Abstract: The invention relates generally to uranium fuel in a nuclear reactor and, more particularly, the inclusion of a fuel additive component to the bulk fuel material. The fuel additive component is selected and provided in an amount such that it is effective to improve one or more properties of the bulk fuel material. The fuel additive component has a grain size that is less than the grain size of the bulk fuel material. The granular fuel additive component coats or covers the granular bulk fuel material.

Abstract: The invention pertains to a nuclear fuel assembly grid or a portion or a part of the grid, such as a grid strap and/or an integral flow mixer that is at least partially constructed of a composition containing one or more ternary compounds of the general formula I: Mn+1AXn??(I) wherein, M is a transition metal, A is an element selected from the group A elements in the Chemical Periodic Table, X is carbon or nitrogen, and n is an integer from 1 to 3. The invention further pertains to a method of making the nuclear fuel assembly grid or a portion of a part of the grid, by employing a sintering process to sinter the composition containing one or more ternary compounds in powder form such that the resulting grid or a portion of or a part of the grid includes a plurality of sintered layers.

Abstract: Exemplary embodiments provide automated nuclear fission reactors and methods for their operation. Exemplary embodiments and aspects include, without limitation, re-use of nuclear fission fuel, alternate fuels and fuel geometries, modular fuel cores, fast fluid cooling, variable burn-up, programmable nuclear thermostats, fast flux irradiation, temperature-driven surface area/volume ratio neutron absorption, low coolant temperature cores, refueling, and the like.

Abstract: A metal particulate fuel system is described. The metal fuel system may include particulate metal fuel for use in nuclear reactors. The particulate metal fuel may include a plurality of particles of at least one enriched alloy where the particles are compacted into a fuel column. The metal particulate fuel system may also include a cladding and/or a gas-filled plenum.

Abstract: The present invention relates to nuclear fuel compositions including triuranium disilicide. The triuranium disilicide includes a uranium component which includes uranium-235. The uranium-235 is present in an amount such that it constitutes from about 0.7% to about 5% by weight based on the total weight of the uranium component of the triuranium disilicide. The nuclear fuel compositions of the present invention are particularly useful in light water reactors.

Abstract: Disclosed embodiments include nuclear fission reactors, nuclear fission fuel pins, methods of operating a nuclear fission reactor, methods of fueling a nuclear fission reactor, and methods of fabricating a nuclear fission fuel pin.

Abstract: A nuclear fuel element including a uranium-molybdenum alloy that provides an enhanced reactivity in research, test and radioisotope production nuclear reactors. In this uranium-molybdenum alloy, the uranium is enriched in the isotope 235-U, while the molybdenum is depleted in the isotope 95-Mo. The thus obtained enhanced reactivity provides, depending on the exact use of the fuel element, a requirement for less uranium in the fuel and the use of the fuel elements during a longer period in the reactor.

Abstract: A nuclear fuel and a method to produce a nuclear fuel wherein a porous uranium dioxide arrangement is provided, the arrangement is infiltrated with a precursor liquid and the arrangement is thermally treated such the porous uranium dioxide arrangement is infiltrated with a precursor liquid, followed by a thermal treating of the porous uranium dioxide arrangement with the infiltrated precursor liquid such that the precursor liquid is converted to a second phase.

Abstract: This disclosure describes a method for metallurgically bonding a complete leak-tight enclosure to a matrix-type fuel element penetrated longitudinally by a multiplicity of coolant channels. Coolant tubes containing solid filler pins are disposed in the coolant channels. A leak-tight metal enclosure is then formed about the entire assembly of fuel matrix, coolant tubes and pins. The completely enclosed and sealed assembly is exposed to a high temperature and pressure gas environment to effect a metallurgical bond between all contacting surfaces therein. The ends of the assembly are then machined away to expose the pin ends which are chemically leached from the coolant tubes to leave the coolant tubes with internal coolant passageways. The invention described herein was made in the course of, or under, a contract with the U.S. Atomic Energy Commission.

Abstract: A method for production of a nuclear fuel element with oxide base, in which the nuclear fuel with oxide base is mixed with Cr and sintered to a solid body. The amount of chrome oxide added is =>50 and <100 ppm with respect to the amount of nuclear fuel with oxide base added.

