Abstract: Hydrogen infused nuclear reactor core monoliths and processes for their production are disclosed. Such monoliths may function as both a core monolith and a moderator, providing structure and at least some moderation. Hydrogen infused monoliths may be complementary to or be used in lieu of separate moderators for thermalizing neutrons.

Abstract: A closed-vessel molten salt reactor (cvMSR) is described herein. A cvMSR may comprise a suspended container, such as a metallic container, within a trench surrounded by a concrete enclosure and a concrete cover having a number of channels. The suspended container may be hollow and a solution of fissile materials and salt materials may be provided within the suspended container. The solution may be capable of undergoing a chain reaction nuclear fission process once a threshold temperature is reached. Heat generated by the solution may heat a fluid surrounding the suspended container. The heated fluid may be transported, through the number of channels of the concrete cover, to an external location where the heated fluid may be used in distributing heat and/or electricity generation.

Abstract: A composite moderator medium for nuclear reactor systems and a method of fabricating a composite moderator block formed of the composite moderator medium. The composite moderator medium includes two or more moderators, such as a low moderating material and a high moderating material. The high moderating material has a higher neutron slowing down power compared to the low moderating material. The low moderating material includes a moderating matrix of silicon carbide or magnesium oxide. The high moderating material is dispersed within the moderating matrix and includes beryllium, boron, or a compound thereof. The high moderating material is encapsulated within the low moderating material such that the high moderating material is not exposed outside of the low moderating material. The method can include selecting a sintering aid and a weight percent of the sintering aid in a composite moderator mixture based on the low moderating material and spark plasma sintering.

Abstract: A precursor formulation of a silicon carbide material that includes a ceramic material and a boron-11 compound. The ceramic material may include silicon and carbon and, optionally, oxygen, nitrogen, titanium, zirconium, aluminum, or mixtures thereof. The boron-11 compound may be a boron-11 isotope of boron oxide, boron hydride, boron hydroxide, boron carbide, boron nitride, boron trichloride, boron trifluoride, boron metal, or mixtures thereof. A material for use in a nuclear reactor component is also disclosed, as are such components, as well as a method of producing the material.

Abstract: A fast reactor 1 controlled with a reflector comprises: a reactor vessel 7 accommodating therein a coolant 5; a reactor core 2 disposed in the reactor vessel 7 and immersed in the coolant 5; and a reflector 4 that vertically moves for adjusting leakage of neutrons generated from the reactor core 2 to control a reactivity of the reactor core 2, the reflector 4 including a neutron reflecting part 4a disposed on an outside of the reactor core 2 in a vertically movable manner, the neutron reflecting part 4a having a neutron reflecting ability higher than that of the coolant 5, and a cavity part 4b positioned above the neutron reflecting part 4a, the cavity part 4b having a neutron reflecting ability lower than that of the coolant 5. The neutron reflecting part 4a is formed of a plurality of metal plates 37 that are stacked on each other. Each of the metal plates 37 has a plurality of coolant channels 36 through which the coolant 5 flows.

Abstract: A method for fabricating a supermirror for forming a neutron guide. In the method, a neutron supermirror, which is widely used in the formation of thin films in cold neutron guides and the spectrometer field, is fabricated with nickel thin films and titanium thin films, having varying thickness, using a combination of monochromator structures in which nickel thin films and titanium thin films, having the same thickness, are stacked in the form of periodic structures. According to the method, a combination of monochromator structures having a variety of different thicknesses is formed, such that the amount of the overlap of peaks due to the monochromator structures can be adjusted to increase reflectivity, and some of the monochromator structures can be removed during the fabrication of the supermirror to make it easy to extract monochromatic beams, such that it is easy to fabricate a transmission monochromator, rather than a reflection monochromator.

Abstract: A method for transmuting spent fuel from a nuclear reactor includes the step of separating the waste into components including a driver fuel component and a transmutation fuel component. The driver fuel, which includes fissile materials such as Plutonium239, is used to initiate a critical, fission reaction in a reactor. The transmutation fuel, which includes non-fissile transuranic isotopes, is transmuted by thermal neutrons generated during fission of the driver fuel. The system is designed to promote fission of the driver fuel and reduce neutron capture by the driver fuel. Reacted driver fuel is separated into transuranics and fission products using a dry cleanup process and the resulting transuranics are mixed with transmutation fuel and re-introduced into the reactor. Transmutation fuel from the reactor is introduced into a second reactor for further transmutation by neutrons generated using a proton beam and spallation target.

Abstract: The subject of the present invention is to provide a nuclear reactor plant of which is a direct cycle nuclear reactor using a carbon dioxide as a coolant such that a heat evacuation for liquefying coolant is reduced while a compressive work is reduced by using a condensation capability of a carbon dioxide for enhancing a cycle efficiency. The nuclear reactor plant is comprised of a nuclear reactor 1, a turbine 2, and wherein, the coolant of supper critical state is heated by a heat of a nuclear reactor to directly drive a turbine, a gaseous coolant discharged from said turbine is chilled and compressed after said turbine is driven for keeping in a critical state, and then said coolant is circulated again into said nuclear reactor, and wherein, a carbon dioxide is used as said coolant, and a predetermined ratio of gaseous coolant discharged from said turbine is liquefied for being compressed in a liquid state while a rest of gaseous coolant is compressed in a gaseous state.

