, and is referred to generally as 600. System 600 includes a machine for delivering a focused radiation beam (AXT, Inc.) indicated generally as 608. In an embodiment, the radiation beam is x-rays and in another embodiment the radiation beam is gamma radiation. Machine 608 has a radiation tube, indicated as 616, for generating radiation of desired type, strength, and power to provide a neurodegeneration-inhibiting amount of the radiation. Radiation generated by tube 616 is delivered to and a focused by a collimator, indicated generally as 624, to more narrowly focus the radiation to provide a delivery area having diameter appropriate for administration to the eye of the subject. For example, collimator 616 may focus the radiation to provide a delivery area having a diameter of at least about 10 microns, such as at least about 50 microns. Focused radiation from collimator 624 is transmitted through an optical channel, e.g., fiber optic cable, indicated generally as 632, to a radiation delivery lens, indicated generally as 640. As shown in FIG. 6, radiation is transmitted by lens 640 to the eye 644 of the subject, for example, mammal 648. Mammal 648 is restrained by means (not shown) so that a therapeutic dose of x-ray radiation may be delivered to eye 644 by lens 640. Mammal 648 is shown in FIG. 6 as resting (while being restrained) on a generally horizontally extending platform 652. Platform 652 is supported and elevated by a stand, indicated generally as 656. It should be appreciated that platform 652 would be modified to address the specific needs of the patient being treated. It should be appreciated that other mechanisms may be utilized to deliver radiation treatment to the eye. For example, a system is disclosed in U.S. Patent Application 2009/0022274 which discloses a system for aiming radiation for treatment purposes. The entire disclosure and contents of this application is incorporated herein by reference in its entirety. Turning now to FIG. 1A through 1F, FIGS. 1A-1F, are images, while FIG. 1G is a graph, showing clinical disease progression and glaucomatous insult is not influenced by radiation treatment. The overall clinical presentation of the iris disease is indistinguishable between treated and untreated groups. Typical images of mice of the indicated ages and treatment groups are shown. The only clinical difference in ocular phenotypes between untreated and treated cohorts was that all treated mice developed radiation induced lens opacities. At 9 months, characteristic peripupillary swellings and dispersed pigment accumulations are evident in both treated and untreated mice. At this age, the degree of peripupillary iris atrophy (evident as white tissue adjacent to the pupil) varies from eye to eye in each treatment group (see FIGS. 1C and 1D). At 12 months, dispersed pigment is clearly evident on the lens and across the surface of the iris (see FIGS. 1E and 1F). At 14 months, there is advanced iris atrophy, which is not restricted to the peripupillary area. Full-thickness iris holes and severely atrophic areas that appear thin and depigmented occur in both groups (see FIG. 1G). IOP profiles showing that treatment did not change the glaucomatous IOP insult (mean±SEM). The thickness of the gray line represents the mean IOP±SEM (11.3±0.25, n=31) for DBA/2J mice at an age before ocular disease (3 months). The number of successful IOP recordings at each age are indicated. Turning now to FIG. 2A through 2F, FIGS. 2A-2B and 2D-2F, are images, while FIG. 2C is a bar graph, showing treated mice are protected from glaucomatous neurodegeneration. Optic nerves are stained with paraphenylenediamine to visualize the myelin sheath of all axons, and differentially darkly stain the axoplasm of damaged and dying axons. This is an extremely sensitive technique that allows for the detection of a single sick/dying axon in the optic nerve which are almost completely composed of normal healthy axons (see FIG. 2B). By 12 months, the majority of optic nerves from untreated DBA/2J mice have severe glaucoma, as defined by massive axon loss (see FIG. 2A). The vast majority of optic nerves from treated mice had no detectable glaucomatous damage, even out to 14 months (see FIG. 2C). A summary of the data from 12- and 14-month-old mice clearly demonstrates the protective effect of treatment, which prevents glaucomatous neurodegeneration in the vast majority of eyes. Because the results did not differ, the data from the experiments at independent times are combined (see FIG. 2C). Nissl-stained flat-mounted retinas from position-matched regions of the superior peripheral retina also demonstrate the profound protective effect of treatment (n=5 flat mounted retinas per group). Young DBA/2J mouse showing normal density of ganglion cell layer cells before glaucomatous damage (see FIG. 2D). Twelve-month-old untreated DBA/2J mouse, showing substantial reduction in the number of soma as a result of glaucoma (see FIG. 2E). Twelve-month-treated DBA/2J mouse with normal number of soma (Scale bar, 50 μM) (see FIG. 2F). FIGS. 3A-3F are images showing treatment prevents glaucomatous optic nerve excavation (see FIG. 3B). The optic nerve heads of control nonglaucomatous DBA/2J mice include large numbers of axons, as evidenced by a thick nerve fiber layer, entering the optic nerve head (nerve fiber layer on left side of optic nerve head is marked by arrowheads) (see FIG. 3A). The thickness of the nerve fiber layer in treated DBA/2J mice (14-month-old example) is indistinguishable from nonglaucomatous controls (see FIG. 3B). In contrast, untreated DBA/2J mice have severe axon loss, as evidenced by a very atrophied nerve fiber layer (see FIG. 3C). Their optic nerve heads are also severely excavated (asterisk), a hallmark of glaucoma (12-month example). See FIG. 3D-3F showing position-matched images of retinal cross sections) with FIG. 3D showing nonglaucomatous DBA/2J control mouse, FIG. 3E showing treated DBA/2J mouse, 14 months old, and FIG. 3F showing untreated DBA/2J mouse, 12 months old. The nerve fiber layer (arrowheads) is of normal thickness in treated DBA/2J retina (compare FIG. 3D with FIG. 3E) and severely atrophied in the untreated glaucomatous DBA/2J retina (compare FIG. 3D with FIG. 3F). There is an obvious loss of somas in the ganglion cell layer (GCL) of the untreated DBA/2J mouse (see FIG. 3F) but not in the treated DBA/2J mouse (see FIG. 3E; compare both to control retina in FIG. 3D). ONL, outer nuclear layer; INL, inner nuclear layer. (Scale bar, 50 μm.) FIG. 4 is a bar graph showing the effect of part body irradiation on glaucomatous optic nerve damage. Treatment groups: Control/DBA/2J; Whole Body+Bone Marrow; Body/No Bone Marrow; Head/No Bone Marrow. (/// (cross hatched)=Severe Damage; □ (open bar)=Moderate Damage; ▪ (solid bar)=Mild Damage). FIG. 5 shows an apparatus where anesthetized mice were placed in the void in the lead cylinder with packing to prevent a change in orientation within the cylinder, only the head region is exposed to radiation. The cylinder is placed upright in the irradiator (following the procedure set forth in Anderson et al. (2005), PNAS, 102(12):4566-4571). Mice were irradiated with 1000 rads, the cylinder was placed on a slowly rotating platform to ensure even radiation. Radiation was applied from a 137Cs source in two equal doses of 500 rads spaced 3-4 hours apart. The following non-limiting examples are illustrative of the present invention, and should not be construed to constitute any limitation of the invention as it is described in the claims appended hereto. The present example is provided to demonstrate the utility of the present invention in an animal model accepted by those of skill in the art as predictive of human forms of glaucoma. By way of example, the form of glaucoma is an age-related form of hereditary glaucoma initiated in DBA/2J mice by the mutation of two genes, Tyrp1 and Gpnmb, see John et al. (1988)36; Chang et al. (1999)37; and Anderson et al. (2002)38. Animal Model for Glaucoma: The DBA/2J mouse model for glaucoma was used in the present study, and is an accepted model for glaucoma in humans. DBA/2J mice were fed a 6% fat (NIH31) diet ad libitum, and drinking water was acidified to a pH of 2.8-3.2. Mice were housed in cages containing white pine bedding and kept in a 21° C. environment with a 14-h light and 10-h dark cycle. Bone Marrow Preparation: The methods used for harvesting and re-infusion of bone marrow in human subjects are generally modifications of the techniques known in the art (Thomas E D, Storb R., (1970)32). Prior to being subjected to high-dose radiation, marrow is preferably harvested by repeated aspirations from the posterior iliac crest until an adequate number of cells have been removed. If a sufficient number of cells cannot be obtained from the posterior iliac crest, marrow can also be harvested from the anterior iliac crest and the sternum. The smallest number of nucleated marrow cells required for long-term repopulation in humans is not precisely known. In practice, the number of cells harvested is usually 100 million to 300 million per kilogram of the recipient's body weight and dependent on the type and intensity of the preparative regimen and whether the marrow graft will be modified in vitro, see Buckner C D, et al. (1984)33; Bortin et al. (1983)34; Kessinger A, Armitage J O, (1987)35. Thus, the effective range of cells harvested may be between about 75 million and about 400 million per kilogram and be considered within the scope of the teachings of the present invention. Generation of Bone Marrow Chimeras: Bone marrow chimeras were generated as follows: 5-8-week-old female DBA/2J mice were irradiated with 1,000 rads of whole-body radiation. During treatment, mice were positioned on a slowly rotating platform to ensure uniform application. Radiation was applied from a 137Cs source in two equal doses of 500 rads spaced 3-4 hours apart. The dose was applied at a rate of 132 rads/minute. Shortly after the second radiation dose, mice received 200 μl of i.v. injections (in the lateral tail vein) containing 5×106 T-cell depleted bone marrow cells. Donor mice in all experiments were 1.7-1.9 months old. Donor marrow was depleted of T lymphocytes with 10 μg/ml purified monoclonal antibodies to CD4 (GK1.5, The Jackson Laboratory Flow Cytometry Service) and CD8a (53-6.72, The Jackson Laboratory Flow Cytometry Service). Before injection, free antibodies were removed by centrifugation. DBA/2J mice develop a pigmentary form of glaucoma that involves iris atrophy and pigment dispersion. A slit lamp was used to determine whether the treatment altered the course of the disease. Eyes were examined with a slit-lamp biomicroscope and photographed through a 40× objective lens. All exams viewed both the left and right eyes. All photographs were taken by using identical camera and light settings. Assessed phenotypes included the degree and pattern of pigment dispersion, the degree and pattern of iris atrophy, the degree and pattern of transillumination, and the depth of the anterior chamber. Next, the intra-ocular pressure (IOP) was measured. Mice were acclimatized to the procedure room environment for at least 1 week before measurement. To record IOP, mice were anesthetized by using intraperitoneal injection of ketamine (Ketalar, Parke-Davis, Paramus, N.J.) and xylazine (Rompun, Phoenix Pharmaceutical, St. Joseph, Mo.). Because the IOPs of C57BL/6J are very consistent, C57BL/6J mice were interspersed with experimental mice during all studies as a methodologic control to ensure consistent equipment calibration and performance. Optic nerve cross sections were examined for glaucomatous damage by using a modified paraphenylenediamine (PPD) staining protocol to stain the myelin sheath of all axons, and the axoplasma of damaged axons. PPD stains all myelin sheaths, but differentially stains the axoplasm of sick or dying axons darkly. Optic nerves were fixed in situ in 0.8% paraformaldehyde, 1.2% gluteraldehyde, 0.08% phosphate buffer, pH 7.4 at 4° C. Sections of nerve between the orbit and chiasm were dissected free, processed, embedded in resin, sectioned, and stained with PPD. Each age group investigated contained left and right nerves. Stained sections were compared with identically processed sections from untreated DBA/2J mice at various disease stages. Counts of normal appearing axons were performed by using established nonbiased counting methods. Before beginning axon counts, the optic nerve was outlined at ×100 magnification and its cross-sectional area was automatically calculated by using a computer program (METAMORPH, VERSION 4.6r9, Universal Imaging, Downingtown, Pa.). Magnification of the same nerve section was increased to ×1,000, and 20×1,000 fields were electronically collected, covering 80-90% of the nerve. The fields were spaced in a regular fashion across the entire nerve, taking care to avoid field overlap and not count the same area twice. The 20 collected images were stacked on the computer screen so that only the final image was visible to the operator. A rectangular box was then drawn near the center of the 20th image. The program (METAMORPH) then “cut” a rectangle centered at the same location in all 20 images. Because the operator could only see the top image, this action removed the possibility of unconscious operator bias and made the selection of axons to be counted random. Axons were counted manually and marked by using the computer. The program tracked the total area counted and the total axon count for all 20 images. The total counted area was >10% of the total nerve area. The final count was calculated and expressed as number of axons per optic nerve. Axon counting is used to quantify the number of axons in nerves of each damage level. When performing this procedure, more than eight nerves of each level were randomly selected for counting. Additionally, to quantitatively assess the effects of treatment, axon counting was performed on randomly selected nerves from treated mice and compared with the values for young pre-glaucomatous strain matched controls. Because of the large number of mice, an optic nerve grading system was used to determine the level of glaucomatous damage in the 158 nerves analyzed in this study. The indicated damage levels are readily distinguishable upon inspection of the nerve without counting. Furthermore, axon counts on a randomly selected subset of DBA/2J nerves of each damage level indicate that the levels represent clearly distinct stages of disease. The damage level for each nerve was scored by taking into account several factors: the number of healthy axons remaining (compared with pre-glaucomatous DBA/2J nerves), the number of damaged axons, and the amount of scarring associated with gliosis. In many mildly damaged nerves, no axon loss/damage is detected. In other nerves, the minor damage exists that is equivalent to that observed in similarly aged mice of various mouse strains that do not develop glaucoma (≦2% of axons appear damaged). Because the mild damage observed in some of these nerves also occurs in old mice of various strains, this mild stage of damage is not considered glaucomatous damage. The average axon count for nerves graded as mild is 5,888±1,441 (average±SEM, n=11). In moderate nerves, significant numbers of sick/degenerating axons are readily detected in many regions of the nerve, but the majority of remaining axons appear healthy. This stage is almost never seen in non-glaucomatous mice, and therefore, this is considered to be glaucomatous damage. The axon count for nerves graded moderate is clearly reduced (31,410±2,199, n=8, P<0.001), compared with the counts for mild DBA/2J nerves. Nerves are classified as having severe glaucoma when the number of damaged axons closely approaches, or surpasses, the number of healthy axons. In fact, for the DBA/2J-untreated mice with severe glaucoma in this study, 82% of optic nerves were judged to have fewer than 5% healthy axons remaining, and the other 18% of optic nerves were judged to have <50% healthy axons remaining. The average axon count for severely damaged nerves is 5,454±1,441 (n=24, P<0.001), compared with mild and moderate axon counts. All nerves were scored by at least two “masked” investigators. Both investigators were unaware of the age of the mouse, or whether the nerve was from a treated or untreated animal. Furthermore, both investigators were unaware of the damage level assigned by the other investigator. Of the 158 nerves analyzed in this study, the investigators assigned the same damage level to approximately 96% of the nerves. In the five cases where the two investigator's grades did not agree, a third investigator (also masked) analyzed the nerve. The third investigator's damage level always agreed with that of one of the first investigators. The most commonly assigned damage level was used as the grade. For retinal sections, whole eyes were removed and immersion-fixed in 0.8% paraformaldehyde, 1.2% gluteraldehyde, 0.08% phosphate buffer, pH 7.4, overnight at 4° C. Eyes were embedded in resin, sectioned, and stained with hematoxylin/eosin. Flat mounting was performed similarly. Briefly, eyes were marked for orientation, enucleated, and whole eyes were immersion-fixed in 4% paraformaldehyde in 0.1% phosphate buffer overnight at 4° C. Eyes were either processed immediately or stored in 0.4% paraformaldehyde in 0.1% phosphate buffer. Eyes were rinsed in PBS (pH 7.4) and the anterior chamber was removed. The resultant eye cup was incubated overnight in 0.3% Triton X-100 in PBS at 37° C. The neuronal retina was dissected free from RPE and sclera. The free-floating retina was rinsed in PBS and then incubated overnight in 3% H2O2, 1% Na2HPO4 at room temperature. Retinas were rinsed in PBS and placed (RGC-side up) onto a microscope slide. After air drying for 5-15 min (until translucent), retinas were flattened overnight under a coverslip with a 10-g weight placed on top. Retinas were then stained by using a brush for approximately 1 min with 1% cresyl violet in water containing 2.5% (freshly added) acetic acid. Stained retinas were dehydrated, washed in xylene, and coverslipped. The clinical phenotypes and IOP profiles of the treated DBA/2J mice were carefully examined at multiple ages and compared with similarly housed, age-matched, untreated mice. IOP was monitored at three key ages during the period of glaucoma-inducing IOP elevation in this mouse strain. No differences were detected between the treated and untreated groups in the iris phenotype. In both treated and untreated mice at all three glaucomatous ages examined, IOP was significantly elevated compared with young preglaucomatous DBA/2J mice (P≦0.001). The degree of IOP elevation in treated mice was similar to that of untreated DBA/2J mice (P>0.3 for two-factor ANOVA for treatment and age). This result indicates that RGCs of both the treated and untreated groups were exposed to similar pressure insults. Treated and untreated mice were aged to 12 months, an age when the majority of DBA/2J eyes have severe glaucomatous damage. Again, the treatment had an overwhelming protective effect and prevented detectable glaucomatous degeneration in the vast majority of nerves. The majority, 83%, of optic nerves from untreated 12-month-old DBA/2J mice had glaucomatous damage, and 73% were characterized by severe glaucoma. Severe glaucoma is defined as very substantial reductions in the number of healthy axons and the presence of many sick and dying axons. In contrast, only 5% of treated 12-month-old mice had any detectable glaucomatous damage, and only 3% had severe glaucoma. Numbers of nerves with each optic nerve grade were: 12-month untreated (62 total), 10 mild, 6 moderate, and 46 severe; 12-month treated (61 total), 58 mild, 1 moderate, and 2 severe. The mild stage occurs in normal mice with age and is not considered glaucoma. To further assess the duration of the protective effect, a subset of mice was aged to 14 months. In agreement with findings at 12 months of age, treatment had conferred almost complete protection from glaucoma. At 14 months of age, only about 3% of treated mice had detectable glaucomatous damage. To determine if there was subtle axon loss in treated nerves that had no obvious glaucomatous damage, axons were counted in the nerves of 10 randomly selected treated mice and compared with the nerves of young preglaucomatous DBA/2J mice. Demonstrating the profound protective effect of the presently described treatment, no significant difference in axon number was detected (young preglaucomatous DBA/2J mice 51,554±1,332, n=8; graded mild treated DBA/2J mice, 48,625±2,309, n=10, P=0.3). Finally, multiple other assays on a subset of eyes also demonstrated a striking prevention of glaucomatous damage. Treated mice had no obvious change in the number or morphology of somas in the RGC layer, whereas untreated mice had massive soma loss. Retinal and optic nerve morphology also appeared normal in the treated mice, whereas nontreated DBA/2J mice had clear loss of RGC axons and optic nerve head atrophy. The present example is provided to demonstrate the utility of the invention for providing a treatment for glaucoma using radiation targeted at a specific area of the body, such as the head, and not the whole body. In addition, the present example demonstrates that this method is as effective at treating glaucoma as a either a combination therapy of whole body radiation plus bone marrow transfer or individually. The apparatus depicted at FIG. 5 was employed to deliver radiation to the head area of a mouse model for glaucoma, specifically a DBA/2J mouse. The data obtained from these studies is presented in the bar graph of FIG. 4. As is demonstrated, the head-only radiation treatment without bone marrow treatment of these animals resulted in a significant reduction in the severity of observable glaucomatous optic nerve damage (95% of animals demonstrating only mild age-related optic nerve damage, 5% demonstrating only moderate glaucomatous optic nerve damage, 0% demonstrating severe glaucomatous optic nerve damage), compared to those animals that received whole-body radiation treatments alone (40% of animals demonstrating only mild age-related glaucomatous optic nerve damage, 0% demonstrating only moderate glaucomatous optic nerve damage, 60% demonstrating severe glaucomatous optic nerve damage). In animals treated with whole body radiation and bone marrow, the protective effect against glaucomatous optic nerve damage was also significant and robust (90% of animals demonstrating only mild age-related optic nerve damage, 8% demonstrating only moderate glaucomatous optic nerve damage, 2% demonstrating severe glaucomatous optic nerve damage). These results are compared to the control group of animals that did not receive radiation treatment or radiation, in which 70% of the animals demonstrated severe glaucomatous optic nerve damage, 8% evidenced moderate glaucomatous optic nerve damage, and 20% of the animals demonstrated mild age-related optic nerve damage. The bar graph in FIG. 4 presents the data obtained using a full-body irradiation treatment regimen and the data obtained with a head-only focused radiation treatment of a DBA/2J glaucoma model mouse. The present example is presented to describe the anticipated protocol to be used in the practice of the present invention for the treatment of glaucoma in humans. In particular, the present invention is provided to demonstrate an anticipated treatment for inhibiting and/or reducing human glaucoma, particularly those hereditary forms of glaucoma. By way of example, such hereditary forms of human glaucoma in humans have been described in relation to genetic changes that occur over time. In order to reduce the amount of radiation exposure to healthy tissue, as well as to reduce the amount of dose inhomogeneity, a procedure known as intensity modulated radiotherapy (IMRT) will be used to administer the appropriate radiation dose the a focused region of the head, and particularly the ocular region. IMRT is described in Nutting et al. (2000)39, which reference is specifically incorporated herein by reference for this purpose. Techniques for providing a directed dose of radiation to a desired isolated region of the human body have been developed for the treatment of cancer of the eye (e.g., retinoblastoma, uveal melanomas). In particular, L. Labroso-Le Rouic et al. (2004)41 describes the technique of brachytherapy, which reference is specifically incorporated herein by reference. Accordingly, the method of the present invention may provide for a focused dose of radiation exposure to the eye using a brachytherapy technique of delivery (radioactive material sealed in needles, seeds, wires, or catheters, and placed directly in the eye region) in the doses as described herein. It is expected that the doses may be significantly reduced in actual practice with the same or similar therapeutic effects according to the present invention. For example, radiation dose ranges of about 1 Gy to about 15 Gy, or in a range of about 5 Gy to about 10 Gy, may be used. These radiation administration techniques may be used in accomplishing the practice of the present methods to provide a treatment for glaucoma and ocular degeneration. The present example is provided to demonstrate the utility of the present invention for use as a screening tool to identify agents and/or treatments useful in the treatment, inhibition and/or progression of neurodegeneration, particularly neurodegeneration that occurs as a consequence of age. In yet another aspect, the invention provides for a method of selecting and screening candidate substance and or treatments for degenerative diseases, particularly degenerative diseases of the eye, such as those that accompany the onset and progression of glaucoma. The method comprises the use of a model for selecting glaucoma-associated neurodegenerative inhibiting agents in an animal, this model being a DBA/2J mouse. In particular, the method comprises administering to an area of interest of a test animal having glaucoma-associated neurodegeneration an amount of a test agent, and measuring the amount of glaucoma-associated neurodegeneration in the animal to provide a potential neuroprotective activity test value; administering to an area of interest of a control animal having glaucoma-associated neurodegeneration an effective amount of radiation and measuring the amount of glaucoma-associated neurodegeneration in said animal to provide a control neuroprotective baseline value for a glaucoma-associated neuroprotective agent; comparing the test value to the control neuroprotective baseline value; and selecting a test agent that demonstrates a test value of 50% or more of the control neuroprotective baseline value in inhibiting of glaucoma-associated neurodegeneration. In selecting an effective neuroprotective agent and/or treatment, agents and/or radiation levels of intensity may alternatively be selected on the basis of observed differences in degeneration levels observed between a glaucoma-afflicted animal that has received the test treatment and/or radiation level being examined and that degeneration level observed in a glaucoma-afflicted animal that has not received the neuroprotective agent and/or treatment. In this manner, potential neuroprotective agents and/or treatments or radiation levels will be selected that result in an observable degeneration level that is less than that observed in an untreated glaucoma-afflicted animal. In this experiment, the effect of administering gamma radiation and x-ray radiation to each eye of DBA/2J mice (2-3 months of age), relative to no treatment with any radiation as the control, is evaluated. Gamma radiation is administered whole body to the DBA/2J mice according the procedure of Experiment 1 using the apparatus shown in FIG. 5. X-ray radiation (720 rads) is administered to each eye of the DBA/2J mice over a 4 minute period using apparatus 600 shown in FIG. 6. The treated and untreated mice are harvested at 12 months of age and the eyes thereof evaluated for glaucoma according to the procedure described in paragraphs above. The results of that evaluation are shown in the bar graph of FIG. 7. The results for the x-ray radiation treatment represent 14 treated DBA/2J mice. As shown in FIG. 7, treatment with x-ray radiation provided protective inhibition of glaucoma in the DBA/2J mice when compared to the untreated DBA/2J mice and the DBA/2J mice treated with gamma radiation. All documents, patents, journal articles and other materials cited in the present application are hereby incorporated by reference. Although the present invention has been fully described in conjunction with several embodiments thereof with reference to the accompanying drawings, it is to be understood that various changes and modifications may be apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims, unless they depart there from. The following references are specifically incorporated herein by reference in their entirety. 1. Ritch, R., et al. (1996), The Glaucomas (Mosby, St. Louis); 2. Weinreb, R. N. & Khaw, P. T. (2004), Lancet 363: 1711-1720; 3. Heijl, A., et al. (2002), Arch. Opthalmol., 120: 1268-1279; 4. Collaborative Normal-Tension Glaucoma Study Group (1998), Am. J. Opthalmol., 126: 487-497; 5. John, S. W., et al. (1999), J. Glaucoma, 8: 400-412; 6. John. S. W., et al. (1998), Invest. Opthalmol. Visual Sci., 39: 951-962; 7. Chang, B., et al. (1999), Nat. Genet., 21: 405-409; 8. Anderson. M. G., et al (2002), Nat. Genet., 30: 81-85; 9. Quigley, H. A., (1998), Frog. Retin. Eye Res., 18: 39-57; 10. Nickells, R. W. (2004), Brain Res. Bull. 62: 439-446; 11. Raff, M. C., et al. (2002), Science, 296: 868-871; 12. Robert A. Good (July, 2000), World Journal of Surgery, 24(7): 797-810; 13. Clift, R. A., et al. (1991), Blood, 77(8): 1660-1665; 14. Matthews, D. C., et al. (1995), Blood, 85(4): 1122-1131; 15. Mackall, C. L., et al. (1997), Blood, 89(10): 3700-3707; 16. Roux, E., et al., (1996), Blood, 87(9): 3984-3992; 17. Champlin, R., et al. (1990), Hematol. Oncol. Clin. North Am., 4: 687; 18. O'Reilly, R. J., et al. (1992), Semin. Hematol., 29(1): 20; 19. Martin, P. J. et al. (1985), Blood, 66: 664; 20. Prentice, H. G., et al. (1982), Lancet, 1: 700; 21. Waldmann, H., et al. (1984), Lancet, 2: 483; 22. Antin, J. H., et al. (1991), Blood, 78: 2139; 23. De Witte, T., et al. (1986), Blood, 67: 1302; 24. Maraninchi, D. et al. (1988), Transplant Int., 1: 91; 25. Soiffer, R. J. et al. (1992), J. Clin. Oncol., 10: 1191; 26. Filipovich, A. H., et al. (1990), Transplantation, 50: 410; 27. Wagner, J. E. et al. (1990), Blood, 75: 1370; 28. Herve, P., et al. (1985), Transplantation, 39: 138; 29. Belkacemi, Y. et al. (1998), Strahlenther Onkol., 174(2): 92-104; 30. Burt, Richard K., et al. (1998), Blood, 92(10): 3505-3514; 31. Horning, S. J., et al. (1994), J. Clin. Oncol., 12: 2552; 32. Thomas, E. D. and Storb, R. (1970), Blood, 36(4): 507-515; 33. Buckner, C. D. et al. (1984), Blood, 64: 630-634; 34. Bortin, M. M. and Buckner, C. D. (1983), Exp. Hematol., 11: 916-921; 35. Kessinger, A., and Armitage, J. O., (1987), Bone Marrow Transplant, 2: 15-18; 36. John, et al. (1988), Invest. Opthalmol. Visual Sci., 39: 951-962. 37. Chang et al. (1999), Nat. Genet., 21: 405-409. 38. Anderson, et al. (2002), Nat. Genet., 30: 81-85. 39. Nutting et al. (2000), The British Journal of Radiology, 73: 459-469. 40. Sanderson, R. J. and Ironside, J. A. D. (2002), BMJ, 325(7368): 822-827. 41. Lumbroso-Le Rouic, et al., (2004) Eye, 18: 911-916. 42. Kipnis, J., et al. (2004), European Journal of Neuroscience, 19: 1191-1198. 43. Bakalash, S., et al. (2005), J. Mol. Med., 83(11): 904-916. 44. Bakalash, S., Schwartz, et al. (2005), Department of Neurobiology, The Weizmann Institute of Science. 45. Takeda, A., et al. (1999), Int. J. Radiation Oncology Biol. Phys., 44(3): 599-605. 46. Phillips, C., et al. (2003), Australasian Radiology, 47: 226-230. 47. Million, Rodney R., and Parsons, James T. (1999), Front. of Radiat. Ther. Oncol., 32: 21-33. 48. Anderson, M. G., et al. (2005), PNAS, 102(12): 4566-4571. 49. Sanderson, R. J. and Ironside, J. A. D. (2002), BMJ, 325(7368): 822-827. 50. Nag, Subir, et al. (2003), International Journal of Radiation Oncology, Biology and Physics, 56(2): 544. 51. Cancer, Principles & Practice of Oncology, Publisher: Philadelphia: Lippincott-Raven, Publication Date: c1997. DeVita, Vincent T., Hellman, Samuel, Rosenberg, Steven A. 52. Anderson et al. (2005), PNAS, 102(12): 4566-4571.
047770112	abstract	A method for checking the dimensions of a nuclear reactor fuel assembly in a water tank uses two mutually parallel probes each having a first probe side carrying an ultrasonic test head at a free end thereof with acoustic directions directed towards each other and each having a second probe side facing away from the ultrasonic test head. The acoustic waves are transmitted with one of the ultrasonic test heads, the transmitted acoustic waves are received with the other ultrasonic test head, one of the second probe sides is brought into contact with a given region of the fuel assembly to be checked, the probes are moved towards each other in the direction of the acoustic waves due to contact pressure with the fuel assembly, the probe movement is indicated and assessed by a reduction of transit time of the acoustic waves between the test heads, and the actual dimension of the fuel assembly region to be checked is derived while accounting for the dimension of probe movement.
	abstract	A production method for a sensor unit that includes a scintillator and a support plate on which a stack of collimator sheets is attached. The production method permits precise positioning of the collimator sheets in respect of the scintillator. In the process, individual scintillator strips are initially produced from a plurality of scintillator pixels adjoining one another along one dimension. Respectively one photodiode strip, made of a plurality of photodiodes in turn adjoining one another along one dimension, is attached to each of the individual scintillator strips along a longitudinal side in order to form a sensor strip. In an embodiment, respectively one photodiode is associated with respectively one scintillator pixel for readout purposes. The sensor strips are subsequently individually assembled on an outer side of the support plate facing away from the collimator sheets in order to form the scintillator.
	description	The present invention relates to a scintillator plate for use in formation of a radiation image of the object. There have been broadly employed radiographic images such as X-ray images for diagnosis of the conditions of patients on the wards. Specifically, radiographic images using a intensifying-screen/film system have achieved enhancement of speed and image quality over its long history and are still used on the scene of medical treatment as an imaging system having high reliability and superior cost performance in combination. However, these image data are so-called analog image data, in which free image processing or instantaneous image transfer cannot be realized. Recently, there appeared digital system radiographic image detection apparatuses, as typified by a computed radiography (also denoted simply as CR) and a flat panel RADIATION detector (also denoted simply as FPD). In these apparatuses, digital radiographic images are obtained directly and can be displayed on an image display apparatus such as a cathode tube or liquid crystal panels, which renders it unnecessary to form images on photographic film. Accordingly, digital system radiographic image detection apparatuses have resulted in reduced necessities of image formation by a silver salt photographic system and leading to drastic improvement in convenience for diagnosis in hospitals or medical clinics. The computed radiography (CR) as one of the digital technologies for radiographic imaging has been accepted mainly at medical sites. However, image sharpness is insufficient and spatial resolution is also insufficient, which have not yet reached the image quality level of the conventional screen/film system. Further, there appeared, as a digital X-ray imaging technology, an X-ray flat panel detector (FPD) using a thin film transistor (TFT), as described in, for example, the article “Amorphous Semiconductor Usher in Digital X-ray Imaging” described in Physics Today, November, 1997, page 24 and also in the article “Development of a High Resolution, Active Matrix, Flat-Panel Imager with Enhanced Fill Factor” described in SPIE, vol. 32, page 2 (1997). The flat panel radiation detector (FPD) is featured in that the apparatus has become more compact than the CR and image quality at a relatively high dose is superior. Meanwhile, an photographing at a relatively low dose results in lowered S/N ratio due to electrical noises of TFT or a circuit itself and has not yet attained a sufficient image quality level. To convert radiation to visible light is employed a scintillator panel made of an X-ray phosphor which is emissive for radiation. The use of a scintillator panel exhibiting enhanced emission efficiency is necessary for enhancement of the SN ratio in radiography at a relatively low dose. Generally, the emission efficiency of a scintillator panel depends of the scintillator thickness and X-ray absorbance of the phosphor. A thicker phosphor layer causes more scattering of emission within the phosphor layer, leading to deteriorated sharpness. Accordingly, necessary sharpness for desired image quality level necessarily determines the layer thickness. Specifically, cesium iodide (CsI) exhibits a relatively high conversion rate of from X-rays to visible light. Further, a columnar crystal structure of the phosphor can readily be formed through vapor deposition and its light-guiding effect inhibits scattering of emitted light within the crystal, enabling an increase of the phosphor layer thickness (as described in, for example, Patent document 1). As is known in the art, an element such as thallium, sodium or rubidium, a so-called activator, was contained in cesium iodide to achieve enhanced emission efficiency. It was also attempted that a reflection plane was provided at the end of a scintillator which was placed far from the light receiving element to achieve enhanced transmission of light from the scintillator to the light receiving element (as described in, for example, Patent document 2). Light which propagates within a crystal via the light-guiding effect is classified to a light heading from the base of the crystal to the top or a light heading from the top to the base. The light heading from the top to the base results in an increased scattering component when reflected by the substrate. Increased luminance results in an increased quantity of light transmitting within a crystal, leading to an increase of scattered light and resulting in problems such as a lowering of sharpness. Patent document 1: JP 63-215987A Patent document 2: JP 7-21560B It is an object of the present invention to provide a scintillator plate which is superior in sharpness and luminance. The object of the invention can be achieved by the following constitution. 1. A scintillator plate comprising sequentially on a substrate a reflection layer and a scintillator layer containing cesium iodide and an activator and having a thickness of L, wherein the following requirement (1) is met:2≦B/A Requirement (1)wherein A is an average activator concentration of the scintillator layer and B is an activator concentration in a region of the scintillator layer from the reflection layer side to the position of L/5.2. The scintillator plate as described in foregoing 1, wherein the scintillator layer is comprised of columnar crystals.3. The scintillator plate as described in foregoing 1 or 2, wherein an average activator concentration is from 0.001 to 50 mol %, based on cesium iodide.4. The scintillator plate as described in any of foregoing 1 to 3, wherein the activator is a thallium compound.5. The scintillator plate as described in any of foregoing 1 to 4, wherein the columnar crystals are crystals formed on the substrate by a process of heating an evaporation source containing cesium iodide and a thallium compound to perform vapor deposition onto the substrate.6. The scintillator plate as described in foregoing 4 or 5, wherein the thallium compound is thallium bromide, thallium chloride, thallium iodide or thallium fluoride.7. The scintillator plate comprising on a substrate a reflection layer and a scintillator layer containing cesium iodide and an activator in the sequence set for the as described in any of foregoing 2 to 6, wherein the following requirement is met:30≧b/a≧1.5wherein “a” is an average equivalent circular diameter of the columnar crystals of the scintillator layer at the position of 10 μm from the substrate and “b” is an average equivalent circular diameter at the top of the columnar crystals. According to the present invention, there was provided a scintillator plate which was superior in sharpness and luminance. 1: Substrate 2: Scintillator layer 10: Scintillator plate 20: Vapor deposition apparatus 21: Vacuum pump 22: Vacuum vessel 23: Resistance heating crucible 24: Rotation mechanism 25: Substrate holder In the following, there will be detailed the present invention. The scintillator plate of the present invention comprises, on a substrate, a reflection layer and further thereon, a scintillator layer containing cesium iodide and an activator and having a thickness of L, featured in that the following requirement (1) is met:2≦B/A Requirement (1)wherein A is an average activator concentration of the scintillator layer and B is an activator concentration within a range of from the reflection layer surface to a thickness of L/5. Further, the scintillator plate comprising on a substrate a reflection layer and a scintillator layer containing cesium iodide and an activator in that order, featured in that the following requirement is met:30≧b/a≧1.5wherein “a” is an average equivalent circular diameter of columnar crystals of the scintillator layer at the position of 10 μm from the substrate and “b” is an average equivalent circular diameter at the top of the columnar crystals. The scintillator layer relating to the invention is one containing a phosphor (scintillator) emitting an electromagnetic wave (light) from an ultraviolet rays to infrared rays throughout visible light, and the layer comprises a vapor-deposited crystal containing cesium iodide and an activator. Substrate The substrate relating to the present invention is a plate or a film which is capable of supporting a scintillator layer and transmitting radiation such as X-rays to transmit at not less than 10% of the incident dose. The substrate may be of various types of glass, polymeric materials and metals. Examples thereof include a plate glass such as quartz, borosilicate glass or chemically reinforced glass; a ceramic substrate such as sapphire, silicon nitride or silicon carbide; a semiconductor substrate such as silicon, germanium, gallium arsine, gallium phosphorus or gallium nitrogen; polymeric film such as cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, polycarbonate film or carbon fiber-reinforced resin sheet; and a metal sheet such as an aluminum sheet, iron sheet or copper sheet, or a metal sheet having a coverage layer of oxides of the foregoing metals. The substrate is preferably a 50-500 μm thick, flexible polymeric film. The expression “flexible” refers to exhibiting an elastic modulus at 120° C. (E120) of 1000 to 6000 N/mm2. Such a substrate is preferably a polymeric film comprising a polyimide or polyethylene naphthalate. The elastic modulus is obtained from a slope of stress versus strain in the region which exhibits a linear relationship of strain and corresponding stress, represented by a marked line of a sample and obtained by using a tensile tester according to JIS C2318. This value is called Young's modulus. In the present invention, this Young's modulus represents an elastic modulus. The substrate usable in the present invention preferably exhibits an elastic modulus at 120° C. (E120) of 1000 to 6000 N/mm2, as described above, and more preferably from 1200 to 5000 N/mm2. Specifically, there are included polymeric films such as polyethylene naphthalate (E120=4100 N/mm2), polyethylene terephthalate (E120=1500 N/mm2), polybutylene naphthalate (E120=1600 N/mm2), polycarbonate (E120=1700 N/mm2) syndiotactic polystyrene (E120=2200 N/mm2) and polyetherimide (E120=1900 N/mm2). These films may be used singly or in their combination, or may be laminated. A polymeric film comprising polyimide or polyethylene naphthalate is specifically preferred. Reflection Layer A reflection layer relating to the present invention is a layer capable of reflecting an electromagnetic wave of fluorescence which has been generated in a scintillator layer and radiantly propagates toward the substrate. A metal thin-film is used for the reflection layer. Such a metal thin film is preferably one which is comprised of a material containing a substance selected from the group of Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt and Au. A metal thin film may be formed of at least two layers, for example, an Au layer formed on a Cr layer. Of the foregoing, it is a preferred embodiment to employ a layer containing aluminum. Scintillator Layer A scintillator layer relating to the invention is one containing a radiative phosphor upon exposure to radiation and is formed of a vapor-deposited crystal containing cesium iodide and an activator. Such an activator relating to the present invention refers to an element which is incorporated in the cesium iodide, thereby enhancing emission efficiency. Examples of an activator include a thallium compound, a sodium compound and a rubidium compound, of which the thallium compound is preferred. To allow such an activator to be incorporated in cesium iodide, for instance, an evaporation source containing cesium iodide and a thallium compound is heated to perform deposition onto the substrate described above. The vapor-deposited crystal relating to the present invention is a crystal formed by heating an evaporation source including cesium iodide and an activator-containing compound, followed by vapor deposition onto the substrate. In the present invention, an activator is preferably a thallium compound and examples of a thallium compound used for vapor deposition include thallium bromide, thallium chloride, thallium iodide and thallium fluoride. An average activator concentration within the deposited crystals is preferably in the range of from 0.001 to 50 mol %, based on cesium iodide in terms of emission luminance, of which a range of from 0.1 to 20 mol % is more preferred. Such a vapor-deposited crystals are preferably columnar crystals. The effect of the present invention can be achieved when a scintillator layer satisfies the requirement 2 B/A in which A is the average activator concentration of the scintillator layer and B is the average activator concentration in a region of ⅕ of the total scintillator layer thickness on the substrate side, and preferably, 2≦B/A≦10. B>10 causes disorder in crystallinity on the substrate side, resulting in a lowered independency of columnar crystals and making it difficult to form a 400 μm or more thick deposited layer. Further, even when such a ⅕ region of the scintillator layer from the substrate is constituted of two or more layers including a layer containing no Tl, the effect of the present invention can be achieved by meeting the above-described requirement. In the present invention, the Tl concentration can be determined by the procedure described below. A columnar crystal is equally divided into five parts in the growth direction of the crystal and the thus divided parts were each measured with respect to activator concentration. The activator concentration is by an inductively coupled plasma atomic emission spectrometer (ICP-AES). This method is a technique in which light generated when a metal element or the like is excited in plasma is spectroscopically divided to perform qualitative analysis from the wavelength inherent to the individual element and qualitative analysis is derived from the emission intensity, whereby trace amounts of inorganic elements contained in an aqueous solution can be determined quantitatively or qualitatively. Typically, the quantity of thallium is determined in such a manner that concentrated hydrochloric acid is added to the phosphor sample which was peeled from the substrate, thermally dried and is again dissolved by adding aqua regia with heating. The thus obtained solution was optimally diluted with super pure water and subjected to measurement. Activator concentration is represented by a molar ratio (mol %) to cesium iodide. An mean value of activator concentrations of the thus divided regions is defined as an average concentration A and of the regions divided into five parts, the average activator concentration of the region closest to the substrate is defined as an average concentration B. When A and B satisfy the relationship of 2≦B/A, yellow-coloring occurs in the crystal region closest to the substrate, whereby emitted light is absorbed in the yellow-colored portion of the crystal bottom. Accordingly, light heading toward the substrate surface is absorbed, whereby scattered components are reduced, achieving enhanced sharpness. Examples of general methods for preparing a scintillator plate of such a structure include a technique in which evaporation sources differing in activator concentration are used in vapor deposition and the timing of deposition is delayed and a technique in which Tl and CsI are separately evaporated from separate evaporation sources. In the present invention, it is preferred to satisfy the requirement of 30≧b/a≧1.5, wherein “a” is the average equivalent circular diameter of columnar crystal of the scintillator layer at the position of 10 μm from the substrate and “b” is the average equivalent circular diameter at the top of the columnar crystals. The equivalent circular diameter of a columnar crystal is measured in such a manner that a scintillator layer formed of columnar crystals is coated with an electrically conductive substance (e.g., platinum palladium, gold, carbon) and observed by a scanning electron microscope (SEM, e.g., S-800, produced by Hitachi Seisakusho Co., Ltd.), and the equivalent circular diameter of the individual columnar crystal is determined from the obtained image. The average equivalent circular diameter is obtained on an average of 30 columns. The average equivalent circular diameter at the top of the columnar crystals is determined by observation of the crystal surface formed at the time when completing deposition, and the average equivalent circular diameter at the position of 10 μm from the substrate is also determined by observation of the crystal surface obtained by shaving the crystal layer surface with a cutter to the position of 10 μm from the substrate. Herein, the equivalent circular diameter refers to the diameter of a circle circumscribing a section of the individual columnar crystal. When an average equivalent circular diameter (a) of columnar crystals of the scintillator layer, at the position of 10 μm from the substrate and an average equivalent circular diameter (b) at the top of columnar crystals satisfy the requirement of 30≧b/a≧1.5, the smaller crystal diameter on the substrate side results in enhanced independency of crystals and the larger crystal diameter at the top results in increased emitting sectional area, leading to enhanced luminance. Values of 30<b/a result in reduced strength of the columnar crystals. Preparation of a scintillator plate of such a structure can be achieved by any commonly known method, for example, in such a manner that inert gas, e.g., Ar gas is introduced in a relatively large amount at the initial stage of deposition and the amount of Ar gas is decreased toward the later stage. Intermediate Layer In the present invention, an intermediate layer may be provided between the reflection layer and the scintillator layer. Examples of an intermediate layer include a layer containing a resin such as a polyester resin, a polyacrylic acid copolymer, a polyacrylamide, its derivatives or its partially hydrolyzed product; a vinyl polymer such as polyvinyl acetate, polyacrylamide or polyacrylic acid ester or its copolymer; a natural product such rosin or shellac and its derivatives. Scintillator Plate There will be described the scintillator plate of the present invention with reference to FIG. 1. As shown in FIG. 1, a scintillator plate 10 for radiation, of the invention is provided with a phosphor layer 2 on a substrate 1. When the phosphor layer 2 is exposed to radiation, the phosphor layer 2 emits an electromagnetic wave at the wavelength of 300 to 800 nm, centered on visible light, upon absorption of incident radiation energy. There will be described a method of forming the phosphor layer 2 on the substrate 1. The phosphor layer 2 is formed by the process of vapor deposition, which is performed in the following manner. The substrate 1 is set inside a commonly known deposition apparatus and raw material for the phosphor layer 2 including prescribed additives is charged into a deposition source. Thereafter, the inside of the apparatus is evacuated to vacuum at 1.333 Pa to 1.33×10−3 Pa, concurrently with introducing inert gas such as nitrogen from the entrance. Subsequently, at least one of raw materials of a phosphor is vaporized with heating by a method such as a resistance heating method or an electron beam method and deposited on the substrate 1 to form a phosphor layer (2) having a prescribed thickness. This deposition process may be repeated plural times to form the phosphor layer (2). For example, plural deposition sources of an identical constitution are prepared and when completing deposition of one deposition source, deposition of the next deposition source is started. These are repeated until reaching the desired layer thickness to form the phosphor layer (2). With reference to FIG. 2, there will be described a deposition apparatus 20, as one example of deposition apparatuses used when performing vapor deposition. The deposition apparatus is provided with a vacuum pump 21 and a vacuum vessel 22 which is internally evacuated by operation of the vacuum pump 21. A resistance heating crucible 23 as a deposition source is provided in the inside of the vacuum vessel. On the upper side of the resistance heating crucible 23, a substrate (1) is provided via a substrate holder 25 which is pivotable through a rotation mechanism 24. A slit to control a vapor stream of a phosphor vaporized from the resistance heating crucible 23 is provided between the resistance heating crucible 23 and the substrate (1). When operating the deposition apparatus 20, the substrate 1 is used while placed on the substrate holder 25. In the preparation method of forming a phosphor layer on the substrate by a process of vapor deposition, the requirement of 2≦B/A can be achieved by evaporating a raw deposition material having a relatively high activator concentration at the initial deposition stage, wherein A is the average activator concentration of the scintillator layer and B is the average activator concentration in the region of ⅕ of the total scintillator layer thickness on the substrate side. Further, thickening a column diameter from the substrate side toward the top can be attained by introducing an inert gas such as Ar gas in a relatively large amount in the initial stage of deposition and decreasing the Ar gas amount in the later stage. The present invention will be described with reference to examples but is by no means limited to these. Preparation of the substrate was conducted in the same manner as Example 1. Preparation of Scintillator Layer Evaporation materials were prepared in the same manner as in Example 1. Subsequently, the inside of a vapor deposition apparatus was evacuated and then, Ar gas was introduced thereto to control an evacuation degree to 0.1 Pa, thereafter, the temperature of the substrate was maintained at 200° C., while rotating the substrate at a rate of 10 rpm. Then, the resistance heating crucible having a material of a higher Tl concentration was heated to allow a phosphor for a scintillator to be deposited. When the scintillator (phosphor layer) reached a thickness of 100 μm, evaporation of a resistance heating crucible having a material of a lower Tl concentration was started in turn. When the total layer thickness reached 400 μm with reducing the amount of Ar gas introduced at the start of deposition, deposition was completed to obtain a scintillator plate. The amount of Ar gas introduced at the completion of deposition was 13/10 of that of the start of deposition. Samples prepared in Examples 1, 2, 3, 4 and 5, and Comparative Examples 1, 2, 3 and 4 were each measured with respect to activator concentration and evaluated with respect to sharpness and luminance, as below. Measurement of Activator Concentration The obtained scintillator layer of each sample was divided along the crystal growth direction into five equal parts and the thus divided parts were individually measured with respect to activator concentration. The activator concentration was measured in an inductively coupled plasma atomic emission spectrometer (ICP-AES), SPS-4000, produced by Seiko Denshi Kogyo. The quantity of Tl was determined in such a manner that concentrated hydrochloric acid was added to a phosphor sample, thermally dried and was again dissolved by adding aqua regia with heating, and the thus obtained solution was optimally diluted with super pure water and subjected to measurement. Activator concentration was represented by mol %, based on cesium iodide. An average activator concentration of five-divided parts and an average activator concentration of the region closest to the substrate of the regions divided into five equal parts are shown in Table 1. Evaluation of Sharpness The obtained scintillator plates were each mounted on Pax Scan 2520 (FPD produced by Varian Co.) and evaluated with respect to sharpness in accordance with the procedure, as below. X-rays at a tube voltage 80 kVp were exposed onto the radiation-incident surface (the side on which no phosphor layer was formed) of each sample through a lead MTF chart, and the image data were detected and recorded onto a hard disk. Then, the data recorded on the hard disk was analyzed via a computer, and the modulation transfer function MTF (MTF values in % of a spatial frequency of 1 cycle/mm) of the X-ray image recorded on the foregoing hard disk was calculated as a measure of sharpness. The results thereof are shown in Table 1. In Table 1, values indicating sharpness are represented by a relative value, based on the sharpness of Example 1 being 100. Evaluation of Luminance Each sample was exposed to X-rays at a tube voltage 80 kVp from the backside (having no scintillator phosphor layer) of each sample. The instantaneous emission was extracted through an optical fiber and the light-emitting amount was measured by a photodiode (S2281, produced by Hamamatsu Photonics Co.). The obtained value was represented as emission luminance (sensitivity), provided that the emission luminance shown in Table 1 was represented by a relative value, based on the emission luminance of the sample of Example 3 being 1.0. TABLE 1ConcentrationAverageat ⅕ B1Concentration(mol %)A (mol %)B/AMTFRemarkExample 11.30.52.6100Inv.Example 21.10.52.294Inv.Example 31.60.53.2115Inv.Comparative0.90.51.858Comp.Example 1Comparative0.50.5140Comp.Example 21average activator concentration of the ⅕ region of the total layer thickness on the substrate side TABLE 2AverageAverageEquivalentEquivalentCircularCircularDiameter a1Diameter b2(μm)(μm)b/aLuminanceRemarkExample 4252.51Inv.Example 511111.00.99Inv.Comparative21.80.90.50Comp.Example 3Comparative22.21.10.63Comp.Example 41Average equivalent circular diameter of columnar crystal at the bottom of 10 μm from the substrate2Average equivalent circular diameter of columnar crystal at the top of the columnar crystal From Table 1, it was proved that scintillator plates according to the present invention were superior in sharpness. From Table 2, it was also proved that scintillator plates according to the present invention exhibited enhanced luminance.
	description	This invention generally concerns systems and methods for radioactive decontamination of deposits at ambient temperature on components in a nuclear power plant and is specifically concerned with disrupting, dissolving, removing and reducing at ambient temperature radionuclides formed on the primary side surfaces of components in a pressurized water reactor and the internal components of a boiling water reactor. In nuclear water reactors, such as pressurized water reactors and boiling water reactors, it is typical for oxide scale-containing radionuclides to be adhered to or generated on surfaces of structures, e.g., components and related parts or piping, which are in contact with fluid, e.g., coolant, over extended time periods during reactor operation. Nuclear water reactors are generally thermal reactors in which water is used as the coolant. The water passes through numerous metal components, such as stainless steel and Alloy 600, Alloy 690 or Alloy 800 conduits. Even though these materials of construction are highly resistant to corrosion, thin oxide coatings (or films) develop over time on the surface areas of components and related parts or piping which are wetted by the coolant during power operation of the reactors. It has been found that portions of the oxide coatings may dissolve into the coolant and may be transported by the coolant throughout the systems, e.g., reactor coolant system. The accumulation of scale and deposits on the surfaces of the structures can have an adverse impact on the operational performance and integrity of the structures. The primary side, e.g., reactor coolant system, surfaces of components in pressurized water reactors (PWRs) and the internal components in boiling water reactors (BWRs) contain radionuclides which are formed during reactor operation. The radionuclides are typically radiocobalt in a nickel ferrite lattice. A variety of systems and methods have been developed in the art to remove or reduce the presence of radionuclides on internal components of BWRs and primary side surfaces of PWR components. It is known in the art to reduce radionuclides by chemical injection. For example, a zinc compound can be injected into the coolant water of a nuclear water reactor at full power to reduce or remove radionuclides. Further, it is known to employ a high temperature process wherein a cleaning solution is prepared, heated and injected into the entire system or injected locally. Many of these known decontamination methods have proven to be cumbersome and require handling of high temperature fluid and multiple chemical steps, such as oxidation and reduction. Thus, known radioactive decontamination typically involves elevated temperature dissolution or mechanically induced turbulence or a combination thereof depending on the intended component to be decontaminated. Further, known techniques require the flow of high temperature fluids, mechanical hand cleaning the case of coolant pumps) and a length of time under mechanical agitation. Furthermore, these techniques require chemistry conditions to be aggressive, e.g., switching from oxidizing to reducing conditions. Generally, known techniques employ temperature, pH and redox potential shifts for the removal or reduction of radionuclides and these techniques are rarely performed at a nuclear reactor plant due to the amount of radioactive waste generated. It is desired in the art to develop a method for localized decontamination and deposit removal which does not require added heat, e.g., can be conducted at ambient temperature, or liquid flow. In one aspect, the invention provides a method for at least partially disrupting or removing radioactive deposits formed on a surface of a structure in a nuclear water reactor. The method includes identifying the structure, taking the structure out of operational service, contacting the surface of the structure with an aqueous solution, and adding an effective amount of an elemental metal in solid form to the aqueous solution. The method is conducted at ambient temperature. The radioactive deposits can include one or more materials selected from the group consisting of radionuclides, oxide scale and corrosion products. The elemental metal can be selected from the group consisting of metals with standard electrochemical potentials anodic to low alloy steel. The electrochemical potential of the elemental metal can be more active than the potential of low alloy steel in the galvanic series of metals and alloys. The elemental metal can be selected from the group consisting of zinc, aluminum, magnesium, beryllium, lithium, iron and mixtures thereof. In certain embodiments, the elemental metal can be zinc. The elemental metal can be in a form selected from the group consisting of slab, granular, powder, colloidal, and combinations thereof. The colloidal form can contain particles selected from the group consisting of micron-sized particles, nano-sized particles and combinations thereof. The method can include adding to the aqueous solution one or more of a material selected from the group consisting of sequestering agent, chelating agent, dispersant, oxidizing agent, reducing agent and mixtures thereof. The method can be performed during out of operational service conditions selected from the group consisting of shutdown and layup. The method can further include disassociating metal ions from the radioactive deposits, precipitating the metal ions and removing the precipitate by employing a process selected from the group consisting of filtration, ion exchange and reverse osmosis. The method can further include one of purifying the disrupted and radioactive deposits, transferring said deposits to a containment sump, adding said deposits to a radioactive waste system and transporting said deposits to a location remote from the nuclear water reactor. In another aspect, the invention provides a composition effective to at least partially disrupt and dissolve radioactive deposits formed on a surface of a structure in a nuclear water reactor when the composition is in contact with the surface of the structure during non-operational conditions. The composition includes an aqueous component and an elemental metal component in a solid form. The composition is effective to disassociate a metal ion from an oxide lattice of the radioactive deposits. The invention relates to systems and methods for the at least partial disruption, dissolution, removal and reduction of radioactive deposits in nuclear water reactors at ambient temperature. The radioactive deposits include radionuclides, oxide scale, and corrosion products, deposited on primary side, e.g., reactor coolant system, component surfaces and associated piping in pressurized water reactors and from internal component surfaces in boiling water reactors. Deposits containing radionuclides can form and build-up on these surfaces as a result of reactor operation. In addition, other corrosion products can also be deposited on these surfaces during reactor operation. For instance, the deposits can include contaminants such as aluminum, manganese, magnesium, calcium, nickel, and/or silicon morphologies. Removal and reduction of these products can be effective to reduce the local dose rate in the system(s) surrounding the components, to prevent or preclude flow obstructions (which occur due to corrosion product build-up), and to inhibit corrosion caused by the presence of radioactive oxide scale. The methods of the invention employ electrochemical techniques at ambient temperature to at least partially disrupt, dissolve, remove and reduce the radioactive oxide scale. The composition of the radioactive oxide scale can vary and typically can include at least one of iron, nickel, cobalt, chromium and their radioisotopes. The invention employs an aqueous solution having an aqueous component and a solid metal component. The aqueous component includes water, e.g., reactor coolant water. The metal component includes elemental metal in solid form. The aqueous solution is effective to disassociate metal ions from an oxide lattice of radioactive deposits. The elemental metal is selected from known metals with standard electrochemical potentials anodic to low alloy steel. In certain embodiments, the electrochemical potential of the elemental metal is more active than the potential of low alloy steel in the galvanic series of metals and alloys. Suitable examples of elemental metal for use in the invention include, hut are not limited to, zinc, aluminum, magnesium, beryllium, lithium, iron or mixtures thereof. In certain embodiments, the elemental metal is zinc. The elemental metal can be in various solid or particulate forms, such as but not limited to, slab, granular, powder, colloidal, and combinations thereof. In certain embodiments, wherein the elemental metal is in colloidal form, it can include micron-sized particles, nano-sized particles and combinations thereof. The elemental metal can be present in varying amounts, and the amount can depend on the volume of the system, component and/or associated equipment intended for decontamination. In certain embodiments, the elemental metal concentration can be from about 0.001 M to about 2 NI based on volume of the aqueous solution. The of the aqueous solution can vary. In certain embodiments, the pH can be adjusted within a range from about 3.0 to about 13.0. Further, the aqueous solution may be borated and contain up to 6 ppm of lithium. The methods of the invention generally include addition of the elemental metal in solid, e.g., particulate, form to circulating coolant in an effective amount, an amount which is sufficient to at least partially disrupt, dissolve, remove or reduce the amount or level of radioactive deposits present on the surface of a structure located in the primary side of a pressurized water reactor or in a boiling water reactor. The methods of the invention can be conducted at ambient temperature and therefore, in the absence of system heat or an external heat source being applied to the structure or the system which contains the structure. Thus, the methods of the invention can be employed when the components and associated piping are taken out of operational service, e.g., during layup or shutdown conditions in a nuclear water reactor. Further, the methods of the invention generally include identifying a component and/or associated equipment, e.g., piping, to be electrochemically decontaminated, taking the component and/or associated equipment out of operational service, isolating the component and/or associated equipment from the remainder of the primary side, e.g., reactor coolant system, employing a recirculating flow of aqueous solution in contact with the component and/or associated equipment or a static immersion of the component and/or associated equipment in aqueous solution, and adding, e.g., injecting, an effective amount of elemental metal in solid or particulate form into the aqueous solution. Without intending to be bound by any particular theory, it is believed that the elemental metal releases one or more of its electrons which is/are accepted by the radioactive deposits, e.g., oxide scale film, present on the surface of the intended structure(s) for radioactive decontamination. A metal ion is released from the deposits and as a result, the surface charge of the deposits is modified, e.g., a charge imbalance occurs. The lattice of the radioactive deposits is destabilized and there is an increased rate of metal ion release, e.g., dissociated metal ions. In certain embodiments, elemental zinc reacts with iron oxide deposits causing the release of iron ions from the lattice. In certain embodiments, the elemental metal can be combined with a sequestering agent, a cheating agent or a mixture or blend thereof. The sequestering and/or chelating agent can be added to the aqueous solution prior to, in conjunction with, or following the addition of the elemental metal. Suitable sequestering and chelating agents can be selected from those known in the art. Non-limiting examples of sequestering agents include acids and salts of orthophosphates, polyphosphates, 1-hydroxy ethylidene-1, 1-diphosphonic acid, and mixtures thereof. Non-limiting examples of chelating agents include ligands selected from ethylenediamine tetraacetic acid (EDTA), hydroxyethyl ethylenediamine triacetic acid (HEDTA), lauryl substituted EDTA, polyaspartic acid, oxalic acid, glutamic acid, diacetic acid (GLDA), ethylenediamine-N,N′-disuccinic acid (EDDS), gluconic acid, glucoheptonic acid, N,N′-ethylenebis-[2-(o-hydroxyphenyl)]-glycine (EHPG), pyridine dicarboxcylic acid (PCDA), nitrilotriacetic acid (NTA), acids and salts thereof, and mixtures thereof. The sequestering and/or chelating agents can be utilized in varying amounts. In certain embodiments, the sequestering and/or chelating agents are present in an amount of from about 0.025 to about 5.0 weight percent based on weight of the solution composition. The use of one or more of these agents can be effective to complex ions released from the deposits, e.g., dissociated metal ions. In certain embodiments, iron, nickel, cobalt and their corresponding isotopes can be complexed from the lattice of radioactive deposits using a sequestering agent, chelating agent or a blend thereof. The dissociated metal ions can also be complexed by allowing the dissociated metal ions to precipitate and removing the colloidal precipitate using a dispersant. Suitable dispersants can be selected from those known in the art. Non-limiting examples of dispersants include polyacrylic acid, amine neutralized polyacrylic acid, polyacrylamide, polymethacrylate, and mixtures thereof. A non-limiting example of a suitable dispersant is commercially available under the trade name OptiSperse PWR 6600 from General Electric Company. The dissociated metal ion can be precipitated from the oxide deposits and the colloidal precipitate can be removed by employing filtration, reverse osmosis, or ion exchange. In certain embodiments, the aqueous solution may be circulated through a spectrophotometer to determine the concentration of complexed metals contained therein. Further, the expended aqueous solution may be drained through an in-line ion exchange bed, stacked filtration assembly or low micron size filter. Without intending to be bound by any particular theory, it is believed that hydrogen gas is generated in situ during the decontamination process and facilitates mixing and mechanical agitation of the solution and particulate. Further, the aqueous solution can be sparged with an inert gas or air for mixing, and the system which contains the intended component and/or associated equipment for decontamination can be under oxidizing or reducing conditions. For oxidizing conditions, an oxygen scavenger can be employed. Suitable oxygen scavengers can be selected from those known in the art. For reducing conditions, a reducing agent can be employed. Suitable reducing agents can be selected from those known in the art. Non-limiting examples of reducing agents include ascorbic acid, citric acid, hydrazine, carbohydrazide, catalyzed hydrazine, hydroquinone, methylethylketoxime, diethylhydroxylamine, erythorbate and mixtures thereof. In certain embodiments, the elemental metal can be added to a local area of the nuclear reactor. Non-limiting examples include adding the elemental metal to a local area containing a jet pump orifice or a reactor coolant pump. In certain embodiments, the deposits, e.g., radionuclides and/or radioactive oxide scale, can be conditioned with a noble metal. This conditioning step may be performed prior to adding the elemental metal to the aqueous solution. In certain embodiments, the system is adiabatic. The deposits, e.g., radionuclides and/or radioactive oxide scale, are at least partially disrupted and/or removed from a surface of a component and/or associated equipment, and are processed. The processing can include purifying the deposits generated by removing the particulate or transferring the deposits to a containment sump or adding the deposits to the radioactive waste system or transporting the deposits from the plant site to another location. Without intending to be bound by any particular theory, it is believed that in accordance with the invention, solid zinc in its elemental form can react with radioactive deposits to produce a byproduct containing zinc ions. In certain embodiments, zinc ions are used during normal operation as inhibitors to stress corrosion cracking. The byproduct zinc ions prevent excessive release of zinc from primary surface oxides which have formed as a result of on-line zinc addition, by the common ion effect. The methods of the invention do not require a rinsing step and may provide carbon molecules which may be beneficial for crud build-up on the nuclear fuel. The methods of the invention are effective to at least partially disrupt, dissolve, remove and reduce deposits in the absence of elevated temperatures, e.g., system heat and/or an external heat source is not required. Thus, the elemental metal in a colloidal or particulate form can be applied at ambient temperature when the system is in a shutdown or layup condition. While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular embodiments disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof. Nickel ferrite dissolution tests were performed in a laboratory under ambient dissolved oxygen boric acid conditions (at shutdown concentrations) and under alkaline non-borated conditions. Samples 1-4 were prepared as follows. Test volumes were 200 ml for each sample. Samples 1 and 2 included boric acid (approximately 2500 ppm boron), and Samples 3 and 4 were alkaline and did not include boric acid. Specifically, Samples 1 and 2 included approximately 1.84 grams of citric acid and 1.29 grams of boric acid. Approximately 0.78 grams of zinc were added to Sample 1, while Sample 2 did not contain any zinc. For Samples 3 and 4, an initial wet layup solution was prepared such that each sample contained approximately 0.009 grams of carbohydrazide and 0.2 mL of ethanolamine, and pH adjustment with added ammonium hydroxide. The final pH of the wet layup solution was approximately 10.2. Approximately 4 grams of EDTA was added to both Sample 3 and Sample 4. Subsequently, 0.8 grams of zinc was added to Sample 4, while Sample 3 did not contain any zinc. After the chemistries for each of Samples 1-4 were established, 2.5 grams of nickel ferrite was added to each and the bottles were capped. During testing, 2-3 samples were pulled from each of the Samples 1-4, and the time was recorded for each sample pull. The sample size was approximately 1 ml. The samples were filtered through a 0.45 μm-syringe filter. The tests were conducted for 23.5 hours. The pulled samples were then prepped with 100 μL of piranha bath solution containing sulfuric acid and hydrogen peroxide, diluted by a factor of 1:20, and analyzed for iron and nickel via inductively coupled plasma (ICP) spectroscopy. The results indicate a six-fold increase in the dissolution rate of corrosion products under both acidic borated conditions and alkaline non-borated conditions, as shown in FIG. 1 and FIG. 2. FIG. 1 shows the influence of elemental zinc on dissolution of nickel ferrite deposits under boric acid conditions, i.e., Samples 1 and 2. FIG. 2 shows the influence of elemental zinc on dissolution of nickel ferrite deposits under reducing conditions, i.e., Samples 3 and 4. The six-fold increase in the slope of measured iron concentration is indicative of the six-fold increase in dissolution rate under both chemistry regimes.