Abstract: Nuclear fuel assembly configurations are provided for mixed oxide fuels. Neutron poisons are provided within the MOX of certain fuel rods in the fuel assembly, those fuel rods being preferentially grouped towards the periphery of the fuel assembly. In this way, optimized reduction of reactivity is provided during the initial part of the fuel cycle but the neutron poison is burnt out so as not to interfere with the reactivity during subsequent parts of the cycle.

Abstract: A sintered nuclear fuel body includes (U, Pu)O2 mixed crystals having a mean particle size in a range from 7.5 &mgr;m to 50 &mgr;m. This sintered nuclear fuel body has a high retention capacity for fission gas in a power reactor. In order to produce the sintered nuclear fuel body by sintering a body in a hydrogen-containing sintering atmosphere, a powered substance selected from the group consisting of aluminum oxide, titanium oxide, niobium oxide, chromium oxide, aluminum stearate, aluminum distearate and aluminum tristearate is added to the starting powder for the body. As an alternative or in addition, the body made from the starting powder is sintered during a holding period of 10 minutes to 8 hours at a sintering temperature of 1400° C. to 1800° C.

Abstract: A method for providing a leak-tight metal enclosure to a fuel matrix penetrated by coolant channels, wherein the mutually contacting surfaces of said metal enclosure and said fuel matrix are metallurgically bonded, comprising placing a metal cladding about the lateral surface of said fuel matrix; disposing metal coolant tubes within said coolant channels; placing a perforated header plate having tubular extensions at each end of the fuel matrix from which the coolant tube ends protrude, said coolant tubes passing through said perforated header plate and said tubular extensions and terminating even with the ends of said extensions; welding, under vacuum, said cladding to said header plates, and the ends of said coolant tubes to the ends of said tubular extensions; exposing the assembly comprising the fuel matrix and enclosure to a gas at high temperature and pressure; and machining said header plates to provide a finished fuel element.

Abstract: A nuclear fuel based on UO.sub.2, ThO.sub.2 and/or PuO.sub.2 having improved retention properties for fission products. The fuel comprises a metal such as Cr or Mo able to trap oxygen in order to form an oxide having a free formation enthalpy equal to or below that of the superstoichiometric oxide or oxides (U, Th)O.sub.2+x and/or (U, Pu)O.sub.2+x (O<x.ltoreq.0.01). Thus, it is possible to trap oxygen atoms released during the fission of U, Th and/or Pu. This leads to an increase in the retention level of the fission products and a possibility of obtaining a high burn-up of nuclear fuel elements.

Abstract: A sintered nuclear fuel body includes (U, Pu)O.sub.2 mixed crystals having a mean particle size in a range from 7.5 .mu.m to 50 .mu.m. This sintered nuclear fuel body has a high retention capacity for fission gas in a power reactor. In order to produce the sintered nuclear fuel body by sintering a body in a hydrogen-containing sintering atmosphere, a powered substance selected from the group consisting of aluminum oxide, titanium oxide, niobium oxide, chromium oxide, aluminum stearate, aluminum distearate and aluminum tristearate is added to the starting powder for the body. As an alternative or in addition, the body made from the starting powder is sintered during a holding period of 10 minutes to 8 hours at a sintering temperature of 1400.degree. C. to 1800.degree. C. in a hydrogen-containing sintering atmosphere, initially with an oxygen partial pressure of 10.sup.-10 to 10.sup.-20 bar and then from 10.sup.-8 to 10.sup.

Abstract: The present invention provides improved nuclear fuel pellets having high thermal conductivity for use in an LWR. This can be achieved by creating a continuous deposition phase of high-thermal conductivity substances in the grain boundaries in the pellets. As a result, the temperature in the center of the fuel rod can be significantly reduced, and the discharge amount of gases generated on the nuclear fission can be efficiently reduced.The present invention also provides a method of manufacturing the above-described nuclear fuel pellets.

Abstract: A process of preparing a fuel pellet for a nuclear reactor, comprising washing the gel particle using an organic solvent miscible with water to substitute the organic solvent for the water, removing the organic solvent, moistening again the dry gel particle, followed by press molding and sintering.

Abstract: The present invention provides improved nuclear fuel pellets having high thermal conductivity for use in an LWR. This can be achieved by creating a continuous deposition phase of high-thermal conductivity substances in the grain boundaries in the pellets. As a result, the temperature in the center of the fuel rod can be significantly reduced, and the discharge amount of gases generated on the nuclear fission can be efficiently reduced.The present invention also provides a method of manufacturing the above-described nuclear fuel pellets.