Abstract: A process for the treatment of radioactive graphite which includes the following steps: (i) reacting the radioactive graphite at a temperature in the range of from 250° C. to 900° C. with superheated steam or gases containing water vapor to form hydrogen and carbon monoxide; (ii) reacting the hydrogen and carbon monoxide from step (i) to form water and carbon dioxide; and (iii) reacting the carbon dioxide of step (ii) with metal oxides to for carbonate salts. The process enables radioactive graphite, such as graphite moderator, to be treated either in-situ or externally of a decommissioned nuclear reactor.

Abstract: A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

Abstract: Method of fabricating a multi-ply carbon fibre fabric, preform or composite material from a layer of unidirectionally aligned carbon fibres of ultra-high modulus and a layer of low modulus carbon fibre comprising the steps of: arranging in superimposed relationship the layer of unidirectionally aligned carbon fibres of ultra-high modulus and the layer of low modulus carbon fibres so that at least a substantial number of the fibres of low modulus are disposed transversely of the fibres of the ultra-high modulus fibre layer, and connecting the two layers by interlacing fibres of the layer of low modulus fibres with those of the layer of ultra-high modulus fibres by needle-punching using felting needles orientated and configured so that their barbs snag only the low modulus fibres during passage through the layers.

Abstract: Deposition of radioactive cobalt on the interior surfaces of a water-cooled nuclear reactor and intergranular stress corrosion cracking are inhibited or substantially prevented by the continuous injection of zinc oxide to the reactor water. The zinc oxide may be prepared in the form of a paste, a slurry, or a preformed aqueous solution.

Abstract: A new design for nuclear reactor internals resulting in reduced fast neutron leakage to the reactor vessel. The first step of the two-stage process reflects high energy or fast neutrons back into the core, by placement of a reflector made of tungsten, stainless steel, or zirconium oxide in the baffle barrel region. The second stage involves reducing the energy of any fast neutrons that may pass through the reflector by the use of a neutron energy reducer, composed of an hydrogenous material such as titanium hydride, surrounding the core barrel in the areas of high neutron flux. In addition to protecting the reactor vessel wall and increasing the operating life of a nuclear reactor, the neutron economy in the core, and hence the operating efficiency of a nuclear power plant, are significantly increased.

Abstract: A gas-cooled high temperature reactor having a core filled with spherical fuel elements is provided comprising a graphite side reflector including at least one nose-like projection comprised of a plurality of graphite nose stones stacked one upon the other, said nose stones each including at least one vertically disposed continuous cavity aligned with at least one vertically disposed continuous cavity in adjacent nose stones, said cavity adapted to receive discrete absorber material elements introduced into the reactor core, said nose stones further including at least one vertically aligned continuous gap which extends into said nose stones from a front portion thereof and is aligned with a corresponding continuous gap in adjacent nose stones, communication between said continuous gap and said cavity being prevented, said nose stones also comprising in top and bottom surfaces thereof sealing means which enable adjacent nose stones to be stacked in a manner sufficient to seal said at least one cavity in a gas-

Abstract: A fuel assembly including a channel box, upper and lower tie plates, fuel rods inserted in the channel box and held at upper and lower end portions by the upper and lower tie plates, a water rod disposed among the fuel rods and spacers for keeping the fuel rods and the water rod spaced from one another. The water rod has a diameter larger than that of each of the fuel rods and the upper end of the water rod has a height substantially as high as an upper end of an effective enriched fuel section of each fuel rod.

Abstract: Deposition of radioactive cobalt on the interior surfaces of a water-cooled nuclear reactor is inhibited or substantially prevented by the continuous injection of zinc oxide to the reactor water. The zinc oxide may be prepared in the form of a paste, a slurry, or a preformed aqueous solution.

Abstract: In water-cooled nuclear reactors where zinc is added to the water to remove or lessen the accumulation of radioactive cobalt, radioactivity arising from the zinc itself as a result of neutron capture is lessened or eliminated entirely by modifying the isotopic composition of the zinc prior to its injection into the system. The modification of the isotopic composition consists of lowering the proportion of .sup.64 Zn or removing this isotope entirely.

Abstract: For safety in storage and transport of nuclear fuel elements outside a nuclear reactor core, they are provided with a coating of a neutron-absorbing substance from a liquid phase, e.g. by immersion, spraying or pouring, utilizing a melt, a solution or immersion so that the possibility of critical mass attainment is eliminated or minimized.