	claims	1. An apparatus comprising:a nuclear reactor comprising an upper head, a reactor vessel shell coupled to the upper head, the reactor vessel shell comprising a cylindrical shape, a lower head provided on a lower portion of the reactor vessel shell, and a core located within an interior of the nuclear reactor;a steam generator surrounding a circumference of the reactor vessel shell, the steam generator comprising a first penetration hole in fluid communication with the interior of the nuclear reactor such that a fluid flows between the interior of the nuclear reactor and an interior of the steam generator; anda steam drum surrounding a circumference of the steam generator and comprising a second penetration hole in fluid communication with an interior of the steam generator such that a fluid flows between an interior of the steam drum and the interior of the steam generator, wherein the steam generator further comprises:a steam generator inner shell connected to or formed in one piece with the reactor vessel shell and surrounding 360 degrees the circumference of the reactor vessel shell, wherein the steam generator inner shell shares a portion with the reactor vessel shell and extends in a longitudinal direction of the reactor vessel shell; anda steam generator outer shell spaced apart from the steam generator inner shell and surrounding 360 degrees the circumference of the reactor vessel shell, wherein the steam generator outer shell extends in the longitudinal direction of the reactor vessel shell,wherein the steam drum further comprises:a steam drum inner shell connected to or formed in one piece with the steam generator outer shell and surrounding 360 degrees the circumference of the steam generator, wherein the steam drum inner shell shares a portion with the steam generator outer shell and extends in the longitudinal direction of the reactor vessel shell; anda steam drum outer shell spaced apart from the steam drum inner shell and surrounding 360 degrees the circumference of the steam generator, the steam drum outer shell extending in the longitudinal direction of the reactor vessel shell,wherein the first penetration hole is provided in a region in which the reactor vessel shell and the steam generator inner shell are connected to or formed in one piece with each other and is used as a flow path allowing a fluid to flow between the interior of the nuclear reactor and the interior of the steam generator,wherein the second penetration hole is provided in a region in which the steam generator outer shell and the steam drum inner shell are connected to or formed in one piece with each other and is used as a flow path allowing a fluid to flow between the interior of the steam generator and the interior of the steam drum. 2. The apparatus of claim 1, wherein the steam generator further comprises:a steam generator upper head connecting an upper portion of the steam generator inner shell to an upper portion of the steam generator outer shell; anda steam generator lower head connecting a lower portion of the steam generator outer shell to the reactor vessel shell,wherein the steam generator upper head has a semicircular or semielliptical cross section and extends in a ring shape along the circumference of the steam generator, and the steam generator lower head has a circular-arc cross section and extends in a ring shape along the circumference of the steam generator. 3. The apparatus of claim 2, wherein a manway is detachably coupled to the steam generator upper head or the steam generator lower head. 4. The apparatus of claim 1, wherein a plurality of first partition plates are arranged at intervals inside the steam generator along the circumference of the steam generator, and steam generator modules each comprising a high-temperature part and a low-temperature part are provided in spaces separated by the first partition plates, andeach of the steam generator modules comprises a second partition plate separating the high-temperature part and the low-temperature part from each other. 5. The apparatus of claim 4, wherein the first penetration hole comprises a first entrance penetration hole communicating with the high-temperature part and a first exit penetration hole communicating with the low-temperature part;a cylindrical core support barrel assembly extending in the longitudinal direction of the reactor vessel shell and accommodating the core is provided inside the nuclear reactor; andthe core support barrel assembly comprises a core penetration hole communicating with the first entrance penetration hole, and the first exit penetration hole communicates with a space between the reactor vessel shell and the core support barrel assembly. 6. The apparatus of claim 1, wherein a lower heat transfer tube sheet is provided in a lower portion of the steam generator, the lower heat transfer tube sheet being coupled to the steam generator inner shell and the steam generator outer shell and having a plate shape along the circumference of the steam generator;an upper heat transfer tube sheet is provided in an upper portion of the steam generator, the upper heat transfer tube sheet being coupled to the steam generator inner shell and the steam generator outer shell having a plate shape along the circumference of the steam generator; andthe externally integrated steam generator type small modular reactor further comprises a heat transfer tube coupled to the lower heat transfer tube sheet and the upper heat transfer tube sheet and extending straight from the lower heat transfer tube sheet to the upper heat transfer tube sheet. 7. The apparatus of claim 6, wherein the lower heat transfer tube sheet or the upper heat transfer tube sheet is connected to or formed in one piece with the steam generator inner shell and the steam generator outer shell. 8. The apparatus of claim 1, wherein the steam drum further comprises:a steam drum upper head connecting an upper portion of the steam drum inner shell to an upper portion of the steam drum outer shell; anda steam drum lower head connecting a lower portion of the steam drum outer shell to the steam generator outer shell,wherein the steam drum upper head has a semicircular or semielliptical cross section and extends in a ring shape along a circumference of the steam drum, and the steam drum lower head has a circular-arc cross section and extends in a ring shape along the circumference of the steam drum. 9. The apparatus of claim 8, wherein a steam outlet nozzle is formed in the steam drum upper head. 10. The apparatus of claim 8, wherein a moisture separator and a steam dryer are provided in the steam drum. 11. The apparatus of claim 8, further comprising a circular-arc shaped shroud extending from an inside of the steam drum lower head to an inside of the steam generator outer shell, the shroud extending in a ring shape along a circumference of the steam drum lower head and a circumference of the steam generator outer shell. 12. The apparatus of claim 1, wherein a pressurizer plate in which a surge hole is formed to allow a fluid to pass therethrough and an electric heater is installed to heat a fluid is provided in the nuclear reactor. 13. The apparatus of claim 12, wherein a protrusion protruding inward from the nuclear reactor and having a stud bolt hole is provided on the nuclear reactor, andthe pressurizer plate is coupled to the protrusion using a stud bolt. 14. The apparatus of claim 1, wherein a cylindrical shell flange protrudes inward from the reactor vessel shell and comprises a stud bolt hole,an upper head flange protrudes outward from the upper head and comprises a stud bolt hole, andthe upper head and the reactor vessel shell are coupled to each other by joining the cylindrical shell flange and the upper head flange using a stud bolt. 15. The apparatus of claim 1, wherein the apparatus is manufactured by coupling a plurality of forged members to each other. 16. The apparatus of claim 1, wherein a space formed on an upper portion of the reactor vessel shell and surrounded by the steam generator inner shell is configured to be filled with a fluid.
	abstract	The invention relates to a method of exposing a target by means of a plurality of beamlets. First, a plurality of beamlets is provided. The beamlets are arranged in an array. Furthermore, a target to be exposed is provided. Subsequently, relative movement in a first direction between the plurality of beamlets and the target is created. Finally, the plurality of beamlets is moved in a second direction, such that each beamlet exposes a plurality of scan lines on the target. The relative movement in the first direction and the movement of the plurality of beamlets in the second direction are such that the distance between adjacent scan lines exposed by the plurality of beamlets is smaller than a projection pitch Pproj,X in the first direction between beamlets of the plurality of beamlets in the array.
	description	The present invention relates to an X-ray lens assembly and a method of manufacturing the assembly. The invention further relates to an X-ray device such as an X-ray spectrometer or an X-ray diffractometer comprising an X-ray lens assembly. The advent of so-called X-ray lenses (also called “Kumakhov lenses”) over two decades ago has prepared the ground for lightweight, portable X-ray devices with a broad spectrum of applications in areas as different as metallurgy, geology, chemistry, forensic laboratories and customs inspection. In a similar way as conventional optical lenses redirect visible or near-visible photons, X-ray lenses redirect electromagnetic radiation in the X-ray radiation band and may thus be used to collimate or focus a beam of X-rays. An X-ray lens is conventionally formed from a plurality of capillaries. Each capillary guides the X-rays captured at a front end thereof to the opposite end by way of total external reflection. This rule applies so long as the angle of incidence at the front end does not exceed a critical angle. If the critical angle is exceeded, X-rays can no longer be captured within the capillary. In such a case, the capillary becomes transparent to the X-rays. Originally, an X-ray lens was a bulky device with dimensions in the region of up to several meters. These large dimensions were mainly the result of separate support structures that were required to keep the individual capillaries in place. Commercial use of X-ray lenses became feasible when it was recognized that the support structures can be omitted if the X-ray lens is produced out of one or more glass capillary bundles using glass drawing techniques. By fusing the capillary mantles together, separate support structures became obsolete. Today, the commercial application of X-ray lenses includes portable X-ray spectrometers, lightweight X-ray diffractometers and many other small-sized devices. Such devices typically comprise an X-ray source (such as an X-ray tube), an X-ray lens and a detector. X-rays emitted from the X-ray source are focused by the X-ray lens onto a tiny spot on a sample. The detector detects the X-rays emitted back from the sample and generates an output signal that can for example be spectrally analysed to determine the chemical elements included in the sample. In X-ray devices the X-ray lenses have to be reliably mounted to ensure a proper operation of the X-ray devices. Often, the X-ray lenses have to be mounted such that the distance of the lens to either one or both of the X-ray source and the sample is adjustable. Due to the fragileness of capillary X-ray lenses the transport, mounting and adjustment of X-ray lenses often poses a challenge. The mounting of X-ray lenses is further complicated by the fact that X-ray lenses may have varying individual dimensions. Accordingly, there is a need for an X-ray lens assembly that facilitates at least one of transport, mounting and adjustment of a capillary X-ray lens. Also, there is a need for an X-ray device including such an X-ray lens assembly and a method for manufacturing the X-ray lens assembly. According to a first aspect of the invention, an X-ray lens assembly comprising a tube member including an inlet opening for X-rays and an outlet opening for X-rays as well as a capillary X-ray lens mounted inside the tube member is provided. The tube member may have internal and external cross-sections of arbitrary shapes. The cross-sections may for example have a circular, oval or polygonal shape. The X-ray lens may comprise one or more capillaries. The capillaries may be grouped into one or several capillary bundles. In one variation, the X-ray lens is mounted inside the tube member by a stabilizing agent. Preferably, the stabilizing agent (e.g. a glue) possesses at least one of hardening and interconnecting properties. In a region between the inlet opening and the outlet opening of the tube member at least one chamber may be defined between the X-ray lens and the tube member. The at least one chamber may serve for various purposes. In one embodiment, the at least one chamber is filled with the stabilizing agent. Between the inlet opening and the outlet opening of the tube member one or more further openings may be provided. Preferably, the one or more further openings are communicating with the at least one chamber. The further openings may be used to fill the stabilizing agent into the chamber. Additionally or in the alternative, the one or more openings may serve as air outlets (e.g. during the insertion of the X-ray lens into the tube member and/or during the filling of the chamber with the stabilizing agent). In addition to the stabilizing agent, or in the alternative, one or more mounting structures may be provided for mounting the X-ray lens inside the tube member. Two axially spaced mounting structures may be provided for limiting the at least one chamber in an axial direction of the tube member. One or more of the mounting structures may have a substantially circular opening in which the X-ray lens is received. The one or more mounting structures may comprises at least one elastic member such as an elastic ring (e.g. an O-ring). The at least one mounting structure may allow for an axial displacement of the X-ray lens within the tube member. An axial adjustment may become necessary when adjusting the position of the X-ray lens in relation to the tube member. Moreover, an axial adjustment may be required in context with positioning the X-ray lens in relation to at least one of an X-ray source and a sample to be irradiated with X-rays. The tube member is preferably made from a material substantially intransparent to X-rays such as steel. In one embodiment, the axial length of the tube member is equal to or larger than the axial length of the X-ray lens. According to a further aspect of the invention, an X-ray device is provided. The X-ray device comprises an X-ray source and an X-ray lens assembly including a tube member having an inlet opening for X-rays and an outlet opening for X-rays as well as a capillary X-ray lens mounted inside the tube member. According to a still further aspect of the invention, a method of manufacturing an X-ray lens assembly is provided. The method comprises the steps of providing a tube member having an inlet opening for X-rays and an outlet opening for X-rays, providing a capillary X-ray lens, and mounting the X-ray lens inside the tube member. The step of mounting the X-ray lens inside the tube member may include the sub-step of arranging the at least two lens mounting structures at an axial distance between the tube member and the X-ray lens. Additionally or in the alternative, the mounting step may include the sub-steps of defining at least one chamber between the tube member and the X-ray lens, and filling a stabilizing agent into the at least one chamber. In the following, the invention will exemplarily be described with reference to a preferred embodiment in the form of an X-ray spectrometer comprising an X-ray lens assembly comprising two axially spaced mounting structures that define a chamber filled with a stabilizing agent. It should be noted that the invention can also be practiced in other X-ray devices such as diffractometers and using different mechanisms for mounting the X-ray lens inside the tube member. For example, the stabilizing agent may be omitted if the mounting structures allow for a sufficiently reliable connection between the X-ray lens and the tube member. Alternatively, the mounting structures may be completely omitted (or subsequently removed) if the stabilizing agent allows for a secure and durable mounting of the X-ray lens in the tube member. Also, the number and types of mounting structures may be varied. FIG. 1 shows a cross sectional view of an X-ray spectrometer 10 according to an embodiment of the present invention. The spectrometer 10 includes an X-ray source 12 constituted by an X-ray tube. The spectrometer 10 further comprises a shutter 14, a positioning/shielding module 16, a sample housing 18 with a sample 20 arranged on a sample positioning platform 22, and a detector 24. An X-ray beam generated within the X-ray source 12 and indicated by reference numeral 26 passes along an optical axis 30 through the shutter 14. A capillary X-ray (or Kumakhov) lens 28 mounted inside a tube member 50 focuses the X-ray beam onto a tiny spot on the sample 20 (note that the size of the sample 20 is exaggerated in the schematic drawing of FIG. 1). The detector 24 collects the X-rays emitted back from the sample 20 and outputs a spectrum signal indicative of the chemical elements included in the sample 20. In the view of FIG. 1, the X-ray source 12 and the shutter 14 have been rotated by 90° about the optical axis 30 of the spectrometer 10 to better illustrate their structure. The spectrometer 10 shown in FIG. 1 has a compact tabletop design and is transportable for in-situ analysis. The samples may be provided in a wide range of physical forms, including solids, powders, pressed pellets, liquids, granules, films and coatings. The typical element detection capabilities of the spectrometer 10 under atmospheric conditions range from aluminum (Al) to uranium (U). The spectrometer 10 allows for a qualitative and quantitative elemental analysis down to very low elemental concentrations and sample sizes of 20 μm. Like conventional X-ray tubes, the X-ray source 12 includes a cathode 32 to emit electrons and an anode 34 to collect the electrons emitted by the cathode 32. Thus, a flow of electrical current is established as the result of a high voltage connected across the cathode 32 and the anode 34. The electron flow within the X-ray source 12 is focussed onto a very small spot (the “hot spot”) 36 on the anode 34. The anode 34 is precisely angled at typically 5 to 15 degrees off perpendicular to the electron current so as to allow the escape of some of the X-rays generated at the “hot spot” 36 upon annihilation of the kinetic energy of the electrons colliding with the anode 34. The X-ray beam 26 thus generated is emitted from the “hot spot” 36 essentially perpendicular to the direction of the electron current and essentially along the optical axis 30 at diverging angles. The X-rays emitted from the X-ray source 12 first pass the shutter 14 attached to a housing 38 of the X-ray source 12. The shutter 14 selectively blocks the X-ray beam 26 generated within the X-ray source 12 and thus provides a control mechanism for selectively switching the irradiation of the sample 20 “on” or “off”. The positioning/shielding module 16 is arranged downstream (in relation to X-ray source 12) of the shutter 14 and is rigidly attached to the shutter 14 by means of an interface member (not shown in FIG. 1). The positioning/shielding module 16 includes an X-ray shielding component 40, a positioning component 42 for the X-ray lens 28, and a lens assembly mounting component 44 for rigidly coupling the tube member 50 with the X-ray lens 28 to the positioning component 42. The individual components 40, 42, 44, which are shown only schematically in FIG. 1, are illustrated in more detail in the various views of FIGS. 2 to 4. As becomes apparent from FIGS. 3 and 4, the X-ray shielding component 40 has an outer flange 46 with two screw holes 48 for rigidly attaching the entire positioning apparatus 16 to the shutter 14 (and thus to the X-ray source 12). The outer flange 46 therefore serves as an interface member of the positioning/shielding module 16 in relation to the shutter 14/the X-ray source 12. The X-ray shielding component 40 further comprises structural elements for limiting the X-ray beam essentially to an inlet opening 90 of the tube member 50. As will be explained in more detail below, the X-ray lens 28 is rigidly mounted inside the tube member 50. The tube member 50 in turn is rigidly coupled to the mounting component 44. The mounting component 44 comprises a base member 52 attached to the positioning component 42. The base member 52 has a central opening for receiving the tube member 50. A plurality of tongues 54 with outer threaded portions 56 extend from the opening of the base member 52 and in the axial direction of the tube member 50. The lens mounting component 44 further comprises a collar member 58 with a central opening through which the tube member 50 extends. The collar member 58 can be screwed onto the tongues 54 and cooperates with their outer threaded portions 56. Be means of an additional screw (not shown) extending in perpendicular to the tube member 50 and through the collar member 58, the free end of at least one of the tongues 54 can be moved towards the tubular member 50 as the screw is screwed into the collar member 58. Accordingly, a clamping connection between the tubular member 50 on the one hand and the lens mounting component 44 on the other hand is established. The positioning component 42 is arranged upstream of the lens mounting component 44 and includes two translation stages 60, 62 as well as two goniometer stages 64, 66. As can be seen from FIG. 2, the base member 52 of the lens mounting means 44 is attached to the bottom of the first translation stage 60. The individual positioning stages 60, 62, 64, 66 are arranged one behind the other. Starting with a first translation stage 60 as the most downstream positioning stage, a second translation stage 62, a first goniometer stage 64 and a second goniometer stage 66 as the most upstream positioning stage follow. Each of the positioning stages 60, 62, 64, 68 has a central X-ray passage 68, 70, 72, 74, respectively, through which the tubular member 50 extends. In combination, the first translation stage 60 and the second translation stage 62 form an xy translation stage. Accordingly, the first translation stage 60 has a first axis of translation, namely the x axis, which in FIG. 2 runs perpendicular to the axis of the tubular member 50 and in parallel to the drawing plane. The second translation stage 62 has a second axis of translation, namely the y axis which runs perpendicular to the x axis and perpendicular to the axis of the tubular member 50. By means of respective knobs, the first and second translation stage 60, 62 can be actuated independently from each other. In an alternative embodiment not shown in the drawings, a third translation stage having a third axis of translation (z axis) that runs perpendicular to both the first and second axis of translation may be provided. The two goniometer stages 64, 66 are arranged upstream of the two translation stages 60, 62. In their combination, the first goniometer stage 64 and the second goniometer stage 66 form a theta-phi goniometer that provides for two independent rotations about a common centre of rotation. This common centre of rotation is substantially constituted by the “hot spot” 36 shown in FIG. 1, i.e. by the X-ray emitting portion of the X-ray source 12. An actuation of the first goniometer stage 64 tilts the tube member 50 (with the X-ray lens) about a first tilting axis that runs through the “hot spot” 36 shown in FIG. 1 and in the drawing plane of FIG. 1 perpendicular to the optical axis 30. An actuation of the second goniometer stage 66 tilts the tube member 50 about a second tilting axis that also runs through the “hot spot” 36 and that is perpendicular to both the first tilting axis and the drawing plane of FIG. 1. The X-ray shielding component 40 (only schematically shown in FIG. 1 and not completely shown in FIG. 4) is attached to the upstream end of the second translation stage 66 via screws extending through openings 92 in the flange portion 46 (FIG. 4). The shielding component 40 is configured to block all X-rays outside the circular X-ray passage defined by the upstream (inlet) opening 90 of the tubular member 50 and thus efficiently shields the positioning component 42 from X-rays. Accordingly, the individual components of the positioning component 42 (such as the translation stages 60, 62 and the goniometer stages 64, 66) can without any X-ray safety problem be manufactured from conventional materials (such as aluminium) which generally are transparent or nearly transparent to X-rays. FIG. 5 shows a cross sectional view of the X-ray lens assembly including the tube member 50 and the capillary X-ray lens 28 mounted inside the tube member 50. In addition to the inlet opening 90 for X-rays already explained with reference to FIGS. 2 and 4, the tube member 50 further includes an outlet opening 94 for X-rays. In the embodiment shown in FIG. 5, the tube member 50 has a length that is larger than the length of the X-ray lens 28. In an alternative embodiment, the length of the tube member 50 could be chosen to be equal or smaller than the length of the X-ray lens 28. The X-ray lens assembly shown in FIG. 5 includes two mounting structures 96A, 96B in the form elastic O-rings. The first mounting structure 26A is arranged close to the outlet opening 94 of the tube member 50, and the second mounting structure 96 is arranged close to the inlet opening 90. The two mounting structures 96A, 96B limit a chamber 98 that is located between an inner surface of the tube member 50 and an outer surface of the X-ray lens 28. The chamber 98 is filled with hardened glue reliably stabilizing the position of the X-ray lens 28 within the tube member 50. The glue has been filed into the chamber 98 through openings 100 provided in a wall of the tube member 50 in a region between the two mounting structures 96A, 96B. The X-ray lens assembly shown in FIG. 5 can be manufactured as follows. First, the two mounting structures (i.e. the O-rings) 96A, 96B are put over the body of the X-ray lens 28 and pre-positioned. Thereafter, the X-ray lens 28 is introduced together with the mounting structures 96A, 96B into the tube member 50. In a next step, the X-ray lens 28 is brought into the correct axial position with respect to the tube member 50. In the embodiment shown in FIG. 5, the correct axial position is obtained by arranging an inlet opening 102 of the X-ray lens 28 in the same plane as the inlet opening 90 of the tube member 50. This plane intersects the axes of the tube member 50 and the X-ray lens 28 at a right angle. Once the X-ray lens has been brought into the correct axial position inside the tube member 50, the mounting structures 96A, 96B are pushed uniformly into the tube member 50. Due to the barrel-shape of the X-ray lens 28 (which is thicker in the centre than at its ends), the elastic mounting structures 96A, 96B get expanded when pushed (from opposite sides) into the tube member 50. By means of this expansion, the X-ray lens 28 is clamped into the tube member 50. Moreover, the mounting structures 96A, 96B provide a fluid-tight termination of the lateral ends of the chamber 98. When pushing the mounting structures 96A, 96B into the tube member 50, the X-ray lens 28 automatically gets centred. More specifically, the longitudinal axis of the X-ray lens 28 is aligned in relation to the longitudinal axis of the tube member 50. In a next step the axial position of the X-ray lens 28 in relation to the tube member 50 is checked again and, if required, corrected. In a last step a viscous glue is introduced into the chamber 98 through one or more of the openings 100 in the wall of the tube member 50. By choosing a glue (such as a silicon glue) having a comparatively high viscosity, the number and dimensions of openings 100 can be reduced. Preferably, the number of openings 100 is reduced to four or less, and in may cases two openings 100 will be sufficient. In the assembled state, the tube member 50 functions as a mechanical protection for the capillary X-ray lens 28 during transport and/or mounting in the mounting component 44 and/or adjustment by means of the positioning component 42. The tube member 50 can accommodate X-ray lenses 28 of different dimensions, so that the mounting component 44 can be pre-adapted to the outer diameter of the tube member 50. Additionally, the reference for the adjustment of the X-ray lens 28 can be chosen to be the plane defined by the inlet opening 90 or the outlet opening 94 of the tube member 50. Accordingly, any necessary variations of the axial position of the X-ray lens 28 (e.g. due to different inlet focus distances of the X-ray lens 28) can be covered by choosing an appropriate axial position of the X-ray lens 28 within the tube member 50. Accordingly, there will be no need for additional customized flanges or adapters to adjust different types of X-ray lenses 28. Any remaining tolerance of the axial position of the X-ray 28 inside the tubular member 50 (of typically ±2.5 mm or less) can be compensated by the positioning unit 42 shown in FIGS. 1 to 4. While the current invention has been described with respect to a particular embodiment, those skilled in the art will recognize that the current invention is not limited to the specific embodiment described and illustrated herein. Therefore, it is to be understood that the present disclosure is only illustrative. It is intended that the invention be limited only by scope of the claims appended hereto.
	summary
047956070	abstract	Gas-cooled high-temperature nuclear reactor having a reactor core comprising individual fuel elements provided with means for forming a barrier against the release of fission products producible therein during reactor operation, the fuel elements being received in a cylindrical barrel formed of an inner graphite layer functioning as a reflector, an outer layer of insulating material surrounding the inner layer, and a metallic receptacle, the inner and outer layers and the receptacle being formed of respective side, bottom and cover portions, the side and cover portions of the inner layer being formed with first channels into which means for controlling the reactors are insertable, the bottom, side and cover portions of the inner layer being further formed with second channels wherein, during reactor operation, cooling gas is circulated under pressure from the bottom to the top of the receptacle, the bottom portion of the inner layer having first openings for introducing cooling gas into the second channels during reactor operation and second openings for withdrawing during reactor operation cooling gas heated by passage through the reactor core; the inner and outer layers and the cylindrical core barrel having a heat conductivity and a thermal capacity and the reactor core having such a size, shape, power density and moderation ratio that a first temperature at which the core becomes subcritical for all possible accident conditions is below a second temperature at which the barrier means are destroyed, and, when loss of pressure of the cooling gas is experienced, after-heat generated in the core being removable by heat conduction and radiation through the inner and outer layers and the core barrel to a heat sink located outside the receptacle, in such a way that the fuel elements remain at a temperature below the second temperature.
	summary
	abstract	A method of determining the intrinsic electrical characteristics of a device under test (DUT) includes determining a set of test measurements for a test structure including the device and determining test measurements for a number of de-embedding test structures. Based on the test measurements, DUT measurements are determined using both open-short and three-step de-embedding processes. The DUT measurements are combined to determine an imperfection error, which is used to adjust the calculations of a four-port de-embedding method. The adjusted calculations provide for a more accurate measurement of the parasitic elements in the test structure, thereby improving the determination of the intrinsic electrical characteristics of the device.
042808731	description	Referring to the figures of the drawing and first, particularly to FIGS. 1 and 2 thereof, there is shown a reactor vessel 1, largely equipped with a double vessel 1a, disposed in a reactor cavity 2 which is made of concrete and serves simultaneously as a radiation shield. Inside the reactor vessel 1, is disposed a fission zone 3 with a breeder blanket, not shown separately, in which the coolant, sodium, for instance, is heated. The sodium fills the reactor vessel 1 up to an operating level 12, or at least up to an emergency level 13. Around the containment, four cooling loops are disposed in the example, which can be operated independently of each other, each of which being built up as follows: The hot coolant is drawn out of the reactor vessel 1 through a suction line 4 by means of a pump 6, and is pushed into at least one intermediate heat exchanger 7, where the primary coolant gives off its heat to a secondary coolant, which is also sodium in the example. From the intermediate heat exchanger 7, the cooled-off coolant returns through a pressure line 5 to the reactor vessel 1 and is conducted by guides 14 into the space under the fission zone 3. The distance between the reactor vessel 1 and the double vessel 1a is constructed so that if the coolant flows out of the vessel 1, the height of the sodium is kept at least at the emergency level 13, which ensures that proper cooling of the fission zone 3 is maintained. The pumps 6 and the intermediate heat exchangers 7 are disposed in component tanks 8 which are grouped about the reactor cavity 2 and are connected thereto through pipe ducts 9. The component tanks 8 and the pipe ducts 9 are surrounded on the outside by thermal insulation 15 and shielding 15a, which are at least partially disassembleable. The pipe ducts 9 and the lines 4 and 5, which are installed in them, lead radially into the reactor vessel 1, but tangentially into the component tank 8. The radiation, which is generated in the fission zone 3 and propagates in a straight line, penetrates the wall of the reactor cavity 2 at the feedthroughs 16 for the pipes 4, 5. However, it does not strike the pump 6 or the intermediate heat exchanger 7, so that these parts are practically only activated by deposits of radioactive substances precipitated out of the coolant. This is helpful for their accessibility for repairs after the insulation 15 and the shielding 15a are removed and the component tank 8 has been opened. At the same time, this type of construction makes it possible to lead each of the suction line 4, and the pressure line 5, into the component tank 8 and to the respective component to be connected in a large expansion loop 11, whereby the changes in length of the pipe lines occurring due to different temperatures are compensated without setting up stresses which endanger their integrity. Inside the component tanks 8, the connecting lines 4, 5 are helically disposed and at least one of heat exchangers 7 and pumps 6 may be disposed within the helix. The reactor vessel 1, the reactor cavity 2 and the component tanks 8 can be secured rigidly, since the pipe ducts 9 are elastic, and can be for instance, in the form of corrugated-pipe compensators. In the embodiment shown in FIGS. 1 and 2, a pump 6 and two intermediate heat exchangers 7 in each loop are accommodated in a common component tank 8. In FIG. 3, an alternative is shown such as may be of advantage for reactors of very large power output and corresponding dimensions of the individual components. In FIG. 3, one pump 6 and an intermediate heat exchanger 7 each are accommodated in a separate component tank 8. A pipe line 10 connecting them is conducted in an additional pipe duct 9. It is common to both embodiments that in the pipe lines 4, 5, valves and/or measuring instruments 17 can be disposed in the region of the pipe ducts 9 and therefore, in relatively easily accessible places. The component tanks and the pipe ducts 9 are moreover filled with a gas, for instance, nitrogen, which is inert vis-a-vis the coolant, in order to prevent reactions of the coolant with the atmosphere in the event of leaks. Nitrogen can also be blown as a cooling gas into a gap 18 between the insulation 15 of the component tank 8, or the pipe duct 9, and the shielding 15a, by means of known gas supply facilities, which are not shown here. It can be seen from FIGS. 5-7 that by enlarging the component tank only slightly over the size required for accommodating the component, an expansion loop 11 which is sufficient for compensating the length changes of the pipe lines at different temperatures can be accommodated. For work on the pump 6 or the intermediate heat exchanger 7, access openings which are closed off by covers 20, are formed in the component tank 8. These covers can be fastened either in the manner of blind flanges by screw bolts or other screw connections 21 (FIGS. 4-6), or they may be welded into the openings 19. To perform work on the pump 6 or the intermediate heat exchanger 7, the flow in the loop in question is shut off from the reactor by means of valves 17 (FIG. 3), the coolant is drained off and one or more of the covers 20 are lifted. Into the opening 18 so exposed, a block 22 (see FIG. 7), of lead glass is inserted, so that the interior of the component tank 8 can be observed from the outside, the personnel being shielded from the radiation which may come from the corrosion products left behind in the pipes 4, 5, for instance. The necessary work inside the component tank 8 can be performed by one of the known manipulators 23, which is built into the glass block 22 and is removed together with the latter when the work is finished.
	description	There are no applications related to this application. However, reference is made to U.S. Pat. No. 6,703,620 granted to the inventor herein. The invention described in this patent was made by an employee of the United States Government and may be manufactured and used by or for the Government for governmental purposes without the payment of any royalties. In general, this invention pertains to hard X-ray, gamma ray, and neutron imaging. Specifically, this invention pertains to Fourier imaging systems, and to integrated systems utilizing this technology, and its use in instruments used in scientific, medical, industrial, and homeland defense imaging areas. The sky contains many active sources that emit X-rays, gamma rays, and neutrons such as our sun, radio galaxies, Seyfert galaxies, and quasars, as well as black holes, and clusters of galaxies. In addition to sources located in the heavens, many terrestrial applications are also associated with the penetrating characteristics of x-rays, gamma rays, and neutrons. Unfortunately hard X-rays, gamma rays, and neutrons cannot be imaged by conventional optics such as lenses or mirrors. As a result hard X-ray astronomy and other imaging applications were originally handicapped because of this lack of imaging capability. This led to the development of several innovative techniques including Fourier telescopes, one such telescope being the subject of U.S. Pat. No. 5,838,757. The theory and capability of Fourier telescopes is well understood. See the reference, “Imaging the Sun in Hard X-rays Using Fourier Telescopes” by J. W. Campbell, the inventor herein, found in NASA Technical Memorandum, NASA TM-108390 (January 1993). Fourier telescopes permit observations over a very broad band of energies that for photons range from the hard X-ray regime to very high energies up to and above several MeV. Depending upon the application, neutron sources across a wide band of high energies may also be imaged. For some applications, 1 eV neutrons may be sufficient while some applications may require imaging at energies up to and above 1 MeV to 100 MeV. In addition, complex sources emitting a mixture of these radiation types may be imaged simultaneously as well. These images may be integrated over all energy bands, or in one or more selected bands to aid in the understanding of the source characteristics. Thus a resulting integrated image may have a high spatial resolution as well as a high energy resolution. In early approaches, multiple grid pairs were necessary in order to create rudimentary Fourier imaging systems. For example, 48 grids were used in a basic telescope design in Campbell, NASA TM-108390 at page 109. At least one set of grid pairs was required to provide multiple real components of a Fourier derived image, and another set was required to provide corresponding multiple imaginary components of the Fourier derived image. Image spatial resolution is limited by the widths of the grid slits (or slats). Requirements for better spatial resolution lead to exponential cost increases for grid fabrication and alignment. It has long been recognized that the expense associated with the physical production of the numerous grid pairs required for its collimator was a primary constraint to achieving higher fidelity imaging. In addition, with imaging system aperture size often limited, improved sensitivity as opposed to higher fidelity and lower cost became an additional compromise. Thus, an innovative approach leading to a reduction in grid pairs and cost without sacrificing imaging sensitivity or fidelity was needed. This was accomplished in my U.S. Pat. No. 6,703,620 by creating Fourier derived images with only two grid pairs. The reduction to only two grid pairs needed for imaging was rendered possible by manipulating the grids through rotation and translation. Since a 24-grid pair Fourier imager can cost as much as ten times more than a two-grid imager to produce, the reduction in the number of grids is a significant reduction in cost. And, it was not believed that a one-grid pair Fourier imaging system was feasible because the first grid pair provides multiple real components necessary for a Fourier derived image, and the second grid pair provides corresponding multiple imaginary components for that Fourier derived image. By this invention, a Fourier derived image can be generated in a system with only one grid pair. In U.S. Pat. No. 6,703,620 the possibility of utilizing only one grid pair was recognized and claimed. However, it was pointed out at the time that the single grid pair theory contemplated a collection of data at discrete, predetermined, points in the available spectrum based on estimating the imaginary component. Such guesswork leads to uncertainties in the accuracy of the final image and may actually result in a totally misleading image. For example, errors in a medical application such as the detection of breast cancer could go either way: (a) a tumor being undetected or (b) unnecessary surgery being indicated. U.S. Pat. No. 6,703,620 is directed to reducing the number of grid pairs in the imaging of hard X rays, gamma rays, and high energy neutrons by Fourier imaging. Two grid pairs are manipulated by rotation and translation in a manner that allows (1) a first grid pair to provide multiple real components of the Fourier derived image and (2) a second grid pair to provide multiple imaginary components of the Fourier derived image. This enables only two grid pairs to provide the same imaging information from photons that has been traditionally collected with multiple grid pairs. It has now been found possible to enhance imaging fidelity by using only one grid pair (two grids), when they are adapted for rotation and translation, if one grid has one more slit than the other grid, and if the detector is modified. Considering one of the two grids to have an even number of (n) slits in a given width, the other grid is provided with (n+1) slits in the same width. In addition, the detector incorporated in the apparatus is provided with at least two segments or elements. When illuminated by the photons, the detector sends detailed photon impingement location information to the software for calculation of the image. A Fourier imaging concept involves sampling selected Fourier components from a wave front emitted by an extended source. By measuring a number of discrete components over a sufficiently large spatial frequency spectrum, a matrix can be formed from which a Fourier surface can be approximated. A Fourier transform of this surface yields an approximate, or dirty, image. For many applications, the dirty image may be sufficient. However, several algorithms developed over the years have been found effective in cleaning the dirty image to produce a meaningful result. This will be understood by reference to a description of the apparatus in conjunction with the accompanying drawings. Since the invention herein is an improvement of the Fourier derived imaging system of U.S. Pat. No. 6,703,620, incorporated herein by reference, a description of this invention should begin with a explanation of that prior art apparatus. In FIG. 1 an imaging system is shown which utilizes four grids (31, 32) and (41, 42), generally referred to as two grid pairs. As can be seen, the instrument includes a frame (10), a drive rod (20), a first disk or plate (30), a second disk or plate (40), a detector (60), and a means for simultaneously rotating and translating the drive rod (70). Frame (10) includes a disk guide (11), which supports the second disk, and a rod guide (12), which supports the drive rod (20). The first disk or grid tray (30) is rotatably connected to an end (21) of the drive rod (20). This grid tray carries a first real grid (31) and a first imaginary grid (32). The second disk or grid tray (40) carries a second real grid (41) aligned with the first real grid (31), and a second imaginary grid (42) aligned with the first imaginary grid (32). The second disk (40) and the first disk (30) are rotatably connected through a plurality of connecting rods (50). The second disk (40) is rotationally guided by disk guide (11) in frame (10) when it is rotated by rods (50) as first disk (30) is rotated. As noted in my earlier patent, the means for simultaneously rotating and translating using the drive rod (20) can be accomplished in a variety of ways described in that patent. When the drive rod (20) is threaded and placed within a shaft, rotation and translation can be accomplished by various gear arrangements affording synchronized rotation of the second grid tray with the first grid tray. And translation can be in either direction. A detector is mounted at (60) in frame (10), and it is aligned with the real grid pair (31, 41) and the imaginary grid pair (32, 42) to act on the detected flux. It remains, now, to discuss the operation of this two grid pair apparatus. By using four grids made up of slits and slats we have two (n, n) grid pairs wherein each pair of grids has the same number (n) of slits (actually, slits and slats). A wave front field of photons and/or neutrons emitted by a source can be adequately described upon arriving at the Fourier imaging system aperture by a Fourier transform of the object function f(x,y). This transform is a complex function F(u,v) made up of a real component and an imaginary component mentioned in conjunction with FIG. 1. The specific rotation and translation positions described hereinbefore provide specific intensity values for (u) and for (v) in each row of a matrix formed thereby. At a specific (u,v), the first (n,n) grid pair, in combination with its associated single grid detector, provides Real image measurements. In addition, at this specific (u,v), the second (n,n)′ grid pair, in combination with a single element grid detector, provides Imaginary image measurements. Hence, by varying (u,v) through rotation and translation and taking associated (Real Image) measurements, a four by N matrix is produced. This matrix is required in order to obtain the image (N being the total number of (u,v) points as noted hereinbefore). It can be seen that, previously for Fourier imaging, two grids (31, 41) have been used for the Real image and two grids (32,42) for the Imaginary image. It has now been found that comparable images can be obtained by the use of only two grids (one grid pair). Referring now to FIG. 2, two grids (33) and (35) are shown. In this invention, grid (35) (nearest the observer by convention) is provided with one more slit than grid (33). In addition detector (60), rather than being a single element detector, is modified to include at least two elements or segments. Thus one grid pair can be eliminated from FIG. 1 as shown in FIG. 2 when, instead of an (n,n) grid pair an (n, n+1) grid pair is used along with a multiple element detector. Generally four to seven elements are sufficient, but it can include as many as 101 elements, determined by fidelity requirements. By collecting data at multiple angular grid positions, and with multiple distances between the first grid and the second grid, an image can be produced as will be described further in the description of the preferred embodiment of the invention that follows. The preferred embodiment of the invention is diagrammatically illustrated in FIG. 3. As can be seen in this embodiment the translation-rotation drive mechanism (in housing 71) has been moved to the side of the unit. For this reason the FIG. 3 embodiment is preferred because the drive rod (20, FIGS. 1 & 2) does not interfere with the location of the grids as it does in FIG. 2. As illustrated in FIG. 3 larger grids (72) and (74) are possible, providing even greater sensitivity for the imaging system. The arrangement of the parts of the device can be more clearly visualized in this diagrammatic presentation. The outer grid plate/tray/disk (70) carries grid (72), and the inner (i.e., opposite) grid plate/tray/disk (73) supports grid (74). Which grid has an even number of (n) slits and which has an odd number of (n+1) slits does not affect the results so long as one grid has one more slit than the other grid over the same width. The center slit of each grid (or, more precisely, the center slit of the grid having an odd number of (n+1) slits and one of the two center slits of the grid having an even number of (n) slits) should be aligned with the center of the detector for best results. As can be seen, the grids are oppositely disposed and they will rotate and translate in those opposite positions by the drive mechanism to be described in conjunction with FIG. 4. The detector (75) is also shown in FIG. 3 and rotates with the grids. It is to be noted that it included two or more segments or elements (76), (77), (78), and (79). Even though the translation-rotation drive mechanism is somewhat more complex the advantages of a side drive outweigh the central drive shaft. Referring now to FIG. 4, the side drive mechanism per se, the two grid plates/trays, (92) and (95) fabricated of a transparent material such as aluminum, and having integrated gear teeth (97), are shown. Rotation is accomplished by drive shaft (96) and drive gear (94) mounted in support bases (91) so that the two grid plates (92) and (95) rotate synchronously. To accomplish the simultaneous rotation necessary, a sub-fractional AC or DC servo motor (90) is used. Translation is achieved by precision lead screw or shaft (85) in combination with translating base (87) that carries recirculating ball bearing assemblies (86). Shaft (85) is rotated by a brushless motor (82), and the unit is stabilized by stationary precision ground shafts (84) and stationary end plates (83) and (89). The multiple-segment detector is not shown in FIG. 4, but it will be aligned as shown in FIG. 3. Grid materials are used extensively in astronomy and need not be discussed at length herein. Desirable grid-slat materials are those that are highly absorptive when exposed to penetrating neutrons (e.g., beryllium), X-rays and Gamma Rays (e.g., tungsten or lead). Slits may be open or composed of a highly transparent material such as aluminum and glass. Likewise, detectors are well known, for instance, germanium detectors (GeD) which cover the entire hard X-ray to gamma ray line energy range (up to ˜20 MeV) with the highest spectral resolution. Sodium iodide detectors are also well known. Photons interacting in a GeD detector generate charge pulses, which are collected and amplified by a transistor-reset amplifier to provide the best energy resolution and high-count rate performance. Image reconstruction of astrophysical sources at hard X-ray or gamma-ray energies by nonfocusing telescopes has always been a challenge, largely due to an intrinsically low signal to noise ratio. This challenge can be met by the specific rotation and translation positions achieved by the apparatus of FIG. 4, which provide specific values for (u) and for (v) as previously indicated. The simultaneous rotation and translation allow data to be collected at multiple angular positions of the outer grid, and the inner grid, and multiple distances between the two grids. When detected using a multiple element detector, the values of (u) and (v), and the phase and amplitude of the radiation can be measured, yielding a real and imaginary data stream directly. With this data matrix and algorithms such as Astronomical Image Processing System (AIPS) the final image can be computed. In actuality there are many techniques for reconstructing dirty images in non-focusing telescopes, for instance, such as correlation and inversion. Various techniques are also employed to improve the quality of dirty images, such as the maximum entropy methods. The procedure herein will now be demonstrated using a coded grid imaging system as explained in following imaging tests and three-dimensional perspective plots. Testing Testing through simulation is a powerful tool for these devices. Many tests have been performed and an example is shown as follows. The test herein involves finding an output response by the use of input extended sources in the object plane. FIGS. 5 and 6 are three-dimensional plots representing input sources producing a wavefront that may be described by a Fourier transform at the imaging system aperture. Shown in the prior art example of FIG. 5 are three point sources of different intensities. Shown in FIG. 6, the example of this invention, are four point sources of approximately the same intensity A two dimensional spatial frequency domain imaging algorithm is obtained by making suitable approximations to the point spread function and obtaining its Fourier transform. The effect of aberrations may be determined by optical transfer functions for focusing errors in a system with a rectangular grid opening. As can be seen in FIGS. 5 and 6, the figures are three-dimensional image plots of location x along one axis, location y along the other axis and intensity H along the z-axis. Multiple component (grids, detectors, drive motors, etc.), subsystem, and breadboard tests have been accomplished over the years and this testing is continuing. In addition, simulation has been found to be a powerful tool in understanding, designing, and optimizing Fourier imaging systems. This is especially true for photon-by-photon simulations. As one example, the test herein involves finding an image of selected input point sources in the object plane. These sources are representative of those that can represent a medical, homeland defense, or industrial application. The effectiveness of this invention is illustrated by the diagrams shown in FIGS. 5 & 6 which are images of three and four point sources. FIG. 5, the prior art, illustrates the ability of an imaging system to accurately locate and represent simple sources of varying intensities. FIG. 6 illustrates the invention's capability of imaging simple sources even of approximately equal intensities. In both instances, during the observation, an image is obtained for every 180 degrees of rotation orientation relative to the source. The figures are three-dimensional plots of x location along one axis, y location along the other axis, and intensity H along the z-axis. Test Results Referring now specifically to FIGS. 5 and 6, the units in the x and y plane represent the location of the simulated test point sources' images in normalized units of length. The z plane shows intensity in normalized units for comparison purposes. The actual imaging of the sources is accomplished by imaging algorithms that have been verified both through computer simulations and experimental results. FIG. 5 shows that the image formation system of the prior art does not eliminate all the noise. This noise appears as small or weak virtual point sources seen at the base of the three desired point sources. In FIG. 6, illustrating this invention, those weak noise sources are greatly reduced and the four desired point sources are clearly visible. It can be seen that by the practice of this invention noise is substantively reduced. In addition, image fidelity is improved by the invention. Imaging system performance in photon limited conditions thus can be greatly improved. Stated differently, many sources not visible using previous technology due to lack of photons reaching the detector will be visible using the invention herein. Clearly, the four point source image of FIG. 6 representing the new design herein is a substantive improvement over the three point source representing the current technology. In both instances, the centroids of the point source locations in the images accurately reflect the locations of the centroids of the actual object point sources. However, by the system herein with a sharper image, the centroid can be more accurately measured. It will be appreciated that the invention herein will be particularly useful in homeland defense imaging and in medical applications as well as in space. And, of course, modifications of the invention will occur to those skilled in the art. Thus, various grid materials and detector elements are within the skill of the art, as well as means for accomplishing the rotation and translation of the grid plates. Such variations are deemed to be within the scope of this invention.
	summary
	claims	1. A nuclear reactor containment arrangement including:A. an open ended reactor pressure vessel which thermally expands and contracts during cyclic operation of the reactor and which has a peripheral wall and a flange that mates with a corresponding flange on a reactor vessel head which forms a removable closure for the open ended reactor pressure vessel;B. an annular refueling ledge which is an annular, radially outward extension of the reactor pressure vessel flange;C. a containment wall spaced apart from and surrounding the peripheral wall of the reactor vessel and defining an annular thermal expansion gap therebetween for accommodating thermal expansion and other movement of the reactor pressure vessel, the containment wall having a plateau which forms a floor of a refueling canal of the nuclear reactor containment; andD. an annular ring seal which sealingly engages and is affixed to and extends between the refueling ledge and the containment wall, and comprises:(I) a rigid cantilevered annular support that is anchored at a first end to one of (i) the floor of the refueling canal or another surface on the containment wall substantially parallel thereto or (ii) the refueling ledge and extends above and over the expansion gap, completely spanning the expansion gap and having a second, distal end; and(II) a generally “C” shaped flexure member having a first end attached to the rigid cantilevered annular support proximate the distal end and a second end anchored to the other of (i) the floor of the refueling canal or another surface on the containment wall substantially parallel thereto or (ii) the refueling ledge;said flexure member being disposed below the cantilevered portion of said cantilevered annular support;wherein the rigid cantilevered annular support includes a substantially horizontal foot that is anchored to the one of (i) the floor of the refueling canal or another surface on the containment wall substantially parallel thereto or (ii) the refueling ledge, a leg having one end connected to the foot, wherein the leg extends from the foot in a generally vertical direction and is attached at an elevation spaced from the foot to an arm which extends out in a generally radial direction over the expansion gap; andwherein a second end of the arm opposite the distal end of the arm that extends over the expansion gap, extends radially past the leg and is attached to a distal end of an “L” shaped flexure member that has another end anchored to the one of (i) the floor of the refueling canal or another surface on the containment wall substantially parallel thereto or (ii) the refueling ledge. 2. The nuclear reactor containment arrangement of claim 1 wherein the first end of the generally “C” shaped flexure member is attached to the rigid cantilevered annular support through a substantially vertically extending flexure link. 3. The nuclear reactor containment arrangement of claim 2 wherein the flexure link is connected to the first end of the generally “C” shaped flexure member at a less than obtuse angle.