Abstract: A process for the production of plutonium-containing mixed oxide nuclear fuel. The process comprises selecting a plutonium-containing solution, determining the plutonium isotopic composition of the solution, precipitating particulate plutonium oxide from the solution, forming a mixture comprising the plutonium oxide and a particulate uranium oxide, and forming nuclear fuel compacts from the mixture. The amount of plutonium in the mixture is controlled in accordance with a given equation.

Abstract: This invention provides nuclear fuel pellets including fission substance of UO.sub.2 or UO.sub.2 having Gd.sub.2 O.sub.3 added thereto, the pellets comprising a satisfactory solid-solution state (homogeneous state), large grain diameters, and a second precipitation phase deposited in grain boundaries, and still having a sufficiently high density. This invention also provides a method of manufacturing the above-described nuclear fuel pellets.The nuclear fuel pellets of this invention comprise UO.sub.2 or (U, Gd) O.sub.2 grains and an aluminosilicate precipitation phase, the precipitation phase being a glass state or a crystalline state, the grains having an average grain diameter of about 20 .mu.m through about 60 .mu.m, the aluminosilicate precipitation phase having a composition including SiO.sub.2 of about 40 wt % through about 80 wt % and Al.sub.2 O.sub.

Abstract: The present invention provides improved nuclear fuel pellets having high thermal conductivity for use in an LWR. This can be achieved by creating a continuous deposition phase of high-thermal conductivity substances in the grain boundaries in the pellets. As a result, the temperature in the center of the fuel rod can be significantly reduced, and the discharge amount of gases generated on the nuclear fission can be efficiently reduced.The present invention also provides a method of manufacturing the above-described nuclear fuel pellets.

Abstract: A method of manufacturing sintered uranium dioxide in which a mixture is formed of single crystals of uranium dioxide and uranium dioxide powder. Compacts are formed from granules of the mixture, the compacts are sintered in carbon dioxide, and then reduced in a hydrogen environment at a substantially lower temperature than the sintering temperature. The quantity of the single crystals is selected so as to inhibit excessive grain growth in the compacts during sintering.

Abstract: The present invention provides improved nuclear fuel pellets having high thermal conductivity for use in an LWR. This can be achieved by creating a continuous deposition phase of high-thermal conductivity substances in the grain boundaries in the pellets. As a result, the temperature in the center of the fuel rod can be significantly reduced, and the discharge amount of gases generated on the nuclear fission can be efficiently reduced.The present invention also provides a method of manufacturing the above-described nuclear fuel pellets.

Abstract: A nuclear fuel body provided by doped uranium dioxide grains having kernels of undoped uranium dioxide. The body is produced by mixing single crystal seeds of uranium dioxide with doped uranium dioxide granules. The mixture is compacted and subsequently sintered. Gadolinia is a preferred dopant for the uranium dioxide.

Abstract: Zirconium-based corrosion resistant alloys for use primarily as a cladding material for fuel rods in a boiling water nuclear reactor consist essentially of by weight percent about 0.5 to 2.0 percent thin, about 0.24 to 0.40 percent of a solute composed of copper, nickel and iron, wherein the copper is at least 0.05 percent, and the balance zirconium. Nuclear fuel elements for use in the core of a nuclear reactor have improved corrosion resistant cladding made from these zirconium alloys or composite claddings have a surface layer of the corrosion resistant zirconium alloys metallurgically bonded to the outside surface of a Zircaloy alloy tube. The claddings may contain an inner barrier layer of moderate purity zirconium metallurigcally bonded on the inside surface of the cladding to procide protection from fission products and gaseous impurities generated by the enclosed nuclear fuel.

Abstract: An improved nuclear fuel element for service in power generating, water cooled nuclear reactors, comprising a fuel cladding container of an alloy of zirconium provided with a barrier lining of unalloyed zirconium metal metallurgically bonded to the container's inner surface, and enclosed therein fissionable nuclear fuel including an additive of aluminum silicate.

Abstract: A particulate mixture of uranium dioxide and additive of magnesium silicate composition is formed into a compact and sintered to produce a nuclear fuel wherein the uranium dioxide grains have an average grain size of at least about 20 microns and wherein substantially all of the grains are each enveloped with glassy magnesium silicate phase.