Abstract: A thermionic energy conversion system assembly is described which comprises a fissionable nuclear fuel which surrounds a cylindrical arrangement of thermionic emitter electrodes which surround corresponding collector electrodes, which in turn surround a cylindrical container of a heat sink material, such as lithium hydride, which can absorb large amounts of waste heat energy through a phase change. The heat sink material may also act as a nuclear moderator to reduce the amount of required nuclear fuel. A heat pipe is enclosed within the container of heat sink material to remove waste heat stored in the material. A thermionic energy conversion module is described which comprises 100 stacked-in-series thermionic converter assemblies. A complete space-based thermionic nuclear reactor is described which comprises an array of 91 thermionic converter modules wherein the heat pipes connect to a lithium hydride radiation shield which acts as a further heat sink.

Abstract: A process and an installation for the securing against excessive pressure in a prestressed concrete pressure vessel of a gas cooled high temperature reactor and for the prevention of activity release into the environment. The process comprises three steps and in each step pressure reducing installations become effective upon the rise of pressure in the prestressed concrete pressure vessel over a predetermined value. In the first step the pressure vessel is relieved by means of the operational gas purification apparatus and a conveying blower into the storage vessels for the cooling gas. In case of a further rise in pressure, in a second step a discharge path equipped with a safety valve and a check valve is opened, which also relieves into the storage vessels while by-passing the gas purification installation.

Abstract: An apparatus for irradiating a continuously flowing stream of fluid is diosed. The apparatus consists of a housing having a spherical cavity and a spherical moderator containing a radiation source positioned within the spherical cavity. The spherical moderator is of lesser diameter than the spherical cavity so as to define a spherical annular volume around the moderator. The housing includes fluid intake and output conduits which open onto the spherical cavity at diametrically opposite positions. Fluid flows through the cavity around the spherical moderator and is uniformly irradiated due to the 4.pi. radiation geometry. The irradiation source, for example a .sup.252 CF neutron source, is removable from the spherical moderator through a radial bore which extends outwardly to an opening on the outside of the housing. The radiation source may be routinely removed without interrupting the flow of fluid or breaching the containment of the fluid.

Abstract: A waste-water concentrate containing boric acid together with chemical residues and radionuclides, especially from a nuclear power plant, is treated to recovering boric acid which can be recycled to the plant. According to the invention, the practically neutral solution is acidified with an acid selected from the group which consists of sulfuric acid, hydrochloric acid, nitric acid and acetic acid to precipitate the boric acid which is separated from the concentrate and subjected to at least one recrystallization step. The boric acid thus obtained is of comparatively high purity.

Abstract: A rotary steam boiler comprises a rotatable member mounted in a housing including heating means. The rotatable member comprises a shaft with a plurality of axially extending ducts arranged about the shaft and a plurality of pipes each having opposite ends connected to one of said ducts and having a spiral configuration, the pipes extending radially about the shaft. Inlet and outlet heads are positioned at opposite ends of the ducts, respectively, and are arranged to communicate with the ducts during rotation of the shaft whereby steam may be continuously directed through the ducts and pipes to heat the steam as the shaft rotates. A preheater and a superheater increase the efficiency of the rotary steam boiler. The rotary steam boiler may be adapted for use with nuclear power stations.

Abstract: Apparatus for protecting the inner wall of a fusion chamber from microexplosion debris, x-rays, neutrons, etc. produced by deuterium-tritium (DT) targets imploded within the fusion chamber. The apparatus utilizes a fluidized wall similar to a waterfall comprising liquid lithium or solid pellets of lithium-ceramic, the waterfall forming a blanket to prevent damage of the structural materials of the chamber.

Abstract: A falling bed of ceramic particles receives neutron irradiation from a neutron-producing plasma and thereby transports energy as heat from the plasma to a heat exchange location where the ceramic particles are cooled by a gas flow. The cooled ceramic particles are elevated to a location from which they may again pass by gravity through the region where they are exposed to neutron radiation. Ceramic particles of alumina, magnesia, silica and combinations of these materials are contemplated as high-temperature materials that will accept energy from neutron irradiation. Separate containers of material incorporating lithium are exposed to the neutron flux for the breeding of tritium that may subsequently be used in neutron-producing reactions. The falling bed of ceramic particles includes velocity partitioning between compartments near to the neutron-producing plasma and compartments away from the plasma to moderate the maximum temperature in the bed.

Abstract: Isotopically enriched helium-4, that is, helium-4 which is low in helium-3, is useful as a nuclear reactor coolant. It is produced from liquefied natural gas source helium by distilling helium-3 therefrom. The coolant is preferably enriched in hydrogen up to about 6 percent by volume to thereby improve the heat transfer characteristics of the coolant, and to reduce the power requirements for circulation of the coolant.

Abstract: A neutron protection thermal insulating material is obtained by adding a boron compound and, if necessary, a hydrous compound, to chrysotile asbestos fibers. To form the material, the asbestos is opened with the use of a surface active agent in the presence of water. The boron compound is added and air bubbles are incorporated into the mixture which is then dried, molded and compressed. The resulting product is characterized by a construction wherein the opened asbestos fibers are oriented in substantially parallel relation to each other and in the direction perpendicular to the compression direction and air pockets are flatly arranged between the fibers and substantially parallel thereto to reduce thermal conduction through the material in the direction parallel to the direction of compression.