	description	1. Field of the Invention The present invention relates to a method and apparatus for water jet peening, and more particularly to a method and apparatus for water jet peening that is preferably applicable to a nuclear power plant. 2. Description of the Related Art It is known that a residual stress mitigation method is available to give compressive residual stress to the surface of a structural member of a nuclear power plant or the like by subjecting such a structural member by applying water jet peening. A water jet peening method described in JP-2010-276491-A subjects the outer surface of a bottom mounted instrument piping to water jet peening by disposing a jet nozzle, which discharges a jet of high-pressure water, at the bottom of a reactor pressure vessel and rotating the jet nozzle, which is discharging a jet of high-pressure water, around the bottom mounted instrument piping. In this manner, compressive residual stress is given to the outer surface of the bottom mounted instrument piping. A water jet peening method for giving compressive residual stress to the inner surface of piping is described in JP-2008-14447-A. This water jet peening method inserts a working device in piping with a jet nozzle into a piping, moves the working device within the piping, and allows the jet nozzle to discharge a jet of high-pressure water toward the inner surface of a welding area of the piping. Hence, compressive residual stress is given to the inner surface of the welding area. A water jet peening method to be applied in a piping is described in JP-2002-200528-A. In order to subject the inner surface of a welding area formed inner side of a piping to water jet peening, a jet nozzle is inserted into the piping from one end of the piping, and the one end of the piping is sealed with a tube plug while the other end of the piping is sealed with a tube plug or with a valve. Water is then filled into a sealed area in the piping. Eventually, the inner surface of the welding area formed on the piping is subjected to water jet peening by allowing the jet nozzle in the water to discharge a jet of high-pressure water. When the jet of high-pressure water is discharged, air existing in the sealed area is expelled outside through a pipe connected to the tube plug. The method described in JP-2002-200528-A forms a water area in the piping targeted for water jet peening and subjects the inner surface of the piping in contact with the water area to water jet peening. However, no tube plug is inserted into the piping in this method. Therefore, it is difficult to subject an arbitrary area in the piping to water jet peening. Further, the water jet peening method described in JP-2002-200528-A is not designed to prevent damage to a structure or electronic device that may exist in the piping and become damaged by shock waves formed by high-pressure water or cavitations. The present invention has been made in view of the above-described circumstances to provide a water jet peening method and apparatus for making it possible to prevent damage to a structure or electronic device that is mounted on a piping and is susceptible to damage by a jet of water or by shock waves. According to one aspect of the present invention, there is provided a water jet peening method including the steps of: preparing a water jet peening apparatus having a supporting member, a first divider plate mounted on one end of the supporting member, a nozzle support body formed by disposing a jet nozzle around the supporting member, and a second divider plate mounted on the supporting member, the jet nozzle being disposed between the first divider plate and the second divider plate; inserting the water jet peening apparatus into a piping in which a structure or electronic device that is susceptible to damage by shock waves is mounted; disposing either the first divider plate or the second divider plate between the jet nozzle and the structure or electronic device; filling water into an internal area formed in the piping between the first divider plate and the second divider plate; and subjecting the inner surface of the piping to water jet peening by allowing the jet nozzle to discharge a jet of water into the water in the internal area. Either the first divider plate or the second divider plate is disposed between the jet nozzle and the structure or electronic device that is mounted on the piping that is susceptible to damage by shock waves. Water is filled into the internal area formed in the piping between the first divider plate and the second divider plate. The inner surface of the piping is subjected to water jet peening by allowing the jet nozzle to discharge a jet of water. Consequently, the water jet peening is performed for the inner surface of the piping by shock waves that are generated upon the collapse of cavitations in the jet of water discharged from the jet nozzle into the water existing in the internal area. Further, the jet of water discharged or the shock waves are blocked by the divider plate disposed between the jet nozzle and the structure or electronic device. This makes it possible to prevent the structure or electronic device from being damaged by the jet of water discharged or by the shock waves. According to the present invention, a structure or electronic device that is mounted on a piping and is susceptible to damage by a jet of discharged water or by shock waves can be prevented from being damaged when the inside of the piping is subjected to water jet peening. Embodiments of the present invention will now be described. First Embodiment A water jet peening method according to a first embodiment of the present invention will be described below with reference to FIG. 1. First of all, a water jet peening apparatus to which the water jet peening method according to the present embodiment is applied will be described. The water jet peening apparatus 6 includes a jet nozzle 20, a nozzle head 21, a supporting member 22 shaped like a round bar, divider plates 23A, 23B, a high-pressure water supply device 38, water supply device 39, a water discharge device 44, a sealing device 51, and a rotation body 56. The supporting member 22 is surrounded by the ring-shaped divider plate 23A. A coupling member 17 couples the divider plate 23A to one end of the supporting member 22. A gap between the divider plate 23A and the supporting member 22 is sealed with a seal member 19 attached to the inner circumference of the divider plate 23A. The supporting member 22 is penetrated through a cylindrical rotation body 56. The inner surface of the rotation body 56 is in contact with the outer surface of the supporting member 22. The rotation body 56 can rotate along the outer surface of the supporting member 22. A gap between the supporting member 22 and the cylindrical rotation body 56 is sealed with seal members 32, 35 attached to the supporting member 22. The rotation body 56 is surrounded by the cylindrical nozzle head 21. The inner surface of the nozzle head 21 is in contact with the outer surface of the rotation body 56. A groove 27 extending in the axial direction of the supporting member 22 is formed in the inner surface of the nozzle head 21. A key 33 mounted on the outer surface of the rotation body 56 is inserted into the groove 27. The length of the groove 27 in the axial direction of the supporting member 22 is longer than the length of the key 33 in the axial direction. Hence, the nozzle head 21 can move in the axial direction of the supporting member 22 along the rotation body 56. A gap between the rotation body 56 and the nozzle head 21 is sealed with a seal member 34 attached to the nozzle head 21. The nozzle head 21 is surrounded by the ring-shaped divider plate 23B. The inner surface of the divider plate 23B is in contact with the outer surface of the nozzle head 21. A gap between the nozzle head 21 and the divider plate 23B is sealed with a seal member 36 attached to the divider plate 23B. The jet nozzle 20 is mounted on a leading end of the nozzle head 21 and inclined with respect to the shaft center of the supporting member 22. A plurality of combining members 47 attached to the outer surface of the supporting member 22 are used to fasten the divider plate 23B to an end of the supporting member 22, which is opposite the end of the supporting member 22 on which the divider plate 23A is mounted. The combining members 47 are spaced at predetermined intervals and disposed in the circumferential direction of the supporting member 22. A stopper structure 62, which comes into contact with one end face of the rotation body 56, is attached to the outer surface of the supporting member 22. A stopper structure 63, which comes into contact with the other end face of the rotation body 56, is attached to the outer surface of the supporting member 22. The stopper structures 62, 63 are not mounted on the rotation body 56. The divider plate 23A forms a scoop (air gathering area) 9 on its surface facing the divider plate 23B. An air emission route 16, which is open in the scoop 9, is formed in the divider plate 23B. An air emission route 14 is formed in the supporting member 22 and extended from one end of the supporting member 22, on which the divider plate 23A is mounted, to the other end of the supporting member 22. The air emission route 14 is connected to the air emission route 16. An air emission hose 43 having a pressure adjustment valve 28A is connected to the air emission route 14. A high-pressure water route 11 is connected to the jet nozzle 20 is formed in the nozzle head 21. The high-pressure water supply device 38 includes a high-pressure pump 26, a water supply pipe 40, and a high-pressure hose 41. The water supply pipe 40, which is connected to a water source 25, is connected to the high-pressure pump 26. The high-pressure hose 41, which is connected to the high-pressure water route 11, is connected to the high-pressure pump 26. The water supply device 39 includes a check valve 29 and a water supply pipe 45. The water supply pipe 45, which is provided with the check valve 29, is connected to a water supply route 12, which is formed through the divider plate 23B. The water supply pipe 45 is connected to the water source 25 and provided with a pump (not shown). The water discharge device 44 includes a pressure adjustment valve 28B and a water discharge pipe 46. The water discharge pipe 46, which has the pressure adjustment valve 28B, is connected to a water discharge route 18, which is formed through the divider plate 23B. The sealing device 51 includes ring-shaped hollow seal members 24A, 24B made of rubber or other elastic material, a compressor 50, and air supply pipes 52, 53. A ring-shaped internal space is formed in the hollow seal members 24A, 24B. The hollow seal member 24A is attached to the outer circumference of the divider plate 23A to surround the divider plate 23A. An air supply route 8 connected to the internal space of the hollow seal member 24A is formed in the divider plate 23A and extended to the inner surface of the divider plate 23A. The air supply route 8 is connected to an air supply route 7 formed in the supporting member 22. The air supply route 7 is connected to the air supply pipe 53, which is mounted on an end of the supporting member 22. The hollow seal member 24B is mounted on the outer circumference of the divider plate 23B to surround the divider plate 23B. An air supply route 10 connected to the internal space of the hollow seal member 24B is formed in the divider plate 23B and extended to the inner surface of the divider plate 23B. The air supply route 10 is in communication with the air supply pipe 52, which is mounted on a lateral surface of the divider plate 23B. The air supply pipes 52, 53 are connected to the compressor 50. An exhaust pipe 58 provided with an on-off valve 59 is connected to the air supply pipe 52. An exhaust pipe 60 provided with an on-off valve 61 is connected to the air supply pipe 53. A motor 54 is disposed at an end of the supporting member 22 that is opposite the other end of the supporting member 22 to which the divider plate 23A is attached, and mounted on the outer surface of the supporting member 22. A gear 55 is coupled to the rotation shaft of the motor 54 through a down speed mechanism (not shown). The gear 55 is in mesh with a gear (not shown) disposed on the outer surface of one end of the rotation body 56. The rotation body 56 is surrounded by the gear disposed on the outer surface of the rotation body 56. The rotation body 56, the motor 54, and the gear 55 form a rotation device for rotating the nozzle head 21. A transfer device 48 is mounted on the outer surface of one end of the rotation body 56. Although not shown, the transfer device 48 includes a cylinder barrel, a piston disposed in the cylinder barrel, and a piston rod coupled to the piston. The piston rod is coupled to one end of the nozzle head 21. An air supply hose 49 connected to the compressor 50 is connected to the cylinder barrel of the transfer device 48. A water jet peening method according to the present embodiment, which is exercised by using the water jet peening apparatus 6, will now be described in detail. A target to be subjected to water jet peening is, for example, a piping 1 connected to a vessel 37. More specifically, the inner surface of a welding area of the piping 1 is subjected to water jet peening. The piping 1 is extended in a vertical direction. There is a gaseous atmosphere in the vessel 37 and in the piping 1. When the supporting member 22 is pressed into the piping 1, the water jet peening apparatus 6 is inserted into the piping 1 from the inside of the vessel 37. In this instance, the divider plates 23A, 23B attached to the supporting member 22 are inserted into the piping 1. As no pressurized air is introduced into the internal spaces of the hollow seal members 24A, 24B, the hollow seal members 24A, 24B are easily deformed and positioned apart from the inner surface of the piping 1. Therefore, the divider plates 23A, 23B can be easily inserted into the piping 1 and moved within the piping 1. When the leading divider plate 23A travels through a residual stress improvement area 2, which is on the inner surface of the piping 1, until the residual stress improvement area 2 is positioned between the divider plate 23A and the divider plate 23B, the water jet peening apparatus 6 stops its travel in the piping 1. The on-off valves 59, 61 are closed. The compressor 50 is driven so that resulting compressed air is discharged from the compressor 50 to the air supply pipes 52, 53. The compressed air discharged to the air supply pipe 52 is supplied to the internal space of the hollow seal member 24B through the air supply route 10. The supplied compressed air causes the hollow seal member 24B to expand so that the outer surface of the hollow seal member 24B comes into contact with the inner surface of the piping 1 involving the entire circumferential surface of the divider plate 23B. A gap between the inner surface of the piping 1 and the outer surface of the divider plate 23B is sealed with the expanded hollow seal member 24B. The compressed air discharged to the air supply pipe 53 is supplied to the internal space of the hollow seal member 24A through the air supply routes 7, 8. The supplied compressed air causes the hollow seal member 24A to expand so that the outer surface of the hollow seal member 24A comes into contact with the inner surface of the piping 1 involving the entire circumferential surface of the divider plate 23A. A gap between the inner surface of the piping 1 and the outer surface of the divider plate 23A is sealed with the expanded hollow seal member 24A. Consequently, an external area 3, which exists outside the divider plates 23A, 23B, and an internal area 4, which is isolated from external area 3, are formed in the piping 1 between the divider plate 23A and the divider plate 23B. The residual stress improvement area 2 of the piping 1 faces the internal area 4. The jet nozzle 20 mounted on the nozzle head 21 is located in the internal area 4. The pressure adjustment valve 28B is closed, whereas the pressure adjustment valve 28A is open. A pump (not shown) disposed in the water supply pipe 45 is driven so that the water in the water source 25 is pressurized, passed through the water supply pipe 45 with the check valve 29 and through the water supply route 12, and supplied into the internal area 4. Air existing in the internal area 4 is pushed upward by the water supplied into the internal area 4, passed through the air emission route 16 and through the air emission route 14, forwarded to the air emission hose 43, and discharged outside. As the water is continuously supplied from the water source 25 to the internal area 4, the level of the water in the internal area 4 rises so that the internal area 4 is filled with the water before long. In this state, the pump disposed in the water supply pipe 45 stops to shut off the water supply to the internal area 4. The preparation for water jet peening for the inner surface of the piping 1 is now completed. The high-pressure pump 26 is driven to, pressurize the water in the water source 25 and discharge the resulting high-pressure water. The high-pressure water discharged from the high-pressure pump 26 is passed through the high-pressure hose 41 and through the high-pressure water route 11 and supplied to the jet nozzle 20. The high-pressure water is then discharged in the form of a jet of high-pressure water from the jet nozzle 20 toward the residual stress improvement area 2, which exists on the inner surface of the piping 1. Cavitations included in the discharged jet of water collapse to generate shock waves. The generated shock waves are applied to the residual stress improvement area 2. The shock waves generate compressive residual stress by improving tensile residual stress, which exists in the residual stress improvement area 2. While discharging a jet of high-pressure water, the jet nozzle 20 rotates in a circumferential direction along the inner surface of the piping 1. The aforementioned rotation device rotates the jet nozzle 20. When the jet nozzle 20 is to be rotated, the motor 54 is driven to transmit the rotation of the motor 54 to the gear 55, which then rotates the rotation body 56. As the key 33 mounted on the rotation body 56 is inserted into the groove 27 formed in the inner surface of the nozzle head 21, the key 33 transmits the rotation of the rotation body 56 to the nozzle head 21. This causes the nozzle head 21 to rotate around the supporting member 22 together with the rotation body 56. Hence, while discharging a jet of water, the jet nozzle 20 attached to the nozzle head 21 rotates in the circumferential direction of the piping 1 to perform water jet peening in the circumferential direction of the residual stress improvement area 2. The transfer device 48 attached to the outer surface of the rotation body 56 rotates together with the nozzle head 21. After the jet nozzle 20 makes one revolution around the supporting member 22, a control device (not shown) exercises control to rotate the motor 54 in opposite direction. As the control device causes the motor 54 to repeatedly rotate in normal direction and in opposite direction, the jet nozzle 20 rotates around the supporting member 22 alternately in normal direction and opposite direction as indicated by an arrow 30. This prevents the high-pressure hose 41 connected to the rotating nozzle head 21 and the air supply hose 49 connected to the transfer device 48 from being wrung off. While the shock waves are applied to the inner surface of the piping 1 in the residual stress improvement area 2 after a jet of water is discharged from the jet nozzle 20, the cavitations that are discharged, included in the jet of water, and left uncollapsed are raised through the water in the internal area 4 and gathered by the scoop 9 formed on the divider plate 23A. The gathered cavitations are then discharged from the scoop 9 to the air emission route 16. Further, the cavitations are discharged to the air emission hose 43 through the air emission route 14. This makes it possible to prevent the internal area 4 from being filled with the cavitations. While the jet of water is being discharged from the jet nozzle 20, the pressure adjustment valve 28B is open so that the water in the internal area 4 is discharged to the water discharge pipe 46 through the water discharge route 18. The degree of opening of the pressure adjustment valve 28B is adjusted so that the water discharged from the jet nozzle 20 to the internal area 4 entirely flows to the water discharge pipe 46 through the water discharge route 18. As the water in the internal area 4 is discharged outside the internal area 4 through the water discharge route 18, it is possible to prevent the pressure in the internal area 4 from being excessively increased by the jet of water discharged from the jet nozzle 20. Compressed air discharged from the compressor 50 is supplied to a lower chamber (not shown) in the cylinder barrel of the transfer device 48 through the air supply hose 49. The piston in the cylinder barrel is then pushed upward so that the nozzle head 21, which is coupled to the piston by way of the piston rod, moves upward in the axial direction of the supporting member 22 (see an arrow 31). The nozzle head 21 moves in the axial direction because the key 33 mounted on the rotation body 56 is inserted into the groove 27 longer than the key 33 to let the nozzle head 21 move along the key 33. Therefore, the jet nozzle 20, which is discharging a jet of water, can be moved upward without allowing the divider plates 23A, 23B to move in the axial direction of the piping 1 while the jet nozzle 20 is rotating around the supporting member 22 within the internal area 4. As the jet nozzle 20 rotates within the internal area 4 and moves in the axial direction of the supporting member 22, the residual stress improvement area 2 in the circumferential direction and axial direction of the piping 1 can be entirely subjected to water jet peening. To move the divider plates 23A, 23B in the axial direction of the piping 1 within the piping 1 to reposition the jet nozzle 20, it is necessary to discharge the water in the internal area 4 to the outside through the water discharge route 18 and expel the compressed air from the hollow seal members 24A, 24B as described later to contract the hollow seal members 24A, 24B. Further, after the supporting member 22, the divider plates 23A, 23B, and the like are moved in the axial direction within the piping 1 to reposition the jet nozzle 20, it is necessary to introduce compressed air into the hollow seal members 24A, 24B and fill the internal area 4 with water. Thus, it takes a long period of time to reposition the jet nozzle in the axial direction of the piping 1 by moving the divider plates 23A, 23B. In the present embodiment, however, the nozzle head 21 can move in the axial direction of the supporting member 22 as described earlier. Therefore, the jet nozzle 20 can move in the axial direction of the piping 1 within a short period of time. After completion of water jet peening for the inner surface of the piping 1, the on-off valves 59, 61 open. The compressed air in the hollow seal member 24A is then discharged outside through the air supply routes 8, 7, the air supply pipe 53, and the exhaust pipe 60. Further, the compressed air in the hollow seal member 24B is discharged outside through the air supply route 10, the air supply pipe 52, and the exhaust pipe 58. The hollow seal members 24A, 24B contract and leave the inner surface of the piping 1. Subsequently, the water jet peening apparatus 6 is extracted from the piping 1 and removed outside the vessel 37. According to the present embodiment, the sizes of the divider plates 23A, 23B, which define the internal area 4, are smaller than the transverse cross sectional area of the inner surface of the piping 1 to be subjected to water jet peening. Therefore, the water jet peening apparatus 6 can be easily inserted into the piping 1 and subjected to water jet peening at an arbitrary position within the piping 1. Particularly, as the contractible, circular, hollow seal members 24A, 24B are disposed on the outer surfaces of the divider plates 23A, 23B, the water jet peening apparatus 6 can be easily inserted into and extracted from the piping 1. When compressed air is introduced into the internal spaces of the hollow seal members 24A, 24B to expand the hollow seal members 24A, 24B while the water jet peening apparatus 6 is inserted in the piping 1, it is possible to seal the gap between the inner surface of the piping 1 and the divider plate 23A and the gap between the inner surface of the piping 1 and the divider plate 23B. Thus, the internal area 4 can be isolated from the external area 3. This makes it possible to fill the internal area 4 with water and subject the residual stress improvement area 2 to water jet peening. The jet nozzle, 20 is disposed between the divider plate 23A and the divider plate 23B. Therefore, even when a sensor or other electronic device 5 (or structure) that may be damaged by shock waves generated upon the collapse of cavitations included in a jet of water discharged from the jet nozzle 20 is disposed in the piping 1, the divider plate 23A can be positioned between the electronic device 5 and the jet nozzle 20. Thus, the shock waves generated in the internal area 4 during water jet peening can be blocked by the divider plate 23A to prevent the shock waves from being applied to the electronic device 5. In the present embodiment, the jet nozzle 20 is disposed between the divider plate 23A and the divider plate 23B. This makes it possible to prevent the electronic device 5 mounted on the piping 1 from being damaged by the shock waves. FIG. 1 shows that the electronic device 5 is protruded inward from the inner surface of the piping 1. However, when the electronic device 5 is mounted on the piping so that a leading end of the electronic device 5 is positioned on the inner surface of the piping 1 without allowing the electronic device 5 to protrude inward from the inner surface of the piping 1, the water jet peening apparatus 6 can be inserted into the piping 1 to the extent that the water jet peening apparatus 6 is positioned behind the electronic device 5. When the inner surface of the piping 1 is to be subjected to water jet peening at a place behind the electronic device 5, the divider plate 23B is disposed between the jet nozzle 20 and the electronic device 5. When water jet peening is performed in this state, the divider plate 23B blocks the shock waves and prevents the electronic device 5 from being damaged by the shock waves. Even when the electronic device 5 is mounted on the piping 1 while it is filled with water, it is possible to prevent the electronic device 5 from being damaged as far as the divider plates 23A, 23B are disposed between the jet nozzle 20 and the electronic device 5. In the present embodiment, the stopper structures 62, 63 prevent the rotation body 56 from moving in the axial direction of the supporting member 22. Therefore, even when the transfer device 48 moves the nozzle head 21 in that axial direction, the rotation body 56 does not move in that axial direction. Further, the stopper structure 62 prevents the rotation body 56 from falling. As the nozzle head 21 is surrounded by the divider plate 23B, it is easy to connect the high-pressure hose 41 to the high-pressure water route 11, which is formed in the rotating nozzle head 21, and connect the air supply hose 49 to the transfer device 48, which rotates together with the rotation body 56. The nozzle head 21 and the transfer device 48 can also be rotated. Further, as the nozzle head 21 is surrounded by the divider plate 23B, the spacing interval between the divider plate 23A and the divider plate 23B can be narrowed to ease the handling of the water jet peening apparatus 6 and improve the installability of the water jet peening apparatus 6 in the piping 1. Second Embodiment The water jet peening method according to a second embodiment of the present invention will now be described with reference to FIG. 2. In the first embodiment, water jet peening is performed for the inner surface of the piping 1 that is vertically extended. In the second embodiment, however, water jet peening is performed for the inner surface of a piping 1A that is horizontally extended. A water jet peening apparatus 6A to which the water jet peening method according to the second embodiment is applied is configured so that the scoop (air gathering area) 9 included in the water jet peening apparatus 6 to which the water jet peening method according to the first embodiment is applied is replaced by a scoop 9A. The other components of the water jet peening apparatus 6A are the same as those of the water jet peening apparatus 6. The scoop (air gathering area) 9A is formed on a circumferential surface of the divider plate 23A in the water jet peening apparatus 6A that faces the divider plate 23B. When the water jet peening apparatus 6A is to be inserted into the piping 1A that is horizontally extended and connected to the vessel 37, the scoop 9A is located at the highest position in the piping 1A as shown in FIG. 2. The water jet peening performed by the water jet peening apparatus 6A with respect to the residual stress improvement area 2, which is the inner surface of the piping 1A, is the same as the water jet peening performed by the water jet peening apparatus 6 according to the first embodiment. The second embodiment provides the same advantages as the first embodiment.
043024190	description	BEST MODE OF CARRYING OUT THE INVENTION Nitrogen gas, contaminated with hydrogen and radioactive particles, is introduced into the recombiner system of FIG. 1 through an inlet line 12. The gas stream from the nuclear reactor systems on line 12 has a flow rate of less than 1.7 cubic feet per minute. The stream is mixed with 40 cubic feet per minute of nitrogen from line 14 to assure that less than 4% hydrogen is contained in the combined inlet stream. During startup, the nitrogen in line 14 is provided by a nitrogen source through valve 16. However, once one of the delay tanks 18 has been sufficiently filled with nitrogen, some nitrogen is recirculated from the tanks through a valve 20. The combined inlet stream is then compressed from about atmospheric pressure to 85 pounds per square inch gauge (psig) in a compressor 22. A sample of the compressed gas is taken through a check valve 24; but the primary gas stream continues through a delay line 26 to a preheater 28. The gas is there preheated to 200.degree. F. under control of heater control 30. Control 30 responds to a temperature sensed downstream at temperature element TE2. A controlled amount of pure oxygen is added to the primary gas stream in a mixer 32 to achieve a stoichiometric mixture of hydrogen and oxygen in the gas stream. The preheated stoichiometric mixture carried by the nitrogen gas stream then passes through a catalytic reactor 36. In the reactor, iodine is first removed from the gas by silver zeolite beads 36. The beads provide a permeable layer in which the iodine is converted to silver iodide. In the preferred embodiment, two inches of CTI Nuclear, type III silver zeolite beads are used. These beads prevent catalyst poisoning by the iodine and also assure that the iodine will not reach the environment. Once cleaned of iodine, the gas stream passes through the catalyst beads 38. The beads are a precious metal catalyst coated on a pelletized ceramic carrier such as the standard recombiner catalyst sold by Oxy-Catalyst Company. A 20 inch layer of catalyst is provided in the 6 inch diameter tank. The resulting exothermic reaction between the hydrogen and oxygen produces water vapor with an accompanying temperature rise to 730.degree. F. The hot gas from the catalytic reactor 34 is cooled by water in a cooler/condenser 40 to about 120.degree. F. The condensed water is then removed from the gas stream in a moisture separator 42. The moisture separator includes a wire mesh coalescer 44 such as that sold by Metex Company. The nitrogen continues through a mesh mist eliminator 46, also available from Metex Company, and water collects in a 5 gallon accumulator 48. The water is drained through a valve 52 by level control 50 which responds to two level sensing elements LE1 and LE2. The radioactive contaminated water is then collected and further treated. The nitrogen gas, cleaned of hydrogen and with a low level of oxygen is passed through a valve 56 to the delay tanks 18. The gas flow through valve 56 is controlled by pressure control 58 which responds to the gas pressure at pressure sensing element PE. A sufficient back pressure in the system is thereby maintained. The cleaned nitrogen is directed through suitable valves to delay tank 60 until that tank is filled. Then the gas is diverted to a second tank 62. Similarly other tanks may be provided. The gas remains in the tank for a sufficient time for the radioactive material therein to decay to acceptable levels. As already noted, it is important that the stoichiometric mix be maintained notwithstanding transient changes in hydrogen concentration in the input line 12. To that end, a control system is provided to meter in the proper amount of oxygen through valve 64 into the mixer 62. A sample of gas at the inlet is taken through a check valve 24 to a hydrogen analyzer 66. With a delay of several seconds, the analyzer provides an indication of the percentage of hydrogen in the gas stream on lead 68 to a control-logic assembly 70. The gas sample is returned through a valve 72 to the primary gas stream ahead of the compressor 22. The hydrogen analyzer 66 may be a Teledyne model 225 analyzer. In response to the hydrogen indication on line 68, the control logic provides a second component control signal on lines 84 and 74 to control the flow of oxygen through valve 64 to the mixer 32. Because the hydrogen analyzer may require up to 11 seconds to provide an output, the sensed gas might pass the mixing point before the oxygen control signal on line 74 could be changed. The system would not be responsive to quick transients. A delay line 26 is thus provided to slow the arrival of the sampled stream at the mixer 32. In this case, the delay line 26 is a 21 foot length of 3 inch inner diameter pipe layed in a serpentine fashion; but the delay line might assume any configuration. The delay time T required for the gas stream to flow from the sampling junction at valve 24 to the mixer 32 must closely match the time required to analyze the gas and deliver the proper amount of oxygen through the valve 64 to the mixer 32. In the present system, that time is a bit greater than 11 seconds and the delay of the control signal through the control logic 70 can be readily adjusted to match the gas delay time T. Downstream of the mixer 32 a second sample is extracted from the primary gas stream through a check valve 76 to an O.sub.2 analyzer 78. The sample is returned to the gas stream through valves 82. The O.sub.2 analyzer provides an indication on lead 80 of the percentage of oxygen which has been delivered to the gas stream. The oxygen indication on lead 80 is compared with the hydrogen indication on line 84 by the initial oxygen controller 98, to determine the error. The controller adjusts the oxygen control signal 74 in the direction to reduce the error toward zero, the hydrogen indication serving as a remote set point for the oxygen control. The hydrogen indicating signal on line 68 is shown in FIG. 2A. The signal does not match the sharp actual change in hydrogen noted in the broken lines in FIG. 2A. Also, the oxygen analyzer 78, requires approximately six seconds to respond. For these two reasons, the signal is compensated by a lead/lag module in the direction to boost or exaggerate changes in the hydrogen indicating signal as shown at 2B. Because the signal on line 90 tends to remain at the set point determined by controller 92, the signal of FIG. 2B is passed through the adder/subtracter 96 to the initial O.sub.2 controller 98 to change the set point of the controller. The initial O.sub.2 controller responds to the differences in the O.sub.2 signal (FIG. 2C) and its new set point to provide a signal shown in FIG. 2D. The signal of FIG. 2D changes the flow through valve 64. The change is made in the direction necessary to reduce the difference in the signals FIG. 2B and 2C, that is to reduce the error. Preferably, the lead lag circuit 94 is a type TL-0176 Fisher lead/lag module, the adder/subtracter 96 is a type TL-173 Fisher adder/subtracter; and the initial and final O.sub.2 controllers 98 and 92 are type TL-101 Fisher process controllers. A final input to the control logic is made from an oxygen analyzer 86 which receives a sample of the output gas stream on line 54 through a valve 88. The signal line 90 indicates an excess of oxygen in the output line which, with proper operation of the system, should equal a set point established in the final oxygen controller 92 in the control logic. The sample is returned to the sample return valve 72 at the inlet. For monitoring, and where necessary for shut down of the system, sensing elements including temperature elements TE, pressure elements PE, and flow elements FE are provided in the system. In addition, a hydrogen analyzer 100 is provided off the output line 54 to assure that the hydrogen contents at the output of the system is held to zero. While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
	abstract	The present invention provides a radiation-shielding container for a radiopharmaceutical that may be magnetically picked and placed, assembled and dis-assembled.
	claims	1. Method for repairing the slides (27) of a radial support assembly (10) for a pressurized water reactor core support plate (5), each slide (27) of U-section being fixed in a housing formed in a side support (26) integral with a nuclear reactor vessel (1) and comprising two essentially parallel lateral branches (27b) equipped with opposing bearing surfaces (27c) designed to collaborate with the lateral faces of a radial support key (15) fixed to the core support plate (5), wherein:the separation between the bearing surfaces (27c) of the lateral branches (27b) of at least one slide (27) that is to be repaired is measured,a relative measurement of the position of the said at least one slide (27) that is to be repaired with respect to the other slides (27) of the support assembly (10) is taken,at least one lateral branch (27b) of the said at least one slide (27) that is to be repaired is cut off and removed,the dimensions of the said at least one lateral branch (27b) are measured and at least one replacement lateral branch (37b) is machined to identical dimensions,open-ended holes (43) intended to accept screw fasteners (44) for screw-fastening the said at least one replacement lateral branch (37b) are pierced in the solid support (26),holes (45) are pierced in the said at least one replacement lateral branch (37b) and these holes (45) are tapped to accept the screw fasteners (44),the said replacement lateral branch (37b) is fixed in the housing of the solid support (26) using the screw fasteners (44),the separation between the bearing surfaces (37c) of the lateral branches (37b) of at least one repaired slide (27) is measured,a relative measurement of the position of the said at least one repaired slide (27) with respect to the other slides (27) of the support assembly (10) is taken,holes (40, 42) are pierced in the solid support (26) and in the said at least one replacement lateral branch (37b) for positioning and load-reacting pins (41), andthe said pins (41) are fitted. 2. Method according to claim 1, wherein the said at least one lateral branch (27b) is cut in the corner of the U-section of the slide (27) that is to be repaired. 3. Method according to claim 1, wherein the said at least one lateral branch (27b) is cut using electron discharge machining. 4. Method according to claim 1, wherein, after piercing the holes (43) in the solid support (26), the said replacement lateral branch (37b) is clamped in the housing of this solid support (26), the holes (45) are pierced, these holes (45) are tapped and the said replacement lateral branch (37b) is fixed in place using the screw fasteners (44). 5. Method according to claim 1, wherein the drilling of the holes (43) in the solid support (26) and the drilling of the holes (45) in the said at least one replacement lateral branch (37b) are operations that are performed separately, the said replacement lateral branch (37b) is clamped in the housing of the solid support (26), these holes (45) are tapped and the said replacement lateral branch (37b) is fixed in place using the screw fasteners (44). 6. Method according to claim 1, wherein, in order to take the measurements of the separation between the bearing surfaces (27c; 37c) of the said at least one slide (27) that is to be repaired and of the said at least one repaired slide, and the position of this slide (27) before and after it has been replaced, use is made of a template (30) equipped, for each of the slides (27) of the support assembly (10), with a key (32) identical to the key (15) of the core support plate (5). 7. Method according to claim 6, wherein at least one key (32) of the template (30) corresponding to a slide (15) that does not require replacement is equipped with equipment for positioning and for measuring the position of the template (30) with respect to the nuclear reactor vessel (1).
	abstract	A data management and networking system and method are provided for automatically retrieving and storing data from a machine tool for distribution to a remote terminal over a network. Raw data related to a machine operation parameter, such as vibrations, are collected. This data is associated with machining operation data, such as the particular cutting tool being used, or the particular feature being cut by the cutting tool. An algorithm is applied to the raw data to generate a parametric representation of the data, thereby significantly reducing the size of the data. At least some data related to non-machining time is separated out, further reducing the size of the data. The associated data is sent to a network server for storage, where it may be accessed by one or more remote terminals.
059490845	abstract	A storage vessel for radioactive material comprising metallic particles that are, preferably but not necessarily spherical, forming a matrix that includes a moderator and absorber of neutrons. The matrix is disposed between an inner vessel and an outer casing having metallic walls. The walls of the inner vessel contains the radioactive materials and shields against photon radiation, and outer the casing, in addition to photon shielding, also serves as a protective layer against physical impact. The metal particles are ideally composed of depleted uranium, however, lead or other high density metals which can attenuate photon radiation can also be utilized. The matrix includes a neutron attenuating and absorbing mixture which fill the interstices between the metallic particles.
	description	The present application is based on, and claims priority from, Korean Patent Application No. 2005-64213, filed Jul. 15, 2005, the disclosure of which is hereby incorporated by reference herein in its entirety. 1. Field of the Invention The present invention relates to a polarized neutron guide, and more particularly, to a polarized neutron guide improved in its yield, solving a problem of a low yield of 50% in the case of a general polarized neutron guide. 2. Description of the Related Art A neutron guide is a hollow tube consisting of glass plates deposited with Nickel or periodic multi-layer (super mirror) for transferring cold neutrons (referred to as neutrons hereinafter) generated from a cold neutron source in a vacuum state to a device located for a long distance with a minimum loss. Referring to FIG. 1, the neutron guide 200 is formed at a desired length extended to a device by serially connecting a plurality of guide units 210. Referring to FIG. 2, the guide units 210 of the neutron guide 200 have a length of about 1 m, with the super mirrors being assembled in a long-box shape having a quadrangular cross-section. In the super mirrors 212, which are capable of enlarging the total reflection angle by two folds or more, a magnetic material of high scattering length density (Ni, Fe, Co) and a non-magnetic material of low scattering length density (Si, Ti, Cu) are selectively deposited on each substrate 212a to form a thin film 212b as a reflective plane on a surface facing the inner path formed by the guide units 210. Therefore, the guide units 210 allow neutrons to be total-reflected within a critical angle in the inside by the super mirrors 212 formed by thin-film deposition. The neutrons in most of elements except some elements (e.g., Gd, Mn) have a positive (+) scattering-length density, which means that an incident angle of neutrons between an incident direction and a medium surface is greater than a refractive angle in the medium unlike electromagnetic waves in a visible light region. Such special property of neutron and an X-ray means that the neutron and the X-ray can be total-reflected from a medium when they are incident on the surface of the ideal material (medium) within a critical angle. Therefore, a basic concept of 58Ni neutron guide capable of moving, i.e., transferring neutrons using the total-reflection property of the neutrons has been suggested in the related art. Since then, a super mirror guide has been used as a neutron guide formed with using the natural nickel and titanium (58Ni: 68%). Neutrons, electrons, X-rays tend to be diffracted in a structure of periodically repeated crystal planes of a crystal of an atom or a molecule. Diffraction can be observed in a thin-film structure where two different materials are artificially repeated periodically. A theory that a diffracted line width can be widened up to a critical angle by changing the thickness of repeated multi-layered thin films has been introduced. A medium capable of widening a total reflection angle of nickel more than two times by applying the above theory is a super mirror 212, which is used for a neutron guide 200. To transfer the neutrons generated from a cold neutron source 300 up to a remotely located device 310 without loss of the neutrons, a neutron guide 200 in a vacuum state is used. As described above, the related art neutron guide 200 uses the property that neutrons are total-reflected when they are incident on the surface of a material (medium) within a critical angle. Neutrons transferred through the neutron guide 200 may sometimes require the spin of the neutron biased in one direction. Using ferromagnetic material and non-magnetic material for the super mirror to form the multi-layer thin film, spin-up polarized neutrons can be separated from spin-down polarized neutrons. In this case, only the type of spin needed for the corresponding apparatus 310 should be used and the rest of the types should be separated to be discarded. To polarize and supply neutrons, a polarized neutron guide is required. The polarized neutron guide can be made of alloys of ferromagnetic materials. A neutron due to its own magnetic moment, has any of two spin directions i.e. a spin-up direction parallel with the direction of a magnetic field and a spin-down direction unparallel with the direction of a magnetic field. The two spin directions of a neutron result in different scattering abilities for a magnetized material. It is possible to polarize a neutron using this property. For the super mirror 212 of a neutron guide 200 for transferring neutrons, if the thin film 400 is composed of FeCo of the magnetic material 410 and Si of the non-magnetic material 412 at a ratio of 89:11, the down-spin neutron ultimately has the same scattering length density as that of Si, the non-magnetic material 412. Thus, when the thin film 400 is formed, the up-spin neutron 422 is diffracted or reflected whereas the down-spin neutron 422b cannot be diffracted but permeates due to the same scattering length density as that of Si, unable to distinguish between FeCo and Si, as illustrated in FIG. 3. The polarized neutron guide may be a residual magnetic polarized guide. The residual magnetic polarized guide is formed so that a thin film 400 magnetized under a magnetic field does not lose magnetization thereof even though the magnetic field disappears afterward. The residual magnetic polarized guide is manufactured using a principle of a recording tape. In the residual magnetic polarized guide, in order to easily perform magnetization, a thin film of FeCoV/TiZr is formed by adding foreign substance to FeCo alloy, or a thin film of FeCo/Ge is formed by using Ge instead of Si. In order to divide and selectively supply neutrons 422 transferred by the neutron guide 200 into spin-up polarized neutrons 422a or spin-down polarized neutrons 422b, a conventional polarized neutron guide 500 was suggested as illustrated in FIG. 4. The conventional polarized neutron guide 500 for generating polarized neutrons is connected at the front with the neutron guide 200 to receive neutrons 422, and separates the neutrons 422 into spin-up polarized neutrons 422a and spin-down polarized neutrons 422b. However, the conventional polarized neutron guide 500 has a disadvantage of collecting only selected polarized neutrons (e.g., spin-up polarized neutrons 422a, which is 50% of the neutrons 422 only), and losing non-selected polarized neutrons (e.g., spin-down polarized neutrons 422b, which is 50% of the neutrons 422), during this process. Various materials can be used for manufacturing the polarized neutron guide 500 for polarizing and separating the neutrons. For representative example, an alloy of ferromagnetic material such as Fe and Co can be used with Si. A thin film of magnetic material 410 of for example FeCo alloy deposited on the surface of a super mirror 510 in the conventional polarized neutron guide 500 is magnetized inside a magnetic field of a magnetic field generating member 520 installed outside the polarized neutron guide 500. Neutrons 422 flowing into the polarized neutron guide 500 under the magnetic field are divided into spin-up polarized neutrons 422a and spin-down polarized neutrons 422b having different scattering length densities, respectively. That is, since the scattering length density of the spin-down polarized neutrons 422b due to the magnetic material 410 of FeCo is matched with the scattering length density of the spin-down polarized neutrons 422b of Si, which is a non-magnetic material 412, regardless of a difference between the two materials 410 and 412, the spin-down polarized neutrons 422b are all transmitted below a critical angle of the super mirror 510 constituting the polarized neutron guide 500. On the contrary, the spin-up polarized neutrons 422a are diffracted and total-reflected by the super mirror 510 constituting the polarized neutron guide 500, and transferred inside the guide 500. With such a principle, the conventional polarized neutron guide 500 can polarize the spin-up polarized neutrons 422a only from the neutrons 422 to collect the same. However, since the conventional polarized neutron guide 500 separates one kind of polarized neutrons, i.e., the spin-up polarized neutrons 422a only without collecting the spin-down polarized neutrons 422b, the neutrons 422 are used in 50% only in viewpoint of the whole collecting efficiency. Unlike the polarized neutron guide 500 consisting of super mirrors 510 using the above-described related art magnetic material 410 and non-magnetic material 412, i.e., FeCo/Si, a neutron inverse-polarization guide (not shown) using super mirrors of a Co/Cu has been suggested, which is designed to transmit and remove the spin-up polarized neutrons 422a, while reflecting and collecting the spin-down polarized neutrons 422b. Therefore, conventionally, where the spin-up polarized neutrons 422a or the spin-down polarized neutrons 422b is required respectively, the polarized neutron guide 500 made of FeCo/Si for separately collecting the spin-up polarized neutrons 422a is used, or a spin-flipper for separately obtaining the spin-down polarized neutrons 422b is used. These polarized neutron guides are very expensive, and require a precise treatment but considered inefficient, since the yield of neutron is only about 50%. Accordingly, the present invention is directed to a polarized neutron guide that substantially obviates one or more problems due to limitations and disadvantages of the related art. An object of the present invention is to provide a polarized neutron guide capable of separating neutrons into spin-up polarized neutrons and spin-down polarized neutrons while minimizing loss of the neutrons. Another object of the present invention is to provide a polarized neutron guide capable of effectively separating polarized neutrons, achieving size reduction, and remarkably lowering installation costs while having a simple structure, not requiring a plurality of polarized neutron guides. Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a polarized neutron guide capable of separating and transferring spin-up polarized neutrons and spin-down polarized neutrons from neutrons, the polarized neutron guide comprising: a body having a vacuum space formed therein through which neutrons are transferred, and including super mirrors disposed on a plane facing the vacuum space and coated with a neutron-reflective thin film; first and second spaces formed inside the body by the vacuum space partitioned by a first plate whose surfaces are coated with neutron-reflective thin films; and a neutron separation space formed by a second plate disposed at an entry of the first space, sloped to a front edge side of the first plate from an inner plane on one side of the body, and a third plate disposed at an entry of the second space, sloped to a front edge side of the first plate from an inner plane on other side of the body, whereby spin-up polarized neutrons and spin-down polarized neutrons are simultaneously separated and transferred to the first and second spaces, respectively. According to an aspect of the present invention, there is provided a polarized neutron guide capable of separating and transferring spin-up polarized neutrons and spin-down polarized neutrons from neutrons, the polarized neutron guide comprising: a body having a vacuum space formed therein through which neutrons are transferred and including super mirrors disposed on a plane facing the vacuum space and coated with a neutron-reflective thin film; a first plate mounted inside the body to partition the vacuum space into first and second spaces, and having surfaces coated with neutron-reflective thin films; a second plate disposed at an entry of the first space, sloped to a front edge side of the first plate from an inner plane on one side of the body, and having a surface coated with a thin film for transmitting spin-up polarized neutrons; and a third plate disposed at an entry of the second space, sloped to a front edge side of the first plate from an inner plane on other side of the body, and having a surface coated with a thin film for transmitting spin-down polarized neutrons, whereby spin-up polarized neutrons and spin-down polarized neutrons are simultaneously separated and transferred to the first and second spaces, respectively. A portion of the body enclosing the first and second spaces and the first plate may be coated with Ni/Ti in the form of a thin film, so that spin-up polarized neutrons or spin-down polarized neutrons are transferred therein. A portion of the body enclosing the first space and the first plate may be coated with FeCo/Si or Ni/Ti in the form of a thin film so that spin-up polarized neutrons are transferred therein, and a portion of the body enclosing the second space and the first plate may be coated with Co/Cu or Ni/Ti in the form of a thin film so that spin-down polarized neutrons are transferred therein. A portion of the body enclosing the first space and the first plate may be coated with Co/Cu or Ni/Ti in the form of a thin film so that spin-down polarized neutrons are transferred therein, and a portion of the body enclosing the second space and the first plate may be coated with FeCo/Si or Ni/Ti in the form of a thin film so that spin-up polarized neutrons are transferred therein. For the first space to transfer spin-up polarized neutrons, the second plate mounted at the entry of the first space may include polarizing-neutron super mirrors for transmitting spin-up polarized neutrons and reflecting spin-down polarized neutrons to the third plate of the second space. For the second space to transfer spin-down polarized neutrons, the third plate mounted at the entry of the second space may include polarizing-neutron super mirrors for transmitting spin-down polarized neutrons and reflecting spin-up polarized neutrons to the second plate of the first space. For the first space to transfer spin-down polarized neutrons, the second plate mounted at the entry of the first space may include polarizing-neutron super mirrors for transmitting spin-down polarized neutrons and reflecting spin-up polarized neutrons to the third plate of the second space. For the second space to transfer spin-up polarized neutrons, the third plate mounted at the entry of the second space may include polarizing-neutron super mirrors for transmitting spin-up polarized neutrons and reflecting spin-down polarized neutrons to the second plate of the first space. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. A polarized neutron guide 1 of the present invention separates spin-up polarized neutrons 22a and spin-down polarized neutrons 22b from neutrons 22 and collects the separated polarized neutrons 22a and 22b, respectively, without loss. The polarized neutron guide 1 has a body 12 consisting of super mirrors 13 so as to transfer polarized neutrons. The super mirrors 13 may include neutron super mirrors of Co/Cu or Ni/Ti for reflecting spin-down polarized neutrons 22b, or neutron super mirrors of FeCo/Si or Ni/Ti for reflecting spin-up polarized neutrons 22a. The polarized neutron guide can maximally obtain the polarized neutrons without loss, by using combination of these super mirrors. Referring to FIG. 6, the inventive polarized neutron guide 1 has a neutron separation space 10 formed at a front side and has the first and second spaces 50 and 60, which are transfer paths of spin-up and spin-down polarized neutrons 22a and 22b, respectively, formed at a front side thereof, so as to make maximum acquisition of polarized neutrons 22a and 22b. To partition a space in the body 12 into the neutron separation space 10 and the first and second spaces 50 and 60, the first plate 30 made of a non-polarized neutron super mirror, the second plate 32 and the third plate 34 made of polarized neutron super mirrors are disposed inside the body 12. That is, the inventive polarized neutron guide 1 has a vacuum space formed therein, through which neutrons are transferred, and has the body 12 consisting of the super mirrors 13 having a surface facing the vacuum space and coated with a neutron-reflective thin film. The body 12 can be coated with Ni/Ti constituting non-polarized super mirrors 13 in the form of a thin film to transfer spin-up polarized neutrons 22a and/or spin-down polarized neutrons 22b. Also, the body 12 can be coated with FeCo/Si so that spin-up polarized neutrons 22a may be transferred therein or can be coated with Co/Cu so that spin-down polarized neutrons 22b may be transferred therein. The inventive polarized neutron guide 1 has the first space 50 and the second space 60 partitioned by the first plate 30. The first plate 30 is mounted inside the body 12 and has a surface coated with a neutron-reflective thin film. The first and second spaces 50 and 60 form passages through which spin-up polarized neutrons 22a or spin-down polarized neutrons 22b are separated and transferred. Referring to FIG. 6, the inner space of the body 12 is divided by the first plate 30. The first plate 30 has a plate-shaped structure and has both edges fixed inside the body 12 to form the first and second spaces 50 and 60 at the upper portion and the lower portion, respectively. Also, the surface of the first plate 30 is coated with Ni/Ti in the form of a thin film so that spin-up polarized neutrons 22a and/or spin-down polarized neutrons 22b may be transferred. Also, the first plate 30 is coated with FeCo/Si so that spin-up polarized neutrons 22a may be transferred or coated with Co/Cu so that spin-down polarized neutrons 22b may be transferred. Also, the first plate 30 may have one side coated with FeCo/Si and the other side coated with Co/Cu. Also, though the first plate 30 is illustrated to divide the inner side space of the body 12 vertically in FIG. 6, the present invention is not limited to this but the first plate 30 can be vertically arranged inside the body 12 to horizontally divide the inner space. The present invention is not limited to this arrangement but includes all of the above arrangements. The inventive guide 1 has a neutron separation space 10 formed at the front side of the first and second spaces 50 and 60. The neutron separation space 10 is formed by the second plate 32 disposed at the entry of the first space 50, sloped to the front edge side of the first plate 30 from an inner plane on one side of the body 12, and the third plate 34 disposed at the entry of the second space 60, sloped to the front edge side of the first plate 30 from an inner plane on other side of the body 12. Therefore, the neutrons 22 flowing into the polarized neutron guide 1 are separated into spin-up polarized neutrons 22a and spin-down polarized neutrons 22b at the neutron separation space 10, and the spin-up polarized neutrons 22a and the spin-down polarized neutrons 22b are transferred through the first and second spaces 50 and 60, respectively, at the rear side. A magnetic field applying member 70 for applying a magnetic field on the neutrons 22 to primarily align the neutrons 22 in parallel or in anti-parallel with the magnetic field is disposed at the outer side of the polarized neutron guide 1. The neutrons 22 are separated into the spin-up polarized neutrons 22a and the spin-down polarized neutrons 22b at the neutron separation space 10 by the magnetic field applying member 70. The polarized neutrons 22a and 22b are transmitted or reflected to the first and second spaces 50 and 60 by the second and third plates 32 and 34, which are super mirrors mounted on a slope. The second plate 32 is disposed at the entry of the first space 50, sloped to the front edge side of the first plate 30 from an inner plane on one side of the body 12, and has a surface coated with a thin film (e.g., Co/Cu) that transmits the spin-up polarized neutrons 22a. The third plate 34 is disposed at the entry of the second space 60, sloped to the front edge side of the first plate 30 from an inner plane on other side of the body 12, and has a surface coated with a thin film (e.g., FeCo/Si) that transmits the spin-down polarized neutrons 22b. The neutrons 22 are separated by the neutrons separation space 10 formed by the second and third plates 32 and 34 within the body 12 to flow into the first and second spaces 50 and 60. The separated neutrons are constantly reflected inside the first and second spaces 50 and 60 and transferred up to a device that requires the polarized neutrons 22a and 22b respectively. For that purpose, a body 12 enclosing the first and second spaces 50 and 60 and the first plate 30 are coated with a thin film of Ni/Ti as illustrated in FIG. 7, so that spin-up polarized neutrons 22a and/or spin-down polarized neutrons 22b may be transferred. Also, referring to FIG. 7, a body 12 enclosing the first space 50 and the first plate 30 are coated with a thin film of FeCo/Si or Ni/Ti so that spin-up polarized neutrons 22a may be transferred, and a body 12 enclosing the second space 60 and the first plate 30 are coated with a thin film of Co/Cu or Ni/Ti so that spin-down polarized neutrons 22b may be transferred. Referring to FIG. 8, unlike the above-described construction, a body 12 enclosing the first space 50 and the first plate 30 may be coated with Co/Cu or Ni/Ti in the form of a thin film so that spin-down polarized neutrons 22b are transferred, and a body 12 enclosing the second space 60 and the first plate 30 may be coated with FeCo/Si or Ni/Ti in the form of a thin film so that spin-up polarized neutrons 22a are transferred. For the first space 50 to transfer spin-up polarized neutrons 22a, the second plate 32 mounted at the entry of the first space 50 comprises polarizing-neutron super mirrors for transmitting spin-up polarized neutrons 22a and reflecting spin-down polarized neutrons 22b to the third plate 34 of the second space 60. Therefore, the second plate 32 has a thin film of Co/Cu deposited thereon. Also, for the second space 60 to transfer spin-down polarized neutrons 22b, the third plate 34 mounted at the entry of the second space 60 comprises polarizing-neutron super mirrors for transmitting spin-down polarized neutrons 22b and reflecting spin-up polarized neutrons 22a to the second plate 32 of the first space 50. Therefore, the third plate 34 has a thin film of FeCo/Si deposited thereon. According to the present invention, the positions of the second plate 32 and the third plate 34, and the positions of the first space 50 and the second space 60 can be changed vertically or horizontally. According to the inventive neutron guide 1 having the above construction, when the neutrons 22 flow into the neutron separation space 10 formed at the front side of the body 12 from a general neutron guide 200, a magnetic field is applied to the neutrons 22 by the magnetic field applying member 70. After the neutrons 22 are primarily aligned in parallel or anti-parallel with the magnetic field by the magnetic field in the neutron separation space 10, the neutrons 22 are separated into the spin-up polarized neutrons 22a and the spin-down polarized neutrons 22b by the two kinds of polarized neutron mirrors, i.e., the second plate 32 and the third plate 34. Since the second plate 32 and the third plate 34 are disposed on a slope facing each other, and deposited with a thin film of Co/Cu or FeCo/Si, the second plate 32 thin-film deposited with Co/Cu transmits the spin-up polarized neutrons 22a and total-reflects the spin-down polarized neutrons 22b to the third plate 34 of the second space 60. Also, the third plate 34 thin-film deposited with FeCo/Si transmits the spin-down polarized neutrons 22b and total-reflects the spin-up polarized neutrons 22a to the second plate 32 of the first space 50. Therefore, only the spin-up polarized neutrons 22a that have passed through the second plate 32 and the spin-up polarized neutrons 22a that have been reflected from the third plate 34 and passed through the second plate 32 exist in the first space 50. The above spin-up polarized neutrons 22a are transferred forward through the first space 50 enclosed by the thin-film layers of Ni/Ti or FeCo/Si of the body 12 and the first plate 30. Also, only the spin-down polarized neutrons 22b that have passed through the third plate 32 and the spin-down polarized neutrons 22b that have been reflected from the second plate 32 and passed through the third plate 34 exist in the second space 60. The above spin-down polarized neutrons 22b are total-reflected to be transferred through the second space 60 enclosed by the thin-film layers of Ni/Ti or Co/Cu of the body 12 and the first plate 30. As described above, the neutrons 22 that have been separated into the spin-up polarized neutrons 22a and the spin-down polarized neutrons 22b are constantly total-reflected and transferred to a desired device through the first and second spaces 50 and 60 within the body 12 consisting of combination of the general non-polarized neutron super mirrors of a Ni/Ti type or the polarized neutron super mirrors of a FeCo/Si type and a Co/Cu type. The first and second spaces 50 and 60 transfer the separated spin-up polarized neutrons 22a and spin-down polarized neutrons 22b through the general neutron guide 200 connected at the rear side of the body 12. Therefore, according to the present invention, since both the spin-up polarized neutrons 22a and the spin-down polarized neutrons 22b are separated and collected, loss of the polarized neutrons can be minimized. Also, though the first and second spaces 50 and 60 for transferring the spin-up polarized neutrons 22a and the spin-down polarized neutrons 22b are vertically partitioned inside the body 12, the present invention is not limited to this structure but the first and second spaces 50 and 60 can be horizontally disposed. According to the present invention, the neutrons can be separated into the spin-up polarized neutrons and the spin-down polarized neutrons and collected, so that loss of the neutrons is minimized and the polarized neutrons can be effectively obtained. The present invention can effectively separate the polarized neutrons in a simple structure without a plurality of polarized neutron guides, thereby achieving an equipment of a small-sized structure and remarkably lowering installation costs of a polarized-neutron separating and collecting device. Also, loss of the spin-up polarized neutrons or the spin-down polarized neutrons is minimized, so that a polarized neutron preparation time at a device where the neutrons are to be used, is reduced and thus process efficiency improves. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