Abstract: A mixture of uranium dioxide and additive of aluminosilicate composition is formed into a compact and sintered to produce a nuclear fuel wherein the uranium dioxide grains have an average grain size of at least about 20 microns and wherein substantially all of the grains are each enveloped by glassy aluminosilicate phase.

Abstract: A particulate mixture of uranium dioxide and additive of magnesium aluminosilicate composition is formed into a compact and sintered to produce a nuclear fuel wherein the uranium dioxide grains have an average grain size of at least about 20 microns and wherein substantially all of the grains are each enveloped with glassy magnesium aluminosilicate phase.

Abstract: Sintered nuclear fuel bodies are manufactured by pressing a powder of UO.sub.2 containing 1-20 percent by weight Gd.sub.2 O.sub.3 and up to 20 percent by weight U.sub.3 O.sub.8 into a pressed body and sintering the pressed body, the Gd.sub.2 O.sub.3 at least partly consisting of monoclinic Gd.sub.2 O.sub.3. The monoclinic Gd.sub.2 O.sub.3 used can be manufactured by heat treatment of cubic Gd.sub.2 O.sub.3 at a temperature of at least 1250.degree. C. By employing monoclinic Gd.sub.2 O.sub.3 a considerably increased homogeneity with respect to solid solution of gadolinium in the UO.sub.2 structure is obtained. Particularly favorable results are obtained if the sintering is carried out in a sintering atmosphere which, at 1750.degree. C., has an oxygen partial pressure which is higher than 10.sup.-7 atm.

Abstract: A plate-shaped high power nuclear fuel element containing low enrichment uranium (5 to 20 percent by weight uranium.sup.235 in the uranium component) as fissionable material, the fuel element essentially comprising a UAl.sub.4 plate provided with an aluminum sheath or a sheath of an Al alloy and impurities inherent in the manufacturing process. A process for producing such a UAl.sub.4 plate comprises (a) intimately mixing a powder of low enrichment uranium or uranium compound U.sub.6 Fe (5 to 20 percent by weight U.sup.235) having a particle size in the range from 0.1.mu. to 90.mu. with aluminum powder having a particle size in the range from 0.1.mu. to 100.mu. in a weight ratio range of uranium to aluminum between 1.1 U:1 Al and 2.

Abstract: An improved nuclear fuel rod comprising a tubular metallic cladding containing a plurality of nuclear fuel pellets has a plurality of ceramic wafers therein, each of which wafers being disposed between a major portion of adjacent fuel pellets. The ceramic wafers are formed from a sintered mixture of natural or depleted uranium dioxide and 1-8 percent by weight gadolinium oxide. The wafers are of a diameter substantially the same as that of the fuel pellets and have a thickness of between 10-100 mils. The wafers freeze out harmful fission products released by the fuel pellets and minimize or prevent pellet-clad interaction failures, while also providing flexibility in power shaping in the reactor system.

Abstract: The invention discloses a metal-actinide mononitride composition with dimensional stability in extended nuclear reactor operations, with a method of operation at surface temperatures in excess of 1700.degree. C. The preferred embodiment and operating method uses a mononitride of uranium and a metal selected from the group consisting of titanium or yttrium. Parameters for determination of the metal element to stabilize the fuel are disclosed.

Abstract: A method for coating a nuclear fuel with a burnable poison and a burnable poison coated nuclear fuel made by the method. The nuclear fuel is surface cleaned, and then a burnable poison layer is sputtered thereon. A sputtering deposition rate is picked that preferably will heat the nuclear fuel surface between 200.degree. C. and 600.degree. C. For deposition rates that result in heating the nuclear fuel surface to less than 200.degree. C., external heat is applied to heat the nuclear fuel surface between 200.degree. C. and 600.degree. C. To make the burnable poison layer less hygroscopic, an overcoat layer of a hydrophobic material is sputtered on the burnable poison layer.

Abstract: Rupture of boiling water reactor nuclear fuel cladding resulting from embrittlement caused by fission product cadmium is prevented by adding the stoichiometrically equivalent amount of CuFe.sub.2 O.sub.4 or CuTiO.sub.3 to the fuel.

Abstract: Rupture of boiling water reactor nuclear fuel cladding resulting from embrittlement by fission product cadmium is prevented by adding the stoichiometrically equivalent amount of V.sub.2 O.sub.4 or V.sub.2 O.sub.5 to the fuel.