047298685	description	DETAILED DESCRIPTION OF THE PRFFERRED EMBODIMENTS FIG. 1 is an elevational view, partly in cross-section, of a pressurized water reactor 10 comprising a vessel 12 of generally conventional configuration including an upper dome 12a, cylindrical sidewalls 12b, and a bottom closure 12c comprising the base of the reactor 10. Within the bottom closure 12c, as schematically indicated, is so-called base-mounted instrumentation 14. The lower barrel assembly 16 comprises a generally cylindrical sidewall 17 affixed at its lower and upper ends to respective lower and upper core plates 18 and 19. Fuel rod assemblies 20 are positioned in generally vertically oriented, parallel axial relationship within the lower barrel assembly 16. A radiation reflection shield 21 is mounted interiorly of the cylindrical sidewalls 17, in conventional fashion. The inner barrel assembly 24 includes a cylindrical sidewall 26 within which are positioned a plurality of rod guides in closely spaced, parallel axial relationship; for simplicity of illustration, only two such rod guides are shown in FIG. 1, namely rod guide 28 housing a cluster of radiation control rods 30 (RCC) and a rod guide 32 housing a cluster of water displacement rods 34 (WDRC). Mounting means 36 and 37 are provided at the respective upper and lower ends of the rod guide 28 and, correspondingly, mounting means 38 and 39 are provided at the respective upper and lower ends of the rod guide 32, the lower end mounting means 37 and 39 mounting the respective rod guides 28 and 32 to the upper core plate 19, and the upper mounting means 36 and 38 mounting the respective rod guides 28 and 32 to a calandria assembly 50. The calandria assembly 50 includes a lower calandria plate 52, an upper calandria plate 54, and a plurality of parallel axial calandria tubes 56 which are positioned in alignment with corresponding apertures in the lower and upper calandria plates 52 and 54 and to which the calandria tubes 56 are mounted at their respective, opposite ends. Calandria extensions 58 project downwardly from the calandria tubes 56 and connect to corresponding mounting means 36 for the upper ends, or tops, of the RCC rod guides 28. As will become apparent hereinafter, the calandria 50 performs significant support functions relative to the rod guides 28 and 32 of the inner barrel assembly 24, including providing a support for the vibration arrestors of the present invention, as hereinafter described. Whereas the vibration arrestors of the invention have numerous applications, they are disclosed initially herein in certain preferred embodiments, as employed in combination with the flexible rod guide support structure of the corresponding entitled application, hereinabove identified. More particularly, as disclosed therein, the upper end mounting means 38 associated with the WDRC rod guides 32 are interconnected by flexible linkages (shown and described in detail hereafter) to the mounting means 36 of the RCC rod guides 28. Thus, in this embodiment, the calandria extensions 58 are directly connected only to the upper end mounting means 36 for the RCC rod guides 28 and not to the upper end mounting means 38 for the WDRC rod guides 32--but serve, through the flexible linkages, to provide both stiff lateral support thereto, as well as resilient axial support thereto to compensate for relative differences in positioning of the tops of the WDRC rod guides 38, without overstressing the flexible linkages. Extending upwardly beyond the upper calandria plate 54 and, more particularly, within the dome 12a of the vessel 12, there is provided a plurality of flow shrouds 60 respectively aligned with the calandria tubes 56. A corresponding plurality of head extensions 62 is aligned with the plurality of flow shrouds 60, with respective adjacent ends thereof in generally overlapping relationship. Control rod cluster (RCC) displacement mechanisms 64 and water displacement rod cluster (WDRC) displacement mechanisms 66 are associated with the respective head extensions 62, flow shrouds 60 and calandria tubes 56 which, in turn, are respectively associated with the respective clusters of radiation control rods 30 and water displacment rods 34. Particularly, the RCC and WDRC displacement mechanisms 64 and 66 connect through corresponding lines to the respective clusters of radiation control rods and water displacement rods 30 and 34, to control the respective vertical positions thereof and, particularly, to selectively lower same through corresponding openings (not shown) provided therefore in the upper core plate 19 into surrounding relationship with respectively associated fuel rod assemblies 20. In this regard, the clusters 30 and 34 have an extent of travel corresponding substantially to the longitudinal, or axial, height of the fuel rod assemblies 20. While the particular control function is not relevant to the present invention, insofar as the control over the reaction within the core is effected by the selective positioning of the respective rod clusters 30 and 34, it is believed that those skilled in the art will appreciate that moderation, or control, of the reaction is accomplished in accordance with the extent to which the control rod clusters 30 are inserted into the core and with the effective water displacement adjustment which is achieved by selective positioning of the water displacement rods 34. FIG. 2 comprises a perspective, exploded and partially broken-away view of rod guides and respectively associated top plates, in conjunction with a flexible linkage in accordance with the aforesaid first embodiment of the present invention. FIG. 3 comprises a top plan view of an exemplary assemblage of a top plate of a first (WDRC) type, as interdigitized with associated top plates of a second (RCC) type disposed in surrounding, mating relationship therewith and, further, as interconnected by a flexible linkage. FIGS. 4 and FIG. 5 comprise elevational, cross-sectional views taken along the lines 4--4 and 5--5, respectively, in FIG. 3. The rod guide 32 for the WDRC rod cluster 34 and the rod guide 28 for the RCC rod cluster 30, as best seen in FIG. 2, have first and second, different configurations, and have respectively associated therewith top plates 38 and 36 corresponding to the respective mounting means 38 and 36 diagramatically illustrated in FIG. 1. Each of the rod guides 28 and 30 is formed of sheet metal and each of the respective top plates 36 and 38 is machined to achieve the configurations as illustrated. The peripheries of the top plates 36 and 38 generally correspond to the peripheries of the respective rod guides 28 and 30, as viewed in cross-section taken in a plane transverse to the vertical axes thereof and thus parallel to the plane of FIG. 3. The top plates 36 and 38 furthermore have interior channels 70 and 72, respectively, the profiles or boundaries of which correspond to the configuration, again in cross-section, of the corresponding RCC rod clusters 30 and WDRC rod clusters 34, the latter being illustrated in simplified schematic form in FIGS. 6 and 7, respectively. In FIG. 6, the RCC rod cluster 80, shown in a simplified perspective view, includes a spider 82 comprising a pair of orthogonally related cross arms 82a and 82b interconnected by a central hub 83, a plurality of RCC rodlets or rods 84 depending from the arms 82a and 82b. Particularly, each of the arms 82a and 82b carries four (4) such rods 84. Correspondingly, as best seen in FIG. 3, the interior channel 70 of the top plate 36 has a profile corresponding to the RCC rod cluster 30, permitting the latter to be lowered axially through the channel 70 thereof under control of the control rod displacement mechanism 64 (FIG. 1) which connects through drive line 86 to the central hub 83 of spider 82 of the RCC rod cluster 30. The interior channel 72 of the WDRC top plate 38 likewise has a profile corresponding to the periphery, again in cross-section, of the WDRC rod cluster 34 (FIG. 1), the latter being shown in a simplified schematic plan view in FIG. 7. The WDRC rod cluster 34 similarly includes a spider 90 having a plurality of radially extending arms 92 connected to a central hub 93; further, alternate ones of the arms 92 include transverse cross arms 92a. A plurality of WDRC rods 94 then are appropriately connected to the arms 92 and 92a and depend therefrom in parallel axial relationship. From FIG. 3, it will be apparent that the respective rod guides 28 and 30 and the associated top plates 36 and 38 are configured so as to permit relatively dense packaging thereof and, more particularly, the assemblage thereof as interdigitized matrices. Particularly, the top plate 38 of the WDRC rod guides 30 is surrounded by a symmetrical, associated sub-array of four RCC top plates 36; further, each of the RCC top plates 36 in turn is configured to engage an associated sub-array of four WDRC top plates 38. While the symmetrical configuration of the respective rod clusters and thus of the corresponding rod guides and associated top plates is a preferred embodiment, alternative configurations are also contemplated as within the scope of the invention, the principal requirement being that interdigitized matrices of the respective rod guides and top plates may be established in a tightly packaged array. The top plates 36 and 38 are now described in detail, with concurrent reference to FIGS. 2-5, common reference numerals being employed to identify the common elements of the symmetrical portions of the respective, individual structures. The WDRC top 38 plate is of a generally annular configuration with a generally square periphery and includes four (4) major arms 100, each each pair of two (2) adjacent arms 100 extending in perpendicular relationship and the totality of four (4) such pairs defining four (4) major exterior vertices, or corners. A diagonal minor arm 102 spans each such vertex and integrally interconnects the pair of associated, adjacent major arms 100. Inwardly transverse, or lateral, extensions 104 are formed at intermediate positions along the length of each of the major arms 100 displaced from the opposite ends thereof, and integrally join a central, link connection vertical stub 106. An outwardly transverse, or lateral wedge-fit extension 106a is formed on the stub 106, extending beyond the outer sidewall surface, or periphery, of the major arm 100. A link connection threaded bore 107 is formed in each vertical stub 106. The RCC top plate 36 (best seen in FIG. 3) includes a corresponding plurality of four (4) equiangularly displaced major arms 110, the interior peripheral edges of each pair of adjacent arms 110 defining an interior vertex which receives therein a corresponding exterior vertex, or corner, of the top plate 38, as defined by a pair of adjacent major arms 100 thereof. The top plate 36 further includes a diagonal minor arm 112 extending across the geometrical interior vertex defined by the major arms 110, the exterior vertical surface of the arm 112 corresponding to the interior vertical surface of the diagonal minor arm 102 of the top plate 38. Transverse, or lateral extensions 114 extend symmetrically from both sides of the major arms 110, each extension 114 corresponding in size and configuration to the corresponding lateral extension 104 of a top plate 38 associated with the corresponding arm 100. As best seen in FIG. 2, the transverse lateral extensions 114 on the respective peripheral edges of a pair of adjacent major arms 110 which define a given interior vertex are continuous with the diagonal minor arm 112, and furthermore the extensions 114 and the included diagonal minor arm 112 have a common planar upper surface, corresponding to the planar upper surface of the major arms 110, but are forshortened in vertical height relative to that of the major arms 110 such that the lower surfaces thereof define an undercut interior peripheral region, or channel, 118. The outer end of each major arm 110 furthermore includes a wedge-fit extension 116 generally aligned with the major axis of the corresponding major arm 110. A stop pin bore 115 is formed in each of the transverse lateral extensions 114 of each arm 110 in a position so as to be aligned with the stop pin bore 105 in the corresponding inward lateral extension 104 of a corresponding arm 100 when the top plates 36 and 38 are assembled, as in FIG. 3. Further, a link connection threaded bore 117 is formed in the integral juncture 110' of adjacent major arms 110 surrounding the interior channel 70 and defining the interior vertex. A groove 120 further is formed in the associated transverse extensions 114 and the included diagonal minor arm 112, extending along the respectively associated peripheral edges of the associated pair of adjacent major arms 110 and communicating with a counter bore 121 which is coaxial with the threaded bore 117. The assembled relationship of the top plates 36 and 38 is best understood from the top plan view of FIG. 3, taken in conjunction with the vertical cross-sectional views of FIGS. 4 and 5, the latter taken along the lines 4--4 and 5--5 in FIG. 3, respectively. As seen in FIG. 4, each diagonal minor arm 102 of the top plate 38 is received within the corresponding diagonal portion of the channel 118 defined by the diagonal minor arm 112 and the integral juncture 110' of an adjacent pair of major arms 110, the diagonal minor arm 112 thus being superposed on diagonal minor arm 102. As seen in FIG. 5, the transverse lateral extensions 114 are superposed on the respective midside, inward lateral extensions 104 of a given major arm 100 of the top plate 38. As best seen from FIG. 3, the free ends of the major arms 110 of two adjacent top plates 36 which bound, or are contiguous with, a common major arm 100 of a top plate 38 are juxtaposed in closely spaced relationship, the respective, aligned wedgefit extensions 116 thereof closely engaging the respective surfaces of the corresponding outward, transverse wedge-fit extension 106a of that associated major arm 100. Stop pins 125 then are positioned in the aligned stop pin bores 105 and 115. Finally, a flexible linkage 130 is received within the channels 120 of the group of top plates surrounding a given top plate 38, which then is bolted in position. Particularly, bolts 132 are received through the apertures 131 in the corners, or vertices, of the linkage 130 and securely threaded into the corresponding, threaded bores 117 and, further, bolts 134 are received through the apertures 133 in the side arms of the linkage 130 and securely threaded into the corresponding threaded bores 107 in the link connector vertical stubs 106. Respective matrices of top plates 36 and 38 thus are interdigitized by virtue of the respective structural components defining the mating, interior and exterior vertices thereof and including the channels 118 and the superposed lateral, or transverse, extensions 114 and 104. Further, the top plates are laterally interlocked (i.e., in a plane perpendicular to the axis of the assembly 24) by the flexible linkages 130 in a two dimensional, concatenated relationship in which each of the top plates 38 is linked rigidly in the lateral direction to four respectively surrounding top plates 36--and, in turn, each of the top plates 36 is laterally interlocked at its four interior vertices to associated exterior vertices of four top plates 38 which are interdigitized therewith. It will be appreciated that whereas the interdigitized relationship exists throughout the majority of the array, as is apparent, the outer edges, or the periphery, of the array necessarily will be defined by one or more peripheral edges of either one or the other of the top plates 36 and 38--typically, the top plates 36. Mounting of the concatenated and interdigitized matrices of top plates 36 and 38, for securing the top ends of the rod guides 28 and 30 in position within the upper end of the inner barrel assembly 24, is achieved by connections provided between the lower calandria plate 52 and the RCC top plates 36. FIG. 8 is an enlarged view of the portion of a lower calandria plate 52 and of a broken-away portion of the upper calandria plate 54, illustrating more clearly the association of the calandria tubes 56 and the calandria plates 52 and 54. More specifically, the calandria tubes 56a which are connected at their lower ends to corresponding calandria extensions 58 are associated with the RCC rod clusters and the associated top plates 36. Calandria tubes 56b on the other hand, are associated with the WDRC rod clusters and the corresponding top plates 38. Provided in the lower calandria plates 52, intermediate the various calandria tubes 56, are flow holes 59 through which the core output flow, exiting upwardly from the inner barrel assembly 24, proceeds through the calandria assembly 50. Corresponding flow holes (not shown) ar provided in the upper calandria plate 54. FIGS. 9, 10 and 11, discussed concurrently, illustrate a first embodiment of a vibration arrestor 140 in accordance with the present invention. More particularly, FIG. 9 is a schematic, top plan view of a portion of the lower calandria plate 52, illustrating (in solid cross-section) the assemblage of calandria tubes 56a and 56b associated with the array of RCC and WDRC top plates 36 and 38, respectively shown in FIG. 3. The vibration arrestors 140 are shown in dotted line form since disposed beneath the calandria plate 52 and thus hidden from direct view in FIG. 9. FIG. 10 is a cross-sectional view illustrating the connection of a top plate 36 to the calandria bottom plate 52 by a calandria extension 58. Particularly, the calandria extension 58, of circular cross-section, is received within the corresponding circular cross-sectional channel 70 of an RCC top plate 36, thus establishing lateral stability of the RCC top plate 36; each top plate 36 receives a corresponding calandria extension 58 in its channel 70. Accordingly, the RCC top plates 36 are supported directly, and the interdigitized and concatenated WDRC top plates 38 thus are supported through the RCC top plates 36, against lateral movement by the plurality of calandria extensions 58 and ultimately by the lower calandria plate 52. FIG. 11 is a plan view taken along a plane substantially coinciding with the lower surface of the lower calandria plate 52 and thus passing through the calandria extensions 58 which appear in cross-section therefore in FIG. 11; in FIG. 11, for clarity of presentation, the associated RCC top plates 36 are shown in simplified, or schematic outline form and the WDRC top plates 38 are omitted. With concurrent reference to FIGS. 9, 10 and 11, each vibration arrestor 140 comprises a central hub 141 having a central aperture 142 therein by which it is received over a calandria extension 58 and a pair of integral springs arms 141-1 and 141-2 extending generally radially from the hub 141 in oppositely oriented, aligned relationship, and thus at a 180.degree. relative angular displacement about the hub 141 and aligned with a diameter therethrough. The hub 141 thus functions as a mounting base of the arrestor 140. As best seen in the cross-sectional view of FIG. 10, and as appear partially in hidden lines in FIGS. 9 and 11, an annular clamping, or stiffening, ring 143 is received over the central hub 141, the ring 143 including a pair of apertures 143a which are positioned in alignment with a corresponding pair of apertures 141a in the hub 141 for receiving bolts 144 which are engaged in threaded bores 52a in the calandria plate 52. As best seen from the plan views of FIGS. 9 and 11, the stiffening rings 143, while of generally annular configuration, have a periphery generally corresponding to that of the hub 141 of the arrestor 140, and thus include lateral extensions 143b corresponding to the portions of the hub 140 which are aligned with the spring arms 141-1 and 141-2. The aligned apertures 141a and 143a for receiving the bolts 144 correspondingly are formed in these mating portions of the hub 141 and lateral extension 143b of the ring 153. As also best seen in FIGS. 9 and 11, the spring arms 141-1 and 141-2 are of sufficient length so as to engage the surfaces of the top plates 36, which are aligned with and next adjacent to a given top plate 36 and associated extension 58 on which a given arrestor 140 is mounted, at positions closely adjacent the junction 100' of the major arms 100 of those adjacent top plates 36, and thus in the vicinity of their respective central apertures 70. With respect to the matrix of RCC top plates 36 and the corresponding RCC calandria tubes 56a, the vibration arrestors 140 are rotated by 90.degree. for successive RCC calandria tubes 56a of a given row, the vibration arrestors 140 for the respective, column-related calandria tubes 56a of successive, adjacent parallel rows being offset by 90.degree.. Further, due to the symmetrical and regular array of calandria tubes 56 and associated extensions 58 with respect to the top plate 36, and the alternating parallel and transverse orientation of the vibration arrestors 140, it will be apparent that each top plate 36 is engaged by a symmetrically loaded force by corresponding spring arms 141-1 and 141-2 of the arrestors 140 associated with the commonly oriented, respectively next adjacent extensions 58, so as to maintain a symmetrical or balanced loading force thereon. The arrestors 140 thus resiliently load the top surfaces of the top plates 36 of the RCC rod guides 28 and generate suffucient lateral, frictional force such that fluctuating steady state loads applied to the guides do not cause slippage; the vibration arrestors 140 also compensate for effects of differential thermal expansion and minimize adverse effects of resulting forces due to such thermal expansion. The configuration of the vibration arrestors 140 of FIGS. 9-11 affords maximum flexibility of installation, accommodating as well the discontinued pattern of the top plates 36 and 38 which necessarily occurs at the periphery of the interleaved arrays thereof. An alternative configuration of the invention, comprising the vibration arrestor 140' shown in FIG. 12, offers the advantage of a further reduction in the total number of parts required, and particularly, the number of vibration arrestors including associated stiffening rings, and is suitable for installation within the regular, repeating pattern of the array and thus with top plates displaced from the array periphery. More particularly, as shown in FIG. 12, of the vibration arrestors 140' comprise multiple spring arms and specifically, for the array configuration illustrated, quadrature related spring arms 141-1', 141-2', 141-3' and 141-4'. The corresponding stiffening ring 143' is again of generally annular configuration and, as with the first embodiment, has an outer periphery corresponding to that of the hub 141' and thus includes lateral extensions 143b' mating the portions of the hub 141' aligned with the respective spring arms 141-1' through 141-4'; likewise, apertures 143a' are provided in the lateral extensions 143b', and aligned with the apertures 141a' in the hub 141' for receiving corresponding bolts 144' for connecting the arrestor 140' to the lower calandria plate 52. As is apparent from FIG. 12, the vibration arrestors 140' are mounted on calandria extensions 58 of alternate rows and the respective spring arms 141-1' to 141-4' thereof engage the top plates 36 of the intermediate rows. It follows that the top plates 36 of the alternate rows of calandria extensions 58 on which the arrestors 140' are mounted do not have spring arms engaged thereon. However, as compared with the array installation of spring arms 140 in FIG. 11 in which all top plates 36 receive two symmetrically disposed spring arms thereon, four spring arms engage each of the top plates 36 of the intermediate, alternating rows thereof in the array configuration of FIG. 12. Significantly, in this embodiment, the WDRC top plates 38 (not shown in FIG. 12) are interengaged and flexibly linked with the RCC top plates 36 of the intermediate, alternate rows which are engaged by spring arms of the arrestors 140' and through their respectively associated flexible linkages 130 (see, e.g., FIGS. 2-5) serve to transmit substantially equal, resilient biasing forces to the RCC top plates 36 of the alternate rows associated with the calandria extensions 58 on which vibration arrestors 140' are disposed. Thus, by the linking together of the successive rows of top plates 36 afforded by the flexible linkages 130, a substantially equal resilient biasing force is applied to each of the top plates 36 of the array, that force corresponding substantially to the compressive force applied to each of the top plates 36 in the array of FIG. 11. Thus, the arrestors 140' of the second embodiment provide both the same effective resilient biasing force and frictional force opposing lateral displacement of the individual top plates 36, in both embodiments. The plan view of FIG. 13 illustrates, on an enlarged scale, the combined use of an arrestor 140' of the second embodiment with an arrestor 140 of the first embodiment, as may be employed at the periphery of the interleaved arrays of top plates 36 and 38, at which periphery the repeating pattern necessarily is disrupted. In this instance, the RCC top plate 36-1 is presumed to be at the periphery of the array whereas the RCC top plate 36-2 is within the interior of the array and thus displaced from the boundary at which the repeating pattern is disrupted. Thus, it will be appreciated that the invention contemplates the combined use of the two embodiments of the arrestors 140 and 140', where appropriate. FIG. 13 also renders clear that the second embodiment arrestor 140', with respect to either of the associated pairs of spring arms 141-1' and 141-2', and 141-3' and 141-4', is the structural equivalent of the arrestor 140 having only a single pair of spring arms 141-1 and 141-2. Due to the enlarged scale of the drawing of FIG. 13, reference is had thereto for a more specific description of details of the arrestors 140 and 140', with particular reference to the latter and taking into account the direct equivalence of the structures, as aforestated. Specifically, the arrestors are formed of a uniform thickness of metal, of 0.33". The spring arms are approximately 8.00" in length, as measured from the boundary of the underlying stiffening ring 143 (143') and taper from a width along that boundary of approximately 2.125" to a width at the tip, or end portion 145 of approximately 0.50". Moreover, the tip 145 extends approximately 0.50" beyond the length of the 8.00" major portion of the arm, and is bent so as to lie flat on the engaging surface of the associated RCC top plate 36, as seen for example in FIG. 10. The minimum outer diameter of the annular stiffening ring 143 (143') is approximately 5.75" and the central aperture 143a therein is approximately 3.75", yielding a minimum annular dimension of 1.00"; the maximum diameter of the arcuate section (i.e., as measured from the center to the hidden line) of the stiffening ring 143 (143') is approximately 7.00". The rings 143 (143') are formed of metal, and are of a uniform thickness of approximately 1.00". The bolts 144 (144') are of 0.750" diameter and are disposed on centers at a radius of 2.75". The spring arms depend angularly from the bottom surface of the lower calandria plate 52 so as to span the approximately 2.00" spacing to the surface of the support plates 36 engaged thereby. Each spring arm is designed to undergo deflection at the tip 145 in a range from an approximate minimum of 0.62" to an approximate maximum of 0.89" in a vertical direction parallel to the axis of the vessel, and exerts a deflection force of a corresponding value in a range of from 500 lbs. to 725 lbs., taking into account the extent of deflection. For these practical operating conditions, suitable materials for fabrication of the vibration arrestors 140 and 140' include INCONEL 718 (TM) and stainless steel 403. If used in a less hostile environment than a nuclear reactor pressure vessel, and/or if less deflection capability is required, the arrestors may be of a similar geometry but employ different materials. The vibration arrestors 140 and 140' of the present invention, while requiring separate and special fabrication, relative to the aforementioned leaf springs, are nevertheless of simple construction which facilitates ease and low cost of manufacture, and affords a significant simplification in their installation, relative to the use of the leaf springs. Significantly, the vibration arrestors 140 and 140' have symmetrical configurations and thus, as mounted on the calandria extensions 58, are fully supported laterally thereby and thus eliminate the requirement that the mounting bolts 144 react lateral loads. Particularly, the symmetry of the vibration arrestors prevents bending forces from being applied to the bolts 144, because the compression load applied to the tips, or ends 145 of the spring arms 141-1 through 141-4 are the same, and thus no net external moment is applied. Effectively, once compression of the spring arms is established, upon installation and assembly of the calandria with the associated rod guides, the bolts 144 effectively are no longer required to support the associated vibration arrestors 140, 140'. By virtue of the configuration, compression generates only an internal moment in the hubs 141, 141' of the vibration arrestors 140, 140' which, since made of high strength material, can withstand the stress. Further, the provision of the stiffening rings 143, 143' is significant in that the latter provide a bearing surface for the attachment bolts 144 and prevents the creation of localized stresses in the central hubs 141, 141' of the arrestors 140, 140', due to bolt preload. The rings 143, 143', while reinforcing the hubs 141, 141', produce only tensile loads on the bolts 144, which is a desirable and acceptable condition. The significant reduction in parts relative to the use of leaf springs is a feature shared by both embodiments of the present invention, the total number of parts required for the single pair-spring arm configuration of the arrestor 140 being 392 and for the quadrature-or two pair-spring arm configuration of the arrestor 140' being only 276, as compared to a total number of parts in excess of 2,000 for the leaf spring installations. Accordingly, whereas the vibration arrestors of the present invention have wide ranges of application, as an alternative to leaf spring or other resilient structures employed under compression, their use is particularly advantageous in conjunction with the flexible rod guide support structure of the above referenced copending application. The requirements which must be satisfied by these structures, and the manner in which the flexible rod guide support structure incorporating the vibration arrestors of the present invention accommodates these conditions and satisfies those requirements, as now may be better appreciated, will be discussed, again with reference to FIG. 1. As before noted, the support structure itself, must not introduce sources of vibration and most significantly must not be susceptible to excessive wear which, over time, would cause the mounting assembly to loosen and eventually permit vibrations to ensue. These criteria are satisfied by the concatenated and interdigitized matrices of the RCC top plates 36 and WDRC top plates 38, which effectively present a single, relatively stiff structure of mutually, or interdependently, supported top plates at the interface of the inner barrel assembly 24 and the lower calandria plate 52, which structure nevertheless permits a limited extent of relative motion between the rod guides 28 and 32 by out-of-plane bending of the flexible linkages 130. The flexible support structure furthermore facilitates assembling the rod guides with the calandria extensions 58--which assembly, as before noted, is accomplished by having the RCC top plates 36 receive the calandria extensions 58 within the respective cylindrical internal channels 70 therein. The extent of relative movement between adjacent top plates 36 and 38, as permitted by inplane tensile elongation of the flexible linkages 130, however, is limited by the stop pins 125 which provide an ultimate load capacity for very large loads. Thus, under very large loads, the stop pins 125 prevent excessive loading of any of the flexible linkages 130 and ensure that loads from the WDRC rod guides 30 are transmitted through the concatenated and interdigitized RCC top plates 36 into the calandria bottom plate 52. The stop pins 25 serve a further function in providing rough positioning of the interdigitized top plates 36 and 38 prior to attachment thereto of the flexible linkages 130. As previously noted, the vibration arrestors 140 and 140' serve to react normal operational fluctuating loads laterally, by the frictional forces generated by their engagement with the top surfaces of the RCC top plates 36. As employed in accordance with the present disclosure, the vibration arrestors 140 (140') may be designed to react nominally a force of 368 lbs. at each RCC guide top plate 36, assuming a coefficient of 0.3 without slippage. More specifically, the nominal force applied to each RCC top plate 36 is with a range of 1000 lbs. to 1,400 lbs. for the two spring arm configuration of the arrestor 140, and double that for the four spring arm configuration of the arrestor 140' for each RCC top plate 36 engaged thereby. The four spring arm configuration effectively applies the same normal force to the tops of all of the RCC top plates 36, in view of the interlinkage of the alternate rows of RCC top plates 36 which are not engaged by vibration arrestors 140', with the intermediate alternate rows of top plates 36 on which four spring arms are engaged. Differential lateral forces across the array thus may be compensated for and reacted to independently by the corresponding vibration arrestors 140 (140'), of both embodiments. The concatenated design of the interleaved and flexibly linked top plates 36 and 38 particularly precludes impact wear from occurring between the rod guide top plates 36 and 38 and the calandria extensions 58. To the extent that such wear does occur, and particularly relative to the calandria extensions 58, the extent and effect of such wear is believed not significant relative to rod guide alignment or the structural capability of the extensions 58 to react to seismic loads. To the extent that wear relative to a particular extension 58 occurs, in like fashion, the vibration arrestors 140 (140') will continue to maintain both axial and lateral alignment, and to react forces tending to cause lateral displacement, thus limiting the excitation and ultimately wear on the RCC guides 34 and WDRC guides 30 and the respective rodlet clusters 92 and 84. The concatenated relationship of the interdigitized matrices of the array affords the further significant benefit of distributing force effects via the flexible linkages and compensating for differential axial expansion and lateral forces acting on the array, throughout the entirety of the interdigitized rod guide top plates 36 and 38, and thus minimizing wear potential with respect to any given calandria extension 58 and its respectively associated top plate 36, and of the interface between any given rod guide and its associated rodlet cluster. Thus, the potential of wear due both to axial sliding forces arising, for example, from core plate vibration and as well due to lateral forces resulting from differential thermal and other effects is greatly decreased, and the structure is self-compensating even as to any specific, individual connection with a given calandria extension 58 which has worn due, for example, to initial mechanical misalignment. As can be appreciated from FIG. 10, only minimal axial space is required to accommodate the array of top plates 36 and 38 and the flexible linkages 130 therein, along with the vibration arrestors 140 (140'); this enables use of the flexible rod guide support structure without requiring any modification of the vessel 10 to accommodate an axially elongated inner barrel assembly 24. As is clear from FIG. 9, taken further in the context of FIGS. 1 and 8, the flexible support structure incorporating the streamlined and low profile vibration arrestors 140 and 140' of the present invention does not interfere with the required free passage of core outlet flow through the openings 59 provided therefor in the lower calandria plate 52. In accordance with the foregoing, first and second embodiments of the vibration arrestors of the invention have been disclosed, respectively comprising a single pair of aligned spring arms 140-1 and 141-2 of the vibration arrestor 140 and a double pair of spring arms 141-1' to 141-4', in quadrature relationship, of the arrestor 140'. Whereas these are preferred configurations, the specific number and relative orientation of the spring arms is understood to be a function of the geometry of the arrays of the top plates with which the spring arms are used and thus are not to be deemed limiting. Accordingly, it will be apparent to those of skill in the art that numerous modifications and adaptations of the invention may be achieved and accordingly it is intended by the appended claims to cover all such modifications and adaptations as fall within the true spirit and scope of the invention.
	description	1. Field of the Invention The present invention relates, in general, to a truss-reinforced spacer grid and a method of manufacturing the same and, more particularly, to a truss-reinforced spacer grid having improved mechanical structural strength and thermal hydraulic performance and a method of manufacturing the same. 2. Description of the Related Art Nuclear fuel assemblies are charged into the core of a pressurized water reactor. These nuclear fuel assemblies are composed of a plurality of fuel rods, into each of which a cylindrical uranium sintered compact (or a cylindrical uranium pellet) is inserted. The fuel rods can be divided into two types, cylindrical and annular, depending on the shape. The fuel rods are structurally vulnerable, because the length is very long in relation to the outer diameter. In order to make up for this drawback, a plurality of supports are used. FIG. 20 is a schematic front view illustrating a conventional nuclear fuel assembly having fuel rods. FIG. 21 is a schematic top plan view illustrating a conventional spacer grid. FIG. 22 is a perspective view illustrating a conventional spacer grid. As illustrated in FIG. 20, the nuclear fuel assembly 100 includes fuel rods 110, guide tubes 120, spacer grids 150, an upper end fitting 160, and a lower end fitting 170. Each fuel rod 110 is enclosed by a zirconium alloy cladding tube and has a structure in which the nuclear fission of a uranium sintered compact or a uranium pellet (not shown) generates high-temperature heat. Each fuel rod 110 has upper and lower end plugs 130 and 140 coupled to lower and upper portions thereof so as to prevent inert gas which has been used to fill up the cladding tube thereof from leaking out. The structure of the fuel rod 110 is considerably long compared to the diameter thereof. When a coolant flows through this structure having such a great elongation ratio, the fuel rod 110 responds by causing flow-induced vibrations. Thus, in order to reduce these flow-induced vibrations, spacer grids 150 are installed in a predetermined section selected with respect to the entire length of the fuel rods 110, so that it is possible to reduce the vibrations of the fuel rods 110 caused by the flow of the coolant. Meanwhile, in the spacer grid 150 as shown in FIGS. 21 and 22, contact portions between an inner grid plate and an outer grid plate, between the inner grid plates, or between the outer grid plates must be welded, and such welding forms beads which increase the magnitude of the pressure drop in the core region, and thus thermal hydraulic performance may become degraded. Further, coolant mixing vanes are formed on the inner or outer grid plate for the purpose of mixing the coolant in the sub-channels where the coolant flows or between neighboring nuclear fuel assemblies. These coolant mixing vanes are another cause of the magnitude of the pressure drop in the core increasing. For this reason, although these coolant mixing vanes are supposed to improve the thermal hydraulic performance of the coolant, they may reduce cooling performance instead. In addition, the spacer grid 150 undergoes a local buckling phenomenon at the outer shell (structurally, the weakest point) when a side receives an impact, so that it is possible to reduce the buckling strength of the entire spacer grid 150. Furthermore, the thickness of the grid plate which forms the spacer grid 150, in the state where the pitch of the fuel rod 110 is fixed for the sake of performance of the nuclear function, is extremely restricted by this external condition. In detail, a grid plate that is too thin may reduce the strength of the spacer grid 150. In contrast, a grid plate that is too thick may reduce the interval between the fuel rods 110 and increase the possibility of a departure from nucleate boiling due to contact being made between the fuel rods or may greatly reduce the performance of the fuel rod 110 due to excessively increasing the magnitude of the pressure drop. Thus, the spacer grid 150 formed of the aforementioned grid plate makes it difficult to continue to solidly support the fuel rods 110 and to further enhance the thermal hydraulic performance. Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and embodiments of the present invention provide a truss-reinforced spacer grid and a method of manufacturing the same, in which truss members having a small diameter are woven to form a truss structure surrounded by an external plate, and the truss structure is joined to the external plate to thereby improve its mechanical structural strength. Embodiments of the present invention provide a truss-reinforced spacer grid and a method of manufacturing the same, capable of supporting fuel rods thanks to the truss structure and striking a coolant to interwoven truss members, thereby imparting thermal hydraulic performance superior to when basing it on coolant mixing vanes. According to an aspect of the present invention, there is provided a truss-reinforced spacer grid, which comprises: a truss structure in which horizontal trusses are formed by horizontally weaving a plurality of truss members and are vertically disposed at regular intervals; and, an external plate joined with ends of the horizontal trusses and surrounding the truss structure. The truss structure may include vertical trusses, which are vertically fastened to vertically corresponding truss intersections of the horizontal trusses to vertically support the horizontal trusses at regular intervals. The truss structure may include unit trusses, each of which has the shape of a hexagon in the center thereof and the shape of a triangle outside the corresponding sides of the hexagon. The truss structure may support fuel rods inserted into the unit trusses. The truss structure may include a guide tube hole into which a guide tube acting as a passage for a control rod is inserted. The guide tube may be surrounded by a cylindrical sleeve, the sleeve and the guide tube being welded. Each truss member may be formed of a wire. Each truss member may be formed of a hollow cylindrical pipe. The hollow cylindrical pipe may have an outer diameter of 0.5 mm to 2.0 mm. Each truss member may have a linear shape. Each truss member may have a circular shape curved at a predetermined curvature. Each truss member may have an angled shape bent at a predetermined angle. According to another aspect of the present invention, there is provided a method of manufacturing a truss-reinforced spacer grid, which comprises: a first step of horizontally weaving a plurality of truss members to form horizontal trusses; a second step of fastening vertical trusses to the horizontal trusses to form a truss structure; and a third step of joining ends of the horizontal trusses to an external plate surrounding the truss structure to form the truss-reinforced spacer grid. The first step may include: a process of weaving the truss members to form unit trusses; and, a process of joining the unit trusses using brazing to form the horizontal trusses. The second step may include: a process of vertically disposing the horizontal trusses at regular intervals; and, a process of vertically fastening the vertical trusses to vertically corresponding truss intersections of the horizontal trusses to form the truss structure. The third step may include joining the horizontal trusses to the external plate using brazing. The method further includes a fourth step of inserting a guide tube into the truss structure. The fourth step may include: a process of forming a guide tube hole in the truss structure, the guide tube hole having a diameter greater than that of the guide tube; a process of inserting a cylindrical sleeve into the guide tube hole; and, a process of inserting the guide tube into the cylindrical sleeve and welding the sleeve and the guide tube. The method may further include a fifth step of inserting fuel rods into the truss structure. According to the truss-reinforced spacer grid and the method of manufacturing the same as described above, the interwoven truss structure minimizes the deformation resulting from a compression such as lateral impact load, withstands a load, and has a post-buckling behavior, i.e. a behavior thereof after buckling occurs, in which the strength is increased rather than reduced. As such, the truss-reinforced spacer grid has considerably high impact resistance compared to a conventional spacer grid constituted of grid plates, and thus even when an earthquake-proof design criterion based on an earthquake and a loss-of-coolant accident is increased to 0.3 G, it is possible to secure sufficient impact strength to ensure better structural soundness. Further, the truss members constituting the truss structure vary the coolant flow which remarkably increases the turbulence of the coolant introduced from the upstream side to more effectively transmit heat generated by nuclear fission, and thus increase thermal hydraulic performance. The interwoven truss members minimize interruption of the coolant in an axial or height direction, and thus the magnitude of the pressure drop does not greatly increase. In addition, unlike a conventional structure in which all the contact portions of a grid plate are welded, the interwoven truss members are brazed once, so that it is possible to significantly reduce the cost of production. An exemplary embodiment of the invention will now be described in greater detail with reference to the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. FIG. 1 is a schematic perspective view illustrating a truss-reinforced spacer grid according to an exemplary embodiment of the present invention, and FIG. 3 is a top plan view of FIG. 1. As illustrated in FIGS. 1 and 3, the truss-reinforced spacer grid 1 according to an exemplary embodiment of the present invention includes a truss structure 10 and an external plate 20. The truss structure 10 is composed of horizontal trusses 11, which are vertically disposed at regular intervals. FIG. 4 is a perspective view illustrating a horizontal truss according to an exemplary embodiment of the present invention. As illustrated in FIG. 4, the horizontal truss 11 is formed by weaving a plurality of truss members 12 in a horizontal direction. FIGS. 12 and 13 are perspective views illustrating a truss member according to an exemplary embodiment of the present invention. As illustrated in 12, the truss member 12 may be formed of a small diameter wire. As illustrated in FIG. 13, the truss member 12 may be formed of a hollow cylindrical pipe, an outer diameter of which ranges from 0.5 mm to 2.0 mm. Accordingly, it is possible to improve the mixture of a coolant, the lateral impact strength, or supporting performance of a fuel rod. Further, the truss member 12 may have a linear shape. Although not illustrated, the truss member 12 may have a circular shape curved at a predetermined curvature, or an angled shape bent at a predetermined angle. The truss structure 10 includes a plurality of unit trusses having truss members 12 woven together. Here, the unit truss may assume a variety of shapes. For example, the unit truss may be configured so that its center 80 (FIGS. 3 and 4) has the shape of a hexagon, and its surroundings outside the corresponding sides of the hexagon have the shape of a triangle. In detail, three truss members 12 may be disposed on the same horizontal plane to form a first triangle, and other three truss members 12 may be disposed on the same horizontal plane to form a second triangle, and may be fastened to the first triangle in inverse relation to the first triangle. Thereby, a total of six truss members 12 may form the unit truss. As described above, the truss structure 10 can be used only to enhance the enhance impact resistance and thermal hydraulic performance thereof, i.e. functional aspects of the spacer grid, without the fuel rod being inserted thereinto. Alternatively, the truss structure 10 may be configured to surround the fuel rod when the fuel rod is inserted thereinto. FIG. 8 is a schematic perspective view illustrating a truss-reinforced spacer grid, into which one fuel rod is inserted, according to an exemplary embodiment of the present invention. As illustrated in FIG. 8, the fuel rod 50 can be inserted into the truss structure 10. Here, the fuel rod 50 is inserted into and supported in a space formed by a grid center 80 of the unit truss. When the unit truss supports the fuel rod 50, the truss members 12 are contracted (curved inwardly) in a central direction of the grid center 80 for receiving the fuel rod 50, and are deformed outwardly in a radial direction of the fuel rod 50 when the fuel rod 50 is inserted. As a result, the fuel rod 50 is supported by a frictional force between the truss members 12 and the fuel rod 50. Thus, the truss structure 10 maintains a shape which does not change in the vertical direction, but it maintains a pattern which is repeated with a predetermined curvature in the transverse direction. FIG. 5 is a top plan view illustrating a truss-reinforced spacer grid, into which one guide tube and one fuel rod are inserted, according to an exemplary embodiment of the present invention. FIG. 6 is a schematic perspective view illustrating a truss-reinforced spacer grid, into which one guide tube is inserted, according to an exemplary embodiment of the present invention. FIG. 10 is a schematic perspective view illustrating a truss-reinforced spacer grid, into which one guide tube and one fuel rod are inserted, according to an exemplary embodiment of the present invention. As illustrated in FIG. 6, a guide tube 40 (used as the passage for a control rod) may be inserted into the truss structure 10. The truss structure 10 is provided with a guide tube hole 13 through which the guide tube 40 can be inserted. Here, a cylindrical sleeve 30 may be inserted between the guide tube hole 13 and the guide tube 40, and then the sleeve 30 may be coupled with the guide tube 40 by welding. The sleeve 30 may be inserted into the truss structure 10 from the top or bottom of the truss structure 10. In addition, as illustrated in FIGS. 5 and 10, the fuel rod 50 and the guide tube 40 may be inserted into and supported by the truss structure 10, as described above. As described above, the truss structure 10 collides with the coolant at various axial heights so as to render it possible to enhance the performance of mixing the coolant introduced from upstream in addition to its mechanical structural function, and thus the flow of the coolant is changed by the truss structure 10. As a result, the mixing performance of the coolant can be enhanced compared to a conventional spacer grid, and this flow strength can be comparatively maintained for a longer time. Meanwhile, the external plate 20 surrounds the truss structure 10, and is joined with ends of the horizontal trusses 11. Thereby, the truss structure 10 is coupled with the external plate 20. Thus, the truss structure 10 coupled with the external plate 20 can resist lateral impact load. Hereinafter, another truss-reinforced spacer grid according to another exemplary embodiment of the present invention will be described in detail. FIG. 2 is a schematic perspective view illustrating a truss-reinforced spacer grid according to another exemplary embodiment of the present invention. As illustrated in FIG. 2, the truss-reinforced spacer grid according to another exemplary embodiment of the present invention includes a truss structure 10 and an external plate 20. Here, the external plate 20 according to another exemplary embodiment has the same configuration as that of the truss-reinforced spacer grid 1 according to an exemplary embodiment. The truss structure 10 includes horizontal trusses 11 and vertical trusses 15. The horizontal truss 11 according to another exemplary embodiment has the same configuration as that of the truss-reinforced spacer grid 1 according to an exemplary embodiment. The vertical trusses 15 are vertically fastened to truss intersections 14 of the horizontal trusses 11 vertically disposed at regular intervals. Here, each vertical truss 15 may be formed of a truss member 12. The truss member 12 according to another exemplary embodiment may have the same configuration as that used for the truss-reinforced spacer grid 1 according to an exemplary embodiment. Thus, as illustrated in FIG. 12, the vertical truss 15 may be formed of a wire having a small diameter. As illustrated in FIG. 13, the vertical truss 15 may be formed of a hollow cylindrical pipe. FIG. 7 is a schematic perspective view illustrating a truss-reinforced spacer grid, into which one guide tube is inserted, according to another exemplary embodiment of the present invention. FIG. 9 is a perspective view illustrating a truss-reinforced spacer grid, into which one fuel rod is inserted, according to another exemplary embodiment of the present invention. FIG. 11 is a perspective view illustrating a truss-reinforced spacer grid, into which one guide tube and one fuel rod are inserted, according to another exemplary embodiment of the present invention. Similar to the truss structure of the truss-reinforced spacer grid 1 according to an exemplary embodiment of the present invention, the truss structure 10 according to another exemplary embodiment allows a guide tube 40 to be inserted therein as illustrated in FIG. 7, a fuel rod 40 as illustrated in FIG. 9, or the guide tube 40 and the fuel rod 59 as illustrated in FIG. 11. Hereinafter, a method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention will be described in detail. FIG. 14 is a block diagram illustrating a method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention, FIG. 17 is a block diagram illustrating the first step of a method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention, and FIG. 18 is a block diagram illustrating the second step of a method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention. As illustrated in FIG. 14, the method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention includes a first step S10, a second step S20, and a third step S30. As illustrated in FIG. 4, the first step S10 is the step wherein a plurality of truss members 12 are horizontally woven to form horizontal trusses 11. As illustrated in FIG. 17, the first step S10 includes a process S11 of forming unit trusses and a process S12 of forming the horizontal trusses. The unit truss forming process S11 is a process of horizontally weaving the truss members 12 to form the unit trusses. Here, as illustrated in FIG. 12, each truss member 12 may be formed of a small diameter wire. As illustrated in FIG. 13, each truss member 12 may be formed of a hollow cylindrical pipe. The unit truss may adopt a variety of shapes. The horizontal truss forming process S12 is a process of joining the unit trusses using brazing to form the horizontal trusses 11. Accordingly, compared to a conventional spacer grid forming method in which grid plates are crossed, fitted and welded at their contact portions, the number of processes is remarkably reduced. As illustrated in FIG. 2, the second step S20 is a step of vertically fastening the vertical trusses 15 to the horizontal trusses 11 to form the truss structure 10. As illustrated in FIG. 18, the second step S20 includes a process S21 of vertically disposing the horizontal trusses and a process S22 of forming the truss structure. As illustrated in FIG. 2, the horizontal truss disposing process S21 is a process used to vertically dispose the horizontal trusses 11 at regular intervals. The truss structure forming process S22 is a process of vertically fastening the vertical trusses 15 to vertically corresponding truss intersections 14 of the horizontal trusses 11 to form the truss structure 10. Here, as illustrated in FIG. 12, each vertical truss 15 may be formed of a small diameter wire. As illustrated in FIG. 13, each vertical truss 15 may be formed of a hollow cylindrical pipe. The third step S30 is a step of joining the ends of the horizontal trusses 11 to the external plate 20 surrounding the truss structure 10 to form the truss-reinforced spacer grid 1. Here, the horizontal trusses 11 may be joined to the external plate 20 by brazing. FIG. 15 is a block diagram illustrating another method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention, and FIG. 19 is a block diagram illustrating the fourth step in a method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention. Meanwhile, as illustrated in FIG. 15, the method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention may include a fourth step S40 following the third step S30. As illustrated in FIG. 7, the fourth step S40 is the step wherein the guide tube 40 is inserted into the truss structure 10. As illustrated in FIG. 19, the fourth step S40 includes a process S41 of forming a hole for the guide tube, a process S42 of inserting a sleeve, and a process S43 of welding the guide tube. The guide tube hole forming (cutting) process S41 is a process of forming a hole having a diameter greater than that of the guide tube 40 in the truss structure 10. The sleeve inserting process S42 is a process of inserting the cylindrical sleeve 30 into the guide tube hole 13. Here, the sleeve 30 may be inserted from the top or bottom of the truss structure 10 into the truss structure 10. The guide tube welding process S43 is a process of inserting the guide tube 40 into the cylindrical sleeve 30 and then welding the sleeve 30 and the guide tube 40. Here, the sleeve 30 and the guide tube 40 may be joined by laser welding. FIG. 16 is a block diagram illustrating yet another method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention. Meanwhile, as illustrated in FIG. 16, the method of forming a truss-reinforced spacer grid according to an exemplary embodiment of the present invention may include a fifth step S50 following the fourth step S40. As illustrated in FIG. 9, the fifth step S50 is the step wherein the fuel rods 50 are inserted into the truss structure 10. Thus, each fuel rod 50 can be supported by the frictional force between it and the truss members 12 included in the truss structure 10. Although an exemplary embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
055219519	abstract	A method and an apparatus for repairing a shroud in which one or more shroud girth seam welds have experienced SCC. The method involves the placement of a plurality of brackets around the outer circumference of the shroud at a plurality of azimuthal positions. Each bracket has circular holes for receiving respective tapered pin assemblies. Corresponding circular holes are machined in the shroud wall at positions which will align with the holes in the bracket. Each tapered pin assembly is inserted and then manipulated remotely from outside the shroud. Each tapered pin assembly consists of three types of parts: a threaded tapered pin, a slotted sleeve with a tapered bore, and a threaded nut. When fully installed, the tapered pin is encased by the sleeve. As the tapered pin is tensioned, the sleeve exerts a radially outwardly directed contact pressure on the cylindrical surface of the aligned circular holes respectively formed in the bracket and shroud.
	description	This application is a continuation-in-part application of International Application No. PCT/JP2007/000115, filed Feb. 22, 2007, and claims the benefit of priority from the prior Japanese Patent Application Nos. 2006-44742, 2006-53660 and 2006-279969, filed on Feb. 22, 2006, Feb. 28, 2006 and Oct. 13, 2006, respectively; the entire content of which is incorporated by reference. This invention relates to a core catcher, a manufacturing method of a core catcher, a reactor containment vessel and a manufacturing method of a reactor containment vessel. In a water cooled reactor, by rundown of water supply into a reactor pressure vessel or a rupture of piping connected to the reactor pressure vessel, a reactor water level may fall, a reactor core may be exposed above the water level and cooling may become insufficient. Supposing such a case, it is designed that a nuclear reactor is shut down automatically under a signal of low water level, the reactor core is covered and cooled by water injected by an emergency core cooling system (ECCS), and a core meltdown accident is prevented. However, although it is a very low probability, it can be assumed that the above mentioned emergency core cooling system would not operate and any other devices for supplying water to the reactor core would not be available. Under such a condition, the reactor core would be exposed due to lowering of the reactor water level and cooling would be insufficient, fuel rod temperature would rise with decay heat generated continuously after shutdown of the nuclear reactor and the reactor core would meltdown eventually. If such a severe accident occurs in the nuclear power plant, the molten core would penetrate the reactor pressure vessel lower head at bottom of the reactor pressure vessel and would fall to a floor of reactor containment vessel. Core debris, a wreckage of the molten core, continues to generate heat as about 1% of reactor thermal power because of decay heat of radioactive material that exists inside. Therefore, if there is no means for cooling, the core debris heats concrete stretched on the containment vessel floor. If temperature of contact surface is high, the core debris would react with the concrete and generate large quantity of non-condensable gas, such as carbon dioxide or hydrogen, while melting and eroding the concrete. Eventually, a lot of radioactive material would be emitted to the environment. The generated non-condensable gas would pressurize and damage the reactor containment vessel and would damage a containment vessel boundary by melting erosion of concrete or reduce structure toughness of the containment vessel. As a result, if the reaction of the core debris and the concrete continues, it would result in a breakage of the containment vessel and a radioactive material in the containment vessel would be emitted to the outside. In order to suppress such a reaction of core debris and concrete, it is necessary to cool the core debris so that temperature of the surface of the concrete contacting with a bottom of the core debris is below erosion temperature (1500K or less for typical concrete) or to avoid that the core debris contact directly with the concrete. In a conventional way, it is designed to suppress the reaction of melting and eroding the concrete by pouring water over the fallen core debris and lowering temperature of the core debris (for example, refer to Japanese Patent Application Publication 2004-333357 and Japanese Patent Application Publication 2005-195595; the entire content of which is incorporated herein by reference). Various countermeasures are proposed against falling of the core debris. A typical one is a core catcher. The core catcher catches and holds the fallen core debris on heat resistant material and cools the core debris with means for supplying water. The core catcher is a safety equipment that assures soundness of the reactor containment vessel by catching the core debris and maintaining it cooled and reduces emission of radioactive material to the outside. In the existing boiling water nuclear power plants (BWR), the probability of occurrence of an accident is suppressed. And very high safety relating to core cooling during an accident is achieved. Such a severe accident has never occurred. Also in a probability risk analysis (PSA), the probability of occurrence of such a severe accident is evaluated so small as it can be ignored. Today, a natural circulation cooling type passive safety boiling water reactor (ESBWR) which constitutes all safety systems with static instruments is proposed. In the ESBWR, the core catcher is installed beneath the reactor containment vessel. This is for further improving completeness of the safety of next generation BWR. If a corium is cooled by boiling of water supplied over the corium at a top surface and a deposition thickness of the corium is so thick, it may not be able to cool the corium fully to the bottom of it. Therefore, it is necessary to make floor area large and to reduce the deposition thickness of the corium so that it can be cooled. However, a structural design of the containment vessel makes it difficult to expand the floor area sufficiently. For example, typical decay heat of corium is about 1% of rated thermal power. In case of a power reactor of 4,000 MW of rated thermal power, the decay heat is about 40 MW. Although an amount of boiling heat transfer on top surface varies depending on the condition of the top surface of the corium, heat flux of about 0.4 MW/m2 can be assumed as the smallest value. In this case, supposing that heat of the corium is removed only by heat transfer at the top surface, about 100 m2 (11.3 m of a diameter) of floor area is necessary. Therefore, as a thermal power of a plant becomes large, necessary floor area of lower drywell becomes large and it becomes more difficult to design the containment vessel. In case that cooling water is supplied over the top surface of the core debris fallen to the floor of the reactor containment vessel, if an amount of removable heat at the bottom of the core debris is small, temperature at the bottom of the core debris may remain high because of decay heat and erosion of concrete of the containment vessel floor may be unable to be stopped. Therefore, some methods for cooling from bottom of the core debris are also proposed (for example, refer to Japanese Patent Application Publication 2005-195595, Japanese Patent Application Publication Hei 7-110392, Japanese Patent Application Publication Hei 6-130169 and Japanese Patent Application Publication Hei 9-138292; the entire contents of which are incorporated herein by reference). The core catcher is located on the floor of the lower drywell with heat resistant member for example so that the core debris does not penetrate the lower part of the reactor containment vessel or radioactive material does not leak. However, the core debris might not be cooled sufficiently only by covering with heat resistant member. And it takes long time and labor to provide a lot of piping for cooling water to run in order to cool the core debris. If the cooling water is supplied only over the corium, the corium is cooled only by boiling of the water at the top surface of the corium. So, if deposition thickness of the corium is so large, it may be unable to cool sufficiently to the bottom of the corium. Therefore, large floor area is necessary to make the corium as thin as it can be cooled. However, structural design of the containment vessel makes it difficult to provide large enough floor area. The present invention has been made to solve the above problems, and has an object of this invention is to improve efficiency which cools core debris generated when a reactor core in a reactor vessel melts and penetrates the reactor vessel. According to an aspect of the present invention, there is provided a core catcher for catching core debris generated when a reactor core in a reactor vessel melts and penetrates the reactor vessel, the core catcher comprising: a main body being placed beneath the reactor vessel and being formed a plurality of cooling channels therein, the cooling channel extending radially so that cooling water supplied from cooling water injecting piping flows therethrough. According to another aspect of the present invention, there is provided a core catcher for catching core debris generated when a reactor core in a reactor vessel melts and penetrates the reactor vessel, the core catcher comprising: a cooling channel defining a debris holding region and a plurality of cooling water flow paths, the debris holding region being surrounded by a bottom surface inclined against to horizon and a wall spreading vertically at a periphery of the bottom surface and being opened upward, the cooling water flow paths extending parallel to each other with a fixed horizontal width along the bottom surface of the debris holding region as a top surface of the cooling water flow rises; and heat resistant material attached to a surface of the cooling channel facing to the debris holding region. According to yet another aspect of the present invention, there is provided a reactor containment vessel containing a reactor vessel, the reactor containment vessel comprising: a core catcher for catching core debris generated when a reactor core in a reactor vessel melts and penetrates the reactor vessel, the core catcher having a main body being placed beneath the reactor vessel and being formed a plurality of cooling channels therein, the cooling channel extending radially so that cooling water supplied from cooling water injecting piping flows therethrough. According to yet another aspect of the present invention, there is provided a reactor containment vessel containing a reactor vessel comprising: a pedestal floor being located beneath the reactor vessel; a pedestal side wall surrounding the pedestal floor and supporting the reactor vessel; and a core catcher placed on the pedestal floor, the core catcher having a cooling channel defining a debris holding region and a plurality of cooling water flow paths, the debris holding region being surrounded by a bottom surface inclined against to horizon and a wall spreading vertically at a periphery of the bottom surface and being opened upward, the cooling water flow paths extending parallel to each other with a fixed horizontal width along the bottom surface of the debris holding region as a top surface of the cooling water flow rises; and heat resistant material attached to a surface of the cooling channel facing to the debris holding region. According to yet another aspect of the present invention, there is provided a method for manufacturing of a core catcher for catching core debris generated when a reactor core in a reactor vessel melts and penetrates the reactor vessel, the method comprising: a body sub piece manufacturing step for manufacturing body sub pieces being formed a plurality of cooling channels therein; a main body allocation step for allocating the body sub pieces beneath the reactor vessel so that the cooling channels extends radially; and a piping connection step for connecting a cooling water injecting piping to the cooling channels, the cooling water injecting piping configured to supply the cooling water. According to the present invention, it is possible to improve efficiency which cools core debris generated when a reactor core in a reactor vessel melts and penetrates the reactor vessel. Hereinafter, embodiments of a core catcher according to the present invention will be described with reference to the drawings. The same symbols are given to same or similar configurations, and duplicated descriptions may be omitted. Although first and second embodiments are explained with a natural circulation cooling type passive safety boiling water reactor (ESBWR) as an example, and third through seventeenth embodiments are explained with a boiling water reactor (BWR) as an example, it is applicable to nuclear reactors of other types. FIG. 3 is a vertical cross sectional view of a reactor containment vessel according to the first embodiment of the present invention. Inside of a reactor containment vessel 36, there is a space called drywell 51. A reactor pressure vessel (RPV) 42 is installed in the drywell 51. The reactor pressure vessel 42 is fixed by RPV support 52 with an RPV skirt 53. Higher part of the drywell 51 than the RPV support 52 is called upper drywell 54 and lower part is called lower drywell 3. Wall surrounding the lower drywell 3 is called a pedestal side wall 1. In an ESBWR, the RPV support 52 is supported by the pedestal side wall 1. A reactor core 41 is contained inside the reactor pressure vessel 42. A gravity-driven cooling system (GDCS) pool 37 is installed in the upper drywell 54. The GDCS pool 37 and the reactor pressure vessel 42 are connected by piping 57 via a blast valve 56. A pressure suppression chamber 58 is located below the upper drywell 54 and surrounds the reactor pressure vessel 42. Suppression pool 59 is located Inside the pressure suppression chamber 58. A passive containment cooling system (PCCS) pool 65 is located above the drywell 51 and stores cooling water. A core catcher 70 is installed inside the lower drywell 3 and beneath the reactor pressure vessel 42. FIG. 2 is a vertical cross sectional view around the core catcher according to this embodiment. The core catcher 70 is installed on bottom structure member 28 located in the bottom of the lower drywell 3. This bottom structure member 28 is made of concrete or heat resistant material. A top surface of the bottom structure member 28 has a cone shape which opens upward. The core catcher 70 has a steel main body 20 which has a round dish shape of about 20 cm thick. A base lid 32 is attached to the bottom of the steel main body 20. The base lid 32 has a conical shape which opens upward along the top surface of the bottom structure member 28. The pedestal side wall 1 is expanded about 50 cm in the radial direction from the bottom end to a certain height that is sufficient to contain the core catcher 70. The core catcher covers whole of the bottom floor of the lower drywell 3. Cooling channels 21 are formed between the steel main body 20 and the base lid 32. A cooling water injection opening 22 is formed in a central region of the bottom surface of the steel main body 20 of the core catcher 70. Injection piping 23 is connected to the cooling water injection opening 22. The injection piping 23 is connected to the GDCS pool via the blast valve 8. The injection piping 23 passes inside the bottom structure member 28 and is connected to GDCS submersion piping 7. A part of the GDCS submersion piping 7 passes inside the pedestal side wall 1. Side wall part channel 25 which rises along with pedestal side wall 1 is formed at a peripheral region of steel main body 20. The top end of this side wall part channel 25 is called as core catcher top end 71. A heat resistant material layer 26 is formed on the top surface of the steel main body 20 of the core catcher 70. The heat resistant material layer 26 consists of magnesia (magnesium oxide) of about 1.5 m thick for example. Heat resistant material, such as zirconia (zirconium oxide), can be used for the heat resistant material layer 26 instead of magnesia. Drain sump 27 is formed on the top surface of the heat resistant material layer 26. Top surface of the heat resistant material layer 26 is covered by a sacrifice concrete layer 29 including a region where the drain sump 27 is formed. The surface of the side wall part channel 25 which contacts with the heat resistant material layer 26 is also covered by the sacrifice concrete layer 29 from the top surface of the heat resistant material layer 26 to the core catcher top end 71. Thickness of the sacrifice concrete layer 29 is 10 cm for example. FIG. 1 is a bottom plan view of a steel main body 20 of core catcher 70 according to a first embodiment. Cooling fins 31 extend radially from the central region and are attached to the bottom surface of the steel main body 20 of the core catcher 70. Width of the cooling fin 31 is constant at about 10 cm for example. The cooling fins 31 are allocated with circumferential intervals extended radially and widen toward the perimeter. The cooling fins 31 constitute cooling channels 21a, 21b with the base lid 32. The steel main body 20 and cooling fins 31 integrated with the steel main body 20 are made of steel and thickness is about 18 cm in total, for example. The thickness of base lid 32 is about 2 cm, for example, and thickness of steel main body 20 is about 40 cm as a whole. The base lid 32 can be made of any material that is watertight and robust. The base lid 32 can be made of steel as well as the steel main body 20 and cooling fins 31. A round distributor 10 is located in the central region of the bottom surface of the steel main body 20. First stage cooling channels 21a extends radially from the distributor 10. The cooling water injection opening 22 is formed at the central region of the distributor 10. An intermediate header 24 is formed as a ring surrounding the first stage cooling channels 21a. Second stage cooling channels 21b extend radially outward from the intermediate header 24. The number of the second stage cooling channels 21b is larger than that of the first stage cooling channels 21a. The side wall part channel 25 is formed as a ring surrounding the second stage cooling channels 21b. If the core debris falls to core catcher 70, the cooling water supplied from GDCS submersion water piping 7 and stored in the GDCS pool 37 is led inside the distributor 10 from the cooling water injection opening 22 through the injection piping 23. The cooling water in the distributor 10 is further led inside of the cooling channels 21a extending radially. The cooling water is led to the intermediate header 24. After that, the cooling water is led inside the second stage cooling channels 21b that are more than the first stage cooling channels 21a. The number of stages of the cooling channels can be increased or decreased to suit with the size of the core catcher. After passing through the second stage cooling channels 21b, the cooling water goes up inside the side wall part channel 25, overflows from the core catcher top end 71, and flows into space surrounded by the sacrifice concrete layer 29 of which height is about 1.5 m. Thus, the core debris fallen to the core catcher 70 is submerged and cooled. Then, the water level of the cooling water continues to go up and reaches depth of about 20 m. The cooling water filled over the core catcher 70 is heated with the decay heat of the core debris and a part of the cooling water continues to evaporate. The generated steam is cooled by a passive containment vessel cooling system pool 65 and becomes condensed water. This condensed water is sent back to the GDCS pool 37, passes through the GDCS submersion water piping 7 and is again used for cooling of the core catchers 70. Thus, the cooling water always re-circulates and supplied to the core catcher 70. And once the depth of the cooling water reaches about 20 m, the depth of the cooling water is maintained almost constant subsequently. Also, the cooling channels 21 of the core catcher are always supplied with the cooling water of low temperature that is cooled by the passive containment vessel cooling system pool 65. As described above, in this embodiment, by attaching the cooling fins 31, the surface area of the main body of the core catcher 70 becomes large and efficiency of cooling increases. The efficiency of cooling can also be increased by narrowing the width of the cooling fins 31 and increasing the number of installed cooling fins 31 as required. Since the cooling water is supplied from the cooling water injecting piping 23 connected to the central region of the distributor 10, the cooling water is supplied at the central region that is heated most, and bypassing of a central region can be avoided. Since the number of cooling channels 21 increases with radial position, it can be avoided that a density of the cooling channels is lower in the peripheral region. The intermediate header 24 formed between two stages of cooling channels 21a, 21b is a mixing region where the cooling water which passes through each cooling channel is intermingled. With this intermediate header 24, even if the number of the second stage cooling channels 21b is larger than that of the first stage cooling channels 21a, the cooling water can be supplied uniformly to the second stage cooling channels 21b. Since the cooling channels 21 are integrated with the steel main body 20, it has a simple structure and is easy to install to an actual plant. So, time and labor to install large amount of cooling piping in the lower drywell 3 can be saved. Although the cooling channels have a shape of square tube in this embodiment, they can be formed as other shape, such as a cylindrical tube. For example, the cooling channels can be formed by arranging piping radially and attaching them to the bottom surface of a steel plate. Even in this case, since the cooling water flows through intermediate header 24 etc., time and labor to connect piping can be saved. According to this embodiment, by installing the sacrifice concrete layer 29, it can be avoided that the heat resistant material separates and disperses in case of normal operation or a design base accident without damage of the reactor core. When the core debris is cooled with the cooling water, the surface would be solidified and coat-like solid material (crust) would be formed. Therefore, if crust adheres to the side wall part channel 25, void would be formed between the surface of the core debris and crust and efficiency of cooling at the debris surface would decrease. In this embodiment, the sacrifice concrete layer 29 is also allocated near the side wall part channel 25 and is intended to be eroded by the core debris. So, the crust formed at the top surface of the core debris separates and falls from the side wall part channel 25 easily. The GDCS submersion water piping 7 located near the top of the core catcher where molten reactor core may disperse is laid inside of the pedestal side wall 1 made of concrete. So, heat attack by the core debris can be prevented and a possibility that the GDCS submersion water piping 7 gets damaged is also small. The pedestal side wall 1 is expanded in the radial direction from the bottom end to a certain height that is sufficient to contain the core catcher 70, while the upper part of the pedestal side wall 1 is not expanded compared with a part where the core catcher 70 is located. Therefore, an area for diffusion of the core debris of the core catcher 70 can be larger and the cooling water to be stored in the GDCS pool can be reduced. That is, a vicious circle, that expansion of the whole lower drywell to enlarge an area for dispersion of the core debris results in a requirement of expanding a capacity of the GDCS pool 37 for fulfilling whole of the lower drywell and it is necessary to expand an inner diameter of the reactor containment vessel so as to contain the expanded GDCS pool 37, can be avoided. In an existing reactor containment vessel of which pedestal side wall 1 is not expanded around the bottom end, the quantity of the cooling water to be stored can also be reduced by installing the core catcher 70 after scraping the pedestal side wall 1 to expand space outward for allocating the core catcher 70 in a radial direction. Since the drain sump 27 is formed at the top of the core catcher 70, the drain sump 27 can coexist with the core catcher 70 without spoiling each function. That is, if a leakage from the reactor pressure boundary occurs during the normal operation, whole of the leakage water is gathered into the drain sump 27, and the leakage that might raise a safety issue can be detected. On the other hand, during an accident accompanied by a reactor core meltdown occurs, even if the drain sump 27 is broken, the core catcher 70 can catch and cool the core debris. Thus, according to this embodiment, a core catcher of which flow resistance of the cooling water is uniform and that cools a central region effectively can be provided. Also, leakage can be detected because the leakage water is gathered to the drain sump. In ESBWR of thermal power of 4,500 MWt, if a diameter of an effective area for dispersion of the core debris of the core catcher is expanded to 11.2 m, the area for dispersion of the core debris becomes about 98.5 m2. It means that the area for dispersion of the core debris per unit thermal power is about 0.022 m2/MWt. A core catcher according to a second embodiment of the present invention uses subdivided body sub pieces 30 in combination for easy installation. FIG. 4 is a perspective view of the body sub piece 30 and the base lid 32 according to the second embodiment. FIG. 5 is a bottom plan view of the body sub piece 30 according to the second embodiment. The cooling fins 31 are formed on a bottom surface of the each body sub pieces 30. The base lid 32 having a same projection shape as the body sub piece 30 is attached to the bottom of the cooling fins 31. Spaces between the cooling fins 31 are the cooling channels 21 through which the cooling water flows. The body sub pieces 30 and the cooling fins 31 integrated with the body sub pieces 30 are made of steel and thickness is about 18 cm in total, for example. Thickness of the base lid is about 2 cm and the thickness of whole of the body sub piece 30 is about 40 cm for example. The base lid 32 can be made of any material that is watertight and robust. The base lid 32 can be made of steel as well as the body sub pieces 30 and the cooling fins 31. A width of the cooling fins 31 is a constant at about 10 cm, for example. The cooling fins 31 are allocated with circumferential intervals extended radially and widen toward the perimeter. In FIGS. 4 and 5, although a shape of the body sub pieces 30 and the base lid 32 is illustrated as a trapezoid, it is not limited to a trapezoid. FIG. 6 is a plan view of a core catcher according to the second embodiment. A steel main body 20 of this embodiment is provided with a distributor 10 of a right octagon, whole of the eight first stage body sub pieces 30a and the sixteen second stage body sub pieces 30b which are arranged substantially as a circle. Although one side of the second stage body sub pieces 30b is illustrated as a part of a circle, the side can be linear. The body sub pieces 30 are tiled on the bottom structure member 28 (FIG. 1) and constitute a cone-shaped main body 20 as a whole. For example, each of the first stage body sub pieces 30a has a trapezoid top-face shape and eight first stage body sub pieces 30a are arranged along with the outer side of the distributor 10 of octagonal shape. Sixteen second stage body sub pieces 30b are arranged along with outer side of the first stage body sub pieces 30a. Outer sides of the second stage body sub pieces 30b are formed as a part of a circle and are smoothly connected with the pedestal side wall part channel of a cylindrical shape. The body sub pieces 30 may be subdivided as necessary. For example, if the body sub pieces 30 are subdivided into more pieces, the whole shape of the outer side of the core catcher 70 becomes closer to a circle. In addition, to subdivide the body sub pieces 30 reduces weight and volume of each body sub pieces 30 and results in an improvement of workability during an installation of the core catcher 70. A gap between the body sub pieces 30 can also be reduced by providing the body sub piece 30 with a protrusion and a depression that fit each other. FIG. 8 is a vertical cross sectional view of a reactor containment vessel according to a third embodiment of the present invention. A pedestal 115 is formed by a pedestal floor 107 located in the lower part and a surrounding pedestal side wall 124 of cylindrical shape in a reactor containment vessel 102. A reactor pressure vessel 101 containing a reactor core 123 is supported by the pedestal side wall 124. A suppression pool 104 is surrounding the pedestal side wall 124 in a lower part of the reactor containment vessel 102. The suppression pool 104 stores water. A molten core cooling device (core catcher) 130 is installed on the pedestal floor 107. Cooling water injection piping 108 is connected to the molten core cooling device 130. The cooling water injection piping 108 is connected to a cistern 105 located in an upper part of the reactor containment vessel 102 via an injection valve 114. A cooling device 106 is allocated above the reactor containment vessel 102. The cooling device 106 draws steam of the reactor containment vessel 102, condenses with a submerged heat exchanger 106a and returns condensed water to the cistern 105, for example. A static containment vessel cooling instruments or the drywell cooler, etc. can be used as a cooling device 106. FIG. 7 is a vertical cross sectional view around the pedestal floor according to this embodiment. Flow of the cooling water is schematically indicated with a broken line arrow in FIG. 7. An appearance of the corium (core debris) 113 fallen and deposited on the molten core cooling device 130 is also illustrated. The molten core cooling device 130 is installed on the pedestal floor 107. The molten core cooling device 130 has a water supply chamber 110, a water channel assembly 131, heat resistant material 112 and recirculation piping 109. The water supply chamber 110 is formed as a hollow disc and located on the pedestal floor 107. The cooling water injection piping 108 is connected to the water supply chamber 110. The water channel assembly 131 goes up from the water supply chamber 110 with an inclination toward the pedestal side wall 124, rises perpendicularly near the pedestal side wall 124 and has an aperture at the top end. An inner part of the water channel assembly 131 than a peripheral part rising perpendicularly has a conical shape opened upward. An end of the recirculation piping 109 is opened between the water channel assembly 131 and the pedestal side wall 124. Another end of the recirculation piping 109 is connected to the water supply chamber 110. Although single recirculation piping 109 and single cooling water injection piping 108 are illustrated at the both side of the water channel assembly in FIG. 7, more number of those piping can be installed. Apertures between the water channel assembly 131 and the pedestal side wall 124 except the openings of the recirculation piping 109 and the cooling water injection piping 108 can be covered with a ring shape lid so that the cooling water does not flow into a space 129 below the water channel 111. The heat resistant material 112 is allocated on an upper surface and an inner surface of a part rising perpendicularly along the pedestal side wall 124 of the water channel assembly 131 so that the whole of the surface is covered. As the heat resistant material 112, metal oxides, such as ZrO2 and MgO or basalt concrete can be used and they can have a two layer structure of the metal oxide and the concrete for example. As the heat resistant material 112, blocks of a rectangular parallelepiped of such a material can be allocated to cover. A shape of the block is not limited to a rectangular parallelepiped in this case. FIG. 9 is a plan view of the water supply chamber 110 and the water channel assembly 131 according to this embodiment. The water channel assembly 131 is a combination of a plurality of the water channels 111 surrounding the water supply chamber 110 and extending radially. A projection shape of each water channel 111 is a sector and the water channels 111 contact without a gap with each other. In this embodiment, although the water channel assembly 131 is a combination of sixteen water channels 111 for example, the number of the water channel 111 can be more or less suitably. Cooling water flow paths 125 formed inside of the water channel 111 spread radially toward perimeter and each of them extends from a lower inlet 121 connected to the water supply chamber 110 to an upper outlet 122. In this embodiment, although the water channel assembly 131 is formed by combining a plurality of water channels 111, any kind of shape having cooling water flow paths 125 which goes up while spreading from the water supply chamber can be adopted. For example, two plates of conical shape held at a specific distance can be adopted. If a core meltdown accident occurs and the corium 113 penetrates the reactor pressure vessel bottom head 103 and falls to the pedestal, the corium will be caught by the heat resistant material 112 of the molten core cooling device 130. If the corium 113 falls, the cooling water will be supplied to the water supply chamber 110 and the cooling water will be distributed to each of the water channels 111 from the lower inlet 121. Heat of hot corium 113 is transferred to the heat resistant material 112, and also is transferred to the cooling water through a wall of the water channel 111. Because the heat of corium 113 is transferred, the cooling water flowing through the cooling water flow paths 125 formed inside of the water channel 111 will be boiled eventually. FIG. 10 is a graph showing experimental results of boiling critical heat flux against an angle of a downward heat transfer surface shown in Ref. 1. In this figure, “ULPUcor” represents a correlation by a ULPU experiment, “SBLBcor” represents a correlation by a SBLB experiment and “ΔTsub” represents a deviation from a saturation temperature. Ref. 1: T. G. Theofanous, et. al., “The Coolability Limits of A Reactor Pressure Vessel Lowerhead”, 1997, Nuclear Engineering and Design, Volume 169, and p. 59-p. 76 FIG. 10 indicates that boiling critical heat flux of downward heat transfer through a surface inclined 20 degree is about 60% larger than that through a horizontal surface (angle of 0 degree), for example. In this embodiment, since the cooling water flow path 125 is inclined, a steam bubble produced by boiling tends to be detached from an inner surface of the water channel 111 which is a heat transfer surface by buoyancy and a heat transfer coefficient becomes larger. In this embodiment, since it is taken into consideration to improve removable heat by spreading the corium 113 and to improve easiness of installation concerned with height, the water channels 111 are inclined about 10 degree-about 20 degree from horizon for example. The cooling water injected into the water channel 111 from the lower inlet 121 goes up through the cooling water flow paths 125 and overflows from the top outlet 122 located in the periphery. Most of the cooling water overflowing from the top outlet 122 flows into a cone part of the water channel assembly 131. The cooling water flowing out of the water channel 111 is spilt on the heat resistant material 112 and forms a water pool on the corium 113. The cooling water forming this water pool is boiled on the surface of the corium 113 and cools the corium 113. Thus, corium 113 is cooled by both boiling inside water channel 111 and boiling at the surface of corium 113. Initial water supply to the water supply chamber is carried out by gravity drop of the pool water located higher than the molten core cooling device through the injection piping 108, for example. After completion of the initial water supply, the cooling water spilt on the water channel assembly 131 in the pedestal 115 is supplied to the water supply chamber 110 through the recirculation piping 109 by natural circulation produced by boiling in the cooling water flow paths 125. Steam generated during cooling of the molten core is condensed by the cooling device 106 installed above the containment vessel and returns to the cistern 105. It is configured that the cooling water which is condensed steam and returns to the cistern 105 is again used for cooling of the corium 113. Natural circulation of water keeps the corium 113 being cooled. Melting point of the heat resistant material 112, which is about 2700 degree C. if ZrO2 is used as the heat resistant material 112, is higher than temperature of the corium 113 (average melting point is about 2200 degree C.) and a possibility of melting is small. Possibility that the wall of the cooling water channel 111 is damaged is also small because installation of the heat resistant material 112 prevents the corium 113 to contact directly with the cooling water channel 111 and heat resistance of the heat resistant material 112 reduces heat flux. Thus, the molten core cooling device 130 of this embodiment decreases the temperature of the corium effectively and the corium 113 is stably held inside the molten core cooling device 130. In addition, erosion reaction of concrete does not occur either because the corium 113 does not contact directly with concrete of the pedestal floor 107. Therefore, a possibility of pressurization due to generation of non-condensable gas such as carbon dioxide, hydrogen, etc. and a possibility that the reactor containment vessel is damaged are reduced. In this embodiment, since it is organized by the water channel 111, the heat resistant material 112, the water supply chamber 110 and combination of piping such as the cooling water injection piping 108, there is no need to manufacture a large-sized container etc. Therefore, even if it is difficult to carry a big object into the pedestal 115 to install a new molten core cooling device in an existing containment vessel, it is easy to install because each member can be manufactured and brought into the pedestal 115 separately and they can be assembled at an installation location. FIG. 11 is a perspective view of a water channel 111 according to a fourth embodiment of the present invention. The water channel 111 of this embodiment is an integration of the water channel of the third embodiment and the heat resistant material 112 sticking to the top surface. Time for installation of the molten core cooling device 130 can be reduced by manufacturing such water channels 111 beforehand at a factory, etc. outside of a nuclear power plant, bringing the water channels 111 inside the pedestal and assembling them. Many dimples are formed on a wall defining the cooling water flow path 125 inside this water channel 111. These dimples enhance heat transfer at the inner surface of the water channel 111 and the corium can be cooled more quickly. A fifth embodiment of the present invention utilizes a water channel assembly 131 that is formed as a convex bowl shape which opens upward instead of conical shape. FIG. 12 is a vertical cross sectional view around a pedestal floor 107 according to the fifth embodiment. The water channel assembly 131 of this embodiment is formed so that an inclination of the cooling water flow path 125 increases stepwise as approaching from the water supply chamber 110 to the pedestal side wall 124. The water channel assembly 131 is a combination of water channels of which projection shape is a sector, similar to the first embodiment. As shown in FIG. 10, as an inclination of a cooling surface from horizon increases, boiling critical heat flux increases and cooling capability increases. Therefore, even if an area of the heat resistant material 112 on which the corium is caught and of a top surface of the water channel assembly 131 that cools the corium through the heat resistant material 112 is reduced, it is possible to cool and hold the corium 113 stably. A sixth embodiment of the present invention relates especially to a control method of the injection valve 114 attached to the injection piping 108 which supplies the cooling water to the molten core cooling device 130. FIG. 13 is an explanatory view of a molten core cooling device illustrated with a vertical cross sectional view of the reactor containment vessel according to the sixth embodiment. An injection valve controller 136 is attached to the injection valve 114. A sensor 137 for detecting an indication that the molten core falls is connected to the injection valve controller 136. It may be configured that internal pressure of pedestal 115, or other force, opens the injection valve 114 automatically. Although it is configured that the injection valve controller 136 opens the injection valve 114 in this embodiment. If the injection valve controller 136 receives a signal from the sensor 137 and judges that an indication of molten core falling exists, the injection valve controller 136 opens the injection valve 114 and supplies the cooling water to the molten core cooling device 130. A thermometer which measures pedestal ambient temperature can be used as the sensor 137 and it can be configured that the injection valve controller 136 opens the injection valve 114 if the pedestal ambient temperature exceeds a predetermined temperature. A thermometer which measures temperature of reactor pressure vessel lower head 103 can be used in place of the thermometer which measures pedestal ambient temperature, and it can be configured that the injection valve 114 is opened if the temperature exceeds a predetermined temperature. A detector which detects a reactor water level can be used as sensor 137 and it can be configured that the injection valve controller 136 judges that an indication of molten core falling exists and opens injection valve 114 if a reactor water level low signal remains for a certain period. Furthermore, these sensors can be combined as the sensor 137. In this embodiment, since an indication of molten core falling can be detected by an appropriate sensor and the cooling water can be supplied to the molten core cooling device 130 if a molten core falls, the corium can be cooled immediately. FIG. 14 is an explanatory view indicating a molten core cooling device according to a seventh embodiment of the present invention with a vertical cross sectional view of a reactor containment vessel. In this embodiment, the cooling water injection piping 108 is connected to external cooling water supply piping 140 extending to an external cooling water tank 138. A pump 141 is inserted in the external cooling water supply piping 140. A pump control device 139 is attached to the pump 141. On detecting an indication of molten core falling, the pump control device 139 starts up the pump 141 and supplies the cooling water from the external cooling water tank 138 to the molten core cooling device 130. Consequently, if external electricity is available for driving the pump 141, not only the cooling water stored in the cistern 105 but also the cooling water stored in the external cooling water tank 138 can be used for cooling of the corium. Therefore, the corium can be cooled more quickly. FIG. 16 is a vertical cross sectional view of a reactor containment vessel according to an eighth embodiment of the present invention. In the lower drywell 216 of the reactor containment vessel 202, a pedestal 215 is formed by a pedestal floor 207 located at the lower part and a surrounding pedestal side wall 224 of cylindrical shape. The reactor pressure vessel 201 containing a core 223 is supported by the pedestal side wall 224. A suppression pool 204 is formed as surrounding the pedestal side wall 224 in the lower part of the reactor containment vessel 202. The suppression pool 204 stores pool water 204a. On the pedestal floor 207, a molten core holding device (core catcher) 230 which holds the molten core 213 fallen through the reactor pressure vessel lower head 203 in case of accident is installed. Injection piping 208 is connected to the molten core holding device 230. The injection piping 208 is connected to a cistern 205 located in an upper part of reactor containment vessel 202 via an injection valve 214. A containment vessel cooling device 206 is installed on the reactor containment vessel 202. The containment vessel cooling device 206 draws steam in the reactor containment vessel 202 to a heat exchanger 266 sunk in water to condense and returns the condensed water to the cistern 205, for example. As such a containment vessel cooling device 206, a static containment vessel cooling facility or a drywell cooler, etc. can be used. FIG. 15 is a vertical cross sectional view around the pedestal floor 207 according to the eighth embodiment of the present invention. Flows of the cooling water are indicated in FIG. 15 by an arrow head with a broken line. An appearance of the corium (core debris) 213 fallen and deposited on the molten core holding device 230 is also illustrated. The molten core holding device 230 is installed on the pedestal floor 207. The molten core holding device structure 230 has a water supply chamber 210, cooling water channels 211, heat resistant material 212 and water supply piping 209. The water supply chamber 210 is formed as a hollow disc and is installed on the pedestal floor 207. The injection piping 208 is connected to the water supply chamber 210. The cooling water channel 211 goes up from the water supply chamber 210 with an inclination toward the pedestal side wall 224, rises perpendicularly near the pedestal side wall 224 and opens at a top exit 222 located at the upper end. The cooling water flow paths 225 are formed inside of the cooling water channel 211. Height of the cooling water flow path 225 is largest at the connection with the water supply chamber 210 and decreases as approaching to the perimeter. A space inner than the vertical part at the perimeter of the cooling water flow channel 211 is a debris holding region 261 which has a conical shape opening upward. The water supply piping 209 has an aperture at an end between the cooling water channel 211 and the pedestal side wall 224. The other end of the water supply piping 209 is connected to the water supply chamber 210. The heat resistant material 212 is allocated on the upper surface and the vertical surface toward the center along the pedestal side wall of the cooling water channel 211 so as to cover whole of this area. ZrO2 can be used as the heat resistant material 212 for example. FIG. 17 is a plan view around the water supply chamber 210 according to the eighth embodiment. In FIG. 17, illustration of the heat resistant material 212 is omitted. Tubular bodies 255 form the cooling water channel 211. Tubular bodies 255 extend radially around the water supply chamber 210 and are allocated without clearance. The cooling water flow paths 225 formed inside of the cooling water channel 211 spread in circumferential direction toward the perimeter from the lower inlet 221 connected to the water supply chamber 210 and extend to the top exit 222. If a core meltdown accident occurs, the corium 213 that penetrates the reactor pressure vessel lower head 203 and falls to the lower drywell 216 is caught by the heat resistant material 212 of the molten core holding device 230. If the corium 213 falls, the cooling water is supplied to water supply chamber 210 and the cooling water is distributed to each cooling water flow path 225 through the lower inlet 221. Heat of the high temperature corium 213 is transferred to the heat resistant material 212 and is transferred to cooling water through the wall of the cooling water channel 211. Since being transferred the heat of the corium 213, the cooling water flowing through the cooling water flow paths 225 is eventually boiled. FIG. 10 indicates that boiling critical heat flux of downward heat transfer through a surface inclined 20 degree is about 60% larger than that through a horizontal surface (angle of 0 degree), for example. In this embodiment, since the cooling water flow path 225 is inclined, a steam bubble produced by boiling tends to be detached from an inner surface of the water channel 211 which is a heat transfer surface by buoyancy and a heat transfer coefficient becomes larger. FIG. 18 is a graph showing an example of relation between distance from the center of a water supply header and a sectional area of a cooling channel flow path assuming a height of the flow path in the cooling channel is constant. FIG. 19 is a graph showing an example of relation between distance from the center of a water supply header core and a height of the flow path in the cooling channel assuming a sectional area of a cooling channel flow path is constant. Assuming that height of the cooling water flow path 225 is constant in a radial direction, a cross sectional area of the cooling water flow path 225 is proportional to a square of distance from the center of the water supply chamber 210. Therefore, flow velocity of the cooling water flowing through the cooling water flow paths 225 tends to be smaller as approaching the perimeter. However, in this present embodiment, since the height of the cooling water flow path 225 decreases as approaching the perimeter, increase of the cross sectional area of the cooling water flow path 225 is suppressed. For example, as shown in FIG. 19, the cross sectional area of the cooling water flow path 225 can be kept constant. The cross sectional area of the cooling water flow path 225 can also be smaller as approaching the perimeter. It is possible to suppress decrease of the flow velocity through the cooling water flow path 225 by suppressing increase in the cross sectional area of cooling water flow path 225 as described above. That is, it can be suppressed to decrease in the cooling water per unit area and per unit time which contributes to remove heat as approaching the perimeter. Therefore, a local rise of temperature of the molten core holding device 230 can be suppressed. The cooling water flowing into the cooling water channel 211 from the lower inlet 221 goes up through the cooling water flow paths 225 and it overflows from the top exit 222 located in the perimeter. The great portion of the cooling water overflowed from the top exit 222 flows over a cone shape part of the molten core holding device 230. The cooling water running out from the cooling water channel 211 is spilt on the heat resistant material 212 and forms a water pool on the corium 213. The cooling water which forms the water pool boils at the surface of the corium 213 and cools the corium 213. In this manner, the corium 213 is cooled by both boiling inside the cooling water channel 211 and boiling at the surface of the corium 213. Initial water supply to the water supply chamber is carried out by gravity drop of the pool water located higher than the molten core cooling device through the injection piping 208, for example. After completion of the initial water supply, the cooling water spilt on the molten core holding device 230 in the pedestal 215 is supplied to the water supply chamber 210 through the water supply piping 209 by natural circulation produced by boiling in the cooling water flow paths 225. Since the water supply piping 209 is piping which circulates the cooling water, it can also be called as the circulation piping. Steam generated during cooling of the molten core is condensed by the cooling device 206 installed above the reactor containment vessel 202 and returns to the cistern 205. It is configured that the cooling water which is condensed steam and returns to the cistern 205 is again used for cooling of the corium 213. Natural circulation of water keeps the corium 213 being cooled. Melting point of the heat resistant material 212, which is about 2700 degree C. if ZrO2 is used as the heat resistant material 212, is higher than temperature of the corium 213 (average melting point is about 2200 degree C.) and a possibility of melting is small. Possibility that the wall of the cooling water channel 211 is damaged is also small because installation of the heat resistant material 212 prevents the corium 213 to contact directly with the cooling water channel 211 and heat resistance of the heat resistant material 212 reduces heat flux. Thus, the molten core holding device 230 of this embodiment decreases the temperature of the corium effectively and the corium 213 is stably held inside the molten core holding device 230. In addition, erosion reaction of concrete does not occur either because the corium 213 does not contact directly with concrete of the pedestal floor 207. Therefore, a possibility of pressurization due to generation of non-condensable gas such as carbon dioxide, hydrogen, etc. and a possibility that the reactor containment vessel is damaged are reduced. FIG. 20 is a vertical cross sectional view around a pedestal floor 207 according to a ninth embodiment of the present invention. In the molten core holding device 230 according to this embodiment, laying thickness of the heat resistant material 212 increases as approaching to the perimeter. The laying thickness of the heat resistant material 212 may not change continuously and may change discontinuously by using heat resistant blocks of different thickness or layering heat resistant blocks. In such molten core holding device, heat transfer from the corium 213 to the cooling water is reduced at the peripheral region where cross sectional area in the cooling water channel 211 is larger and flow velocity of the cooling water is smaller. Therefore, local rise of temperature of the cooling water channel 211 can be reduced and it is possible to hold the molten core stably and to cool continuously. FIG. 21 is a vertical cross sectional view around a pedestal floor 207 according to a tenth embodiment of the present invention. The molten core holding device 230 according to this embodiment has first heat resistant material 252 allocated in the inner region and second heat resistant material 253 of which heat transfer coefficient is smaller than the first heat resistant material allocated in the outer region. Height of the flow path in the cooling water channel 225 is constant. A plurality of kinds of heat resistant material may be allocated so that thermal conductivity is smaller as approaching to the perimeter. In such a molten core holding device, heat transfer from the corium 213 to the cooling water is reduced at the peripheral region where cross sectional area in the cooling water channel 211 is larger and flow rate of the cooling water is smaller. Therefore, local rise of temperature of the cooling water channel 211 can be reduced and it is possible to hold the molten core stably and to cool continuously. FIG. 22 is a vertical cross sectional view around a pedestal floor according to an eleventh embodiment of the present invention. In the molten core holding device 230 according to this embodiment, a upside surface of the water supply chamber 210 has a conical shape which opens upward. In such a molten core holding device 230, since the top surface of the water supply chamber 210 has an inclination, bubbles generated at the ceiling flow toward the cooling water channel 225 without stagnation. Therefore, local rise of temperature of the water supply chamber 210 can be reduced and it is possible to hold the molten core stably and to cool continuously. FIG. 23 is a plan view around a cooling channel according to a twelfth embodiment of the present invention. FIG. 24 is a cross sectional view as viewed in the direction of arrow XXIV-XXIV of FIG. 23. FIG. 25 is a cross sectional view as viewed in the direction of arrow XXV-XXV of FIG. 23. In FIG. 23, illustration of the heat resistant material 212 is omitted. The molten core holding device 230 of this embodiment has two kinds of water supply piping 291, 292. The first water supply piping 291 is connected to the water supply chamber 210. The second water supply piping 292 is connected to the cooling water channel 211 between the lower inlet 221 and the top exit 222. In such a molten core holding device, cold cooling water is supplied more in a peripheral region where cross sectional area of flow path in the cooling water channel 211 is larger and flow velocity of the cooling water is smaller. Therefore, local rise of temperature of the cooling water channel 211 can be reduced and it is possible to hold the molten core stably and to cool continuously. FIG. 26 is a cross sectional view around a pedestal floor according to a thirteenth embodiment of the present invention. In the molten core holding device 230 according to this embodiment, dam 251 is formed between the top exit 222 and the water supply piping 209. The dam 251 leans toward the top exit 222. Bubbles generated with heat transferred from the corium 213 in the cooling water while flowing through the cooling water channel 225 are emitted with the cooling water from the top exit 222. The dam 251 reduces direct inflow to the water supply piping 209 of the cooling water containing bubbles. Therefore, inflow to the water supply piping 209 of bubbles in the cooling water is reduced and more cooling water is supplied to the water supply chamber 210. FIG. 27 is a cross sectional view around a pedestal floor according to a fourteenth embodiment of the present invention. FIG. 28 is a cross sectional view as viewed in the direction of arrow XXVIII-XXVIII of FIG. 27. FIG. 29 is a cross sectional view as viewed in the direction of arrow XXIX-XXIX of FIG. 27. FIG. 30 is a cross sectional view as viewed in the direction of arrow XXX-XXX of FIG. 27. The molten core holding device 230 according to this embodiment has the cooling channel 211 installed on the pedestal floor 207 of which projection shape is roughly square. A corium holding area 261 which consists of a leaning base and a wall which surrounds the base and spreads vertically is formed above the cooling water channel 211 and the corium is held there. The heat resistant material 212 is allocated on the surface of the cooling water channel 211 facing to the area 261 where the corium is held. Beneath the corium holding area 261, a plurality of the cooling water channels 225 are formed in the cooling water channel 211. The cooling water channels 225 are parallel to each other. The cooling water channel 225 extends with a constant horizontal width from the inlet 262 to the exit 263. The upside surface of the cooling water channel 225 goes up from the inlet 262 toward the exit 263 along the bottom face of the corium holding area 261. The bottom surface of the cooling water channel 225 contacts with the pedestal floor 207 formed horizontally. The injection piping 208 has an aperture near the inlet 262 and the cooling water supplied from the injection piping 208 is spilt on the pedestal floor 207 surrounded by the pedestal side wall 224 and at least a part of it flows into the cooling water channel 225 from the inlet 262. The cooling water passing through the cooling water channel 225 is emitted from the exit 263. The cooling water supplied from the injection piping 208 is stored in a space surrounded by the pedestal side wall 224, will flow into the corium holding area 261 if a water level exceeds wall surrounding the corium holding area 261 and will form a water pool on the corium 213. The cooling water forming this water pool is boiled on the surface of the corium 213 and cools corium 213. In such a molten core holding device 230, since a top surface of the cooling water channel 225 has an inclination, bubbles generated by boiling tends to be detached by buoyancy from the top surface of the cooling water channel 225 which is a heat transfer surface and a heat transfer coefficient becomes larger. In addition, since horizontal width of the cooling water channel 225 is constant, decrease of the flow velocity of the cooling water along the top surface of the cooling water channel 225 which is a heat transfer surface from the corium 213 is reduced. Therefore, local rise of temperature of the cooling water channel 211 can be reduced and it is possible to hold the molten core stably and to cool continuously. The molten core holding device 230 according to the fifteenth embodiment of the present invention is seen same as the molten core holding device 230 according to the fourteenth embodiment if it is seen from the top. FIG. 31 is a cross sectional view around a pedestal floor according to a fifteenth embodiment of the present invention. FIG. 31 is corresponding to a cross sectional view as viewed in the direction of arrow XXVIII-XXVIII of FIG. 27. The molten core holding device 230 according to this embodiment differs from the fourteenth embodiment in that the pedestal floor is not horizontal and is parallel to the bottom surface of the corium holding area. That is, the cooling water channel 225 extends with a constant cross sectional area of the flow path from the inlet 262 to the exit 263. Therefore, the cooling water flows without decrease of velocity, local rise of temperature of the cooling water channel 211 can be reduced and it is possible to hold the molten core stably and to cool continuously. FIG. 32 is a cross sectional view around a pedestal floor according to a sixteenth embodiment of the present invention. FIG. 33 is a cross sectional view as viewed in the direction of arrow XXXIII-XXXIII of FIG. 32. The molten core holding device 230 according to this embodiment has entry side vertical flow paths 281 and exit side vertical flow paths 282 both extending vertically which are installed so as to contact respectively to the inlet 262 and the outlet 263 of the cooling water channel of the molten core holding device 230 according to the thirteenth embodiment. The entry side vertical flow paths 281 and the exit side vertical flow paths 282 have an aperture at the top ends. The injection piping 208 extends to near the top end of the entry side vertical flow paths 281. The cooling water emitted from the injection piping 208 flows into the entry side vertical flow paths 281, flows through the cooling water channel 225 and spills from the exit side vertical flow paths 282. A part of the cooling water spilt from the exit side vertical flow paths 282 flows into the corium holding area 261. In such a molten core holding device 230, it becomes easy for cold cooling water supplied from the injection piping 208 to flow into the cooling water flow paths 225, and the corium 213 can be cooled effectively. The molten core holding device 230 according to the Seventeenth embodiment of the present invention is seen same as the molten core holding device 230 according to the sixteenth embodiment shown in FIG. 32 if it is seen from the top. FIG. 34 is a cross sectional view around a pedestal floor according to a seventeenth embodiment of the present invention. FIG. 34 is a cross sectional view as viewed in the direction of arrow XXXIII-XXXIII of FIG. 32. In the molten core holding device 230 according to this embodiment, the pedestal floor 207 according to the sixteenth embodiment is modified as it has upward inclination from the entry side vertical flow paths 281 to the exit side vertical flow paths 282 In such a molten core device 230, since cross sectional area of the cooling water flow paths 225 is kept constant from the entry side vertical flow paths 281 to the exit side vertical flow paths 282, flow velocity of the cooling water does not decrease. Therefore, the corium 213 can be cooled effectively. Above mentioned embodiments are just examples, and the present invention is not limited to these. Also each feature of the embodiments can be combined together.
	abstract	The present invention relates to an apparatus for generating, extracting and selecting ions used in a heavy ion cancer therapy facility. The apparatus comprises an independent first (ECRIS 1) and an independent second electron cyclotron resonance ion source (ECRIS 2) for generating heavy and light ions, respectively. Further is enclosed downstream of spectrometer magnet (SP1, SP2) for selecting heavy ion species of one isotopic configuration positioned downstream of each ion source (ECRIS 1, ECRIS 2): a magnetic quadrupole triplet (QT1, QT2) positioned downstream of each spectrometer magnet (SP1, SP2); a switching magnet (SM) for switching between high-LET ion species and low-LET ion species of said two independent first and second ion source.
050842307	claims	1. A tool for removing a top nozzle from a guide thimble of a nuclear fuel assembly, said tool comprising: (a) a handling assembly including an upper handle and an elongated handle pole having spaced upper and lower ends, said handle pole being attached at said upper end to said upper handle and extending downwardly therefrom; (b) a lower tool head including an anchor assembly and a lift assembly, said anchor assembly being matable with the guide thimble and actuatable between disengaged and engaged conditions with the guide thimble; (c) means for coupling said anchor assembly to said lower end of said handle pole and for coupling said lift assembly to said lower end of said handle pole, said coupling means being operable for connecting said lift assembly and handle pole in a first connected relation in which said lift assembly is rotatably movable, by rotation of said handle pole, between unlocked and locked positions relative to the top nozzle and unlatched and latched positions relative to said anchor assembly or in a second connected relation in which said lift assembly is axially movable, by rotation of said handle pole, along said handle pole relative to said anchor assembly to cause lifting and detaching of the top nozzle from the guide thimble once said lift assembly is disposed in said latched position relative to said anchor assembly and in said locked position relative to the top nozzle and said anchor assembly is disposed in said engaged position with the guide thimble; and (d) means connected to said anchor assembly for actuating said anchor assembly between said disengaged and engaged conditions with the guide thimble, said actuating means being mounted on said handle pole and extending from said upper handle to said lower tool head. a pressurized fluid supply mounted on said handle pole adjacent said handle of said handling assembly; and a pressurized fluid supply line extending from said supply to said fluid-driven actuator connected to said probe member. a central hub defining an internally threaded hole; and a central sleeve extending upwardly from said central hub and slidably fitted to said lower end of said handle pole. a screw shaft member mounted to said lower end of said handle pole and threaded into said threaded hole of said central hub of said lift assembly spider yoke; a pin attached to said lower end of said handle pole; means defined in said central sleeve of said lift assembly spider yoke for receiving said pin in a seated relationship; and means engaging said pin and said central sleeve for normally imposing a biasing force on said pin that moves said pin toward an unseated relationship with said central sleeve in which said lift assembly assumes said second connected relation with said handle pole such that rotation of said pole causes threading rotation of said screw shaft relative to said central hub and thereby axial movement of said lift assembly relative to said handle pole and anchor assembly, said pin capable of being moved into said seated relationship with said central sleeve, by imposing a downward force on said handle pole sufficient to overcome the biasing force toward said lift assembly, in which said lift assembly assumes said first connected relation with said handle pole such that rotation of said pole causes rotation of said lift assembly relative to said anchor assembly between said locked and unlocked positions relative to the top nozzle. (a) a handling assembly including an upper handle and an elongated handle pole having spaced upper and lower ends, said handle pole being attached at said upper end to said upper handle and extending downwardly therefrom; (b) a lower tool head including an anchor assembly and a lift assembly, said anchor assembly having a plurality of elongated probe members being insertable into the guide thimbles, each probe member having an expansion sleeve actuatable between expanded and contracted positions for engaging and disengaging the respective guide thimbles; (c) means for coupling said anchor assembly to said lower end of said handle pole and for coupling said lift assembly to said lower end of said handle pole, said coupling means being operable for connecting said lift assembly and handle pole in a first connected relation in which said lift assembly is rotatably movable, by rotation of said handle pole, between unlocked and locked positions relative to the top nozzle and unlatched and latched positions relative to said anchor assembly or in a second connected relation in which said lift assembly is axially movable, by rotation of said handle pole, along said handle pole relative to said anchor assembly to cause lifting and detaching of the top nozzle from the guide thimbles once said lift assembly is disposed in said latched position relative to said anchor assembly and in said locked position relative to the top nozzle and said anchor assembly is disposed in said engaged position with the guide thimbles; and (d) means connected to said anchor assembly for actuating said anchor assembly between said disengaged and engaged conditions with the guide thimble, said actuating means being mounted on said handle pole and extending from said upper handle to said lower tool head. a pressurized fluid supply mounted on said handle pole adjacent said handle of said handling assembly; and a pressurized fluid supply line extending from said supply to said fluid-driven actuator connected to each of said probe members. a central hub defining an internally threaded hole; and a central sleeve extending upwardly from said central hub and slidably fitted to said lower end of said handle pole. a screw shaft member mounted to said lower end of said handle pole and threaded into said threaded hole of said central hub of said lift assembly spider yoke; a pin attached to said lower end of said handle pole; means defined in said central sleeve of said lift assembly spider yoke for receiving said pin in a seated relationship; and means engaging said pin and said central sleeve for normally imposing a biasing force on said pin that moves said pin toward an unseated relationship with said central sleeve in which said lift assembly assumes said second connected relation with said handle pole such that rotation of said pole causes threading rotation of said screw shaft relative to said central hub and thereby axial movement of said lift assembly relative to said handle pole and anchor assembly, said pin capable of being moved into said seated relationship with said central sleeve, by imposing a downward force on said handle pole sufficient to overcome the biasing force toward said lift assembly, in which said lift assembly assumes said first connected relation with said handle pole such that rotation of said pole causes rotation of said lift assembly relative to said anchor assembly between said locked and unlocked positions relative to the top nozzle. 2. The tool as recited in claim 1, wherein said anchor assembly includes an elongated probe member insertable into the guide thimble, said probe member having an expansion sleeve movable between expanded and contracted positions for engaging and disengaging the guide thimble. 3. The tool as recited in claim 2, wherein said anchor assembly also includes a fluid-driven actuator drivingly coupled to said probe member for actuating said expansion sleeve between said expanded and contracted positions. 4. The tool as recited in claim 3, wherein said actuating means includes: 5. The tool as recited in claim 1, wherein said lift assembly includes a spider yoke having an upper central portion and a plurality of legs projecting radially outwardly and then downwardly from said central portion and terminating in abutments that underlie a lip on the top nozzle when said lift assembly is rotated to said locked position with the top nozzle and clear the lip on the top nozzle when said lift assembly is rotated to said unlocked position therewith. 6. The tool as recited in claim 5, wherein said central portion of said lift assembly spider yoke includes: 7. The tool as recited in claim 6, wherein said coupling means includes: 8. The tool as recited in claim 7, wherein said biasing force imposing means is a coil spring. 9. The tool as recited in claim 1, wherein said coupling means includes a universal joint coupling said anchor assembly to said lower end of said handle pole to permit unidirectional pivotal movement of said anchor assembly relative to the guide thimble for aligning the anchor assembly therewith for mating with the guide thimble. 10. A tool for removing a top nozzle from guide thimbles of a nuclear fuel assembly, said tool comprising: 11. The tool as recited in claim 10, wherein said anchor assembly also includes a plurality of fluid-driven actuators drivingly coupled to said respective probe members for actuating said expansion sleeves thereof between said expanded and contracted positions. 12. The tool as recited in claim 11, wherein said actuating means includes: 13. The tool as recited in claim 10, wherein said lift assembly includes a spider yoke having an upper central portion and a plurality of legs projecting radially outwardly and then downwardly from said central portion and terminating in abutments that underlie a lip on the top nozzle when said lift assembly is rotated to said locked position with the top nozzle and clear the lip on the top nozzle when said lift assembly is rotated to said unlocked position therewith. 14. The tool as recited in claim 13, wherein said central portion of said lift assembly spider yoke includes: 15. The tool as recited in claim 14, wherein said coupling means includes: 16. The tool as recited in claim 15, wherein said biasing force imposing means is a coil spring. 17. The tool as recited in claim 10, wherein said coupling means includes a universal joint coupling said anchor assembly to said lower end of said handle pole to permit unidirectional pivotal movement of said anchor assembly relative to the guide thimbles for aligning said probe members of said anchor assembly for mating with the guide thimbles.
	summary
056169280	summary	FIELD OF THE INVENTION This application relates to an apparatus for protecting personnel and the environment from emissions of harmful radiation, such as radioactive emissions emanating from radioactive waste. More particularly, it relates to such an apparatus which includes a shielding part or parts so located as to be in a path of the radiated emissions and to absorb such emissions, at least in part, so that the electrical potential of the shielding part will be changed, and electrically conductive means for connecting such shielding part with a sink through an electrical load so as to consume the electrical energy generated and so as to remove the electrical charge from the shielding part, thereby enabling such part better to absorb additional radiation, and helping to stabilize the material of such part and prevent potentially explosive buildup of energy therein. The invention also relates to processes for protecting personnel and the environment from radiation. DESCRIPTION OF RELATED ART The closest references known such as U.S. Pat. No. 3,939,366 to Ato et al., No. 4,178,524 to Ritter, and an article in Chemical and Engineering News, Vol. 32, No. 7, at page 592, issued Feb. 15, 1954. The Ato et al. patent teaches the direct generation of electricity from radioactive materials by means of semiconductors. The Chemical and Engineering News article mentions a semiconductor crystal with an impurity in it to form a junction similar electrically to a junction in a junction transistor and mentions strontium-90 as a source of radiant energy. The Ritter patent is for a radioisotope photoelectric generator to produce electrical energy at a high voltages, e.g., 25,000 volts. Ritter intentionally builds up potential difference while in accordance with the present invention such build-up is prevented. Ritter specifies that his photon-producing radioactive source of energy must be a source of energy less than 1 million electron volts and Ritter teaches the use of pure isotopes, rather than mixtures of different radioactive material, such as are found in nuclear wastes. A very significant distinction between Ritter and the present invention is in the fact that Ritter is attempting to produce electricity and the object of the invention is to protect personnel and the environment from radioactive emissions. Ritter does not teach varying resistance to consume the energy of the emissions and his "load" may not be sufficient to handle a burst of energy. Ritter does not mention such protective function for his apparatus and the lead shielding of the Ritter apparatus, which has no part in the electrical functions thereof, is the means by which he prevents harmful radiation from the radioactive source from reaching any personnel and the environment. Certainly, the environment is not protected by Ritter's "battery". Thus, it is seen that the present invention is novel, useful and unobvious from the "prior art" mentioned. For many years intensive efforts have been made to protect personnel and the environment from harmful radiations from various sources and in recent years extensive research has been performed in an effort to reduce the harmful effects of various radioactive wastes, especially mixed wastes, such as those from spent fuel rods used for power generation, and those known as "weapons wastes". Various treatments of such nuclear wastes that have been tried include calcining, gas diffusion, concentration, solidification, fusion and incorporation in vitreous matrices, synthetic organic polymers or inorganic sorbents. After concentration and "solidification" in a suitable matrix, as described above, such wastes are transported to disposal sites, such as salt domes, and are buried therein. Although such treatments and storage may seem to be comparatively safe, there is always the possibility that radiation and heat released by the decaying radioactive material will fracture the matrix, and earth movements and water flows could carry released radioactive materials away from the disposal site, to areas where they may be harmful to humans, animals, fish and the environment in general. The present invention provides a means for converting at least a portion of the harmful radiation from radioactive wastes (and from other sources of harmful radiated emissions) to environmentally acceptable, safe, and often useful form, and it does this at relatively low voltage and low temperature so that any danger of explosion is minimized. Thus, harmful radiation is converted to useful electrical power, although the object of this invention is to protect the environment, rather than to produce power. The removal of electrical energy from the radiation absorbing means of this invention promotes further absorption of such radiation and also improves the resistance of the absorbing means to deterioration by radiation. Utilization of pairs of electrically conductive absorber-converters in paths of the radiation, which absorbers are connected to a load to draw off electrical charges therefrom, is preferred, and the employment of pairs of such absorbers, connected to common conductors to carry electricity to the load, is a further preferred mode of the invention. SUMMARY OF THE INVENTION In accordance with the present invention an apparatus for protecting organisms and the environment from harmful emissions of radiation from a source thereof by shielding said organisms and the environment from at least a portion of such emissions comprises a plurality of shielding parts located so as to be capable of absorbing radiation emissions from the source thereof, with one such part being located farther away from the source than the other and with the shielding parts both being in the path of the same emissions, so that an electrical potential difference between such shielding parts is established, due to different absorptions of radiation by them, and electrical conductors communicating with such shielding parts and transmitting such difference in potential to a means for consuming electric power located remote from the radioactive source. In preferred embodiments of the invention the shielding parts are of electrically conductive materials, such as metals of different atomic numbers, separated by an insulator, e.g., epoxy resin, ceramic, mica, glass, air and means are present to induce initial charging of the shield(s) and to produce the resulting electric current. Also, it is often preferable for the shielding members to be in roughly spherical form and for pluralities of pairs of such shielding members to be used so that radiation passing through the first set(s) of members may be absorbed by subsequent set(s). In a broader aspect of the invention an electrically conductive shield acts to collect energy from harmful radiation and discharges such energy through an electrical load. The invention also relates to various processes for protecting humans and the environment and for reducing radioactivity.
	abstract	An ion detector includes collision surfaces for converting both positively and negatively charged ions into emitted secondary electrons. Secondary electrons may be detected using an electron detector, than may, for example include an electron multiplier. Conveniently, secondary electrons (or electrons emitted by the multiplier) may be detected using an electron pulse counter.
	claims	1. A reflective lithography mask comprising:a substrate; and a reflective coating overlying the substrate that is reflective to radiation and is patterned so as to correspond to a desired circuit layout, wherein the substrate is substantially absorbent to EUV radiation and exposed top surface portions of the substrate not covered by the patterned reflective coating are roughened so as to be more absorbent to EUV radiation. 2. The mask of claim 1, the substrate comprising a low-thermal expansion material or a mixed glass composition of about 92.6 wt. % SiO2 and about 7.4 wt. % TiO2. 3. The mask of claim 1, the reflective coating including at least one of silicon, molybdenum, beryllium, ruthenium and boron carbide. 4. The mask of claim 1, the reflective coating including a plurality of layers of one or more EUV reflective materials. 5. The mask of claim 4, the layers having respective thicknesses within a range of about 1-10 nm. 6. A method of making a reflective lithography mask comprising:forming a reflective coating that is reflective to lithography radiation on a top surface of a substrate that is substantially absorbent to lithography radiation; forming a masking material over the reflective material; patterning the masking material so as to correspond to a desired circuit layout; patterning the reflective coating so as to correspond to the desired circuit layout with the patterned masking material serving as a mask, where the reflective coating is patterned through so that top surface portions of the substrate are roughened so as to be more absorbent to EUV radiation; and removing the masking material. 7. The method of claim 6 further including depositing a plurality of layers of one or more EUV reflective materials to form the reflective coating. 8. The method of claim 7, the one or more EUV reflective materials including at least one of silicon, molybdenum, beryllium, ruthenium and boron carbide. 9. The method of claim 7, the layers having respective thicknesses within a range of about 1-10 nm. 10. The method of claim 6, the reflective coating including a plurality of layers of one or more EUV reflective materials. 11. The method of claim 6, the one or more EUV reflective materials including at least one of silicon, molybdenum, beryllium, ruthenium and boron carbide. 12. The method of claim 6, the layers having respective thicknesses within a range of about 1-10 nm. 13. The method of claim 6, the reflective coating patterned via etching. 14. The method of claim 6, the substrate comprising a low-thermal expansion material (LTEM) or a mixed glass composition of about 92.6 wt. % SiO2 and about 7.4 wt. % TiO2. 15. The method of claim 6 further comprising:optically inspecting the mask by directing substantially visible, UV or deep-UV radiation onto the mask and evaluating the light passing through the mask. 16. The method of claim 15, wherein the inspection includes determining a contrast pattern of light passing through the mask. 17. The method of claim 6, the masking material including a photoresist. 18. A method of optically inspecting a mask as described in claim 1 comprising:directing light having a wavelength of between about 190 and about 90 nanometers on the mask; and evaluating light that passes through the mask.
	summary
	claims	1. An illumination system, particularly for microlithography with wavelengths≦193 nm, comprising:a primary light source(8001, 8101, 8401) ; a first optical component; a second optical component(8021, 8121, 8421) ; an image plane(8029, 8129, 8429) ; and an exit pupil(8033, 8133) , wherein said first optical component transforms said primary light source(8001, 8101, 8401) into a plurality of secondary light sources that are imaged by said second optical component in said exit pupil(8033, 8133) , wherein said first optical component includes a first optical-element optical element having a plurality of first raster elements (8009, 8109, 8409) that are imaged into said image plane(8029, . . . ) , producing a plurality of images being superimposed, at least partially, on a field in said image plane(8029, . . . ) , wherein said first optical component comprises a collector unit(8003, 8103, 8403) and a second optical element having a plurality of second raster elements(8015, 8115, 8415) , said illumination system further comprising: a first optical axis(8045.1) between said collector unit(8003, . . . ) and said first optical element, wherein said first optical element is reflective; a second optical axis(8045.2) between said first optical element and said second optical element, wherein said second optical element is reflective; and a third optical axis(8045.3) between said second optical element and said second optical component(8021, 8121, 8421) , wherein the a directional vector(8046.1) of the first optical axis(8045.1) and the a directional vector (8046.2) of the second optical axis (8046.2) define a plane and wherein said first and second optical elements are tilted to cause a crossing or of the projection of said third optical axis (8045.3) into said plane and said first optical axis, second optical element, wherein said second optical element is reflective; and a third optical axis (8045.3) between said second optical element and said second optical component (8021, 8121, 8421), wherein the directional vector (8046.1) of the first optical axis (8045.1) and the directional vector (8046.2) of the second optical axis (8045.2) define a plane and wherein said first and second optical elements are tilted to cause a crossing of the projection of said third optical axis (8045.3) into said plane and said first optical axis . 2. The illumination system according to claim 1, further comprising:a first beam path along said first optical axis) ; a second beam path along said second optical axis) ; and a third beam path along said third optical axis, wherein said first and said second optical elements are tilted to cause a crossing of said third beam path and said first beam path. 3. The illumination system according to claim 1,wherein said primary light source produces a beam cone oriented in a first direction, wherein said image plane has a surface normal that is substantially perpendicular to said first direction, wherein said first optical component comprises at least one first mirror, and wherein said second optical component comprises at least one second mirror, said illumination system having a beam path between said primary light source and said image plane that is bent with said at least one first mirror and said at least one second mirror. 4. The illumination system according to claim 1, further comprising:a straight line from a center of said field in said image plane to a center of said exit pupil; and an angle between said straight line and a surface normal of said image plane, wherein said angle is between 3° and 10°. 5. The illumination system according to claim 1, wherein each of a plurality of rays intersects said first and second optical components with incidence angles of greater than 65° or less than 25°. 6. The illumination system according to claim 1, wherein said second optical component comprises an even number of normal incidence mirrors having incidence angles of loss less than 25°. 7. The illumination system according to claim 1,wherein said plurality of first raster elements deflect a plurality of incoming ray bundles to produce a plurality of deflected ray bundles with first deflection angles, and wherein at least two of said first deflection angles are different form one another. 8. The illumination system according to claim 1,wherein each of said plurality of first raster elements corresponds to one of said plurality of second raster elements, wherein each of said plurality of first raster elements deflects one of said plurality of incoming ray bundles to said corresponding one of said plurality of second raster elements, and wherein said plurality of second raster elements and said second optical component image said corresponding first raster elements into said image plane. 9. The illumination system according to claim 8, wherein said plurality of second raster elements are concave mirrors. 10. The illumination system according to claim 1,wherein said field is a segment of an annulus, wherein said plurality of first raster elements are rectangular, and wherein said second optical component comprises a first field mirror for shaping said field to said segment of said annulus. 11. The illumination system according to claim 10,wherein said first field mirror has negative optical power, and wherein said second optical component comprises a second field mirror with positive optical power. 12. The illumination system according to claim 10,wherein said second optical component comprises a third field mirror, and wherein said third field mirror has negative optical power. 13. The illumination system according to claim 12, wherein said third field mirror, has positive optical power. 14. A projection exposure apparatus for microlithography comprising:the illumination system of claim 1; a reticle being located at said image plane; a light-sensitive object on a support system; and a projection objective to image said reticle onto said light-sensitive object. 15. The projection exposure apparatus of claim 14, further comprising:an illumination beam path between said primary light source and said reticle that passes through said first optical component and said second optical component; and a projection beam path between said reticle and said light-sensitive object that passes through said projection objective, wherein said illumination beam path and said projection beam path do not cross. 16. The projection exposure apparatus of claim 14, further comprising:a projection beam path between said reticle and a first imaging element of said projection objective, wherein said reticle is reflective, and wherein said projection beam path is tilted towards an optical axis of said projection objective.
	description	This invention relates to methods and apparatuses for producing very high localized energies. It relates particularly, although not exclusively, to generating localized energies high enough to cause nuclear fusion. The development of fusion power has been an area of massive investment of time and money for many years. This investment has been largely centered on developing a large scale fusion reactor, at great cost. However, there are other theories that predict much simpler and cheaper mechanisms for creating fusion. Of interest here is the umbrella concept “inertial confinement fusion”, which uses mechanical forces (such as shock waves) to concentrate and focus energy into very small areas. Much of the confidence in the potential in alternative methods of inertial confinement fusion comes from observations of a phenomenon called sonoluminescence. This occurs when a liquid containing appropriately sized bubbles is driven with a particular frequency of ultrasound. The pressure wave causes bubbles to expand and then collapse very violently; a process usually referred to as inertial cavitation. The rapid collapse of the bubble leads to non-equilibrium compression that causes the contents to heat up to an extent that they emit light [Gaitan, D. F., Crum, L. A., Church, C. C., and Roy, R. A., Journal of the Acoustical Society of America, 91(6), 3166-3183 June (1992)]. There have been various efforts to intensify this process and one group has claimed to observe fusion [Taleyarkhan, R. P., West, C. D., Cho, J. S., Lahey, R. T., Nigmatulin, R. I., and Block, R. C., Science, 295(5561), 1868-1873 March (2002)]. However, the observed results have not yet been validated or replicated, in spite substantial effort [Shapira, D. and Saltmarsh, M., Physical Review Letters, 89(10), 104302 September (2002)]. This is not the only proposed mechanism that has led to luminescence from a collapsing bubble; however it is the most documented. Luminescence has also been observed from a bubble collapsed by a strong shock wave [Bourne, N. K. and Field, J. E., Philosophical Transactions of the Royal Society of London Series A-Mathematical Physical and Engineering Sciences, 357(1751), 295-311 February (1999)]. It is this second mechanism, i.e. the collapse of a bubble using a shockwave, to which this invention relates. It has been proposed in U.S. Pat. No. 7,445,319 to fire spherical drops of water moving at very high speed (˜1 km/s) into a rigid target to generate an intense shock wave. This shock wave can be used to collapse bubbles that have been nucleated and subsequently have expanded inside the droplet. It is inside the collapsed bubble that the above-mentioned patent expects fusion to take place. The mechanism of shockwave generation by high-speed droplet impact on a surface has been studied experimentally and numerically before and is well-documented (including work by one of the present patent inventors, [Haller, K. K., Ventikos, Y., Poulikakos, D., and Monkewitz, P., Journal of Applied Physics, 92(5), 2821-2828 September (2002)].) The present invention differs from U.S. Pat. No. 7,445,319, even though the fundamental physical mechanisms are similar, because it does not utilize a high speed droplet impact. The present invention aims to provide alternatives to the aforementioned techniques and may also have other applications. When viewed from a first aspect the invention provides a method of producing a localized concentration of energy comprising creating at least one shockwave propagating through a non-gaseous medium so as to be incident upon a pocket of gas within the medium wherein the pocket of gas is attached to a surface comprising a depression shaped so as partially to receive the gas pocket. The invention also extends to an apparatus for producing a localized concentration of energy comprising: a non-gaseous medium having therein a pocket of gas, wherein the pocket of gas is attached to a surface comprising a depression shaped so as partially to receive the gas pocket; and means for creating at least one shockwave propagating through said medium so as to be incident upon said pocket of gas. It is known to those skilled in the art that in general an interaction between a shockwave in a non-gaseous medium and a gas bubble in that medium can generate a high speed transverse jet of the non-gaseous medium that moves across the bubble, impacting the leeward bubble wall. This is one of the mechanisms which gives rise to the well-known problem of cavitation damage of surfaces when shockwaves are generated in the presence of micro-bubbles formed on the surface. In accordance with the present invention however, the inventors have appreciated that this naturally-occurring phenomenon can be appropriately adapted and harnessed to produce very high localized energy concentration which can be used, e.g. to create nuclear fusion as will be explained later. In embodiments of the invention, the phenomenon of a jet being formed during bubble collapse is controlled to promote formation of this transverse jet and enhancement of its speed, and the surface depression is designed to receive the transverse jet impact whilst trapping a small volume of the original gas pocket between the impacting jet and itself. This leads to various physical mechanisms that cause very substantial energy focusing in this volume of trapped gas. More particularly by designing the surface depression explicitly to receive the high speed jetting formed by the interaction of the incident shockwave with the gas pocket, then as the incident shock interacts with the surface of the gas pocket it forms a transmitted shock and a reflected rarefaction. If the contact is the correct shape, i.e. curving away from the incident shockwave, then this rarefaction will act to focus the flow to a point. This then results in the formation of the high speed transverse jet which can, purely as an example, reach over 2000 ms−1 for a 1 GPa shockwave. When this jet strikes the surface of the depression a strong shockwave is generated within by the force of the impact in a manner analogous to the high speed droplet impact situation described in U.S. Pat. No. 7,445,319. The shape of the surface in the depression opposite where the shockwave is incident could be flat so that the jet contacts the surface at a point. In a preferred set of embodiments however the surface depression and gas pocket are arranged such that the initial contact region is a curve which forms a closed loop—e.g. a ring. This makes it possible to trap a portion of the gas pocket between the jet tip and the edge of the depression. To achieve this, a section of the target surface has a curvature greater than that of the tip of the jet and this part of the surface is placed such that the jet impacts into it. Upon impacting, a toroidal shockwave is generated whose inner edge propagates towards the base of the depression and towards the trapped portion of gas. Combining this with the ‘piston’ effect of the gas halting the motion of the impacting jet yields extremely strong heating of the trapped gas. For example, for a given strength of shockwave the peak temperatures can be increased by over an order of magnitude by these arrangements as compared to a bubble attached to a planar surface. The depression could take a number of shapes. In a set of embodiments it tapers in cross-section away from the mouth. The depression could resemble a dish—e.g. being continuously curved. The surface need not be continuously curved however. In a set of embodiments the surface more closely resembles a crack rather than a dish shape. This could be defined by stating that the depth is greater than the width or by the presence of a region of curvature at the tip of the crack greater than the curvature (or maximum curvature) of the portion of the gas pocket received in it. In one set of embodiments the surface comprises a plurality of discrete portions, e.g. with a gradient discontinuity between them. The portions could themselves be partial ellipses, parabolas, and so on, but equally could be straight. A particular set of embodiments of surfaces made from discrete portions could be described as piecewise polynomial. As above, the bubble could be small in comparison to the dimensions of the crack such that it is attached only to one side or it could be of similar size so as to close it off. It is not essential that there is only one depression which partly receives the gas pocket; a gas pocket could extend across, and be partially received by, a plurality of depressions. In a particular set of embodiments the high speed jet is arranged to strike an area of surface that has been prepared with a particular roughness or microscopic shape such that many small portions of the pocket of gas are trapped between the jet tip and the target surface, i.e. the many small depressions are small in comparison to the size of the transverse jet tip. When viewed from a second aspect the invention provides a method of producing a localized concentration of energy comprising creating at least one shockwave propagating through a non-gaseous medium so as to be incident upon a pocket of gas suspended within the medium, wherein the pocket of gas is spaced from a surface shaped so as at least partially to reflect said shockwave in such a way as to direct it onto said gas pocket. The invention also extends to an apparatus for producing a localized concentration of energy comprising: a non-gaseous medium having therein a pocket of gas, wherein the pocket of gas is spaced from a surface; and means for creating at least one shockwave propagating through said medium so as to be incident upon said pocket of gas,wherein said surface is shaped so as at least partially to reflect said shockwave in such a way as to direct it onto said gas pocket. Thus it will be seen that in accordance with this aspect of the invention the surface can be used to increase energy concentration in the gas by reflecting and/or focusing the shockwave onto it. The arrangement could be such that the shockwave impacts the surface before the gas pocket, but preferably the incident shock interacts with the gas pocket, causing it to collapse, and subsequently the incident shock and/or any of the numerous shocks generated by the cavity collapse (the existence of which will be known to those skilled in the art) interact with the target surface in such a way that they are reflected back towards the remains of the gas pocket, causing it to be collapsed a second or further times and thus enhancing the heating obtained. There are many shapes and configurations which the surface might take. The configuration of the surface will determine how the shockwave interacts with it and the shape of the surface relative to the placement and shape of the gas pocket will determine how the shockwave interacts with the gas pocket, which it may do so before, simultaneously or after it interacts with the surface. This in turn affects the dynamics of the collapse and hence can increase temperatures and densities that are achievable through compression of the gas by the shockwave. In some embodiments, the peak temperatures can be increased by over an order of magnitude, when compared with a similar shock interacting with an isolated bubble. The surface could be planar, but preferably it is non-planar—e.g. curved. The surface need not be continuously curved. For example, in one set of embodiments the concave surface comprises a plurality of discrete portions, e.g. with a gradient discontinuity between them. The portions could themselves be partial ellipses, parabolas, and so on, but equally could be straight. A particular set of embodiments of surfaces made from discrete portions could be described as piecewise polynomial. Preferably the surface is shaped in such a way that the reflected shocks are focused on the gas pocket. The spacing and geometry of the surface will determine (among other factors such as the speed of the shockwave through the medium) what interaction there is between the originally-incident and reflected shockwaves and the interaction of both of these with the gas pocket. In a preferred set of embodiments the surface is shaped to focus the reflected shock to a point. Thus, for example, in the case of an essentially planar incident shockwave the surface could be parabolic or elliptic with the gas pocket at its focal point. However other shapes could be used to account for curvature in the wavefronts of the shockwave. It will be appreciated that the considerations are somewhat analogous to those in the focusing of radio waves and other electromagnetic waves. The optimum spacing between the gas pocket and the surface will depend inter alia on the relative shapes of the reflecting surface and the gas pocket. In a particular set of embodiments of the invention the gas pocket is placed no more than three times the maximum radius of curvature of the closest section of surface away from the surface. In a particular example, the edge of the gas pocket closest to the surface is spaced from it by a distance of less than five times the dimension of the widest part of the bubble gas pocket, preferably less than three times the widest dimension, e.g. less than twice the widest dimension. In a set of embodiments of the second aspect of the invention the shockwave is first incident upon the pocket of gas, compressing the volume of the pocket, and then the shockwave is reflected from the reflecting surface and is incident again on the pocket of gas, compressing it further. The spacing could be arranged so that the reflected shockwave is incident upon the pocket of gas when the volume of the pocket is still contracting from the initial shockwave, when it has reached a point of minimum volume from being compressed by the initial shockwave, or while the volume of the pocket is expanding after compression by the initial shockwave. The collapse of the gas pocket by the incident shockwave produces several strong shockwaves as a result. In another set of embodiments in which the gas pocket is spaced from the surface, the target surface is optimized to reflect these generated shocks back towards the collapsed bubble. For example, the impact of the high speed transverse jet (described in the context of the first aspect of the invention) generates a shockwave that moves outwards from the point of impact dissipating as it travels. The surface could be shaped to conform to this shockwave and reflect it back towards the bubble, which would cause it to become a converging shockwave and to focus its energy back into the collapsed gas pocket. When viewed from a third aspect the invention provides a method of producing a localized concentration of energy comprising creating at least one shockwave propagating through a non-gaseous medium so as to be incident upon a pocket of gas within the medium wherein the pocket of gas is attached to a non-planar surface shaped to concentrate the intensity of the shockwave which is incident upon the pocket of gas. The invention also extends to an apparatus for producing a localized concentration of energy comprising: a non-gaseous medium having therein a pocket of gas, wherein the pocket of gas is attached to a surface; and means for creating at least one shockwave propagating through said medium so as to be incident upon said pocket of gas,wherein said surface is shaped to concentrate the intensity of the shockwave which is incident upon the pocket of gas. In accordance with this aspect of the invention the geometry of the surface can be used to control the reflections of the incident shockwave before it reaches the bubble such that the collapse of the bubble is intensified, for example such that the initially incident shockwave is more conforming to the bubble surface. As before, there are many shapes and configurations which the surface might take to provide suitable regions for attaching the pocket of gas to the surface and the configuration of the surface will determine how the shockwave interacts with it and the shape of the surface relative to the placement and shape of the bubble will determine how the shockwave interacts with the gas pocket, which it may do so before, simultaneously or after it interacts with the surface. This in turn affects the dynamics of the collapse and hence can increase temperatures and densities that are achievable through compression of the gas by the shockwave. In some embodiments, the peak temperatures can be increased by over an order of magnitude, when compared with a similar shock interacting with an isolated bubble. In a preferred set of embodiments, the surface is concave which has the effect of focusing the energy and intensifying the initial formation of the shockwave. In some non-limiting examples, the surface could have an ellipsoid or paraboloid shape. The surface need not be continuously curved. For example, in one set of embodiments the concave surface comprises a plurality of discrete portions, e.g. with a gradient discontinuity between them. The portions could themselves be partial ellipses, parabolas, and so on, but equally could be straight. A particular set of embodiments of surfaces made from discrete portions could be described as piecewise polynomial. The gas pocket could be attached to any part of the surface but is preferably attached to the bottom or center point. The dimensions of the gas pocket could be small in comparison to the width or depth of the concave surface—e.g. so as to be attached only to one side of the concavity, or it could of similar size—e.g. so as to attach to the surface in an annulus around the base of the depression. The concavity could resemble a bowl—e.g. being continuously curved. In a set of embodiments however the surface more closely resembles a crack rather than a bowl shape. This could be defined by stating that the depth is greater than the width or by the presence of a region of curvature at the tip of the crack greater than the curvature (or maximum curvature) of the bubble. As above, the gas pocket could be small in comparison to the dimensions of the crack such that it is attached only to one side or it could be of similar size so as to close it off. In one set of embodiments the shape of the surface is configured to trigger a transition from regular to Mach reflection of the incident shockwave, thus altering the shape of the shockwave that then reaches the gas pocket. In another set of embodiments the shape is controlled such that the reflections overlap and interact with one another, again acting to change the shape of the shockwave or interacting system of shockwaves when it contacts the gas pocket. By carefully controlling these factors an intensification of the peak temperatures can be obtained over the case where the surface is planar. In a particular set of embodiments the surface might have a plurality of concave portions. Additionally or alternatively the or each concave portion may have a plurality of gas pockets attached thereto. The aspects of the invention set out above are not mutually exclusive. Thus, for example, the surface might comprise a depression shaped so as partially to receive the gas pocket, thereby exploiting the jetting phenomenon and away from the depression the surface could be shaped to concentrate the intensity of the shockwave which is incident upon the pocket of gas. This could allow the properties of the jet—e.g. its speed—to be controlled to maximize the concentration of energy. Such combinations could be beneficial in providing the desired behavior of the shockwave within the depression in other ways. In any embodiments where the bubble is attached to the surface this could be over a single contact patch or, by appropriate design of the surface texture, at a plurality of discrete contact points/regions. As well as creating a particular shape for the target surface, in one set of embodiments the micro-structure or wetting characteristics of the surface can be optimized to control the speed of the shockwave near the surface, e.g. to increase the speed near the surface, thereby changing the shockwave's shape and hence the nature of the interaction between the shockwave and the gas pocket. As previously discussed, an appropriately shaped gas pocket can be used in this set of embodiments to match the shape of the shockwave to the shape of the gas pocket, thereby allowing the dynamics of the gas pocket's collapse to be controlled in order to maximize the temperature and density achieved on compression. The surface to which the gas pocket is attached is not limited to having a single depression (e.g. to exploit the jetting phenomenon described above) and thus in one set of embodiments, the target surface comprises a plurality of depressions. Each individual depression may be shaped to encourage energy focusing by causing the shockwave to converge on one or more bubbles. That is to say, the surface may be prepared with more than one site where the shockwave will interact with a shaped section of surface containing either an attached or nearby gas pocket, thus providing infinite scalability. An advantage of employing a plurality of depressions is that a greater proportion of the shockwave energy may be harnessed. For example, a large pocket of gas could be spread across a plurality of depressions, or smaller individual volumes of gas could be located within each individual depression. For the former case, depending upon the number of such depressions, the size of an individual depression will be significantly smaller than the size of the pocket of gas. For a larger volume of medium able to accommodate a large number of depressions, this points towards simplicity of manufacturing for an energy-producing fusion apparatus. Such pluralities of depressions could be formed in a number of ways. For example, a solid surface could be drilled or otherwise machined to produce depressions or pits. In one set of embodiments, however, the depressions are created by the surface texture of the surface. For example, the surface could be blasted with an abrasive material, etched or otherwise treated to give a desired degree of surface roughness which provides, at the microscopic level, a large number of pits or depressions. The surface could be constructed from a solid, as implied in many of the embodiments outlined above, but it could equally well be a liquid. In the case of a solid, any of the proposed materials in U.S. Pat. No. 7,445,319 could be suitable. In the case of a liquid the required surface shape could be achieved in a number of ways. For example, the surface of a volume of liquid could be excited with a suitable vibration (e.g. using ultrasound or another method) to generate a wave having the desired shape. Alternatively the desired shape could be achieved through the contact angle between a liquid and a solid surface with appropriately matched wetting properties. Of course, this latter example shows that the surface could comprise a combination of solid and liquid. Where the target surface comprises a liquid it will generally be denser than the non-gaseous medium. Of course, as has already been alluded to, some embodiments may comprise a plurality of pockets of gas within the medium. These pockets of gas may all be attached to the surface, may all be positioned near the target surface, or there may be a mixture. The aspects of the invention described herein provide alternatives to the technique described in U.S. Pat. No. 7,445,319 which may carry their own benefits. The present inventors have recognized that there are significant challenges in the nucleation of a bubble in a droplet fired at high speed into a target, as suggested in U.S. Pat. No. 7,445,319. The timing will have to be very precise for the bubble to be at a favorable moment of its expand-collapse cycle when the shock strikes. The method by which the high speed droplets are created as required by U.S. Pat. No. 7,445,319 and detailed in U.S. Pat. No. 7,380,918 is also complex and expensive. By contrast such complexity and associated expense can be avoided in accordance with at least preferred embodiments of the present invention. Thus, the various aspects of the present invention provide much simpler techniques for compressing a volume of gas entrapped in a gas pocket as a shockwave simply needs to be created within the medium in which the gas pocket is formed. Moreover the theoretical and computer modeling of both techniques carried out by the present inventors suggests that the method in accordance with the present invention can give pressure and temperature intensities which are an order of magnitude greater than the method detailed in U.S. Pat. No. 7,445,319. The more static framework that can be employed in accordance with the invention to compress a gas pocket using a shockwave allows much greater control (compared to a free bubble) over how the shockwave strikes and interacts with the pocket. The initial shockwave could be created in a number of different ways by a number of different devices depending on the pressure required. For example, an explosive plane wave generator could be used to provide high intensity shockwaves. In preferred embodiments such an explosive device can create a shockwave pressure of between 0.1 GPa and 50 GPa. The Applicant notes that the scope of the present invention does not extend to the shockwave comprising an ultrasound shockwave and thus being created by a device that generates ultrasound shockwaves, e.g. a lithotripsy device. Thus the scope of the present invention does not include the pocket of gas being collapsed through the process of sonoluminescence. The term “gas” as used herein should be understood generically and thus not as limited to pure atomic or molecular gases but also to include vapors, suspensions or micro-suspensions of liquids or solids in a gas or any mixture of these. The “non-gaseous medium” should be understood generically and thus could include liquids, non-Newtonian liquids, semi-solid gels, materials that are ostensibly solid until the passage of the shockwave changes their properties, suspensions or micro-suspensions and colloids. Examples include but are not limited to water, oils, solvents such as acetone, hydrogels and organogels. It should be understood that the liquid will have a greater density than the gas in the pocket. The non-gaseous medium could be any suitable substance for creating a shockwave in, such as a liquid or a semi-solid gel. The gas pocket can then be provided by a bubble suspended within the liquid or gel medium in the required location, either near to or attached to the target surface. Using a gel or a viscous liquid has the advantage that it is easier to control the location of the bubble within the medium, compared to a lower viscosity liquid in which the buoyancy of the bubble may overcome the viscosity of the liquid. As will be appreciated, being able to control the position of the bubble is particularly important in the set of embodiments in which the bubble is located near to the target surface rather than being attached to it. In the set of embodiments in which the bubble is attached to the target surface, the nature of the target surface, e.g. the material, or any indentations or depressions in it, could help to adhere the bubble to the target surface. Using a gel or viscous liquid also has the advantage that it will be easier to control the detailed shape of the bubble. Due to the more static nature of the setup of the device when compared to U.S. Pat. No. 7,445,319, much more control can be exercised over the shape of the bubble. In the set of embodiments where the bubble is attached to the surface, it may be spherical in shape apart from where it is truncated by its attachment to the target surface, for example it could be hemi-spherical. In some embodiments the bubble joins the target surface normal to it whereas in others a different angle is required. In a superset of these embodiments the bubble itself is not spherical in nature but takes a different shape that includes but is not limited to ellipsoids, cardioids, variations from spherical, cardioid or ellipsoid shape in which the surface has perturbations that could be described, for example, by a Fourier series and bubbles with other distinct shapes such as cones or trapezoids. It will be apparent that, for example, a conical bubble would be difficult to achieve in a true liquid medium but that in the case of a gel medium this set of embodiments becomes possible and could be advantageous. In the aspect of the invention in which the bubble is not attached to the surface, it is free from the constraints of the surface and is therefore able to take any shape required, such as ellipsoids, etc. In a set of such embodiments the shape of the bubble and the shape of the target surface can be appropriately matched, e.g. if the depression is hemispherical, the bubble would be spherical. The gas pocket itself must be formed in some manner. In a particular set of embodiments it is nucleated using a system similar to that described in U.S. Pat. No. 7,445,319, where a laser is used in conjunction with nano-particles in the liquid to nucleate a bubble. In a different set of embodiments a bubble could be nucleated using an unstable emulsion of different liquids. In another set the bubble is nucleated using an appropriately targeted pressure wave designed to induce cavitation in the liquid. In the set of embodiments where the gas pocket is attached to the wall, a specifically controlled volume of gas could be pumped in through a passage in the target surface in order to expand a bubble on the surface. This set of embodiments has the advantage of great control over the contents and size of the gas pocket generated. In the set of embodiments where the liquid medium is a gel the gas pocket can be pre-manufactured by punching or otherwise cutting out or molding the correct shape from the gel block to be used. In another set of embodiments the gas pocket is formed with the use of a pre-manufactured membrane that defines the boundary between the gas pocket and the medium and hence also defines the gas pocket's shape. The use of a thin membrane in this manner allows a decoupling of the liquid and gas materials, allowing any choice of combination of compositions to be made. It also allows the shape of the gas pocket to be controlled with a precision not available to other methods. The membrane could be formed from any suitable material, e.g. glass e.g. plastic e.g. rubber. Having a prefabricated membrane allows a liquid medium to be used more easily as the volume of gas is trapped against the target surface and therefore cannot float away or be otherwise disturbed. In a particular set of embodiments the membrane is frangible and is arranged to break upon impact from the shockwave such that it has no influence on the resulting dynamics. In one set of embodiments the prefabricated membrane includes a line or region of weakness, so that upon impact from the shockwave it breaks along the line or in the region of weakness. The line or region of weakness can be arranged so that the position of the breach has an influence on the ensuing flow patterns, for example this could help control the formation and dynamics of the transverse jetting. In another set of embodiments the membrane is designed to deform with the collapsing cavity. In the set of embodiments where the gas pocket is not attached to the surface, the concept of a gas pocket contained within a membrane is also useful. In a particular set of embodiments the gas pockets near the surface take the form of small glass beads filled with an appropriate gas. This has the same advantage of giving control over the shape of the gas pocket. In a preferred set of embodiments, the methods described herein are employed to generate nuclear fusion reactions. The fuel for the reaction could be provided by the gas in the pocket, the medium, or the fuel could be provided by the target surface itself. Any of the fuels mentioned in U.S. Pat. No. 7,445,319 is suitable for use in the present invention. The device in the present invention is not as restricted, regarding size, as U.S. Pat. No. 7,445,319 where the size of the droplet constrains the maximum bubble size. It may be advantageous to have a larger apparatus where a larger volume of gas is heated. The volume of gas in each pocket may be chosen depending on the circumstances but in one set of preferred embodiments it is between 5×10−11 and 5×10−3 liters. The fusion reactions which can be obtained in accordance with certain embodiments of the invention could be used for net energy production (the long term research aim in this field), but the inventors have appreciated that even if the efficiency of the fusion is below that required for net energy production, the reliable fusion which is obtainable in accordance with embodiments of the invention is advantageous for example in the production of tritium which can be used as fuel in other fusion projects and is very expensive to produce using currently existing technologies. The fusion can also be beneficial in giving a fast and safe neutron source which has many possible applications that will be apparent to those skilled in the art. Moreover, it is not essential in accordance with the invention to produce fusion at all. FIGS. 1a and 1b show schematically arrangements in accordance with two respective embodiments of one aspect of the invention. In each case a solid surface 6, for example made from high strength steel, is placed inside a non-gaseous medium 8 in the form of a hydrogel, for example a mixture of water and gelatine. Defined in the hydrogel medium 8 is a gas pocket 2 filled with vaporous fuel suitable for taking part in a nuclear fusion reaction. In both cases the gas pocket 2 is attached to the target surface 6 inside a concave depression. In the case of the first embodiment in FIG. 1a, the depression 4 is parabolic and relatively large such that only one side of the gas pocket 2 is attached to the surface 6. The size of the apparatus is flexible but a typical dimension of this diagram could be between 0.1 and 1×10−5 m. In the case of the second embodiment in FIG. 1b, the gas pocket 2 is received in a much smaller, V-shaped tapering depression 5 which could be machined or formed as the result of a naturally occurring crack in the surface 6. In operation a shockwave 10 is created from an explosion, for instance with a pressure of 5 GPa, within the gel medium 8. This is represented in both FIGS. 1a and 1b as a line propagating in the direction of the arrow towards the pocket of gas 2. First the shockwave 10 strikes the upper parts of the target surface 6, causing the shockwave 10 to change shape as it advances towards the pocket of gas 2. In this manner the shape of the shockwave 10 that advances into the pocket of gas 2 can be explicitly controlled by shaping the surface 6 accordingly. The shaped shockwave 10 will then strike the pocket of gas 2, compressing it against the target surface 6 as the shockwave 10 propagates through the gas pocket 2. Reflections of the shockwave 10 from the surface 6 after it has propagated through the pocket 2 travel back through the pocket, reinforcing those propagating from the original direction and further compressing the gas pocket. The compression of the gaseous fuel inside the pocket causes intense local heating which can be sufficient to generate a nuclear fusion reaction. FIGS. 2a, 2b and 2c show three successive stages of a shockwave interacting with a pocket of gas 12 spaced from a surface 16 in accordance with another aspect of the invention. In this embodiment the pocket of gas 12 is immobilized in the gel 18 in a concave depression 14 in the surface 16. FIG. 2a shows a shockwave 20 propagating through the gel medium 18, in the direction of the arrow, approaching the gas pocket 12. FIG. 2b shows the shockwave 20 as it is incident for the first time upon the gas pocket 12. The shockwave acts on the volume of gas 12 to compress it, in a similar manner to the embodiments shown in FIGS. 1a and 1 b. At the same time the shockwave 20 is reflected from the upper sides of the concave depression 14 in the surface 16. FIG. 2c shows the third snapshot in the sequence, by which time the shockwave 20 has passed through the volume of gas 12, compressing it significantly. Also by this time, the shockwave 20 has been reflected from the surface 16 and is travelling back towards the pocket of gas 12 in the direction indicated by the arrow. The reflected shockwave 20 now has a shape resembling the shape of the concave depression 14 and is focused towards the pocket of gas 12 upon which it is incident for a second time, compressing it further and therefore further increasing the temperature and pressure within it. FIGS. 3a and 3b show, in accordance with yet another aspect of the invention, two successive stages of a shockwave interaction with a pocket of gas 22 attached to a surface 26 so as to cover and fill a V-shaped tapering depression 24. Although the tapering depression 24 is of a similar shape to that in FIG. 1b, relative to the size of the tapering depression, the volume of gas in the pocket 22 is much greater than it is in FIG. 1b. For example the width of the bubble could be of the order of 1 cm. FIG. 3a shows the shockwave 30 propagating through the medium 28 (which could be the same material as in previous embodiments or a different material could be used), in the direction of the arrow, towards the gas pocket 22. FIG. 3b shows a later stage in the interaction, after the shockwave 30 has struck the gas pocket 22. The portion 27 of the shockwave 30 that has struck the edge of the pocket of gas 22 is reflected as a result of the large change in density from the medium 28 to the gas 22. This reflected portion 27 forms a rarefaction fan which propagates away from the gas pocket 22 and therefore creates a low pressure region between the reflected portion 27 and the gas pocket 22. The medium 28 flows into this low pressure region as a jet 29 which then traverses the gas pocket 22, trapping a fraction of the gas therein between the tip of the jet 29 and the tapering depression 24 in the surface 26, thereby causing compression and heating of the gas in the manner previously described. FIG. 1b shows a further configuration which is also suitable as an embodiment of this aspect of the invention. FIG. 4 shows a further embodiment of the previous aspect of the invention in which a pocket of gas 32 is attached to a target surface 36 in a tapering depression 34. This embodiment is different from those previously described in that the pocket of gas 32 is separated from the medium 38 by a prefabricated membrane 33. The prefabricated membrane 33 is frangible i.e. it is designed to break on the impact of the shockwave 40. Once the prefabricated membrane 33 has been broken by the impact of the shockwave 40, the shockwave 40 continues to propagate into the depression 34 compressing the pocket of gas 32 in the same manner as for the previous embodiments. FIG. 5 is a variant of the embodiment shown in FIG. 3a. In this embodiment there are multiple smaller depressions 42 at the bottom on a large depression 44. The pocket of gas 46 is partially received both by the large depression 44 and by the multiple smaller depressions 42. In operation of this embodiment the jet formed when the shockwave (not shown) hits the pocket of gas 46 will highly compress multiple small volumes of the gas by trapping them in the small depressions 42, in a similar manner to that described above with reference to FIGS. 3a and 3b. Although specific examples have been given, it will be appreciated that there are a large number of parameters that influence the actual results achieved, for example liquid or gel medium density, ambient pressure and temperature, composition of the gas and of the liquid or gel, impact angle of the shockwave, target surface shape and micro-structure of the target surface. In each of the embodiments described above, the diagrams shown are a vertical cross-section through a three-dimensional volume of gas and target surface and hence they depict embodiments that are rotationally symmetric. However, this is not essential to the invention. In particular the surface could comprise discrete surface portions in the rotational direction either instead of, or as well as in the vertical cross-section shown. In the latter case the target surface would be multi-facetted. Each facet could give rise to separate but converging shockwaves. In all of the embodiments described, the apparatus can be used by creating a shockwave in the medium which is incident upon a volume of gas containing deuterated water vapor. In numerical modeling of the experiment, the techniques described herein give rise to a peak pressure of ˜20 GPa which is sufficient to cause temperatures inside the collapsed volume of gas in excess of 1×106 Kelvin which can be sufficient for a nuclear fusion reaction of the deuterium atoms. In some non-limiting examples the resulting neutrons could be used in other processes, or could be absorbed by a neutron absorber for conversion of the kinetic energy of the neutrons to thermal energy and thus conventional thermodynamic energy generation.
	summary
054250641	description	The present invention is practiced in the context of a nuclear reactor 100 as shown in FIG. 1. A reactor vessel 102 houses fuel bundles 104 containing fissionable material. The reactor core 103 is formed by the fuel bundles 104 which are ordered and supported in the vessel by a top guide 106. A core plate 108 provides lateral support for control rods 110. Control rods 110 can be inserted into and withdrawn from spaces between the fuel bundles 104 by means of control rod drives 112. Monitoring of the core is effected by a reciprocating probe assembly 132. In reactor 100 water is the coolant. The coolant flow 900 in the core 103 and the steam production in reactor 100 take place in the following manner. Water 910 in liquid form enters the vessel through a coolant inlet 116 and enters fuel bundle inlet 118. As the liquid water flows into the fuel bundles 104 it absorbs thermal energy and rises in temperature until a mixture 902 of steam and water is produced. Because of the space occupied by steam this mixture is less dense than saturated or sub-cooled water 912 arriving beneath the core. The less dense mixture of water and steam rises due to buoyancy forces and is continuously replaced by non-voided coolant 912 entering from beneath the core. As the steam and water mixture 902 leaves the core 103 it rises in a chimney 120 to steam separators 122 where water 904 is separated by centrifugal forces and added to the return flow via a downcomer annulus 124. The wet steam 906 leaves the top of separators 122 and passes into a wet steam chamber 126 below a steam dryer assembly 128. The moisture is removed by steam dryer assembly 128 and returned through a series of drains to the downcomer annulus 124. The dried steam 908 exits through a steam nozzle 130 to drive a turbine which powers an electricity generator. Through coolant inlet 116 water is admitted into a feedwater sparger to cool the returning coolant and aid circulation. A fuel bundle inlet 118 contains a turbine flow meter according to the present invention. A system 200 according to the invention comprises a core coolant flow 109 which causes rotation of a turbine assembly 204 to produce modulations in a radiation field 206 at a radiation detector 208, which transforms the radiation field modulation into an electrical current or voltage modulation as shown in FIG. 2. The readings from radiation detector 208 are transferred through an electrical connection 210 to the converter 212, which is a frequency analyzer and converts the detector signal to a frequency profile and determines the peak value of this profile. The peak value is then transferred through an electrical connection 214 to a computer 216 which uses it to calculate the coolant flow rate. In an alternative embodiment the flow rate value can be communicated to the reactor operator who can then consult a calibration table to determine the coolant flow rate. A representative fuel bundle inlet 118 is depicted in FIG. 3. Coolant enters the fuel bundle inlet 118 and rises inside the fuel bundle 104 as it heats. The rising coolant sets a turbine rotor 304 into rotation about a turbine shaft 306. Turbine rotor 304 is substantially composed of a ferritic chrome steel. The rotor is coupled to the shaft 306 via a rotor assembly comprising graphite sleeve bearings arranged on an Inconel spindle. A wafer 308 composed of cadmium 113 is embedded in a blade 310 of turbine rotor 304. Cadmium wafer 308 has a diameter of 2 centimeters (cm) and a thickness of 1 millimeter (mm). During normal operation of the reactor free neutrons are produced and move through the core. When neutrons strike cadmium wafer 308, some are captured by the cadmium nuclei with production of activated (radioactive) cadmium in the reaction .sup.113 Cd(n,g).sup.114 Cd. Neutron capture by Cd-113 results in the immediate emission of gamma rays. The activation of cadmium wafer 308 causes formation of a gamma field 206 which can be detected by radiation detector 208. The detector is inside the reciprocating probe assembly 132 placed outside fuel bundle 104. The reciprocating probe assembly 132 comprises a semi-rigid cable 318 coupled to a reciprocating in-core probe 320 at the end of the cable situated inside the reactor core. For the purpose of signal detection a window 316 is formed in an outer wall 312 of fuel bundle 104 close to the reciprocating in-core probe assembly. The window is formed by removing or omitting the stainless steel cladding 314 over a small area (about 6 cm.sup.2) of outer wall 312 of fuel bundle 104. Because the radioactive material is arranged along only a portion of the circumference of the rotor, the gamma field 206 is temporally modulated as turbine rotor 304 rotates. Because field strength decreases at least as the inverse square of the distance, radiation detector 208 will receive a strong gamma pulse when the cadmium wafer 308 passes close by, wherein the field strength falls off rapidly as wafer 308 moves further away. At a constant rotation rate the spinning rotor 304 will produce a regular pattern of temporally modulated pulses, wherein the pulse frequency corresponds with the rotation rate of turbine rotor 304 and thus with the flow rate of the coolant. The apparatus according to the present invention responds to temporal variations in the gamma field 206. The coolant flow rate can thus be accurately determined despite variations in the average flux of particles at the detector, and can be accurately determined despite other sources of gamma radiation, such as delayed gamma rays from radioactive decay. The radiation detector 208 comprises an ionization chamber which detects current pulses. Gamma rays entering the ionization chamber of radiation detector 208 bring about a certain amount of ionization. Electrical pulses resulting from ionization are detected by detector 208 and provide a measure of the gamma rays entering the chamber of detector 208. Alternative configurations of rotor 304 are shown in the FIGS. 4A, 4B and 4C, showing more particularly representative rotor blades and alternatives to nuclear-active material 308. A small rotor 402 as shown in FIG. 4A fits a turbine with a throat diameter of 40 millimeters (mm) and is suitable for a coolant flow rate of 1 to 6.5 liters per second (l/s). The rotor is composed substantially of ferritic chrome steel. Nuclear-active material 404 is embedded in one of the blades 406 of rotor 402. Nuclear-active material 404 is a wafer of cobalt-59 that is activated (made radioactive) by the neutron field prevailing during operation according to the reaction .sup.59 Co(n,g).sup.60 Co after placement in the reactor inlet. Delayed gamma rays from the 5.27-year half-life cobalt-60 can be detected by radiation detector 208. As rotor 402 rotates, modulations in the gamma field emitted by the cobalt wafer are detected by detector 208. The detector signal is converted by converter 212 to a reciprocal time value from which computer 216 can determine the coolant flow rate. An alternative rotor 408 fits a turbine with a throat diameter of 59 mm and is suitable for a coolant flow rate in a range of 1.5 to 10 l/s, as shown in FIG. 4B. The rotor is composed substantially of ferritic chrome steel. The nuclear-active material 410 is a wafer comprising cobalt-59 which has not been preactivated before placement in the reactor inlet. The cobalt wafer is activated by the capture of neutrons generated by the normal operation of the reactor. After activation delayed gamma rays from the decay of the cobalt-60 can be detected by detector 208. As rotor 408 rotates, modulations in the gamma field emitted by the cobalt wafer after activation are detected by detector 208, enabling the coolant flow rate to be determined as described above. A large rotor 412 as shown in FIG. 4C fits a turbine throat diameter of 150 mm. Nuclear-active material 414 is a wafer comprising gadolinium. The gadolinium wafer has a high neutron capture cross section and absorbs sufficient neutrons to depress the local neutron field in the region of the turbine. As rotor 412 rotates, modulations in the neutron field are detected by a neutron-sensitive detector similar to detector 208, enabling the coolant flow rate to be determined as described above. FIG. 5A shows the disposition of elements inside reactor core 102 in a cross section along plane 5A of FIG. 1. Control cell 502 comprises fuel pins 504 ordered into fuel bundles 104 which are placed around control rods 110 as shown in FIG. 5B. A reciprocating in-core probe assembly 132 containing a radiation detector 208 is positioned outside fuel bundles 104, as shown in FIG. 5B. A channel wall 506 around each fuel bundle 104 defines a channel 508 through which flows coolant. Coolant flowing through the channel 508 envelops the fuel pins 504 and is therein heated by thermal neutrons generated during operation of the reactor. A method 600 according to the present invention comprises four steps 601-604 as shown in FIG. 6. Method 600 is applied in practice in the context of reactor 100. In the first step 601 a turbine assembly 204 is placed in the path of the flowing coolant of a nuclear reactor 100 so that the coolant flow 900 causes the rotor 304 of the turbine assembly 204 to rotate. Temporal variations in the radiation field corresponding to spatial variations in the emission of radioactive particles are then detected at 602. An oscillation speed is determined at 603 from the output signal of the detector. Finally, the coolant flow rate is determined at 604 from the rate of the temporal variations. An alternative method 700 according to the present invention comprises five steps 701-705 as depicted in FIG. 7. Nuclear-active material is preactivated at step 701 to emit delayed gamma rays before the rotor assembly containing the nuclear-active material is placed at 702 into the path of the flowing coolant of a nuclear reactor 100. When the flowing coolant 900 turns the rotor 304 of the turbine assembly 204, temporal variations in the gamma flux are detected at 703. An oscillation rate is determined at 704 from the detector output signal. Finally, the coolant flow rate is determined at 705 from the rate of the temporal variations. An alternative method 800 according to the present invention comprises five steps 801-805 as designated in FIG. 8. According to method 800, applied in practice in the context of reactor 100, a turbine assembly 204 comprising a rotor with nuclear-active material 404 is placed at 801 in the path of the flowing coolant of a nuclear reactor 100 so that the coolant flow 900 causes the rotor 304 of the turbine assembly 204 to rotate. According to method 800, a rotor with nuclear-active material 404 is used as shown in FIG. 4A. The nuclear-active material, cobalt-59, is activated in-situ at 802 by the neutrons produced in reactor core 103 during operation of the reactor. After activation the nuclear-active material emits delayed gamma rays. Temporal variations in the radiation flux emitted from the activated material can then be detected at 803, enabling the oscillation rate to be determined at 804 and the coolant flow rate to be calculated at 805. FIG. 9 shows a reactor vessel 901 with a core 903 comprising fuel bundles 902 which is connected via a liquid inlet piece 904 to a support plate 905. Connecting onto the inlet piece 904 is a cylindrical housing of the turbine assembly 907 according to the invention which passes through the support plate 905. The turbine assembly 907 comprises a rotor 908 rotatably mounted in housing 906 in that a bearing housing 909 is connected to housing 906 via guide plates 910 and 911. The rotor blades 912 are manufactured from a composite material (alloy) on a basis of cadmium/indium/silver. The neutron field as well as the gamma field can thus be modulated with the rotor blades 912. Arranged axially along the core 903 is a detector tube 913 through which a detector assembly can be guided for detecting fluctuations in the neutron field and/or gamma field which are converted into a detector signal that is fed to the converter which forms part of the measuring device according to the invention and with which the detector signal is converted with a value corresponding to the water flow 915 through an inlet 916 of core 903. The system also provides for other systems, such as a piston assembly, which comprise a nuclear source material enabling the flow rate to be determined from modulations in the radiation field. In the case of an apparatus with a piston, the movement of the piston causes temporal variations in the radiation flux. The nuclear-active material need not be in wafer form and can be rigidly attached to the rotor or, in an alternative embodiment, be included in the rotor. The nuclear-active material does not have to be confined to a small area on the rotor; it can be distributed over the whole rotor as long as the resulting distribution produces a sufficiently varying field, as for instance in the case where there are gaps between the rotor blades. The field modulation need not take place as a consequence of rotation of nuclear-active material, but can occur when a rotor comprises a material with a moderator strength differing from that of water; the rotor displaces water so that rotation of the water causes a differential moderation of the core fast neutrons, which will cause modulations in the radioactive field at the detector which correspond to the rotor rotation rate. Rotors may have other configurations than those shown and may be composed of any material suitable for a turbine used in the reactor core environment of a nuclear reactor. A rotor can be coupled to a shaft by any means enabling a rotation which results in radiation field modulation, including rotor assemblies with sapphire ball bearings in steel races. The invention comprises the use of other sources of prompt gamma rays, such as boron, gadolinium, chlorine, indium, mercury, samarium, manganese and neodymium. Other sources of delayed gamma rays comprise iridium. The detected radiation is not limited to gamma rays and thermal neutrons but may comprise any radiation which creates a field which can be detectably modulated by the described system. The invention provides for reactors of other types, including forced circulation reactors, and for other than nuclear environments in which a system as disclosed can be installed. These and other variations to and modifications of the described embodiments are provided for by the present invention, the scope of which is limited only by the following claims.
054328284	claims	1. Method of replacing an adaptor (3) for penetrating the vessel head (1) of a nuclear reactor, of rounded shape, disposed, after dismounting, so as to have a convex outer surface (1a) facing upwards and a concave inner surface (1b) facing downwards, each of the adaptors (3) having a vertical disposition and being fixed in a penetration opening (2) in the head (1) by means of a weld (5) in the vicinity of the concave inner surface (1b) and carrying an item of equipment (13, 4) resting on one end of the adaptor (3, 3'), this end projecting outside the head (1), the method consisting in machining a lower portion of the adaptor (3) to be replaced, in the vicinity of the inner surface (1b) of the head (1), and at least one portion of the weld (5) for fixing the adaptor (3), in extracting the adaptor (3) to be replaced from the opening in the head (1), in inserting a replacement adaptor (50) into the opening and fixing it therein, and in welding the replacement adaptor (50) to the head, characterized in that the replacement is performed from a repair area located above the convex face (1a) of the head and in that at least one of the operations of machining the adaptor to be replaced (3') after dismounting the item of equipment (4, 13) resting on its upper end and of welding the replacement adaptor (50) is carried out by inserting a repair means (14) via the upper end of the adaptor (3, 50). 2. Method according to claim 1, characterized in that the item of equipment resting on the upper part (3a) of the adaptor to be replaced (3') is constituted by a mechanism (13) for driving a reactivity control rod and by a thermal sleeve (4) disposed inside the adaptor (3). 3. Method according to claim 2, characterized in that, in order to install the repair means (14) in the adaptor to be replaced (3'), at least one drive mechanism (13) resting on an adaptor (3) other than the adaptor (3) being replaced is dismounted. 4. Method according to any one of claims 1 to 3, characterized in that a portion of the repair means (14) is mounted from beneath the head, in a manual manner, from inside a biological-shield chamber (11). 5. Method according to any one of claims 1 to 3 characterized in that the lower portion of the adaptor to be replaced (3) and a portion of the weld (5) are removed by machining by means of a boring tool (40). 6. Method according to any one of claims 1 to 3, characterized in that a narrow bevel (36) is machined in the metal of the weld (5), after removal by machining of the lower portion of the adaptor (3) to be replaced and of a portion of the weld (5). 7. Method according to claim 6, characterized in that a weld is formed by deposition of filler metal in the narrow bevel (36) using a welding head (49, 59) rotating at a speed which can be varied during the welding. 8. Method according to any one of claims 1 to 3, characterized in that, after removal by machining of the lower portion of the adaptor (3) and of a portion of the weld (5) of the adaptor to be replaced, that portion of the adaptor (3) remaining inside the opening (2) of the head is rebored. 9. Method according to claim 8, characterized in that, after reboring the remaining portion of the adaptor (3), a wall (47) of the adaptor (3), obtained after reboring, is compressed so as to separate the wall (47) from the penetration opening (2) of the head (1). 10. Method according to claim 1, characterized: in that the head (1) is positioned on a repair stand (6) with its convex outer surface facing upwards; in that the item of equipment (4, 13) resting on the upper portion of the adaptor (3, 3') being replaced is dismounted; in that the repair means (14) is installed on the upper portion of the adaptor (3), at least one portion of which means is inserted into the bore of the adaptor (3, 3'); in that a first machining tool is fixed to that portion of the repair means (14) inserted into the adaptor (3, 3') from beneath the head (1); in that a lower portion of the adaptor (3, 3') and a portion of the weld (5) are removed by machining; in that the first machining tool is replaced by a second tool and in that a welding bevel (36) is machined in a remaining portion of the weld (5); in that the second machining tool is replaced by a third tool and in that that portion of the adaptor (3, 3') remaining in the opening (2) of the vessel head (1) is rebored; in that the rebored portion of the adaptor (3, 3') remaining in the opening (2) of the head (1) is compressed and in that the remaining portion of the adaptor (3, 3') is removed from the opening (2) in the head (1); in that a replacement adaptor (50) is installed at a low temperature and in that it is shrink-fitted to the opening (2); and in that the welding bevel (36) is filled with filler metal.
	description	This invention relates to the domain of treatment and particularly concentration of small particles. These particles may be biological particles such as liposomes, animal or vegetable cells, viruses or micro-organisms, macromolecules, for example such as DNA, RNA or proteins, or inorganic particles such as microballs. Application domains may then be chemical or biomedical analysis or quality control (calibration of micro-particles). Known approaches in terms of particle cell sorting, such as flow cytometry, reach their limits particularly for the analysis of rare or very minority cell populations. The technique of optical clamps is based on the confinement of a particle (microball, or cell or macromolecule) by the intensity gradient generated at the waist of a continuous laser beam. For example, it is described in the article by “Ashkin and Dziedic” entitled “Observation of radiation-pressure trapping of particles by alternating light beams” published in Physics Review Letters, 54(12), 1985. This operation is made possible by balancing of radiation pressures. Once this operation has been done, the particle is displaced by displacing the beam. Thus, displacement distances on this type of device are usually limited to a few hundred microns. Finally, treatment and particularly concentration of particles is not possible. FIG. 1 shows the principle of such a device. A particle 2 is confined by a beam 4 in a liquid medium 6. FIG. 2 is a diagram showing a force field generated by the device, on each side of the laser beam 4; the particle is confined in a mechanical force field (induced by the radiation pressure provoked by the electrical field of the laser) which makes it possible to trap it. This type of device has a disadvantage: displacement of particles is based on use of a dedicated mechanical system, which may be difficult and expensive to set up. Recent work, for example such as that described in the article by T. Tanaka et al, published in Applied Physics Letters, Vol. 77, p. 3131, 2000, makes use of guided optical devices, and suggests the possibility of designing a device for displacement of cells by optical forces; this technique is limited to objects very much smaller than a biological cell (balls and colloids with a size of the order of a few microns). As illustrated in FIG. 3, this device uses a waveguide 10 with a strip made on a substrate 12. A particle is displaced by a force with photonic pressure, which is proportional to the light intensity at the particle. The particle is held in place in the guide by a force that is proportional to the gradient of the intensity. If the waveguide is single mode, there is a maximum light intensity at the location at which the particle will be trapped. Furthermore, if it is desired to concentrate objects such as biological cells, special care must be taken not to damage them. Concentration methods involving liquid flows (for example concentration by retention on a membrane) cause the problem of a possible overpressure that is highly damaging to cells and that can occur following a blocking in the guide circuit. The use of optical clamps, although less damaging for cells, is also not feasible since each clamp can only handle a single object and in this case it will be necessary to make one manipulation for every particle to be displaced. This method is fairly tedious and requires qualified personnel and/or very delicate computer control. The problem arises of finding a method and a device for concentrating particles simply and efficiently. The invention relates to systems for concentrating particles or objects, for example with biological interest. The invention uses at least one waveguide, for example with a length between a few micrometers and a few centimetres. Particles may then be concentrated in one or several clusters: the particles to be concentrated are firstly placed close to a portion of the guide. Light radiation is then injected into the waveguide which produces forces that attract all particles and concentrate these particles in a cluster. In particular, these forces may be short range optical forces (of the order of a few micrometers and/or forces related to convection of a fluid above the guide, which have a longer range (several tens of micrometers). The invention may also use several waveguides so that particles can be concentrated in one or several clusters. These clusters may be distributed on one or several guides, or possibly on each of the waveguides. According to one variant, this can be achieved by adding light radiation into each of the waveguides, during the step in which light radiation is inserted. According to another variant, light radiation can be inserted into one or several particular guides among the set of waveguides. The said waveguides may be put adjacent on a support without intersecting. They may also be multiplexed and joined together at least at one concentration point. In this case, the injection step can be used to concentrate the particles into a single cluster on this concentration point. Once concentrated on one or several waveguides, the particles may tend to displace; the particle cluster(s) formed may then tend to dislocate. According to one characteristic of the invention, stationary waves may be used to prevent this displacement. These stationary waves may be formed from the light radiation used, for example using a diffraction grating or an optical loop formed by the waveguide. The use of stationary waves may also help to hold particles concentrated in several clusters fixed on the same waveguide. The said injected light radiation may be between the ultraviolet and infrared. It is chosen particularly according to criteria such as the nature of the particles to be concentrated, and the velocity at which this concentration has to be done. The particles to be concentrated may be objects derived from a micro-manufacturing method for example such as microballs with a size between a few nanometres and about a hundred micrometers. These particles may also for example be biological elements such as cells, macromolecules such a proteins, DNA, RNA. According to one particular characteristic of the method according to the invention, the particles to be concentrated may be marked before being placed on the said support used. This provides means for increasing the difference in the index of particles with respect to their environment and can thus improve their concentration when light radiation is injected. For example, when the particles to be concentrated are cells, marking may be done by other marking particles, for example based on metal such as gold or polymer. These marking particles may for example be microballs. The method according to the invention may be done in a liquid medium such as water or a buffer solution, or a cell suspension medium. The method may be carried out in such a medium particularly when the particles to be sorted are biological elements. The invention also relates to a particle concentration device including one or several waveguides, the waveguides being surrounded on each side by at least two diffraction gratings. A general example of the method according to this invention will now be described with reference to FIGS. 4A and 4B. This method is used to concentrate or to group a set of particles 100. Grouping may be done so as to form one or several particle clusters. Particles mean organic or inorganic elements or objects with a size varying from 5 nanometres to 100 micrometers. These particles may for example be biological elements such as liposomes, viruses, micro-organisms, animal or vegetable cells, macromolecules for example such as proteins, DNA, RNA or micro-objects, for example such as microballs based on a metal or a dielectric material. The concentration method according to the invention is done on a support 104, for example made of glass or silicon, with an optical index preferably different from or very different from the optical index of the particles that are to be grouped. This support 104 comprises at least one integrated multi-mode or single mode waveguide 108 for example with a length of between a few micrometers and a few centimetres. According to a first step in the method, the particles 100 are placed firstly in an area 102 close to and/or on the waveguide 108, using a manual or automated method. Then, using an optical device 112 that may or may not be integrated into the support 104, light radiation R is injected into the optical guide. The injected radiation has a wavelength between the near ultraviolet and infrared, for example between 300 nm and 1200 nm (FIG. 4A). The light radiation R may be chosen particularly depending on the type of particles to be concentrated, and possibly the velocity at which these particles are to be grouped. For example, in the case in which the particles are biological elements such as cells, a wavelength between the red and infrared could be used, for example using a YAG laser with a wavelength of 1064 nm. The radiation power could be of the order of a few tens of milliwatts to a few hundred milliwatts, for example between 50 mW and 1 W, for example close to 150 mW. The light radiation R through the waveguide 108 creates forces {right arrow over (f)} towards the waveguide. These forces may attract and concentrate particles 100 on the waveguide 108. These particles 100 then form a cluster 106 (FIG. 4B). The velocity at which the particles are grouped can vary depending on the mass, the volume, optical index of the particles, and the wavelength of the light radiation used. If the light radiation injection step is prolonged, the cluster 106 may tend to be dislocated. Particles can tend to displace along the waveguide 108 along the direction of propagation of light radiation. If it is required to prevent this phenomenon, according to one variant, the injection of light radiation can be stopped as soon as the cluster 106 of particles 100 is formed. According to another variant, the particles 100 can be blocked once they are on the waveguide, for example using stationary waves. These stationary waves may be formed by transforming the light radiation R in the waveguide, for example using one or several diffraction gratings, or by making an optical loop system. FIG. 5A relates to a device like the one illustrated in FIGS. 4A and 4B. The waveguide 108 also comprises an integrated diffraction grating 200 used to transform light radiation produced by the optical device 112 into stationary waves. The use of stationary waves through waveguide 108 can also concentrate and maintain particles in several clusters 202, 204, 206 formed along the same guide 108. These clusters 202, 204, 206 are located at locations on the waveguide at which the light intensity is maximum. The curve C illustrated in FIG. 5A represents the variation in the amplitude of a stationary wave derived from the radiation R, along a z axis transverse to the waveguide and along the direction of propagation of the radiation R. The maximum values of the curve C correspond to the locations on the waveguide 108 at which particle clusters are grouped. According to one variant, a stationary wave can be made in the waveguide using a guide forming at least one loop 210 like that illustrated in FIG. 5B. This type of loop can enable light radiation, when it passes along the waveguide, to adopt one or two different trajectories. Thus, two light waves with the same length and the same amplitude propagating in different directions, can come into contact and interfere. The method for concentration of particles according to the invention may also be used with a device comprising several waveguides. It is required to concentrate a group of particles placed in an area close to the different waveguides into one or several clusters using such a device. For example, this variant may be produced using a support comprising several adjacent waveguides with certain spacing between them. These waveguides may have different lengths and/or different widths and may be made of different materials. A first method of grouping particles consists of injecting light radiation into one of the waveguides. If the distance between the different adjacent waveguides is small enough, coupling between the guides can occur and the light radiation then propagates in one or more of the other guides. When coupling occurs, the particles may be attracted by forces from the different guides and may be concentrated in different clusters distributed on these different guides. However, when coupling occurs between several guides, it is possible that a particle oscillation phenomenon can occur from one waveguide to another. Another phenomenon can also occur in which particles remain blocked between two waveguides. In order to optimise the concentration method and prevent these two phenomena, the distance between the waveguides may be fixed equal to a value greater than a minimum distance that will enable coupling between the different guides. However, this minimum distance depends particularly on the geometric properties of the guide, the refraction index of the materials from which it is made, and the wavelength of the radiation used. It may be of the order of a few micrometers, for example more than 5 μm, to several tens of micrometers, for example between 5 μm and 50 μm. An example of a device comprising several adjacent waveguides 211, 212, 213 at a spacing of a distance e, is illustrated in FIG. 6A. The distance e is fixed so as to avoid coupling between the different waveguides, at a value for example of the order of one or several tens of micrometers, for example 10 or 20 μm. Different light radiation R1, R2, R3 can be injected into each of the waveguides 211, 212, 213, to concentrate the particles 100 located close to the waveguides 211, 212, 213 (FIG. 6A). This provides a means of concentrating the particles 100 into different clusters 214, 215, 216 distributed on the different waveguides (FIG. 6B). At the end of this method, it will be possible to group the different particle clusters distributed on several waveguides into a single cluster. To achieve this, a support 104 can be used including several adjacent and multiplexed waveguides. These guides join together at a concentration point 220 (FIG. 7). The injection of light radiation through each of the waveguides causes concentration of particles into several clusters distributed on the different waveguides. Then, if the emission of light radiation is prolonged, the particles 100 tend to displace along radiation propagation directions (indicated by the arrows in FIG. 4). The particles 100 then move towards the concentration point. The particles 100 are concentrated in a single cluster. One method of improving the concentration of particles consists of producing additional radiation forces {right arrow over (F)}add on the particles 100, added to forces created by the waveguide. These additional radiation forces {right arrow over (F)}add may for example be produced by diffraction gratings 232 located on each side of the waveguide through which additional light radiation R′ is injected (FIG. 8). The method according to this invention may be applicable to biological particles such as animal or vegetable cells to be concentrated. A support, for example made of glass, comprising at least one waveguide will be used to concentrate biological particles. The support may be immersed in a liquid solution, preferably biocompatible, to preserve cells. In a heterogeneous cell sample, an attempt is made to isolate a given sub-population characterised by a specific phenotype, for example the presence of a certain type of surface macromolecules, for example such as proteins. Furthermore, probe molecules such as antibodies are available capable of recognising and bonding with these phenotypic markers with a very strong affinity. In the case of antibody type probe molecules, the phenotypic markers are called antigens. Antibodies are fixed by means known to those skilled in the art to balls chosen for their particular characteristics, for example gold balls. These functionalised gold balls are then grafted onto the surface of cells, for example these cells may be lymphocytes isolated from blood and that are to be concentrated. A group of marked cells is sampled firstly, for example, using a pipette. The next step is to place the said sample in a support receptacle. This receptacle may be a chamber, for example such a Gene Frame® type chamber. This self-sticking chamber is very simple and has a joint system impermeable to gas, providing resistance at high temperatures. The receptacle is not limited to this type of chamber. The cells group may be transferred from the receptacle to a zone placed close to the waveguide, for example one or several capillaries. The next step is to inject light radiation through said waveguide. The radiation used during a cell sort would preferably be inoffensive towards the cells. Thus, the light radiation used may be laser radiation emitting at a wavelength between far red and near infrared, for example between 1000 nm and 1200 nm, for example close to 1064 nm. The passage of laser radiation through the waveguide creates forces directed towards the guide to attract the cells. The cells are then concentrated into a cluster. In general, observation means may be provided, for example a CCD camera located above the guide 108. These means enable monitoring of the sort made as described above. FIG. 9 shows a particle concentration system 100 on a support 104 incorporating a guide system according to the invention. An objective 300 focuses a laser beam R (for example a YAG beam at 1064 nm) in a guide 108. The particles to be sorted are contained in a chamber 310 located on a slide 320. A camera 330 is used to make an image of the concentration, for example using a focusing device or a zoom 340. Means 350, 360 (objective, camera) of forming an image of the transmitted radiation may also be placed at the output from the device. A device for implementing a concentration method according to the invention like those described above, particularly including for example a support and one or several waveguides, may be integrated in a MEMS (micro-electromechanical system) or in a lab on a chip. Waveguides used during the method according to the invention can for example be made by thin layer manufacturing techniques, or for example by an ion exchange method. The support on which these guides are formed may for example be based on glass. To form the waveguide, the first step is to cover the support 140 with a metallic thin layer 142, for example based on aluminium, by a method such as evaporation or sprinkling. This aluminium layer is then covered by a resin layer 144, for example a photoresist resin layer. To make the patterns of waveguides in the support, the first step is to expose the photoresist resin layer for example using a beam of ultraviolet rays 148 through a mask 146, for example made of chromium. The mask 146 includes a copy of the waveguide patterns or negatives of the waveguide patterns (FIG. 10A). The areas of the resin layer 144 that are not concealed by the mask have their chemical structures modified. The next step after the exposure step is to develop the layer of photoresist resin 144. Thus, the areas on which the chemical structure was modified by insolation are etched (FIG. 10B). The next step is to etch the aluminium layer through the resin layer (FIG. 10C), for example by dipping the support in an aluminium etching solution (AluEtch). This solution does not etch the resin. Thus, only the previously developed parts are etched. The resin layer 144 is then removed, for example using acetone (FIG. 10D). An ion exchange step is then carried out to form the waveguides. The support is then immersed in a salt bath containing silver nitrate and sodium nitrate. The proportion between these salts determines the silver content that is exchanged in the glass 140. The bath generally contains between 10% and 50% of silver depending on the application. Since the salt melting temperature is about 310° C., the exchange step is carried out at between 320° C. and 350° C. (FIG. 11). The aluminium layer is then removed by etching. Annealing can possibly be done; the glass plate is heated without any contact with a bath. This step enables silver ions to penetrate more deeply towards the inside of the support. A guide 104 like that illustrated in FIG. 1A can be formed in this way. Other methods can also be used, for example to make a guide on a silicon substrate. Braking forces on particles caused by friction with the upper surface of the guide can be reduced, by coating the guide with a special coating, for example a thin Teflon based layer. Another example embodiment will be given. In this example, the waveguides used are surface guides made by a potassium ion exchange (glass slide substrate). These ions are produced at a temperature of 280° C. for an exchange time of 2 h 15. Losses of these guides are of the order of 0.2 to 0.5 dB/cm at a wavelength of 1064 nm. The displaced particles to be concentrated are glass balls with a refraction index of 1.55 and a diameter of 2 μm, or gold balls with a diameter of 1 μm. The device used is of the type shown in FIG. 9. Light is coupled through the edge using a continuous YAG laser at 1064 nm (P=10 W) and balls are observed through the top using a zoom system 340 coupled to a video camera 330 for monitoring their displacement. Experiments carried out on 1 μm diameter gold balls have demonstrated spontaneous grouping of balls on the guide followed by their displacement at velocities of the order of 4 μm/s along the guide. Similarly, the possibility of grouping and displacing glass balls is demonstrated. Thus, FIGS. 12A to 14C illustrate: FIGS. 12A to 12D; displacement of metallic particles over a distance of 70 μm, at t=0 s, 2 s, 3 s. FIG. 13: a metallic particles concentration effect. FIGS. 14A to 14C: progressive grouping of glass balls 101 along a 70 μm portion of the guide, at t=0 s, 4 s, 8 s successively.
050769995	claims	1. A passive decay-heat removal system for a water-cooled nuclear reactor having a reactor vessel and a reactor core disposed in said vessel for passage of coolant water through said core, said coolant water extending upward to a level substantially above said core in normal operation condition, comprising: an open-topped box located above said core and immersed in said coolant water at its normal operating level; a passive closed heat transfer loop including first and second heat exchangers, the first heat exchanger disposed inside said box and forming one end of the loop, and the second heat exchanger disposed outside of said reactor vessel in communication with an outside environment and above the level of first heat exchanger; means communicating an outlet of said first heat exchanger with an inlet of the second heat exchanger and an outlet of said second heat exchanger with an inlet of the first heat exchanger; heat-exchanging fluid contained in said loop; and means for draining said box; whereby during normal operations, a small amount of heat is removed by said closed heat transfer loop and, when water falls to a level below the first heat exchanger, exposing the same to steam, a large amount of heat will be removed from said reactor by condensation of the steam in the box and fluid inside the heat transfer loop. 2. A system as defined in claim 1 wherein said first heat exchanger comprises evaporating coils, and said second heat exchanger comprises condensing coils. 3. A system as defined in claim 1 wherein said drain means comprises a pipe having a heat-exchanging section disposed below and adjacent to an outlet at the bottom of said box. 4. A system as defined in claim 1 wherein said means communicating said heat exchangers comprises a pair of metal tubes disposed to convey vapor from said first to said second heat exchanger in one tube and to return condensed liquid to said first heat exchanger in the other tube. 5. A system as defined in claim 3 wherein said drain pipe has a size selected to enable the rate of removal of heat from said first heat exchanger to be determined by the flow rate of water through said drain paper. 6. A system as defined in claim 1 wherein said reactor is a boiling water reactor.
048572640	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The composite of FIGS. 1A And 1B (referred to hereinafter as FIG. 1) is an elevational view, partly in cross-section, of a pressurized water reactor 10 comprising a pressure vessel 12 including an upper dome, or head assembly, 12a, cylindrical sidewalls 12b, and a bottom closure 12c comprising the base of the reactor 10. Plural radially oriented inlet nozzles 11 and outlet nozzles 13 (only one (1) of each appearing in FIG. 1) are formed in the sidewall 12b, adjacent the upper, annular end surface 12d of the sidewall 12b. Whereas the cylindrical sidewall 12b may be integrally joined, as by welding, to the bottom closure 12c, the head assembly 12a is removably received on the upper, annular end surface 12d of the sidewall 12b and secured thereto. The sidewall 12b further defines an inner, generally annular mounting ledge 12e for supporting various internal structures as later described. Within the bottom closure 12c, as schematically indicated, is so-called bottom-mounted instrumentation 14. The lower barrel assembly 16 comprises a generally cylindrical sidewall 17 affixed at its lower end to a lower core plate 18, which is received on mounting support 18b, as generally schematically illustrated. The cylindrical sidewall 17 extends substantially throughout the axial height of the vessel 12 and includes an annular mounting ring 17a at the upper end thereof which is received on the annular mounting ledge 12e thereby to support the assembly 16 within the vessel 12. As will be rendered more apparent hereafter, the sidewall 17 is solid in the vicinity of the inlet nozzles 11, but includes an aperture 17b having a nozzle ring 17c mounted therein which is aligned with and closely adjacent to the outlet nozzle 13, for each such nozzle. An upper core plate 19 is supported on a mounting support 17d affixed to the interior surface of the cylindrical sidewall 17 at a position approximately one-half the axial height thereof. Fuel rod assemblies 20 are positioned in generally vertically oriented, parallel axial relationship within the lower barrel assembly 16 by bottom mounts 2 carried by the lower core plate 18 and by pin-like mounts 23 carried by, and extending through, the upper core plate 19. Flow holes 18a and 19a (only two of which are shown in each instance) are provided in predetermined patterns, extending substantially throughout the areas of the lower and upper core plates 18 and 19, respectively. The flow holes 18a permit passage of a reactor coolant fluid into the lower barrel assembly 16 in heat exchange relationship with the fuel rod assemblies 20, which comprise the reactor core, and the flow holes 19a permit passage of the core output flow into the inner barrel assembly 24. A neutron reflector and shield 21 is mounted interiorly of the cylindrical sidewalls 17, in conventional fashion. The inner barrel assembly 24 includes a cylindrical sidewall 26 which is integrally joined at its lower edge to the upper core plate 19. The sidewall 26 has secured to its upper, open end, an annular mounting ring 26a which is received on an annular hold-down spring 27 and supported along with the mounting ring 17a on the mounting ledge 12e. The sidewall 26 further includes an aperture 26b aligned with the aperture 17b and the output nozzle 13. Within the inner barrel assembly 24, and densely packed within the cylindrical sidewall 26, are positioned a plurality of rod guides in closely spaced, parallel axial relationship; for simplicity of illustration, only two such rod guides are shown in FIG. 1, namely rod guide 28 housing a cluster 30 of radiation control rods (RCC) and a rod guide 32 housing a cluster 34 of water displacement rods (WDRC). The rods of each RCC cluster 30 and of each WDRC cluster 34 are mounted individually to the respectively corresponding spiders 147 and 90. Mounting means 36 and 37 are provided at the respective upper and lower ends of the RCC rod guide 28 and, correspondingly, mounting means 38 and 39 are provided at the respective upper and lower ends of the WDRC rod guide 32. The lower end mounting means 37 and 39 rigidly mount the respective rod guides 28 and 32 to the upper core plate 19, as illustrated for the RCC rod guide mounting means 37 by bolt 37'. The upper mounting means 36 and 38 mount the respective rod guides 28 and 32 to a calandria assembly 50, and particularly to a lower calandria plate 52. The calandria assembly 50, in more detail, comprises a generally cylindrical, flanged shell 150 formed of a composite of the flange 50a, an upper connecting cylinder 152 which is welded at its upper and lower edges to the flange 50a and to the upper calandria plate 54, respectively, and a lower connecting cylinder, or skirt, 154 which is welded at its upper and lower edges to the upper and lower calandria plates 54 and 52, respectively. The lower connecting cylinder, or skirt, 154 includes an opening 154a aligned with each of the outlet nozzles 13 such that the axial core outlet flow received within the calandria 52 through the openings 52a in the lower calandria plate 52 may turn through 90.degree. and exit radially from within the calandria 52 through the opening 154a to the outlet nozzle 13. The annular flange 50a which is received on the flange 26a to support the calandria assembly 50 on the mounting ledge 12e. Plural, parallel axial calandria tubes 56 and 57 are positioned in alignment with corresponding apertures in the lower and upper calandria plates 53 and 54, to which the calandria tubes 56 and 57 are mounted at their respective, opposite ends. Extending upwardly beyond the upper calandria plate 54 and, more particularly, within the head assembly 12a of the vessel 12, there are provided plural flow shrouds 60 and 61 respectively aligned with and connected to the plural calandria tubes 56 and 57. A corresponding plurality of head extensions 62 and 63 is aligned with the plurality of flow shrouds 60, 61, the respective lower ends 62a and 63a being flared, or bell-shaped, so as to facilitate assembly procedures and, particularly, to guide the drive rods (not shown in FIG. 1) into the head extensions 62, 63 as the head assembly 12a is lowered onto the mating annular end surface 12d of the vessel sidewall 12b. The flared ends 62a, 63a also receive therein the corresponding upper ends 60a, 61a of the flow shrouds 60, 61 in the completed assembly, as seen in FIG. 1. The head extensions 62, 63 pass through the upper wall portion of the head assembly 12a and are sealed thereto. Control rod cluster (RCC) displacement mechanisms 64 and water displacement rod cluster (WDRC) displacement mechanisms 66 are associated with the respective head extensions 62, 63 flow shrouds 60, 61 and calandria tubes 56, 57 which, in turn, are associated with respective clusters of radiation control rods 30 and water displacement rods 34. The RCC displacement mechanisms (CRDM's) 64 may be of well known type, as are and have been employed with conventional reactor vessels. The displacer mechanisms (DRDM's) 66 for the water displacer rod clusters (WDRC's) 34 may be in accordance with the disclosure of U.S. Letters Pat. No. 4,439,054-Veronesi, assigned to the common assignee hereof. The respective drive rods (not shown in FIGS. 1A and 1B) associated with the CRDM's 64 and the DRDM's 66 are structurally and functionally the equivalent of elongated, rigid rods extending from the respective CRDM's 64 and DRDM's 66 to the respective clusters of radiation control rods (RCC's) 30 and water displacement rods (WDRC's) 34 and are connected at their lower ends to the spiders 100 and 120. Apertures 58 and 59 in the lower calandria plate accommodate the corresponding drive rods. The CRDM's and DRDM's 64 and 66 thus function through the corresponding drive rods to control the respective vertical positions of, and particularly, selectively to lower and/or raise, the RCC's 30 and the WDRC's 34 through corresponding openings (not shown) provided therefore in the upper core plate 19, telescopingly into or out of surrounding relationship with the respectively associated fuel rod assemblies 20. In this regard, the interior height D.sub.1 of the lower barrel assembly 16 is approximately 178 inches, and the active length D.sub.2 of the fuel rod assemblies 20 is approximately 153 inches. The interior, axial height D.sub.3 is approximately 176 inches, and the extent of travel, D.sub.4, of the rod clusters 30 and 34 is approximately 149 inches. It follows that the extent of travel of the corresponding CRDM and DRDM drive rods is likewise approximately 149 inches. While the particular control function is not relevant to the present invention, insofar as the specific control over the reaction within the core is effected by the selective positioning of the respective rod clusters 30 and 34, it is believed that those skilled in the art will appreciate that moderation or control of the reaction is accomplished in accordance with the extent to which the control rod clusters 30 are inserted into or withdrawn from the core and with the effective water displacement which is achieved by selective positioning of the water displacement rod clusters 34. The flow of the reactor coolant fluid, or water, through the vessel 10 proceeds, generally, radially inwardly through a plurality of inlet nozzles 11, one of which is seen in FIG. 1, and downwardly through the annular chamber 15 which is defined by the generally cylindrical interior surface of the cylindrical side wall 12b of the vessel 12 and the generally cylindrical surface exterior surface of the sidewall 17 of the lower barrel assembly 16. The flow then reverses direction and passes axially upwardly through flow holes 18a in the lower core plate 18 and into the lower barrel assembly 16, from which it exits through a plurality of flow holes 19a in the upper core plate 19 to pass into the inner barrel assembly 24, continuing in parallel axial flow therethrough and finally exiting upwardly through flow holes 52a in the lower calandria plate 52. Thus, parallel axial flow conditions are maintained through both the lower and inner barrel assemblies 16 and 24. Within the calandria 50, the flow in general turns through 90.degree. to exit radially from a plurality of outlet nozzles 13 (one of which is shown in FIG. 1). The inlet coolant flow also proceeds into the interior region of the head assembly 12a through perimeter bypass passageways in the mounting flanges received on the ledge 12e. Particularly, a plurality of holes 170, angularly spaced and at a common radius, are formed in the flange 17a and provide axially-directed flow paths from the annular chamber 15 into the annular space 172 intermediate the spring 27 and the interior surfaces of the sidewalls of the vessel 12; further, a plurality of aligned holes 174 and 176 extend through the flanges 26a and 50a, the holes 174 being angularly oriented, to complete the flow paths from the annular space 172 to the interior of the head assembly 12a. The flow of coolant proceeds from the head region through annular downcomer flow paths defined interiorly of certain of the flow shrouds 60, 61 and calandria tubes 56, 57, as later described, from which the head coolant flow exits into the top region of the inner barrel assembly 24, just below the lower calandria plate 52, to mix with the core outlet flow and pass through the calandria 50, exiting from the outlet nozzles 13. A first plurality of calandria extensions 58 project downwardly from the calandria tubes 56 and connect to corresponding mounting means, or top end supports, 36 for the upper ends, or tops, of the RCC rod guides 28. The top end supports 36 may be in accordance with the structure disclosed in the concurrently filed patent application entitled LATERAL SUPPORT FOR CANTILEVER-MOUNTED ROD GUIDES OF A PRESSURIZED WATER REACTOR Ser. No. 936,301,filed 11-3-86or, alternatively, in the pending patent application entitled FLEXIBLE ROD GUIDE SUPPORT STRUCTURE FOR INNER BARREL ASSEMBLY OF PRESSURIZED WATER REACTOR Ser. No. 798,220 filed 11-14-85 ), both assigned to the common assignee hereof. A second plurality of calandria extensions 59, in interleaved relationship with the plurality of extensions 58, projects downwardly from the respectively corresponding calandria tubes 56, each extension 59 telescopingly connecting to a corresponding, frictionally loaded top end support mounting means 38 for a WDRC rod guide 32 in accordance with the present invention. As before briefly noted, each of the mounting means 38 for the WDRC rod guides in accordance with the present invention provides a frictionally loaded, telescoping interconnection between the lower calandria plate 52 and the respectively associated WDRC rod guide 32, thereby not only affording axial alignment and lateral support of the top end of the associated, individual WDRC rod guide 32, but also preventing vibration of the rod guide 32 and the upper core plate 19. The calandria extensions 59, moreover, function, in cooperation with and in response to the frictionally loaded mounting means 38, to react seismic forces from the rod guides 32 into the calandria, while accommodating axial height variations arising from structural tolerances and thermal stresses at the interface of the upper ends of the rod guides 32 and the lower calandria plate 52. FIG. 1C is a schematic, top plan view of the calandria plate 52 indicating in hidden lines the general, outer peripheral configuration of the RCC rod guides 28 and the WDRC rod guides 32. As later explained, threaded holes 87 provide for engaging the top end supports for the WDRC rod guides to the calandria plate 52. Holes 56 and 57 respectively labelled "C" and "D" identify the corresponding holes through the lower calandria plate 52 through which pass the RCC and the WDRC drive rods 56 and 57. Holes 52A are flow holes through the lower calandria plate 52, as likewise seen in FIG. 1A. FIG. 1C serves to illustrate the dense packing of the RCC and WDRC rod clusters and the geometrically interspersed arrays thereof within the upper internals 24 and, as well, the complexity of the structure within the calandria assembly 50. The frictionally loaded top end support for cantilever-mounted water displacement rod guides of a pressurized water reactor in accordance with the present invention will be explained with concurrent reference to FIGS. 2, 3 and 4. FIG. 2 is an elevational view of the mounting means 38 comprising the frictionally loaded top end support for a WDRC rod guide 32. FIG. 3 is a cross-sectional view of the mounting means 38 taken along the line 3--3 in FIG. 2. FIG. 4 is a vertical cross-sectional view of the mounting means 38 taken along the lines 4--4 in each of FIGS. 2 and 3. The WDRC rod guide 32, throughout substantially its entire axial length, comprises a relatively thin metal sidewall 70 of generally square cross-sectional configuration which carries, at its upper extremity, a reinforced, generally coaxial sleeve 72 having a generally square cross-sectional configuration corresponding to the outer perimeter of the thin sidewall 70 and which is permanently joined at its bottom end to the top end of the latter at their common outer perimeters, as illustrated by weld bead 74. The sleeve 72 receives in telescoping relationship therein a generally cylindrical, fixed support 80 comprising a cylindrical sidewall 81 and an end closure 82. The end closure 82 includes a central, annular projection 83 which is received within a corresponding annular recess 53 in the lower calandria plate 52, thereby interlocking the support 80 with the lower calandria plate 52 against lateral displacement. A central aperture 82' in the cylindrical support 80 is of a diameter corresponding to, and is aligned with, the aperture 52' in the lower calandria plate 52. A calandria extension 59 is received through the apertures 52', 82' and may extend downwardly through the aperture 82', serving to further stabilize the support 80 to the lower calandria plate 52. Typically, the calandria extension 59 is permanently secured to the lower calandria plate 52, as indicated by weld bead 59'. Flow holes 100 are disposed in a symmetrical array about the axis of the calandria extension 59 associated with the WDRC rod guide 32 and its associated top end support 38, which must be unobstructed so as to permit unimpeded passage of the core output flow axially therethrough and into the calandria assembly 50. Accordingly, the end closure 82 includes a number of arcuate indentations, or recesses, 82" corresponding to the inner perimeter portions of the flow holes 100 adjacent the calandria extension 59. The cylindrical sidewall 81 of the fixed support 80 correspondingly is segmented, i.e., is discontinuous, and terminates at the corresponding perimeters of the flow holes 100 and thus comprises a plurality of arcuate segments 81', defining a plurality of arcuate flanges 84 (best seen in FIG. 3), each bounded at its opposite ends by the corresponding perimeters of the adjacent flow holes 100. The arcuate flanges 84 comprise the frictional load bearing components of the frictionally loaded top end support of the invention, as will be described. The end closure 82 furthermore includes a number of countersunk bores 85 through which bolts 86 are received and secured in tightly threaded engagement within the corresponding threaded bores 87 in the calandria lower plate 52. Inner cylindrical bores 88a and outer cylindrical bores 88b are optionally formed in the support 80 for a purpose to be described. As best seen in FIG. 3, the outer bores 88b may be centered at a radius slightly greater than the inner surface of the arcuate flanges 84. The rod guide sleeve 72, as before noted, has an outer periphery of a predetermined geometric configuration corresponding substantially to that of the thin metal sidewall 70; particularly, it is of a eight-sided configuration, comprising two pairs of opposed major faces 72a and two pairs of opposed minor faces 72b. A leaf spring 110 is formed in each of the major faces 72a, in a central portion 113 which integrally connects an upper, continuous annular collar portion 112 and a lower, continuous annular base portion 114. Each leaf-spring 110 is machined so as to have a planar, interior surface 111a which is angled relative to the vertical outer surface and defines a tapered integral shank portion extending upwardly from the annular base portion 114, and an integral arcuate segment lip portion 111b. The arcuate segment lip portions 111b normally extend radially inwardly of the continuous annular collar portion 112. In the telescopingly assembled relationship with the fixed cylindrical support 80, the interior arcuate surface 72' of the sleeve 72 is annularly spaced from the exterior surfaces of the arcuate segments 81' of the cylindrical sidewall 81 of the fixed cylindrical support 80, whereas the arcuate segment lip portions 111b are frictionally loaded onto the annular flange extensions 84. The rod guide sleeve 72 furthermore is machined so as to define an interior surface configuration which is in mating and complementary relationship with the exterior surface configuration of the cylindrical sidewall 81. As best seen in FIG. 3, the rod guide sleeve 72 includes plural interior arcuate surfaces 72' in mating relationship with the corresponding exterior surfaces of the arcuate segments 81' of the cylindrical sidewall 81, and generally arcuate recesses 72" conforming to the corresponding outer perimeter portions of the flow holes 100 and complementing the arcuate recesses 82" of the end closure 82 of the fixed support 80. Within each of the arcuate recesses 72" there additionally are formed axially extending grooves 75, for a purpose to be explained. FIG. 5 is a simplified, schematic plan view of the WDRC rod cluster 34, which more particularly comprises a spider 90 having a plurality of radially extending arms 92 connected to a central hub 93; further, alternate ones of the arms 92 include transverse cross-arms 92a. A plurality of WDRC rods 94 are appropriately connected to the arms 92 and the cross-arms 92a and depend therefrom in parallel axial relationship. With concurrent reference to FIGS. 2 to 5, the grooves 75 and bores 88a, 88b are designed to accommodate respective, individual WDRC rods 94 when the cluster 34 is raised to a refueling position, as shown in phantom lines in FIG. 4. As shown by phantom lines as well in FIG. 3, the grooves 75 formed in the interior arcuate surface 72" corresponding to a given flow hole 100 receive the respective rods 94 of an outer pair mounted on an outermost cross-bar 92, whereas the radially inner and outer bores 88a and 88b in the fixed support 80 accommodate the corresponding, radially inner and outer rods 94 mounted on the single radial arms 92. As shown by phantom lines in FIG. 4, a drive rod or drive shaft 95 is connected to the hub 93 of the spider 90 and extends upwardly through the calandria extension 59, as previously described, for raising or lowering the WDRC rod cluster 34 within its associated rod guide 32. The grooves 75 and the bores 88a and 88b avoid the necessity of increasing the height of the inner barrel assembly 24 in the event that adequate axial height is not available for permitting the cluster 34 to be raised to the required height during refueling. Where adequate vertical space is available, the grooves 75 and the bores 88a and 88b are not required, and accordingly are optional. In accordance with the WDRC top end support 38 afforded by the present invention, during normal reactor operation, the radial load provided by the four leaf springs 110 prevents vibration of the sleeve 72 in a radial, or lateral, direction and thus maintains the spaced, concentric relationship of the sleeve 72 and the mount 80 and Specifically the nominal spacing of the respective, opposed arcuate surfaces 72' and 81' so as to avoid frictional wear therebetween. The axial friction load produced by the radial load, furthermore, prevents axial vibration of the rod guide 32 and, through the plurality of rod guides 32, vertical vibration of the core plate 19, as well. During abnormal load conditions, such as seismic and LOCA, in which the loading, or force, of the springs 110 is exceeded, the fixed cylindrical support 80 functions as a rigid abutment stop to the continuous annular collar portion 112 of the sleeve 72, and reacts any such abnormal load directly into the lower calandria plate 52. The frictional loaded top end support of the present invention therefore substantially eliminates any continuous frictional wear between the contiguous but nominally spaced surfaces of the sleeve 72 and the support 80, affording long life and reduced maintenance. Nevertheless, the support of the invention maintains the desirable feature of a telescoping interconnection of the sleeves 72 and the corresponding fixed cylindrical supports 80, which permits the calandria 50 to be raised and withdrawn for gaining access to the rod clusters 34 within the respective guides 32, for normal maintenance purposes, and thereafter re-installed, simply by being lowered into position with the fixed mount and respective sleeves 72 axially aligned. To facilitate the installation, the inner upper edges 78 of the collar portion 112 are outwardly bevelled and the lower outer edge of the flanges 84 of the fixed support 80 are inwardly bevelled to facilitate the telescoping assembly; likewise, the arcuate segment lips 111b of the leaf springs 110 have arcuate cross-sectional configurations in a vertical plane passing therethrough, as shown in FIG. 4, for facilitating the telescoping interconnection during assembly. In an actual pressurized water reactor of the advanced design herein contemplated and incorporating the present invention, the thin wall section 70 of the rod guide 32 is formed of sheet metal of approximately 1/8 inch thickness. The rod guide 32 is approximately 12 inches wide, in both dimensions of its generally square cross-section, and approximately 174" (14-1/2 feet) in height. The rod guide sleeve 72 has an outer periphery, in cross-section, corresponding to that of the rod guide 70, and may have a diagonal dimension between the opposed minor faces 72b of 14.8 inches and a transverse dimension between the opposed major faces 72a of 12.3 inches. The axial height of the sleeve 72 may be 9.0 inches, that of the collar portion 112 being somewhat over 2 inches, that of the leaf spring 110 being somewhat less than 5 inches and that of the lower annular base portion 114 being approximately 2 inches. To achieve the desired uniform spring deflection/loading force characteristics, the leaf spring 110 is tapered in its planar dimensions as seen in FIG. 2 from a base width of 6 inches to a width of somewhat over 4 inches at the lip portion 111b. An annular clearance of a nominal 0.007 inches is sufficient for the spacing between the cylindrical surface 81' of the fixed support 80 and the interior, mating surfaces 72' of the collar portion 112, the surfaces 72' lying on a diameter of approximately 11 inches. It furthermore is believed sufficient, to achieve the requisite radial loading of the springs 110, that the interior surfaces of the arcuate lip portions 111b lie on a diameter, in their nondeflected positions, which is at most several thousandths of an inch less than the diameter of the fixed cylindrical support 80. Further, it has been determined to be sufficient that the annular flanges 84 extend approximately 1 inch beyond the lower surface of the end closure 82 of the support 80 which in turn may be approximately 2.5 inches in axial height, or thickness. Further, the annular extension 83 and correspondingly the annular recess 53 may be of approximately 0.25 inches. FIG. 6 is a plan view of the reinforced sleeve for the RCC mounting means, or top end support 36, illustrating in hidden lines the corresponding configuration of the thin metal wall rod guide 28; FIG. 7 is a cross-sectional, elevational view taken in a plane through the line 7,8--7,8 in FIG. 6; and FIG. 8 is a cross-sectional view as in FIG. 7, of the assembled top end support 36 comprising the reinforced sleeve 172 with the calandria extension 58 received therein, the calandria extension 58 moreover being secured to the lower calandria plate 52. Reference is had concurrently thereto in the following. The reinforced sleeve 172 is of a generally X-shaped cross-sectional configuration, as best seen in the plan view of FIG. 6, and is slightly larger in its lateral dimensions than the corresponding dimensions of the thin metal sidewall 170 of the RCC rod guide 28. The sleeve 172 thus has generally 90.degree. displaced, radially oriented arms 172a defining therebetween an interior, or included vertex of truncated configuration defined by the short, interior face 172b. As seen in FIG. 1C, each interior vertex of sleeve 172 receives a corresponding exterior vertex of an adjacent WDRC sleeve 72, the interior face 172b being contiguous the corresponding minor face 72b, when in assembled relationship. The sleeve 172 is joined to the metal sidewall 170 for the rod guide 28 by a weld bead 174 (FIGS. 7 and 8). The lower end 173 of the sleeve 172 comprises an annular base portion of fixed inner and outer diameters, the sidewalls tapering slightly in the axial upward direction to the upper end 177; further, annular flange 175 extends inwardly from the base portion 173 and defines an opening of an interior diameter sufficient to receive coaxially therethrough a drive rod 145 connected to a spider 147 to which the rods of the RCC rod cluster 30 are secured, the latter in conventional fashion. The upper end 177 of the sleeve 172 forms a continuous annular and non-yielding collar, the interior surface 177a comprising a load pick-up surface, as later described. Leaf springs 210 are symmetrically disposed about the center axis of the support 172; in the preferred embodiment illustrated, four such leaf springs 210 are disposed at 90.degree. displaced positions about the axis. The base portion 213 of each spring 210 has an inner, flat surface 213a and an outer, arcuate segment surface 213b which conforms to the generally cylindrical interior surface 173a of the lower portion 173 of sleeve 172, as best seen in the cut-away view of the topmost spring 210 in FIG. 6. Shank portion 215 of the spring 210 is joined through a compound curved and integral section 214 to the base portion 213 and thereafter is of tapered and rectangular cross-sectional configuration in the generally axial direction, in accordance with proper design for stress efficiency of a leaf spring. Integral neck portion 216 (the opposite edges of which are seen in the hidden lines in FIG. 6') joins shank 215 to an arcuate segment lip portion 217 (best seen in FIGS. 6 and 7). Bolts 220, 221 and 222 are received through corresponding apertures in the base portion 173 of the sleeve 172 and engaged in respective, threaded bores in the base portion 213 of the spring 210. A clearance bore 217a is formed in the lip portion 2I7, in alignment with and for receiving therein a retaining pin 219 which extends radially through hole 218 of the collar portion 177 of the sleeve 172 and is secured in position by a weld bead 219a. With reference to the elevational and cross-sectional assembly drawing of FIG. 8, the RCC sleeve 172 is axially aligned with and receives therein the downwardly extending calandria extension 58. Flange 58a is received in an annular recess 152 in the lower calandria plate 52 and secured in position by weld bead 153. Tapered end surface 58b of the calandria extension 58 facilitates the alignment and telescoping insertion thereof into the generally axially aligned, cylindrical boundary defined by the interior surfaces 217b of the lip portions 217 of the springs 210. It will be understood that the annular gap between the calandria extension 58 and the load pick-up surface 177a of the collar portion 177 of sleeve 172 is slightly greater than the radial depth of the intervening lip portions 177, and that the latter normally exert a lateral, radially inward resilient force, produced by flexible shank 215, against the exterior surface of the calandria extension 58. The lateral force of the leaf springs 210 serves to stabilize and maintain alignment of the sleeve 172 and thereby the RCC rod guide 28, as against the influences of flow-induced lateral loading during normal reactor operation, the frictional, axially oriented loading force as well serving to stabilize the RCC rod guide 28 against vertical displacement and in turn stabilizing the spaced relationship between the upper core plate 19 and the lower calandria plate 52. Excessive lateral forces acting on the RCC rod guide 28, as may occur during normal operating conditions or as a result of accident situations (seismic or LOCA) and which exceed the center biasing effect of the leaf springs 210, are transferred to the non-yielding, load pick-up surface 177a of the continuous annular collar portion 177 and directly through the intervening lip portion 217 of the correspondingly positioned leaf spring 210 to the calandria extension 58 and into the lower calandria plate 52. As best seen in FIG. 6, and taken in conjunction with the broken-away and hidden view of the RCC rod cluster 30 in FIG. 8, the sleeve 172 is configured internally to permit telescoping passage therethrough of the RCC rod cluster 30 including the RCC spider 147 which is connected to drive rod 145 and the associated RCC control rods; more particularly, the sleeve 172 includes passageways 224 extending radially from the axis and centrally of the arms 172a, having rounded openings 225 and 226 respectively corresponding to the vanes 147c and 147d and the mounting hubs 147a and 147b for the respective, radially displaced RCC rods 30a and 30b, the vanes being connected to a central hub 147e of the RCC spider 147 mounted on the drive rod 145. Thus, when the calandria 50 is removed from an engaged position with the sleeve 172, the corresponding RCC cluster 30 may be withdrawn vertically and in sliding, telescoping relationship relatively to the RCC rod guide 28 and through the sleeve 172, without requiring any disassembly of the latter. As noted, the RCC top end supports 36 are less massive than the WDRC top end supports 38, as is permissible in view of the smaller lateral forces which must be reacted thereby. On the other hand, the smaller spatial envelope presents alternative design constraints. By way of comparison, the height of the RCC sleeve 172 may be approximately 7.25 inches and the cross-sectional width of the central portion, as seen in cross-section in FIG. 8, approximately 4.75 inches. The width of the arms 172a may be 1.75 inches and the radial length thereof, from the central axis, 6.25 inches. The leaf springs 210 may have a height of approximately 6.6 inches, the shank portion 215 tapering from 0.45 inches to approximately 0.20 inches adjacent the arcuate lip portion 217. The sidewall of the sleeve 172 tapers outwardly from an interior diameter of approximately 3.5 inches at the bottom to 4 inches at the top, thereby affording the clearance gap relative to the calandria extension 58, the latter having an outer diameter of approximately 3 inches, within which gap the arcuate segment lip portions 217 of the leaf spring are received. The specific configuration and structural dimensions of the WDRC and RCC top end supports as provided hereinabove are significant, in that they establish the capability of achieving a practical implementation in accordance with the design configurations as set forth herein, despite the extremely limited spatial envelope available therefor within the reactor internals, taking further into account the necessity of accommodating the requisite flow passages and the like. While of relatively low size, they afford the necessary structural strength for reacting both axial and transverse loading forces and yet are compliant for ease of performing assembly and disassembly operations. Nevertheless, they are of reduced complexity, affording reduced costs of manufacture and installation. Numerous modifications and adaptations of the present invention will be apparent to those of skill in the art and thus it is intended by the appended claims to cover all such modifications and adaptations as fall within the true spirit and scope of the invention.
	abstract	An inspection apparatus for inspecting jet pump beams of nuclear reactors is provided. The inspection apparatus includes a base straddlingly mountable on a jet pump beam. The base includes a beam bolt opening sized to receive a jet pump beam bolt. A first transducer holder is coupled to a first side portion of the base, and a second transducer holder coupled to a second side portion of the base. The first side portion is opposed to the second side portion. Each holder includes an adjustment cylinder configured to contact the jet pump beam when activated.
054835623	claims	1. A device for volume delimitation when working with radioactively contaminated parts within the device, such as a control rod for a nuclear power plant for preventing contamination of a total volume of liquid medium surrounding the device and forming a pool, such as a nuclear reactor pool, said device comprising a transportable tank with a substantially horizontal bottom part and with substantial vertical side walls and an open top, means within the tank connectable with cleaning equipment for the cleaning of liquid medium delimited within the tank, wherein at least the side walls are foldable and are comprised of a material of synthetic fibers of a strength resistant to puncture, the material comprising polyethylene. 2. A device for volume delimitation when working with radioactively contaminated parts within the device, such as a control rod for a nuclear power plant, for preventing contamination of a total volume of liquid medium surrounding the device and forming a pool, such as a nuclear reactor pool, said device comprising a transportable tank with a substantially horizontal bottom part and with substantially vertical side walls and an open top, means within the tank connectable with cleaning equipment for the cleaning of liquid medium delimited within the tank, wherein at least the side walls are foldable and are comprised of a material of organic or synthetic fibers of a strength resistant to puncture, the material comprising at least one layer of fabric. 3. A device according to claim 2, wherein the material comprises a plurality of laminated fabric layers forming a stiff plate. 4. A device for volume delimitation when working with radioactively contaminated parts within the device, such as a control rod for a nuclear power plant, for preventing contamination of a total volume of liquid medium surrounding the device and forming a pool, such as a nuclear reactor pool, said device comprising a transportable tank with a substantially horizontal bottom part and with substantially vertical side walls and an open top, means within the tank connectable with cleaning equipment for the cleaning of liquid medium delimited within the tank, wherein at least the side walls are foldable and are comprised of a material of organic or synthetic fibers of a strength resistant to puncture, the material comprising at least one layer of cloth. 5. A device according to claim 4, wherein the material comprises a plurality of laminated cloth layers forming a stiff plate. 6. A device according to claims 1, 2 or 4, wherein the side walls of the tank have fold notches. 7. A device according to claims 1, 2 or 4 wherein the side walls of the tank comprise channels detachably mounted to the bottom part. 8. A device according to claims 1, 2 or 4, wherein the side walls of the tank are formed of a sack which is detachably mounted to the bottom part. 9. A device according to claims 1, 2 or 4, wherein the bottom part is made as a part integral with the side walls. 10. A device according to claims 1, 2 or 4 wherein a gas hood is arranged in the tank for exhaustion of gas evolved during the work. 11. A device according to claims 1, 2 or 4, wherein the bottom part is of stainless steel. 12. A device according to claims 1, 2 or 4, where in the bottom part is made of aluminum. 13. A device according to claims 1, 2 or 4, wherein support rods capable of being dismantled are arranged to support the side walls in at least the vertical direction, said support walls being of the same material as the side walls. 14. A device according to claims 1, 2 or 4, wherein support rods capable of being dismantled are arranged to support the side walls in at least the vertical direction, said support rods being of aluminum. 15. A device according to claims 1, 2 or 4, wherein the tank is provided with a sluice for passing objects in and out, whereby only a small liquid volume need be cleaned between each transport. 16. A device according to claims 1, 2 or 4, wherein at least one section of the side walls is separately raisable and lowerable for passing objects in and out. 17. A device according to claims 1, 2 or 4, wherein at least two wall sections, one inner and one outer, are arranged to overlap each other, forming a flow passage between the reactor pool and the interior of the tank. 18. A device according to claim 21, wherein the inner wall section can be pushed against the outer wall section for sealing the flow passage. 19. A device according to claim 1, 2 or 4, wherein at least said side walls are combustible. 20. A device for volume delimitation when working with radioactively contaminated parts within the device, such as a control rod for a nuclear power plant, for preventing contamination of a total volume of liquid medium surrounding the device and forming a pool, such as a nuclear reactor pool, said device comprising a transportable tank with a substantially horizontal bottom part and with substantially vertical side walls and an open top, means within the tank connectable with cleaning equipment for the cleaning of liquid medium delimited within the tank, wherein at least the side walls are foldable and are comprised of a material of organic or synthetic fibers of a strength resistant to puncture, and a stand for separated scrap being arranged in the tank. 21. A device for volume delimitation when working with radioactively contaminated parts within the device, such as a control rod for a nuclear power plant, for preventing contamination of a total volume of liquid medium surrounding the device and forming a pool, such as a nuclear reactor pool, said device comprising a transportable tank with a substantially horizontal bottom part and with substantially vertical side walls and an open top, means within the tank for cleaning liquid medium delimited within the tank, wherein at least the side walls are foldable and are comprised of a material of organic or synthetic fibers of a strength resistant to puncture, and the tank having a water transmitting inner sack.
047770163	summary	BACKGROUND OF THE INVENTION This invention relates to a fuel assembly for a light water reactor, and more particularly to a fuel assembly having a water rod suitable for reducing a pressure loss and improving the core reactivity gain. A boiling water reactor is provided with a plurality of fuel assemblies in a core thereof so that the fuel assemblies are spaced from one another. Each fuel assembly consists of a plurality of fuel rods, water rods, upper and lower tie plates, spacers and a channel box. The water rods are provided with holes in the upper and lower portions of their side surfaces, and a coolant is passed through the interior of each of the water rods via these holes. In the interior of the fuel assembly, the coolant of water flows to remove the thermal energy which occurs due to a reaction of a fission substance existing in the fuel rods. The water also flows in the spaces among the fuel assemblies, i.e. the exterior of the channel box. The water functions also as a moderator. The fast neutrons flying out into the water turn into moderated thermal neutrons due to the water. When such thermal neutrons collide with a fission substance, a fission reaction occurs. However, voids occur due to the heat generated by the fuel rods in the channel box. The spaces among the fuel rods are narrower than those among the fuel assemblies, and the former contains more water than the latter. Accordingly, the local atomic ratio of water to fuel in the central portion of the fuel assembly becomes smaller than that in the peripheral portion thereof. As a result, it is difficult for the fast neutrons be moderated in the central portion of the fuel assembly, so that the thermal neutron flux therein tends to become low. This causes the fuel rod power distribution in the fuel assembly to become unbalanced, and has a disadvantageous effect on the economy of fuel. In order to solve this problem, a moderator-container or the water rod is provided in the fuel assembly, which is disclosed in, for example, Japanese Patent Laid-open No. 40986/1975. In recent years, a method of increasing the exposure of a fuel for the purpose of improving the economical efficiency of a nuclear power plant, and of increasing the the diameter of a water rod so as to improve the water to fuel atomic ratio and thereby cope with the increase in the enrichment of fuel has been studied. Providing a large-diameter water rod or a container, in which a moderator, such as water is held, in the central portion of a fuel assembly is disclosed in Japanese Patent Laid-open Nos. 40986/1975 and 13981/1984. It is known that, owing to such a water rod or container, the distribution of thermal neutron flux in a fuel assembly becomes uniform to cause the simplification of the enrichment distribution and an increase in the reactivity, which enable the economical efficiency of the fuel to be improved. However, if the diameter of the water rod is increased, the cross-sectional area of the flow passage for a coolant in the fuel assembly decreases. This causes an increase in the pressure loss and a decrease in the thermal margin. Therefore, it is necessary that a suitable countermeasure be provided. SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel assembly having a water rod which is capable of minimizing a pressure loss while maintaining an atomic ratio of water to fuel in an optimum level. Briefly stated, the present invention resides in a fuel assembly having a water rod the length of which is reduced to such an extent that does not disadvantageously affect the nuclear characteristics of the fuel, thereby to reduce a friction pressure loss, which occurs due to the steam-liquid two phase flow, to a low level. An aspect of the present invention is characterized in that the water rod is larger in diameter than that of the fuel rod and has a height substantially as high as the upper end of an effective enriched fuel section of the fuel rod.
	claims	1. A scanning probe microscope comprising a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip, wherein;the electrostatic surface actuator includes a movable member that has a first surface and a stationary member that has a second surface;the movable member includes a first plurality of electrodes disposed on the first surface;the stationary member includes a second plurality of electrodes disposed on the second surface;the movable member is resiliently coupled to the stationary member so that the first and second surfaces are disposed in a confronting relationship and so that the movable member is capable of being displaced with respect to the stationary member in a first direction;the first and second electrodes are configured to generate electrostatic forces in response to voltages applied thereto, the electrostatic forces being aligned to displace the movable member in the first direction generally parallel to the first and second surfaces; andthe movable member is mechanically attached to the scanning probe tip such that the scanning probe tip in controllably positioned by displacement of the movable member;wherein the voltage applied to one of said first plurality of electrodes differs from the voltage applied to at least one other of said first plurality of electrodes by a predetermined amount. 2. The microscope of claim 1, wherein the scanning probe tip includes at least one of:an atomic force microscope tip;a magnetic force microscope tip;a scanning tunneling microscope tip; anda scanning field emission tip. 3. A scanning probe microscope comprising a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip, wherein;the electrostatic surface actuator includes a movable member that has a first surface and a stationary member that has a second surface;the movable member includes first electrodes disposed on the first surface;the stationary member includes second electrodes disposed on the second surface;the movable member is resiliently coupled to the stationary member so that the first and second surfaces are disposed in a confronting relationship and so that the movable member is capable of being displaced with respect to the stationary member in a first direction;the first and second electrodes are configured to generate electrostatic forces in response to voltages applied thereto, the electrostatic forces being aligned to displace the movable member in the first direction generally parallel to the first and second surfaces;the movable member is mechanically attached to the scanning probe tip such that the scanning probe tip in controllably positioned by displacement of the movable member;the movable member constitutes a first movable member;the electrostatic surface actuator further includes a second movable member having a third surface;the second movable member further includes a third plurality of electrodes disposed on the third surface;the first movable member has a fourth surface and includes a fourth plurality of electrodes disposed on the fourth surface; andthe third and fourth pluralities of electrodes are configured to generate electrostatic forces in response to voltages applied to the third and fourth plurality of electrodes, the electrostatic forces being aligned to laterally displace the movable member in a second direction generally orthogonal to the first direction and generally parallel to the first and second surfaces. 4. The microscope of claim 3, wherein:the first movable member includes a first plurality of flexures that are attached to the stationary member;the flexures of the first plurality of flexures have a structural property to resiliently yield to movement of the first movable member relative to the stationary member such that the first movable member may be displaced relative to the stationary member in the first direction;the second movable member includes a second plurality of flexures that are attached to the first movable member; andthe flexures of the second plurality of flexures have a structural property to resiliently yield to movement of the second movable member relative to the first movable member such that the second movable member may be displaced relative to the first movable member in the second direction. 5. The microscope of claim 4, wherein the scanning probe tip includes at least one of:an atomic force microscope tip;a magnetic force microscope tip;a scanning tunneling microscope tip; anda scanning field emission tip. 6. The microscope of claim 3, further comprising a piezoelectric actuator, wherein;the piezoelectric actuator is disposed with respect to the electrostatic surface actuator so that the piezoelectric actuator is movable in a third direction, the third direction being generally orthogonal to both the first and second directions. 7. The microscope of claim 6, wherein the scanning probe tip includes at least one of:an atomic force microscope tip;a magnetic force microscope tip;a scanning tunneling microscope tip; anda scanning field emission tip. 8. A scanning probe microscope comprising a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip, wherein:the electrostatic surface actuator includes a movable member that has a first surface and a stationary member that has a second surface;the movable member includes first electrodes disposed on the first surface;the stationary member includes second electrodes disposed on the second surface;the movable member is resiliently coupled to the stationary member so that the first and second surfaces are disposed in a confronting relationship and so that the movable member is capable of being displaced with respect to the stationary member in a first direction;the first and second electrodes are configured to generate electrostatic forces in response to voltages applied thereto, the electrostatic forces being aligned to displace the movable member in the first direction generally parallel to the first and second surfaces; andthe movable member is mechanically attached to the scanning probe tip such that the scanning probe tip in controllably positioned by displacement of the movable member;further comprising a two-dimensional actuator, wherein:the two-dimensionally actuator is capable of displacing a mounting stage in each of a second direction and a third direction;the second and third directions are generally orthogonal; andthe electrostatic surface actuator is mounted on the mounting stage so that the first direction is defined normal to a plane of the second and third directions. 9. The microscope of claim 8, wherein the two-dimensional actuator is one of a two-dimensional piezoelectric actuator and a two-dimensional electrostatic surface actuator. 10. The microscope of claim 8, wherein:the scanning probe tip includes a cantilever, andthe cantilever is inclined with respect to the plane of the second and third directions by an offset angle sufficient to ensure that a clearance is maintained between the electrostatic surface actuator and a sample to be measured. 11. The microscope of claim 10, wherein the offset angle is greater than 0 degrees and less than or equal to 10 degrees. 12. A scanning probe microscope comprising a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip, wherein:the electrostatic surface actuator includes a movable member that has a first surface and a stationary member that has a second surface;the movable member includes first electrodes disposed on the first surface;the stationary member includes second electrodes disposed on the second surface;the movable member is resiliently coupled to the stationary member so that the first and second surfaces are disposed in a confronting relationship and so that the movable member is capable of being displaced with respect to the stationary member in a first direction;the first and second electrodes are configured to generate electrostatic forces in response to voltages applied thereto, the electrostatic forces being aligned to displace the movable member in the first direction generally parallel to the first and second surfaces; andthe movable member is mechanically attached to the scanning probe tip such that the scanning probe tip in controllably positioned by displacement of the movable member; andwherein the first electrodes are positioned on the first surface of the movable member such that a repeat distance associated with the first electrodes divided by a gap distance between the first electrodes and the second electrodes is less than approximately sixteen. 13. A scanning probe microscope comprising a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip, wherein;the electrostatic surface actuator includes a movable member that has a first surface and a stationary member that has a second surface;the movable member includes first electrodes disposed on the first surface;the stationary member includes second electrodes disposed on the second surface;the movable member is resiliently coupled to the stationary member so that the first and second surfaces are disposed in a confronting relationship and so that the movable member is capable of being displaced with respect to the stationary member in a first direction;the first and second electrodes are configured to generate electrostatic forces in response to voltages applied thereto, the electrostatic forces being aligned to displace the movable member in the first direction generally parallel to the first and second surfaces; andthe movable member is mechanically attached to the scanning probe tip such that the scanning probe tip in controllably positioned by displacement of the movable member; andwherein:the electrodes of the first electrodes are thin strips of conductive material that are positioned substantially in parallel with each other on the first surface;the electrodes of the second electrodes are thin strips of conductive material that are positioned substantially in parallel with each other on the second surface anda first electrode of the first electrodes is positioned substantially in parallel with a first electrode of the second electrodes. 14. A scanning probe microscope comprising a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip, wherein;the electrostatic surface actuator includes a movable member that has a first surface and a stationary member that has a second surface;the movable member includes first electrodes disposed on the first surface;the stationary member includes second electrodes disposed on the second surface;the movable member is resiliently coupled to the stationary member so that the first and second surfaces are disposed in a confronting relationship and so that the movable member is capable of being displaced with respect to the stationary member in a first direction;the first and second electrodes are configured to generate electrostatic forces in response to voltages applied thereto, the electrostatic forces being aligned to displace the movable member in the first direction generally parallel to the first and second surfaces; andthe movable member is mechanically attached to the scanning probe tip such that the scanning probe tip in controllably positioned by displacement of the movable member; andfurther comprising a voltage controller, wherein:the voltage controller is electrically coupled to the second electrodesthe voltage controller is capable of selectively providing voltages to the second electrodes that vary along the second electrodes such that predetermined voltage patterns are established; andthe predetermined voltage patterns define the electrostatic forces between the movable member and the stationary member. 15. The microscope of claim 14, further comprising a voltage source, wherein:the voltage source is electrically coupled to the first electrodes; andthe voltage source is configured to apply a repeating spatially alternating voltage pattern to the first electrodes. 16. A scanning probe microscope comprising a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip, wherein;the electrostatic surface actuator includes a movable member that has a first surface and a stationary member that has a second surface;the movable member includes first electrodes disposed on the first surface;the stationary member includes second electrodes disposed on the second surface;the movable member is resiliently coupled to the stationary member so that the first and second surfaces are disposed in a confronting relationship and so that the movable member is capable of being displaced with respect to the stationary member in a first direction;the first and second electrodes are configured to generate electrostatic forces in response to voltages applied thereto, the electrostatic forces being aligned to displace the movable member in the first direction generally parallel to the first and second surfaces; andthe movable member is mechanically attached to the scanning probe tip such that the scanning probe tip in controllably positioned by displacement of the movable member;further comprising a voltage source, wherein:the voltage source is electrically coupled to the first electrodes; andthe voltage source is configured to apply a repeating spatially alternating voltage pattern to the first electrodes. 17. The microscope of claim 1, wherein:the movable member includes a plurality of flexures that are attached to the stationary memory; andthe flexures have a structural property to yield to movement of the movable member such that the movable member may be displaced in the first direction. 18. A scanning probe microscope comprising a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip, wherein;the electrostatic surface actuator includes a movable member that has a first surface and a stationary member that has a second surface;the movable member includes first electrodes disposed on the first surface;the stationary member includes second electrodes disposed on the second surface;the movable member is resiliently coupled to the stationary member so that the first and second surfaces are disposed in a confronting relationship and so that the movable member is capable of being displaced with respect to the stationary member in a first direction;the first and second electrodes are configured to generate electrostatic forces in response to voltages applied thereto, the electrostatic forces being aligned to displace the movable member in the first direction generally parallel to the first and second surfaces; andthe movable member is mechanically attached to the scanning probe tip such that the scanning probe tip in controllably positioned by displacement of the movable member;further comprising dielectric fluid disposed between the first and second surfaces. 19. A scanning probe microscope comprising a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip, wherein;the electrostatic surface actuator includes a movable member that has a first surface and a stationary member that has a second surface;the movable member includes first electrodes disposed on the first surface;the stationary member includes second electrodes disposed on the second surface;the movable member is resiliently coupled to the stationary member so that the first and second surfaces are disposed in a confronting relationship and so that the movable member is capable of being displaced with respect to the stationary member in a first direction;the first and second electrodes are configured to generate electrostatic forces in response to voltages applied thereto, the electrostatic forces being aligned to displace the movable member in the first direction generally parallel to the first and second surfaces; andthe movable member is mechanically attached to the scanning probe tip such that the scanning probe tip in controllably positioned by displacement of the movable member;further comprising:a first hydrophobic dielectric film disposed on the movable member; anda second hydrophobic dielectric film disposed on the stationary memory. 20. A method of scanning a sample using a surface electrostatic actuator, the method comprising:mounting a probe on a movable member of the surface electrostatic actuator having a plurality of electrodes;displacing the movable member relative to a stationary member in a direction generally parallel to the surface of the movable member to scan the probe over the sample by applying voltages to said electrodes, wherein the voltage applied to one of said plurality of electrodes differs from the voltage applied to at least one other of said plurality of electrodes by a predetermined amount;sensing a property of the probe in responsive to the scan of the probe over the sample. 21. The method of claim 20, further comprising displacing the movable member in a second direction generally orthogonal to the first direction and generally parallel to the surface of the movable member. 22. The method of claim 21, further comprising displacing the movable member in a third direction generally orthogonal to both the first and second directions. 23. The method of claim 20, further comprising displacing the electrostatic surface actuator within a plane, wherein a cantilever of the probe tip is inclined with respect to the plane by an offset angle sufficient to ensure that a clearance is maintained between he electrostatic surface actuator and the sample. 24. The method of claim 23, further comprising displacing the movable member in a second direction generally orthogonal to the first direction and generally parallel to the surface of the movable member.
	abstract	A device for centering a temperature measurement device inside a tube reactor that will be filled with catalyst, including a single inflatable bladder mechanically and fluidically attached to a centering ring.
	summary
	summary
	claims	1. A charged particle beam apparatus comprising:a charged particle beam optical system that irradiates a specimen housed in a specimen chamber with a primary charged beam, detects a secondary charged particle beam generated from the specimen, and outputs a signal of a detection result;first potential measuring means measures potentials on a surface of the specimen at a plurality of locations on a line segment including a center location of the specimen before irradiation of the specimen with the primary charged beam during transfer of the specimen towards a specimen stage of the charged particle beam optical system;height measurement means, which measures a height of the surface of the specimen on the specimen stage before irradiation of the specimen with the primary charged beam; anda control unit that controls the charged particle beam optical system on a basis of height information obtained by height measurement means and potential information obtained by the first potential measurement means,wherein the control unit:estimates a potential distribution for the line segment by a first interpolation on a basis of the potentials measured by the first potential measuring means before irradiation of the specimen with the primary charged beam; andestimates a potential at any location on the specimen by a second interpolation in a circumferential direction of the specimen on a basis of the potential distribution estimated along the line segment before irradiation of the specimen with the primary charged beam. 2. A charged particle beam apparatus comprising:a charged particle beam optical system that irradiates a specimen housed in a specimen chamber with a primary charged beam, detects a secondary charged particle beam generated from the specimen, and outputs a signal of a detection result;first potential measuring means which measures potentials on a surface of the specimen at a first plurality of locations on a first line segment including a center location of the specimen, before irradiation of the specimen with the primary charged beam during transfer of the specimen towards a specimen stage of the charged particle beam optical system;second potential measuring means, which measures potentials on a surface of the specimen at a second plurality of locations on a second line segment parallel to the first line segment, before irradiation of the specimen with the primary charged beam and during transfer of the specimen towards the specimen stage of the charged particle beam optical system;third potential measuring means, which measures potentials on a surface of the specimen at a third plurality of locations on a third line segment parallel to the first line segment and such that the first line segment is interposed between the second line segment and the third line segment, before irradiation of the specimen with the primary charged beam and during transfer of the specimen towards the specimen stage of the charged particle beam optical system;a control unit that controls the charged particle beam optical system on a basis of potential information obtained by the first, second and third potential measurement means,wherein the control unit:estimates potential distributions for each of the first line segment, second line segment and third line segment using a first interpolation on a basis of the potentials measured by the first potential measuring means, second potential measuring means and third potential measuring means, respectively,estimates a potential distribution for a circular area of the surface of the specimen by a second interpolation in a circumferential direction of the specimen on a basis of the potential distribution of the first line segment included in the circular area, where the circular area is defined by a center location corresponding to the central location of the specimen and a radius equal to a distance between the first line segment and the third line segment, andestimates a potential distribution of an outer area defined by a periphery of the specimen and the circular area by a third interpolation in a circumferential direction of the specimen on a basis of the potential distributions of the first line segment, second line segment and third line segment included in the outer area. 3. A charged particle beam apparatus comprising:a charged particle beam optical system that irradiates a specimen housed in a specimen chamber with a primary charged beam, detects a secondary charged particle beam generated from the specimen, and outputs a signal of a detection result;first potential measuring means which measures potentials on a surface of the specimen at a first plurality of locations in a circumferential direction of the specimen along a circle defined by a center location of the specimen before irradiation of the specimen with the primary charged beam during transfer of the specimen towards a specimen stage of the charged particle beam optical system;second potential measuring means, which measures potentials on a surface of the specimen at a second plurality of locations on a line segment including the center location of the specimen, before irradiation of the specimen with the primary charged beam during transfer of the specimen towards a specimen stage of the charged particle beam optical system;a control unit that controls the charged particle beam optical system on a basis of potential information obtained by the first and second potential measuring means,wherein the control unit:estimates a potential distribution for the line segment by a first interpolation on a basis of the potentials measured by the second potential measuring means at the plurality of second locations before irradiation of the specimen with the primary charged beam,estimates a potential distribution for the circle by a second interpolation in a circumferential direction of the specimen on a basis of the potentials measured by the first potential measuring means before irradiation of the specimen with the primary charged beam, andestimates a potential at any location on the surface of the specimen by a third interpolation in a circumferential direction of the specimen on a basis of the potential distribution estimated along the line segment and the potential distribution estimated for the circle before irradiation of the specimen with the primary charged beam. 4. A charged particle beam apparatus of claim 1,further comprising: a transfer mechanism for transferring the specimen into the specimen chamber; andthe first potential measuring means is provided on a transfer path for the transfer mechanism to transfer the specimen. 5. A charged particle beam apparatus of claim 2,further comprising: a transfer mechanism for transferring the specimen into the specimen chamber; andthe first potential measuring means is provided on a transfer path for the transfer mechanism to transfer the specimen. 6. A charged particle beam apparatus of claim 3,further comprising: a transfer mechanism for transferring the specimen into the specimen chamber; andthe first potential measuring means is provided on a transfer path for the transfer mechanism to transfer the specimen. 7. A charged particle beam apparatus of claim 1,further comprising:a transfer mechanism for transferring the specimen into the specimen chamber;a specimen exchange chamber for storing the specimen temporarily before the specimen is brought into the specimen chamber; andthe measurement of the potentials at the plurality of locations is performed during a linear transfer operation of the transfer mechanism to transfer the specimen into the specimen exchange chamber. 8. A charged particle beam apparatus of claim 2,further comprising:a transfer mechanism for transferring the specimen into the specimen chamber;a specimen exchange chamber for storing the specimen temporarily before the specimen is brought into the specimen chamber; andthe measurement of the potentials by the first, second and third potential measurement means is performed during a linear transfer operation of the transfer mechanism to transfer the specimen into the specimen exchange chamber. 9. A charged particle beam apparatus of claim 3,further comprising:a transfer mechanism for transferring the specimen into the specimen chamber;a specimen exchange chamber for storing the specimen temporarily before the specimen is brought into the specimen chamber; andthe measurement of the potentials by the first and second potential measurement means is performed during a linear transfer operation of the transfer mechanism to transfer the specimen into the specimen exchange chamber. 10. A charged particle beam apparatus of claim 1, wherein:the control unit has a circumferential direction potential estimating means that executes the second interpolation. 11. A charged particle beam apparatus of claim 1, wherein:the first potential measuring means measures potentials on a line segment including a center of the specimen and a notch on the specimen. 12. A charged particle beam apparatus of claim 2, wherein:the first potential measuring means measures potentials on a line segment including a center of the specimen and a notch of the specimen. 13. A charged particle beam apparatus of claim 3, wherein:the first potential measuring means measures potentials on a line segment including a center of the specimen and a notch of the specimen. 14. A charged particle beam apparatus of claim 11, further comprising: an aligner that performs angle adjustment of the specimen relative to the notch. 15. A charged particle beam apparatus of claim 1, wherein:spline interpolation is employed for the first interpolation and the second interpolation. 16. A charged particle beam apparatus of claim 1, wherein:a plurality of potential measuring means including the first potential measuring means measure the potentials on the surface of the specimen at a plurality of locations on three to five line segments. 17. A method of controlling a charged particle beam apparatus, in which a specimen is measured on a basis of distribution data of secondary charged particles generated by irradiating the specimen with a charged particle beam, comprising:measuring a plurality of potentials on a line segment including a center of the specimen, before irradiation of the specimen with the primary charged beam and during transfer of the specimen towards a specimen stage of the charged particle beam optical system;estimating a potential distribution for the line segment by a first interpolation on a basis of the potentials measured on the line segment before irradiation of the specimen with the primary charged beam;estimating a potential at any location on a surface of the specimen by a second interpolation in a circumferential direction of the specimen on a basis of the potential distribution estimated along the line segment; andadjusting the charged particle beam apparatus according to the potential estimated by the second interpolation.
	abstract	Easily and correctly measuring a dimension of a pattern of a photomask or of an OPC pattern of the photomask.
	description	The present patent application claims priority from Japanese Patent Application No. 2005-007263 filed on Jan. 14, 2005. 1. Field of the Invention The present invention relates to an X-ray focusing device for used in X-ray monitors in outer space, or radiation counters or microanalyzers on the ground. 2. Description of the Background Art Differently from visible light, a normal-incidence optics is difficult to use for X-rays. Therefore, a grazing-incidence optics utilizing total reflection from a metal surface based on a property of metals, i.e. a refractive index less than one for X-rays, is used for X-rays. In view of the fact that a critical angle for the total reflection of X-rays has a small value of about 1 degree, the grazing-incidence optics has to be designed to ensure a sufficient effective area of a reflecting surface. In this context, there has been known a technique of concentrically arranging a plurality of metal cylindrical-shaped reflecting mirrors different in diameter. This technique, however, leads to a problem; namely an increase in total weight of an obtained X-ray reflecting device, which makes it difficult to transport the device from the ground for use in outer space. Further, each reflecting mirror in the X-ray reflecting device can have a certain level of reflectance only if its surface has smoothness to the degree of an X-ray wavelength. For this purpose, the conventional X-ray reflecting device has been prepared by subjecting each reflecting surface to a polishing process, so as to ensure a desired surface smoothness. As a measure to ensure the desired smoothness, there has been developed a technique of preparing a numbers of replica mirrors by pressing a thin film onto a polished master block (see “X-ray Imaging Optics, T. Namioka, K. Yamashita, BAIFUKAN Co., Ltd.”: Non-Patent Document 1). In either case, a number of reflecting mirrors have to be prepared one by one by spending a lot of time and effort. With the aim of achieving a reduction in weight, an X-ray reflecting device using silicon pore optics has also been proposed (see “Beijersbergen et al., (2004) Proc. SPIE Vol. 5488, pp. 868-874”: Non-Patent Document 6). This device comprises a plurality of polished silicon substrates each having a front surface serving as a reflecting mirror and a back surface formed with a groove for ensuring an X-ray optical path, wherein the adjacent silicon substrates are arranged in close contact with one another. However, this reflecting device is limited in weight reduction achieved, because the thickness (usually referred to as “P”) of walls which define slits (which corresponds to slits 121, 122, . . ., 12n in the undermentioned FIG. 1) is determined by a thickness (200 to 500 μm) of each of the silicon substrates. Moreover, the polished mirrors take a lot of time and effort to be prepared, as with the above metal-based device. While an optics using a glass fiber as an X-ray waveguide has recently come into practical use (see, for example, “Kumakov & Sharov (1992) Nature 357, 390”: Non-Patent Document 2), it involves a problem about an increase in cost. In view of the above problems, it is therefore an object of the present invention to provide an X-ray reflecting device and an X-ray reflecting element constituting the X-ray reflecting device, capable of facilitating a reduction in weight and being prepared in a relatively simple manner. In order to achieve this object, according to a first aspect of the present invention, there is provided an X-ray reflecting element comprising a body composed of a silicon or metal plate, and a plurality of slits formed in the body in such a manner as to penetrate from a front surface to a back surface of the body. Each of the slits has a wall surface serving as an X-ray reflecting surface. The slits are formed through an etching process when the body is composed of a silicon plate or through an X-ray LIGA process when the body is composed of a metal plate. In the X-ray reflecting element of the present invention, the X-ray reflecting surface may have a surface roughness of 100 angstroms or less, more preferably 30 angstroms or less. In the X-ray reflecting element of the present invention, the body may include fastening means for allowing a plural number of the X-ray reflecting elements to be fastened to each other. According to a second aspect of the present invention, there is provided an X-ray reflecting device comprising a plural number of the X-ray reflecting elements set forth in the first aspect of the present invention. To allow the slits in the respective X-ray reflecting elements to be located in a given positional relationship with each other, the plurality of X-ray reflecting elements are formed into a layered structure in such a manner as to allow the slits in the respective X-ray reflecting elements to be located in a given positional relationship with each other, or arranged side-by-side in a horizontal direction, or stacked on each other in a vertical direction to form a stacked structure in such a manner as to allow the slits in the respective X-ray reflecting elements to be located in a given positional relationship with each other. Further, the X-ray reflecting device may comprise a plural number of the stacked structures arranged side-by-side in a horizontal direction. In the X-ray reflecting device of the present invention, the plurality of X-ray reflecting elements may be arranged side-by-side, or stacked in a vertical direction, in such a manner as to allow the slits in the respective X-ray reflecting elements to be located in a given positional relationship with each other, so as to approximately form as an X-ray collecting/focusing optics based on a combination of the slits. As mentioned above, in the X-ray reflecting element of the present invention, the slits are formed in the body in a solid lump through an etching process when the body of the elements is composed of a silicon plate or through an X-ray LIGA process when the body of the elements is composed of a metal plate. This makes it possible to facilitate formation of the slits. Further, even at the current technical level, the etching process or X-ray LIGA process allows the slits to be formed with a wall surface roughness of at least 100 angstroms or less, or 30 angstroms or less, so that each wall surface of the slits can be used as a desirable X-ray reflecting surface. Thus, the X-ray reflecting element can be formed in a relatively simple manner. In addition, the etching process or X-ray LIGA process allows each of the slits to be formed with a micro-gap. Thus, the X-ray reflecting element can be reduced in size and weight to prevent an increase in weight of an X-ray reflecting device to be obtained by combining a plural number of the X-ray reflecting element together. This is significantly advantageous, particularly, for an X-ray reflecting device for use in outer space. With reference to the drawings, one embodiment of the present invention will now be described. FIG. 1 is a perspective view showing an X-ray reflecting element 10 according to one embodiment of the present invention. The X-ray reflecting element 10 illustrated in FIG. 1 generally has an approximately rectangular shape. The X-ray reflecting element 10 has a number of slits formed through an etching process to penetrate therethrough vertically. Specifically, the X-ray reflecting element 10 illustrated in FIG. 1 is prepared by placing a mask on a silicon wafer having a thickness L, and forming a number of slits 121, 122, - - - (when a specific one of the slits is not designated, each or all of the slits are defined by a reference numeral 12), each having a gap or width D, in a direction perpendicular to the silicon wafer at a pitch of about 10 μm or less through an anisotropic etching process or a combinational process of a dry etching process and an anisotropic etching process. The X-ray reflecting element 10 may be made of a metal material. In this case, a metal plate is prepared by forming a resist pattern having a negative configuration relative to that of the element in FIG. 1, and forming a structure with a number of slits through an X-ray LIGA process using the resist pattern as a template. The metal to be used as a material of the X-ray reflecting element may be nickel which has a high X-ray reflectance and a proven reliability in forming a structure through the X-ray LIGA process. In this embodiment, each side or lateral wall of the slits 12 formed in the above manner is used as a reflecting surface for X-rays. Specifically, an X-ray enters into either one of slits from above the X-ray reflecting element 10. Then, the X-ray is reflected by the lateral wall of the slit, and emitted out of the slit downward. From previous researches on semiconductor processes, it is know that, when such a lateral wall is formed by subjecting a silicon substrate to an anisotropic etching process, or a combinational process of an anisotropic etching process and another wet etching process or a dry etching process, or subjecting a metal substrate to an X-ray LIGA process, an extremely smooth surface having a surface roughness of about several ten angstroms can be obtained (see “Song et al., (1999) SPIE 3878, 375”: Non-Patent Document 3, “Kondo et al., 2000, Microsystem. Technologies, 6, 218: Non-Patent Document 4, “Nilsson et al., 2003, J. Micromech. Michroeng., 13, 57”: Non-Patent Document 5). However, there has been no conception of using such a wall as an X-ray mirror. In FIG. 1, a ratio D/L of the width D of the slit 12 to the thickness L of the X-ray reflecting element 10 will hereinafter be referred to as “aspect ratio”. An X-ray reflecting device capable of efficiently collecting or focusing X-rays can be achieved only if the aspect ratio is set approximately to a certain value near a critical angle for the total reflection of X-rays. If D=10 μm is achieved through an etching process, a conventional cylindrical-shaped X-ray reflecting device, which previously had a length (a length of an axis of the cylinder) of several cm to several ten cm, can have a length of 1 mm or less. It is known that an X-ray reflectance is a function of an X-ray energy, an X-ray incident angle and a surface roughness. FIG. 2 is a graph showing a calculation result of an X-ray reflectance. FIG. 2(A) shows changes in X-ray reflectance depending on an X-ray incident angle, under the conditions that an X-ray energy is fixed at 600 eV, and a surface roughness is fixed at 0, 30, 100 or 300 angstroms. FIG. 2(B) shows changes in X-ray reflectance depending on an X-ray energy, under the conditions that an X-ray incident angle is fixed at 0.1 degrees, and a surface roughness is fixed in the same manner as that in FIG. 2(A). At the current technical level, a silicon wafer can be subjected to an etching process to obtain a surface having a surface roughness of about 30 angstroms or less. As seen in FIGS. 2(A) and 2(B), on the assumption that the silicon wafer has a surface roughness of 30 angstroms, the silicon wafer exhibits an excellent reflectance substantially equal to an optimal surface (roughness=zero angstrom) for soft X-rays having an X-ray energy of 1 keV or less. Preferably, the lateral wall serving as a reflecting surface is formed to have a surface perpendicular to a principal surface or front and back surfaces of the silicon wafer, as shown in FIG. 1. For example, a silicon wafer having the (110) face along a front surface thereof is subjected to an etching process using a KOH solution as an etching liquid, in such as manner as to form a slit with a lateral surface having the (111) face perpendicular to the (110) face. Alternatively, a silicon substrate carved out to have a front surface slightly inclined relative to the (111) face may be subjected to an etching process to obtain a slit with a lateral wall slightly inclined relative to the front surface of the silicon substrate. For the anisotropic etching process, various etching liquids, such as TMAH and hydrazine, may be used as well as KOH. If it is necessary to form a deep opening so as to increase an effective area for reflection, a deep hole may be formed in a substrate through a dry etching process, and then subjected to an anisotropic etching process to smoothly finish a lateral wall thereof (see the Non-Patent Document 5). Instead of the X-ray reflecting element made of silicon prepared based on an anisotropic etch technique using a silicon wafer as shown in FIG. 1, an X-ray reflecting element made of metal, such as nickel, may be prepared by fabricating a resist pattern with a high degree of accuracy through an X-ray LIGA process, and electrodepositing nickel using the resist pattern as a template (see the Non-Patent Document 4). While a surface accuracy in this technique is determined by energy of irradiated light to be used in the X-ray LIGA process, a surface accuracy equal to or higher than that in a silicon substrate subjected to a wet etching process can be expected if X-rays having a high energy of 10 keV or more are used in the X-ray LIGA process. For example, such high-energy X-rays may be formed using a large-scale light radiation facility (Spring-8) of the Japan Synchrotron Radiation Research Institute. The metal plate-shaped X-ray reflecting element (not shown) prepared through the X-ray LIGA process may be used in the same manner as the aforementioned X-ray reflecting element made of silicon. The X-ray reflecting element prepared through the X-ray LIGA process has advantages, for example, of being able to use a metal having a larger atomic number than that of silicon so as to achieve a higher reflectance, and to allow the lateral wall of the slit to be formed as a curved surface so as to provide an enhanced X-ray focusing performance. While the X-ray reflecting element 10 in FIG. 1 generally has a rectangular shape, it may be formed to have a fan or sector shape, as shown in FIGS. 4 and 5 and described in detail later. The X-ray reflecting element 10 may be formed with concave and convex portions at a position where they do not hinder the original functions, e.g. in a peripheral portion or an upper or lower portion thereof. When a plural number of the X-ray reflecting elements 10 are stacked on each other or arranged side-by-side, as described later, the concave and convex portions are used for positioning and fastening the X-ray reflecting elements 10 to each other. FIG. 3 is a schematic diagram showing the level of reduction in weight in the X-ray reflecting element (on the right side in FIG. 3) in FIG. 1 as compared with a conventional X-ray reflecting mirror (on the left side in FIG. 3). If a single X-ray reflecting surface in the X-ray reflecting element according to this embodiment is downsized at a ratio of 1/C relative to that of the conventional mirror, the single X-ray reflecting surface will have a weight reduced in proportion to C−3, and a number density increased in proportion to C2. That is, an optics (e.g. an after-mentioned X-ray reflecting device 20 illustrated in FIG. 4) to be formed of a plural number of the X-ray reflecting elements according to this embodiment is reduced in weight in proportion to C−3+2=C−1 as a rough estimate. Further, as described above, the width and pitch of each slit of the X-ray reflecting element according to this embodiment can be set at a significantly small value of about 10 μm, or the value of C is extremely large. Thus, the optics can have a weight reduced by about two in a digit number. An X-ray reflecting device prepared by combining a plural number of the X-ray reflecting elements 10 in FIG. 1 together will be described below. FIG. 4 is a top plan view showing an X-ray reflecting device 20 prepared by closely arranging a plurality of the sector-shaped X-ray reflecting elements 10 to form a circular shape. FIGS. 5(A) and 5(B) are fragmentary sectional views of the X-ray reflecting device 20. As shown in FIGS. 5(A) and 5(B), four of the X-ray reflecting elements 10 are stacked in a vertical direction to form a stacked or layered structure, and X-rays enter into the slits of the X-ray reflecting elements 10 from above the drawing sheet of FIG. 4. As shown in FIG. 4, each of the X-ray reflecting elements 10 has a convex portion 101 and a concave portion 102 each formed at a given position in such a manner as to allow the convex portion 101 and the concave portion 102 formed, respectively, in the horizontally adjacent X-ray reflecting elements 10 to be fitted into one another. As described in connection with FIG. 1, a large number of slits are formed in each of the X-ray reflecting elements 10 in FIG. 5(A). In one arrangement illustrated in FIG. 5(A), as to an angle of the slits relative to a front surface in each of the X-ray reflecting elements, the slits of the X-ray reflecting element in the lower layer are increased in the slit angle as compared with that of the X-ray reflecting element in the upper layer, as shown in FIG. 5(A). This is intended to gradually incline the reflecting surfaces in a direction from the upper layer toward the lower layer within a range allowing the total reflection of X-rays to be maintained, so as to allow the X-rays to be finally focused onto a given zone. In another arrangement illustrated in FIG. 5(B), while an angle of each of the slits relative to a front surface in each of the X-ray reflecting elements 10 is designed to be the same, the X-ray reflecting elements 10 themselves are arranged to have a gradually increased inclination in a direction from the upper layer toward the lower layer, so as to allow the X-rays to be finally focused onto a given zone. For this purpose, a support member 24 is interposed between the adjacent X-ray reflecting elements to allow the slits in each of the layers to have a given angle. The X-ray reflecting device 20 obtained in the above manner can be significantly reduced in weight as compared with the conventional device, as described in connection with FIG. 3. This provides an advantage of being able to provide an X-ray reflection device suitable for transport for use in outer space, for example, in the state when the X-ray reflecting device 20 is placed on a satellite. FIG. 6 shows an X-ray reflecting device 30 prepared by stacking four of X-ray reflecting elements 10 in FIG. 1 on each other to form a stacked or layered structure as shown in FIG. 5, and then arranging a plural number of the stacked structures side-by-side along a hypothetical spherical surface, so as to form a so-called “lobster eye optics”. X-rays entering from above the X-ray reflecting device 30 are collected through the X-ray reflecting device 30, and focused onto a narrow zone on the side opposite to the incident side. Alternatively, an optics similar to a Woelter type I x-ray optics may be prepared by arranging a plural number of the X-ray reflecting elements 10 in a planar pattern while changing an inclination of each of the X-ray reflecting elements 10, to form a planar structure, and stacking two or four of the planar structures on each other. FIG. 7 is a graph (arbitrary unit) showing a simulation result of X-ray focusing to be obtained when X-rays enter in parallel into the X-ray reflecting device 30 in FIG. 6. According to this graph, a peak of the collected/focused X-ray can be observed in the center of the field of vision. FIG. 8 shows an optics prepared by arranging two of the X-ray reflecting devices 30 in FIG. 6. X-rays emitted from a single left point 34 are converted to parallel rays through the left X-ray reflecting device 301, and the parallel rays are re-focused onto a point 36 through the right X-ray reflecting device 302. The optics illustrated in FIG. 8 is one example of optics used on the ground. For example, the optics may be used in a microanalysis for detecting a slight amount of X-rays emitted from a target substance irradiated with electron beams from an electron beam source, to identify the substance. In particular, this optics can be effectively used when an X-ray detector cannot be placed at a position close to a target substance. As compared with the conventional device, each of the X-ray reflecting devices in FIGS. 6 and 8 can be drastically reduced in weight, and prepared in a simple manner.
	abstract	According to one embodiment, an X-ray computed tomography apparatus includes an X-ray tube to generate X-rays, X-ray detector to detect the X-rays transmitted through an object, top to place the object, rotation driving unit to rotate a rotating frame with the X-ray tube and the X-ray detector around the object, movement driving unit to relatively reciprocate the rotating frame and the top over a plurality of times along a long-axis direction of the top, and scan control unit to control the movement driving unit in the relative reciprocal movement such that moving loci of the X-ray tube corresponding to the respective forward movements are matched with each other and moving loci of the X-ray tube corresponding to the respective backward movements are matched with each other.
	claims	1. A reactor core of a fast neutron reactor, said reactor core comprising:a plurality of fuel rods; anda reactivity control rod disposed at a central portion of the reactor core for controlling a reactivity therein, said reactivity control rod comprising a wrapper tube surrounded by said plurality of fuel rods, and a plurality of neutron absorber rods arranged in parallel to one another in the wrapper tube, wherein at least one of the plurality of neutron absorber rods includes a cladding tube and a mixture filled in the cladding tube, wherein said mixture is composed of a first percentage of a neutron absorber that absorbs a neutron and a second percentage of a neutron moderator that moderates the neutron, wherein only one reactivity control rod is provided within the reactor core, wherein the neutron absorber is gadolinium and the neutron moderator is zirconium hydride, and wherein the second percentage is larger than the first percentage in an initial structure of the reactor core. 2. A reactor core according to claim 1, wherein each of the plurality of neutron absorber rods includes a cladding tube and the mixture filled in the cladding tube. 3. A reactor core according to claim 1, wherein no fuel rod is provided within said wrapper tube. 4. A reactor core according to claim 1, wherein the fuel rods and the reactivity control rod are arranged so as to provide a hexagonal shape. 5. A reactor core according to claim 1, wherein the wrapper tube has a hexagonal shape, and seven neutron absorber rods are provided withinthe wrapper tube. 6. A reactor core according to claim 2, wherein the wrapper tube has a hexagonal shape, and seven neutron absorber rods are provided within the wrapper tube.
	claims	1. A radiation blocking clothing material comprising:a first thread fiber, a second thread fiber and a third thread fiber, said first thread fiber, said second thread fiber and said third thread fiber being structured such that the radiation blocking clothing material has a first side and a second side, said first thread fiber and said second thread fiber being manufactured from a conductive material, said first side and said second side of the radiation blocking clothing material being comprised of different materials, said first side being comprised of said first thread fiber and said second thread fiber; andwherein the first thread fiber and second thread fiber having the conductive material are structured so as to be proximate each other and provide an electromagnetic shielding of at least 50 dB and wherein said first thread fiber is a FDY conductive metal thread fiber having a denier between the range of 70D to 94D. 2. The radiation blocking clothing material as recited in claim 1, wherein said second thread fiber is a DTY conductive metal thread fiber having a denier between the range of 80D to 95D. 3. The radiation blocking clothing material as recited in claim 2, wherein the first side of the radiation blocking clothing material has a surface resistance having a range between 0.01 to 0.5 ohms. 4. The radiation blocking clothing material as recited in claim 3, wherein the third thread fiber is cotton. 5. The radiation blocking clothing material as recited in claim 3, wherein the third thread fiber is a cotton synthetic blend material. 6. The radiation blocking clothing material as recited in claim 5, wherein the conductive metal is selected from one of the following: copper or silver. 7. The radiation blocking clothing material as recited in claim 5, wherein the conductive metal comprises between 48 to 62 percent of the radiation blocking clothing material. 8. The radiation blocking clothing material as recited in claim 7, wherein the radiation blocking material is utilized to manufacture undergarments. 9. A radiation blocking clothing material comprising:a body, said body being flexible in manner, said body having a first thread fiber, a second thread fiber and a third thread fiber, said first thread fiber, said second thread fiber and said third thread fiber being structured such that the body of the radiation blocking clothing material has a first side and a second side, said first side being manufactured from said first thread fiber and said second thread fiber, said first thread fiber and said second thread fiber including silver; andwherein the first thread fiber and second thread fiber are structured utilizing a double sided knit structure so as to be proximate each other in order to provide a low surface resistance for the first side of the body and provide an electromagnetic shielding of at least 50 dB. 10. The radiation blocking clothing material as recited in claim 9, wherein the first side of the body of the radiation blocking clothing material has a surface resistance having a range between 0.01 to 0.5 ohms. 11. The radiation blocking clothing material as recited in claim 10, wherein said first thread fiber is a FDY silver thread fiber having a denier between the range of 70D to 94D. 12. The radiation blocking clothing material as recited in claim 11, wherein said second thread fiber is a DTY silver thread fiber having a denier between the range of 80D to 95D. 13. The radiation blocking clothing material as recited in claim 12, wherein the silver thread fiber comprises between 48 to 62 percent of the radiation blocking clothing material. 14. The radiation blocking clothing material as recited in claim 13, wherein the third thread fiber is cotton. 15. The radiation blocking clothing material as recited in claim 13, wherein the third thread fiber is a cotton synthetic blend material. 16. A radiation blocking clothing material comprising:a body, said body being flexible in manner, said body having a first thread fiber, a second thread fiber and a third thread fiber, said first thread fiber, said second thread fiber and said third thread fiber being structured utilizing a double sided knit structure such that the body of the radiation blocking clothing material has a first side and a second side, said first side being manufactured from said first thread fiber and said second thread fiber, said first thread fiber and said second thread fiber including silver, said first thread fiber being a 84D FDY silver thread fiber, said second thread fiber being a 90D DTY silver thread fiber; andwherein the first thread fiber and second thread fiber are structured utilizing a double sided knit structure so as to be proximate each other in order to provide a resistance having a range between 0.01 to 0.5 ohms for the first side of the body and provide an electromagnetic shielding of at least 50 dB. 17. The radiation blocking clothing material as recited in claim 16, wherein the silver content of the first thread fiber and the second thread fiber comprises between 48 to 62 percent of the radiation blocking clothing material. 18. The radiation blocking clothing material as recited in claim 17, wherein the third thread fiber is cotton. 19. The radiation blocking clothing material as recited in claim 18, wherein the radiation blocking material is utilized to manufacture undergarments.
053696760	description	DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Illustrated schematically in FIG. 1 is a portion of a nuclear reactor building 10 which includes a conventional containment vessel 12 in which is supported a conventional reactor pressure vessel 14. Disposed inside the pressure vessel 14 is a conventional nuclear reactor core 16 having an outer cylindrical core shroud 18. The vessel 14 is illustrated without its conventional upper head thereon and without the typical assemblies disposed therein above the core 16 which have been conventionally removed therefrom in order to allow refueling of the core 16. Disposed above the vessels 12, 14 and the core 16 is a conventional upper, or refueling, pool 20 which is suitably filled with water during the refueling operation (not shown in FIG. 1, but shown in FIG. 2). Bridging the floor over the pool 20 is a conventional refueling gantry or platform 22 which conventionally operates to carry fuel bundles 24 one at a time from a storage area underwater through the pool 20 to above the core 16, with the telescoping mast of the refueling platform 22 then lowering the fuel bundle 24 into an empty one of the several cells 26 in the reactor core 16. In a typical boiling water reactor (BWR), the core 16 includes a two-dimensional horizontal array of the cells 26 defined by a top guide within the circular core shroud 18 with the cells 26 spaced inwardly from the perimeter having square configurations, with each cell 26 being configured for receiving four of the fuel bundles 24 side-by-side in a square array. During conventional operation, the refueling platform 22 begins the refueling cycle by removing one of the spent fuel bundles 24 from the core 16 upwardly through the pool 20 and then laterally therethrough for storage in a suitable location within a remote portion of the pool 20. A replacement fuel bundle 24 is retrieved from another storage location within the pool 20 and carried underwater laterally through the pool and then downwardly through the upper portion of the pressure vessel 14 and into the empty cell 26. Since only about 30 percent of the total number of fuel bundles 24 are typically replaced in each refueling cycle, many of the fuel bundles 24 must be temporarily removed from their respective cells 26 to allow the proper positioning of the replacement fuel bundles 24 and the shuffling of partially spent fuel bundles 24 between the various cells 26 of the core 16. To accomplish the total refueling operation with the single refueling platform 22 takes a substantial amount of time. Furthermore, the cells 26 are typically square, and the fuel bundles 24 are also square and configured for a relatively close fitting tolerance within the cells 26 which increases the difficulty and therefore the duration of the refueling process. Since the refueling platform 26 is located at a substantial elevation above the reactor core 16, for example about 30 meters, substantial time is required for close-in positioning of the fuel bundles 24 within their respective cells 26. In accordance with the present invention as illustrated in FIG. 2, a portable reactor refueling assembly or mechanism (RRM) 28 is temporarily positioned above the reactor core 16 by a conventional gantry crane (not shown) typically contained in the reactor building 10. The RRM 28 is preferably used in conjunction with the conventional refueling platform 22 to decrease the time required for completing the entire refueling process by shuffling the fuel bundles 24 between the various cells 26 in the core 16, as well as being used to remove spent fuel bundles 24 therefrom and insert replacement fuel bundles 24 therein, with the spent fuel bundles 24 being moved to a temporary location for final removal by the refueling platform 22, and with the replacement fuel bundles 24 being brought to a temporary location by the refueling platform 22 for pickup by the RRM 28. Since the RRM 28 is portable, it may be configured for resting on top of the open reactor pressure vessel 14 (not shown), or in the preferred embodiment illustrated in FIG. 2, the RRM 28 is positioned on the core shroud 18 inside the pressure vessel 14 and is therefore in close proximity to the reactor core 16. FIG. 3 illustrates with more particularity the RRM 28 resting on top of the core shroud 18 above the reactor core 16. The RRM 28 includes a rotating bridge 30 which spans the reactor core and is positioned directly above the core 16 and supported by the core shroud 18. Since the top of the core shroud 18 has an accurately machined surface, the RRM 28 preferably also includes an annular or ring rail 32 as shown in FIG. 3, and in cross section in FIG. 4, which is first positioned by the gantry crane on the top of the annular core shroud 18 for protecting the top of the core shroud 18 while providing a suitable surface for supporting the bridge 30 on the core shroud 18 above the core 16 and allowing movement thereof on the rail 32. As shown in FIG. 4, the rail 32 has a horizontal portion which rests atop the core shroud 18, and vertical, cylindrical flanges vertically aligned along the inner diameter of the core shroud 18 to form a generally T-transverse configuration. Disposed on the bridge 30 is at least one traveling trolley or carriage 34, and in the preferred embodiment illustrated in FIG. 3 a pair of identical trolleys 34 are carried thereon. Identical rotating elevators 36 are disposed on respective ones of the trolleys 34, with each elevator 36 including a vertically movable mast 38 having a conventional grapple 40 at a lower end thereof for releasably holding a load such as the fuel bundle 24 by its bail 24a. The grapple 40 may also be used for holding the conventional blade guides (not shown) of the cells 26 if desired. Referring again to FIG. 3, means are provided for selectively rotating the bridge 30 around the core 16 on the rail 32 relative to the vertical centerline axis of the core 16, with the rotating directions being illustrated by the double headed arrow designated R.sub.b. Means are also provided for selectively translating each of the trolleys 34 independently across or over the bridge 30, with the translation directions being illustrated by the double headed arrow labeled T. Means are also provided for selectively rotating each of the elevators 36 themselves on their respective trolleys 34, with the rotation directions being illustrated by the double headed arrow labeled R.sub.e. And, means are also provided for selectively vertically moving the mast 38 of each of the elevators 36 independently to position the respective grapples 40 vertically relative to the core 16, with the vertical directions being illustrated by the double headed arrow V. The grapple 40 may take any conventional form such as a simple hook (not shown), or a pair of grapple fingers as illustrated in FIG. 5, for conventionally releasably holding each of the fuel bundles 24 by their bails 24a for example. Accordingly, the RRM 28 illustrated in FIG. 3 may be used for positioning the grapple 40 at any desired one of the cells 26 of the core 16 for inserting therein or removing therefrom the fuel bundles 24. The combined rotation R.sub.b of the bridge 30 and the translation T of the trolley 34 is used to horizontally position the grapple 40 vertically above a desired cell 26 in the two-dimensional horizontal array. And, rotation R.sub.e of the elevator 36 may be used to rotate the square fuel bundle 24 carried by the grapple 40 to align it in its respective square cell 36 for accurate vertical insertion therein along the vertical direction V. Since the fuel cell array is checkerboard in pattern, and since the bridge 30 is configured for rotation around the core shroud 18, the rotation of the elevator 36 provides the required rotation of the square fuel bundle 24 being carried by the mast 38 for accurate alignment into its mating square space between adjacent fuel bundles 24 in its cell 26. Referring again to FIG. 3, the bridge 30 in this exemplary embodiment includes a center frame 42 in the form of two laterally spaced and parallel straight rails extending diametrally across the ring rail 32, and also includes first and second substantially identical end frames 44, 46 fixedly joined transversely on opposite ends of the center frame 42 in a generally I-configuration and disposed on the ring rail 32 by a plurality of spaced wheels 48 rotatably joined to the end frames 44, 46. The wheels 48 are part of the bridge rotating means which support the bridge 30 on the ring rail 32 and allow movement thereon, with a conventional bridge drive motor 50, such as an electrical motor, being joined to a respective one of the end frames 44, 46 for driving at least one of the wheels 48 on the rail 32 to rotate the bridge 30. In the embodiment illustrated in FIG. 3, a drive wheel 48 is positioned on each end of the respective end frames 44, 46, with each wheel 48 being powered independently by a separate motor 50 which may be conventionally operated to rotate the bridge 30 either clockwise or counterclockwise in the R.sub.b direction around the circumference of the core shroud 18 on the ring rail 32. In other embodiments, one motor 50 could be suitably configured to drive both of the wheels 48 on a respective end frame 44, 46. In other embodiments, the drive wheels 48 could be in the form of pinion gears, and the top of the ring rail 32 could have a complementary annular gear rack in a rack-and-pinion type driving arrangement. As shown in FIGS. 3 and 4, an idler wheel 48a is suitably mounted on each end of the center frame 42 equidistantly between the respective ends of the first and second end frames 44, 46 adjacent to the inner diameter of the ring rail 32 to further guide rotation of the bridge 30 circumferentially around the ring rail 32. An exemplary one of the trolleys 34 is illustrated with more particularity in FIG. 5, and is slidably disposed on the rails of the center frame 42 for translation therealong in the T direction. The trolley translation means may take any conventional form including, for example, a straight rack gear 52 fixedly joined to one of the rails of the center frame 42 and a cooperating trolley pinion gear 54 operatively joined thereto. A conventional trolley drive motor 56, such as an electrical motor, is suitably fixedly joined to the trolley 34 for driving the trolley pinion gear 54 to translate the trolley 34 fore or aft as desired in the T direction along the center frame 42 between the first and second end frames 44, 46. An exemplary one of the elevators 36 is illustrated schematically in FIG. 5 and includes an elongate, vertical, square housing 58 containing therein the mast 38 which may also be square for example. The housing 58 is rotatably supported on the trolley 34 by suitable bearings for allowing the rotation thereof in the R.sub.e direction. The elevator rotating means may take any conventional form including an external ring gear 60 suitably joined to the housing 58, and a conventional pinion gear 62, such as a worm gear, is operatively joined thereto with a conventional elevator drive motor 64, such as an electrical motor, being joined to the trolley 34 for driving the elevator pinion gear 62 to rotate the elevator housing 58 and the mast 38 therein in the R.sub.e direction about the vertical centerline axis thereof. Also shown schematically in FIG. 5 are exemplary means for moving the mast 38 in the vertical V direction which includes a conventional cable 66 suitably joined at one end to the top end of the mast 38 and at its opposite end to a takeup spool 68 at the top of the housing 58, with a conventional mast drive motor 70, such as an electrical motor, being operatively joined to the spool 68 to reel in or wind out the cable 66 for raising and lowering the mast 38. Other conventional means such as a ball-and-screw, or rack-and-pinion, may instead be used for suitably raising and lowering the mast 38. The grapple 40 illustrated in FIG. 5 is in the exemplary form of a pair of pivoting hooks or fingers which are suitably conventionally operated for grasping or releasing the fuel bundle bail 24a. The grapple 40 may take any other conventional form such as a simple fish-type hook for catching the bail 24a. Referring again to FIG. 3, conventional means are also provided for selectively controlling the bridge rotating means by the drive motors 50, the trolley traveling means by the trolley motor 56, and the elevator rotating means by the elevator motor 64, as well as the mast moving means by the mast motor 70, and the grapple 40 in a conventional fashion. Such control means are illustrated schematically as a programmable digital computer controller 72 operatively joined by suitable connections to all of the various drive motors 50, 56, 64, and 70 of the bridge 30 and the respective trolleys 34 and the elevators 36, as well as to the respective grapples 40. Where the respective motors are electrical motors, the controller 72 may be conventionally joined thereto by suitable electrical lines for selectively providing power thereto to operate the respective motors in opposite rotating directions for obtaining the required movements R.sub.b, T, R.sub.e, and V. The controller 72, therefore, is used to control and coordinate the several motors for positioning the grapple 40 at any desired or selected location (R.sub.b, T) in the two-dimensional horizontal plane above the reactor core 16, and at the selected elevation (V) at that location, and at a selected rotated position (R.sub.e) at that location for aligning, for example, the square fuel bundle 24 in its square receptacle. In the preferred embodiment, a pair of the trolleys 34 and elevators 36 are disposed on the center frame 42 of the bridge 30 and are independently controllable by the controller 72. In operation, one of the trolleys 34 may be positioned over a desired one of the cells 26 by rotating the bridge 30 either clockwise or counterclockwise in the R.sub.b direction and by translating the trolley 34 fore or aft in the T direction. In this way, the mast 38 and grapple 40 may be positioned directly above one of the fuel bundles 24, with the mast 38 being lowered adjacent to the bail 24a. The mast 38 may be rotated either clockwise or counterclockwise in the R.sub.e direction to align the grapple 40 with the bail 24a after which the grapple 40 suitably clasps the bail 24a. The mast 38 may then be raised for removing the captured fuel bundle 26 from its cell 26 for transfer to a temporary storage location or for insertion into a vacant one of the cells 26 at a different location in the core 16 for the reshuffling thereof. To insert one of the fuel bundles 24 into its cell 26, the bridge 30 is again rotated either clockwise or counterclockwise in the R.sub.b direction as required, and the trolley 34 is translated either fore or aft along the bridge 30 in the T direction to position the fuel bundles 24 directly over the required cell 26. The elevator 36 may then be rotated either clockwise or counterclockwise in the R.sub.e direction as required to align the square fuel bundle 24 over its square receptacle in the cell 26. The mast 38 may then be lowered for lowering the fuel bundle 24 accurately into the cell 26. The grapple 40 is then released for leaving the fuel bundle 24 in its cell 26. The two trolleys 34 and elevators 36 thereon are operated independently for separately removing or installing the fuel bundles 24 for further decreasing the overall time for accomplishing the refueling process. In an exemplary refueling cycle wherein about one third of the core fuel bundles are replaced and the remaining two thirds shuffled, the RRM 28 can reduce the refueling time up to about one third. The RRM 28 may be operated at the rate of three shuffles per shuffle of the refueling platform 22 and simultaneously therewith. For example, each time the refueling platform 22 either brings to the core 16 or removes therefrom one of the fuel bundles 24, the RRM 28 may be used to perform three shuffles of the fuel bundles 24 either into or from the respective cells 26. The RRM 28 may be operated from a suitably remote location for reducing or eliminating radiation exposure to the operator thereof. And, since the RRM 28 may be positioned closely adjacent to the core 16 by resting on the core shroud 18 in the preferred embodiment, accuracy of operation is improved resulting in shorter reshuffling times. As indicated above, the RRM 28 could be configured for being positioned on top of the pressure vessel 14 instead of the core shroud 18 which increases its distance from the core 16 but would nevertheless still improve the refueling operation, Upon completion of the refueling operation, the entire RRM 28 assembly is conventionally removed by the gantry crane and stored at a suitable location in the reactor building 10. While there have been described herein what are considered to be preferred and exemplary embodiments of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein, and it is, therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention.
055747582	abstract	A gamma-rays measurement method of radionucludes (iodine-131, cobalt-60, etc.) coexisting with radionuclides (nitrogen-13, fluorine-18, cobalt-58, etc.) each emitting a pair of annihilation gamma-rays, particularly in primary water of a nuclear reactor by the use of a gamma-ray spectrometric system which includes a primary detector for detecting the gamma-rays and the one annihilation gamma-rays as pulses, a secondary detector for detecting the other annihilation gamma-rays as pulses, and shield detector for detecting gamma-rays Compton-scattered and escaped from the primary to shield detectors as pulses. The method comprises counting the pulses of the secondary detector in anticoincidence with the pulses of the primary detector, thereby to reject the recording of the annihilation gamma-rays from the primary detector, thus minimizing the annihilation gamma-rays disturbing to the measurement, followed by determining count numbers of the gamma-rays. Detection limits of the gamma-rays can be elevated significantly thereby. Simultaneously, further anticoincidence counting of the shield detector with the primary detector can be conducted to diminish the Compton-scattered gamma-rays.
052395634	description	DETAILED DESCRIPTION OF THE INVENTION As depicted in the schematic drawing of FIG. 1, momentum flux of the plasma stream on target 10 is transferred via quartz rod 22 and carbon plug 12 to transducer 28, comprised of diaphragm 29 and capacitor 30. Quartz rod 22 is suspended by pairs of wires 14 and 16 from adjustable supports 18 and 20, respectively. Metal shield 34 protects pairs of wires 14 and 16 from plasma bombardment. Leads 24 and 26 allow for biasing and monitoring the temperature of target 10. Carbon target 10 is manufactured from ATJ graphite. It is shaped as two coaxial disks, roughly 1 and 3.5 cm in diameter, each 0.5 cm thick. The smaller disk has a coaxial hole 5 mm in diameter that allows it to be securely placed onto quartz rod 22. The diameter of the larger disk was chosen to exceed the diameter of the plasma jet by about 1 cm. Those skilled in the art will recognize that targets of different materials, shapes, and orientations may be substituted for target 10. Quartz rod 22 has an i.d. of 3 mm, an o.d. of 5 mm, and a length of 68.5 cm. Quartz is used because of its electrical insulating properties, light weight, rigidity even at elevated temperatures, and low thermal conductivity. Calculations show that, even after 1 hour of plasma bombardment of target 10 at 10 W/cm.sup.2, the temperature rise of quartz rod 22 at diaphragm 29 is less than 30 degrees centrigrade and that the increase in length of rod 22 will not alter calibration. Hollow quartz rod 22 provides a channel to run wires to target 10. This allows for electrical biasing of target 10 or monitoring the temperature of target 10 with a thermocouple (not shown) through leads 24 and 26. In applications where a magnetic field is present, it is advisable to orient leads 24 and 26 parallel to the field to avoid magnetic forces. Quartz rod 22 has a carbon plug 12 on the end opposite target 10 that presses against diaphragm 29. This distributes force evenly over diaphragm 29, preventing plastic distortion. Between carbon plug 12 and diaphragm 29 is cushion 27 which reduces bouncing of quartz rod 22 off of diaphragm 29 when an impulsive load is applied. Transducer 28 is comprised of diaphragm 29 and capacitor 30. In the preferred embodiment, transducer 28 is a Baratron.RTM., commonly used as a pressure sensor in the range 10.sup.-6 to 10.sup.4 mTorr for room-temperature gases. The Baratron.RTM. is a capacitance manometer, i.e. a pressure differential causes elastic deflection of a thin, tensioned, circular, metallic diaphragm 29 which is one electrode of a capacitor 30. From the specifications of the head used, forces in the range of 10.sup.-5 -10.sup.-1 N can be measured with an accuracy of 1%, once the conversion from pressure to force has been obtained. Use of Baratron.RTM. heads with higher pressure capabilities, to 10.sup.4 Torr, allows extension of the measurable force range to .about.10.sup.3 N. Other pressure transducers, such as piezoelectric or strain gauges or torsion pendula, may be used. However, they are less suitable for application in an intense magnetic field an pulsed plasma environment. Quartz rod 22 is maintained in a horizontal position by means of two pairs of .about.3-mil chromel wires 14 and 16 that suspend quartz rod 22 at points about 10 and 30 cm from target 10 and carbon plug 12, respectively. The exact location of each support pair is chosen to avoid integral and fractional length resonances in tube bending. At each suspension point each wire within pairs of wires 14 and 16 is at 45.degree. with respect to the vertical. Each pair of wires 14 and 16 is coplanar and perpendicular to the axis of rod 22. The length of each wire, controlled by adjustable micrometer-type mounts 18 and 20, is about 10 cm. This suspension allows only longitudinal, axial displacement of quartz rod 22. A thin metal shield 34 protects pairs of wires 14 and 16 from plasma bombardment. Quartz rod 22 and pairs of wires 14 and 16 are mounted in a stainless-steel vacuum housing 32 with port crosses for mounts 18 and 20. Diaphragm 29 is attached to one end of housing 32 by use of stainless-steel welded bellows 31. The length of bellows 31 is set with micrometer mount 33. This is used to control contact between carbon plug 12, damping cushion 27, and diaphragm 29 and is an essential element in the calibration routine. The pressure data output by transducer 28 (.chi.), the force F.sub..chi. exerted on target 10 by the plasma column, and the plasma momentum flux .PHI., are related by EQU .PHI.=F.sub..chi. /S.sub.plasma =.chi.S.sub.eff /S.sub.plasma(1) where S.sub.eff is the effective interaction area of diaphragm 29 and S.sub.plasma is the plasma cross section. For a circular tensioned diaphragm, deformed by a uniformly applied force, S.sub.eff can be easily calculated by analytic methods. But, because the exact shape of deformation caused by the contact of carbon plug 12 with diaphragm 29 is not readily measured, the apparatus needs to be calibrated to experimentally determine S.sub.eff. Calibration may be accomplished by several different methods, many of which rely on gravity. Referring to FIG. 1, in the preferred embodiment of the present invention calibration is accomplished by moving diaphragm 29 axially relative to quartz rod 22 using bellows 31. When diaphragm 29 is moved towards quartz rod 22, the angle .theta. of pairs of wires 14 and 16 with respect to vertical increases. The resulting increment in gravitational force .DELTA.F.sub.g, is related to displacement, .DELTA.x, of quartz rod 22 by EQU .DELTA.F.sub.g =M.omega..sub.0.sup.2 .DELTA.x=Mg sin .theta.(2) where g is the gravitational acceleration, M is the total mass of quartz rod 22 and attachment, e.g., target 10, and pairs of wires 14 and 16, and .omega..sub.0 is the free oscillation frequency of the pendulum. Mass is measured using a precision microbalance; natural frequency is measured using a pickup coil near target 10 and a small (<0.05 g) magnet, temporarily attached to target 10. The total mass of the pendulum and the pendulum frequency were found to be 34.225.+-.0.001 g and 16.16.+-.0.02 Hz, respectively. The force increment is related to transducer 28 output by EQU .DELTA.F.sub.g =.DELTA.XS.sub.eff. (3) Defining the output of transducer 28 as EQU R=.DELTA.X/.DELTA.x (4) from a gravitational loading, giving EQU S.sub.eff =M.omega..sub.0.sup.2 /R. (5) From a least squares fit of the pressure data versus diaphragm displacement shown in FIG. 2, we get R=103.06 mTorr/mm (with .sigma..sub.R =0.47 mTorr/mm) or R=1.374.times.10.sup.3 dyne/cm.sup.3 (with .sigma..sub.R =6 dyne/cm.sup.3), from which S.sub.eff =6.51.+-.0.04 cm.sup.2. (The geometrical area of diaphragm 29 is about 20 cm.sup.2.) This calibration yields the conversion of gauge pressure to applied force (both in practical units), EQU F.sub..chi. (grams)=8.86.+-.0.05.times.10.sup.-3 .chi.(mTorr).(6) To obtain the momentum flux, the cross-sectional area of the plasma must be known [Eq. (1)]. For a plasma which is uniform, measurements of momentum flux are averages over the plasma cross section. Transducer pressure data in FIG. 2 start at .about.30 mTorr. This value is a fixed offset applied to transducer 28 of the preferred embodiment by shortening the length of bellows 31 by use of micrometer mount 33. It is useful to preload cushion 27 between carbon plug 12 and diaphragm 29 to reduce compression during subsequent loads because motion of quartz rod 22 causes a reduction in force applied to transducer 28 by an amount Mg sin .theta.. Smaller preloads are to be used for detecting smaller forces. This method of calibration allows in situ recalibrations, without the need to vent housing 32 to air. Also, calibrations done with the apparatus exposed to air require a pumpable chamber on the back face of diaphragm 29. Without this pumpable chamber, exposure to atmospheric pressure causes the diaphragm to seat itself on the counter electrode. In the preferred embodiment the variable capacitor 30 comprising transducer 28 is part of an RF capacitance bridge that operates at 10 kHz. The high accuracy of transducer 28 requires an electronic averaging time of typically 10 cycles. This gives an intrinsic response time of 1 ms. (The response of the Baratron.RTM. to gas pressure changes can be longer due to vacuum conductances.) The response time of the present invention is longer, however, due to the natural frequency and mass of quartz rod 22, the natural frequency of diaphragm 29, and the small, but finite, compression of cushion 27. The compression of cushion 27 is approximately linear with applied force at low forces, but rapidly saturates at high forces. From the nonlinearity of the data in FIG. 2, at .chi..about.-55.35 mm, it appears that compression saturates at a F.sub.s <0.001 g, corresponding to a displacement of (F.sub.s /M.omega..sub.0).about.0.001 cm. This will add less than 1/4 an oscillation period to the response time of the apparatus, corresponding to .about.75 ms for the undamped pendulum and <30 ms for the damped pendulum. FIG. 3a is an idealized plot of response time of the present invention for the impulse of an He gas plasma onto a negatively biased target. The response time of the apparatus was measured using plasma pulses of varying duration from a linear plasma device. Short duration plasma pulses, <20 ms, provide a current to target 10. The force is essentially impulsive, followed by a decay time of .about.10 ms. The apparatus output rises to a peak about 25 ms after the impulse and then decays in a similar time. Plasma pulses of longer duration have a more complicated time evolution. Again there is a rapid rise, .about.1 ms in plasma current to target 10. This is followed by the same .about.10-ms decay to a valley roughly equal to 1/4 the peak value. This is followed by a rise in plasma current in 30 ms to a plateau that is about twice the amplitude of the valley. Measuring from the time of breakdown of the gas, the formation of the plasma takes about 50 ms to stabilize at the plateau level. When the plasma is terminated, the current drops to zero in about 1 ms. From that instant, the output signal falls to 1/e of its peak in 50 ms, as shown in FIG. 3b, for plasma pulses of two different durations. As depicted in the preferred embodiment, then, this invention enables measurement of momentum flux from an intense plasma stream onto surfaces defining the plasma boundary. It is particularly useful when the plasma stream is accompanied by high heat fluxes, in an intense magnetic field, and in a pulsed plasma environment. In other embodiments, the apparatus of the present invention may be applied as well to determine other forces in equally inhospitable environments, for example, the force of intense pulsed laser beams on material surfaces, or the force due to chemical reactions on a surface. The apparatus of the present invention may be used to measure static, slowly varying, and/or pulsed forces. The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments described explain the principles of the invention and practical applications and should enable others skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.
	claims	1. A method for removing cesium in a clay mineral, comprising:(a) mixing a cesium-contaminated clay mineral with hydrogen peroxide to induce interlayer expansion;(b) desorbing the cesium from the clay mineral by contacting the clay mineral with an ion-exchangeable cation; and(c) separating the desorbed cesium from the clay mineral. 2. The method of claim 1, wherein the clay mineral in step (a) includes a clay mineral having a 2:1 layered structure. 3. The method of claim 1, wherein the clay mineral in step (a) includes one or more selected from the group consisting of hydrobiotite, a smectite-based mineral, vermiculite, a mica-based mineral, and illite. 4. The method of claim 3, wherein the smectite-based mineral includes one or more selected from the group consisting of montmorillonite, beidellite, nontronite, hectorite, and sauconite. 5. The method of claim 3, wherein the mica-based mineral includes one or more selected from the group consisting of biotite, muscovite, phlogopite, and lepidolite. 6. The method of claim 1, wherein the hydrogen peroxide in step (a) is added as a 30 to 50% hydrogen peroxide aqueous solution. 7. The method of claim 1, wherein the cation in step (b) includes a divalent cation. 8. The method of claim 7, wherein the divalent cation is one or more selected from the group consisting of a magnesium ion, a calcium ion, and a barium ion. 9. A method for removing cesium in a clay mineral, comprising:(a) mixing a cesium-contaminated clay mineral with hydrogen peroxide to induce interlayer expansion;(b) desorbing the cesium from the clay mineral by mixing the clay mineral with an ion-exchangeable cation; and(c) separating the desorbed cesium from the clay mineral.
052805107	summary	BACKGROUND OF THE INVENTION The present invention pertains to nuclear fuel assemblies, and more particularly, to the coating of fuel assembly components. Although coating the inside of fuel assembly components has been recognized as providing significant advantages, the small inside diameters, high aspect ratios, and high costs of conventional coating processes, have stymied commercialization of such improved fuel assembly components. Two pending U.S. applications represent a significant advance in the state of the art in this respect. U.S. patent application Ser. No. 07/924,731, "Sputtering Process Burnable Poison Coating" (Bryan et al), is directed to a method for sputter coating the inside surface of a fuel assembly tubular component with absorber material such as a burnable poison or hydrogen getter. U.S. patent application Ser. No. 07/924,732, "Fuel Assembly Sputtering Process" (Bryan et al), is directed to a method for sputter coating the inside surface of fuel assembly tubular components such as nuclear fuel rods or control rod guide tubes, with wear or corrosion resistant material. The foregoing U.S. applications, the disclosures of which are hereby incorporated by reference, describe the so called Linear Magnetron Sputtering process as the preferred sputtering technique. The sputtering process disclosed in these applications requires active confinement of a plasma within the tubular substrate to be coated, as well as an active cooling system. SUMMARY OF THE INVENTION It is thus an object of the present invention to provide an apparatus and method for coating burnable poison material, wear resistant and corrosion resistant materials, or hydrogen getter materials, on the inner surface of nuclear fuel assembly tubular components such as fuel rods, control rods, poison rods instrument thimbles, and the like. It is a related object of the invention, to deposit microparticle coatings on the inside of nuclear fuel assembly components, by an apparatus and a process that is simpler and more cost effective than prior art sputtering. These objects are achieved by a method and apparatus for coating the inside surface of a tubular component of a nuclear fuel assembly, in which the component is supported within a vacuum chamber, and a source rod having an evaporatable field emitter structure is positioned within the component. The field emitter is formed of a material to be coated on the inside surface of the component. An electrical current is passed through the rod at an amperage sufficient to evaporate at least a portion of the emitter structure. The evaporated material of the emitter then deposits on and adheres to the component surface, as a microparticle coating. In some embodiments, the desired coating is a compound, such as BN, which cannot itself constitute the source rod. In such a case, the vacuum chamber is backfilled with a reactive gas, such as nitrogen, and the source rod material, such as boron, when evaporated from the emitter structure chemically reacts with the gas to form the compound, which adheres to the component inner surface. The invention facilitates coating the inside of fuel rod cladding and other components, with a high degree of uniformity. Moreover, the invention allows the simultaneous deposition of multiple atom species to form alloys. The crystal instructure of the coating can be adjusted by adjusting the incident ion energy with respect to the work pieces (i.e., component inner surfaces) to be coated. The small size and variable density of emitter arrays afford great flexibility in the nature of the coatings that can be deposited.
	claims	1. An inspecting apparatus comprising:a plurality of detectors each for receiving an electron beam emitted from a sample to acquire image data representative of the sample; anda switching mechanism for causing the electron beam to be incident on one of said plurality of detectors, wherein said plurality of detectors are disposed within the same vacuum chamber and wherein said switching mechanism comprises a deflector for selectively switching a traveling direction of the electron beam between one of said plurality of detectors and another one of said plurality of detectors, said one of said plurality of detectors being disposed at an angle with respect to an optical axis of said vacuum chamber and said another one of said plurality of detectors being disposed on said optical axis. 2. An inspecting apparatus as claimed in claim 1, wherein said one of said plurality of detectors comprises an EB-CCD sensor. 3. An inspecting apparatus as claimed in claim 2, wherein said EB-CCD sensor is operable to obtain 20-10000 electrons per pixel. 4. An inspecting apparatus as claimed in claim 1, wherein said another one of said plurality of detectors comprises any one of an EB-TDI sensor and a TDI sensor. 5. An inspecting apparatus as claimed in claim 4, wherein said TDI sensor is operable to obtain 10-1000 electrons per pixel. 6. An inspecting apparatus as claimed in claim 1, wherein said one of said plurality of detectors comprises an EB-CCD sensor and said another one of said plurality of detectors comprises any one of an EB-TDI sensor and a TDI sensor. 7. An inspecting apparatus as claimed in claim 6, wherein said EB-CCD sensor is operable to obtain 20-10000 electrons per pixel and said TDI sensor is operable to obtain 10-1000 electrons per pixel. 8. An inspecting apparatus as claimed in claim 1, wherein said electron comprises any one of a secondary electron, a reflected electron, a back-scattered electron and an Auger electron. 9. An inspecting apparatus as claimed in claim 1, wherein said electron comprises a photoelectron. 10. An inspecting apparatus as claimed in claim 1, further comprising a mapping optical system having a tablet lens which is dual telecentric. 11. An inspecting apparatus as claimed in claim 10, wherein said mapping optical system further comprises an ExB. 12. An inspecting apparatus as claimed in claim 1, wherein electrons emitted from the sample reach said plurality of detectors at least through a first lens, a first aperture, a second lens, a third lens, a second aperture and a fourth lens. 13. An inspecting apparatus as claimed in claim 1, further comprising an electric field adjusting lens. 14. An inspecting apparatus as claimed in claim 1, further comprising an electron source for irradiating electrons to the sample. 15. An inspecting apparatus as claimed in claim 1, wherein said electron beam has a rectangular or elliptic cross-section. 16. An inspecting apparatus as claimed in claim 1, further comprising an electromagnetic wave source for irradiating an electromagnetic wave to the sample. 17. An inspecting apparatus as claimed in claim 16, wherein the electromagnetic wave comprises any one of a UV ray, a DUV ray, an X ray and a laser beam. 18. An inspecting apparatus as claimed in claim 1, further comprising an electron source for irradiating electrons to the sample and an electromagnetic wave source for irradiating an electromagnetic wave to the sample. 19. An inspecting apparatus as claimed in claim 18, wherein the electromagnetic wave comprises any one of a UV ray, a DUV ray, an X ray and a laser beam. 20. An inspecting apparatus as claimed in claim 1, wherein the sample comprises any one of a wafer and an exposure mask. 21. An inspecting apparatus as claimed in claim 1, wherein said inspecting apparatus is used for a foreign material inspection. 22. An inspecting apparatus as claimed in claim 1, wherein said inspecting apparatus is used for defect inspection of a surface of the sample using a scattered beam from the sample. 23. An inspecting apparatus as claimed in claim 1, wherein said inspecting apparatus is used for pattern defect inspection. 24. An inspecting apparatus as claimed in claim 1, wherein said one of said plurality of detectors comprises any one of CCD sensors and EB-CCD sensors for conducting step-and-repeat inspection. 25. An inspecting apparatus as claimed in claim 1, wherein inspection is conducted on a cell by cell basis or a die by die basis. 26. An inspecting apparatus as claimed in claim 1, wherein inspection is conducted to detect misalignment in position of marks on upper and lower layers.
	abstract	An emergency core cooling system removes decay heat generated by a reactor core of a reactor system. A reactor vessel uses water as a coolant. A containment structure surrounds the reactor system. A reactor cavity surrounds the reactor vessel. A first cavity pipe extends into the reactor vessel and provides a recirculation loop of cooling water by discharging vapor generated in the reactor vessel and supplying condensed water collected in the reactor cavity in an opposite direction.
	claims	1. A spacer grid for a nuclear fuel assembly including a plurality of elongated fuel rods and a coolant flowing over the fuel rods, the spacer grid comprising:a plurality of interlocking grid straps forming a plurality of four-walled cells structured to support the fuel rods therein, the four-walled cells each including four cell walls having a longitudinal axis; anda plurality of mixing vanes extending from each of the grid straps, each of the mixing vanes including a middle ligament directly extending from a top portion of a corresponding one of the grid straps, an upper piece extending from an upper portion of the middle ligament, and a lower piece extending from a lower portion of the middle ligament,wherein each of the upper piece and the lower piece has at least one of a predetermined bend angle and a predetermined degree of twist, and the middle ligament has at least one of a predetermined rotation angle and a predetermined degree of twist, in order to provide a predetermined affect on the coolant as it flows over the fuel rods and through the fuel assembly. 2. The spacer grid of claim 1, wherein the middle ligament extends in a substantially orthogonal direction with respect to the longitudinal axis of the cell wall. 3. The spacer grid of claim 1, wherein at least one of the upper piece and the lower piece of at least one of the mixing vanes is bent leftwardly or rightwardly with respect to the longitudinal axis of the cell wall, wherein the longitudinal axis is parallel to a vertical coolant flow stream through the fuel assembly. 4. The spacer grid of claim 1, wherein each of the grid straps has a corresponding plane; and wherein the middle ligament of at least one of the mixing vanes is rotated with respect to the plane. 5. The spacer grid of claim 1, wherein the middle ligament includes at least one pivot point; and wherein the middle ligament is twisted with respect to at least one of the at least one pivot point. 6. The spacer grid of claim 1, wherein at least one of the upper piece and the lower piece of at least one mixing vane is twisted. 7. The spacer grid of claim 1, wherein the upper piece is bent towards the four-walled cell structured to support a fuel rod; and wherein the lower piece is bent away from the four-walled cell structured to support a fuel rod, wherein both the upper piece and lower piece are bent with respect to the same longitudinal axis in order to provide the mixing vane with a generally S-shaped configuration. 8. The spacer grid of claim 1, wherein the upper piece is bent towards an adjacent one of the fuel rods; and wherein the lower piece is also bent toward the adjacent one of the fuel rods, in order to provide the mixing vane with a generally parabolic shape. 9. The spacer grid of claim 1, wherein one said mixing vane is extending from each cell wall of the spacer grid. 10. The spacer grid of claim 1, wherein the grid straps interlock in a generally perpendicular configuration in order to form the four-walled cells; and wherein at least one of the four-walled cells of the spacer grid includes four mixing vanes. 11. A nuclear fuel assembly comprising:a plurality of elongated fuel rods;anda plurality of spacer grids for securing the elongated fuel rods in an organized array, at least one of the plurality of spacer grids comprising:a plurality of interlocking grid straps forming a plurality of four-walled cells for supporting the fuel rods therein, each of the four-walled cells including four cell walls having a longitudinal axis, anda plurality of mixing vanes extending from each of the grid straps, each of the mixing vanes including a middle ligament directly extending from a top portion of a corresponding one of the grid straps, an upper piece extending from an upper portion of the middle ligament, and a lower piece extending from a lower portion of the middle ligament,wherein each of the upper piece and the lower piece has at least one of a predetermined bend angle and a predetermined degree of twist, and the middle ligament has at least one of a predetermined rotation angle and a predetermined degree of twist, in order to provide a predetermined affect on a coolant as it flows over the fuel rods and through the fuel assembly. 12. The nuclear fuel assembly of claim 11, wherein the middle ligament extends in a substantially orthogonal direction with respect to the longitudinal axis of the cell wall. 13. The nuclear fuel assembly of claim 11, wherein at least one of the upper piece and the lower piece of at least one of the mixing vanes is bent leftwardly or rightwardly with respect to the longitudinal axis of the cell wall, wherein the longitudinal axis is parallel to a vertical coolant flow stream through the fuel assembly. 14. The nuclear fuel assembly of claim 11, wherein each of the grid straps has a corresponding plane; and wherein the middle ligament of at least one of the mixing vanes is rotated with respect to the plane. 15. The nuclear fuel assembly of claim 11, wherein the middle ligament includes at least one pivot point; and wherein the middle ligament is twisted with respect to at least one of the at least one pivot point. 16. The nuclear fuel assembly of claim 11, wherein at least one of the upper piece and the lower piece of at least one mixing vane is twisted. 17. The nuclear fuel assembly of claim 11, wherein the upper piece is bent towards the four-walled cell structured to support a fuel rod; and wherein the lower piece is bent away from the four-walled cell structured to support a fuel rod, wherein both the upper piece and lower piece are bent with respect to the same longitudinal axis in order to provide the mixing vane with a generally S-shaped configuration. 18. The nuclear fuel assembly of claim 11, wherein the upper piece is bent towards an adjacent one of the fuel rods; and wherein the lower piece is also bent toward the adjacent one of the fuel rods, in order to provide the mixing vane with a generally parabolic shape. 19. The nuclear fuel assembly of claim 11, wherein one said mixing vane is extending from each cell wall of the spacer grid. 20. The nuclear fuel assembly of claim 11, wherein the grid straps interlock in a generally perpendicular configuration in order to form the four-walled cells; and wherein at least one of the four-walled cells of the spacer grid includes four mixing vanes. 21. The spacer grid of claim 1, wherein the bend angle and/or the degree of twist of the upper piece being independent from the bend angle and/or the degree of twist of the lower piece. 22. The nuclear fuel assembly of claim 11, wherein the bend angle and/or the degree of twist of the upper piece being independent from the bend angle and/or the degree of twist of the lower piece. 23. A spacer grid for a nuclear fuel assembly including a plurality of elongated fuel rods and a coolant flowing over the fuel rods, the spacer grid comprising:a plurality of interlocking grid straps forming a plurality of four-walled cells structured to support the fuel rods therein, the four-walled cells each including four cell walls having a longitudinal axis; anda plurality of mixing vanes extending from each of the grid straps, each of the mixing vanes including a middle ligament extending from a top portion of a corresponding one of the grid straps, an upper piece extending from an upper portion of the middle ligament, and a lower piece extending from a lower portion of the middle ligament,wherein each of the upper piece and the lower piece has at least one of a predetermined bend angle and a predetermined degree of twist, the bend angle and/or the degree of twist of the upper piece being independent from the bend angle and/or the degree of twist of the lower piece, and the middle ligament has at least one of a predetermined rotation angle and a predetermined degree of twist, in order to provide a predetermined affect on the coolant as it flows over the fuel rods and through the fuel assembly. 24. The spacer grid of claim 23 wherein the middle ligament is directly extending from a top portion of a corresponding one of the grid straps. 25. A nuclear fuel assembly comprising:a plurality of elongated fuel rods; anda plurality of spacer grids for securing the elongated fuel rods in an organized array, at least one of the plurality of spacer grids comprising:a plurality of interlocking grid straps forming a plurality of four-walled cells for supporting the fuel rods therein, each of the four-walled cells including four cell walls having a longitudinal axis, anda plurality of mixing vanes extending from each of the grid straps, each of the mixing vanes including a middle ligament extending from a top portion of a corresponding one of the grid straps, an upper piece extending from an upper portion of the middle ligament, and a lower piece extending from a lower portion of the middle ligament,wherein each of the upper piece and the lower piece has at least one of a predetermined bend angle and a predetermined degree of twist, the bend angle and/or the degree of twist of the upper piece being independent from the bend angle and/or the degree of twist of the lower piece, and the middle ligament has at least one of a predetermined rotation angle and a predetermined degree of twist, in order to provide a predetermined affect on a coolant as it flows over the fuel rods and through the fuel assembly. 26. The nuclear fuel assembly of claim 25, wherein the middle ligament is directly extending from a top portion of a corresponding one of the grid straps. 27. A spacer grid for a nuclear fuel assembly including a plurality of elongated fuel rods and a coolant flowing over the fuel rods, the spacer grid comprising:a plurality of interlocking grid straps forming a plurality of four-walled cells structured to support the fuel rods therein, the four-walled cells each including four cell walls having a longitudinal axis; anda plurality of mixing vanes extending from each of the grid straps, each of the mixing vanes including a middle ligament extending from a top portion of a corresponding one of the grid straps, an upper piece extending from an upper portion of the middle ligament, and a lower piece extending from a lower portion of the middle ligament,wherein each of the upper piece and the lower piece has at least one of a predetermined bend angle and a predetermined degree of twist, and the middle ligament has at least one of a predetermined rotation angle and a predetermined degree of twist, in order to provide a predetermined affect on the coolant as it flows over the fuel rods and through the fuel assembly, and wherein the upper piece and lower piece are structured such that the upper and lower pieces are not directly extending from a top portion of a corresponding one of the grid straps. 28. The spacer grid of claim 27 wherein the middle ligament is directly extending from a top portion of a corresponding one of the grid straps. 29. The spacer grid of claim 27 wherein the bend angle and/or the degree of twist of the upper piece being independent from the bend angle and/or the degree of twist of the lower piece.
	abstract	Scintillators of various constructions and methods of making and using the same are provided. In some embodiments, a scintillator comprises at least one radiation absorption region and at least one spatially discrete radiative exciton recombination region.
	summary
	abstract	A fuel assembly attains high burnup and increases reactor shut-down margin when loaded into a reactor core wherein a water gap width on a control rod side and a water gap width on a side opposite to the control rod side are almost equal to each other. The fuel assembly has a plurality of fuel rods arranged in a square lattice pattern, each fuel rod being filled with nuclear fuel pellets and also has at least one neutron moderator rod shifted toward one corner where a control rod is inserted, away from a cross sectional center of the fuel assembly.

Subsets and Splits

No community queries yet

The top public SQL queries from the community will appear here once available.