Abstract: The application discloses a preparation method of monocrystal uranium dioxide nuclear fuel pellets, comprising: granulating and pelleting UO2 powder to obtain UO2 pellets; then coating surfaces of the UO2 pellets with monocrystal growth additive micro powder to form core-shell structure particles; and activated-sintering the core-shell structure particles at high temperature, liquefying the monocrystal growth additive on the surface of the core-shell structure particle at high temperature and then diffusing into UO2 pellets, dissolving the UO3 in the liquid monocrystal growth additive, and recrystallizing the UO2 to form the monocrystal UO2 nuclear fuel pellets.

Abstract: A tungsten trioxide thermal shield for electronic components in a gun launched munition includes tungsten trioxide grains suspended in a binder. The thermal shield is made such that a tungsten trioxide rich layer is adjacent the electronic component and a binder rich layer opposes the tungsten trioxide rich layer.

Abstract: The invention relates to nuclear physics, and specifically to reactor fuel elements and units thereof, and particularly to the composition of solid ceramic fuel elements based on uranium dioxide, intended for and exhibiting characteristics for being used in variously-purposed nuclear reactors. The result consists in a more reliable, special structure and a simple composition of uranium dioxide without heterogeneous fuel pellet additives, approaching the characteristics of a monocrystal having enhanced, and specifically exceeding reference data, thermal conductivity as temperature increases, and a simple production method thereof. The result is achieved in that pores of between 1 and 5 microns in size are distributed along the perimeters of grains in the micro-structure of each metal cluster in a nuclear fuel pellet, and in that located within the grains are pores which are predominantly nano-sized. In addition, the metal clusters comprise between 0.01 and 1.0 percent by mass.

Abstract: The invention relates to a powder of an alloy comprising uranium and molybdenum in ?-metastable phase, a composition of powders comprising this powder, and the uses of said alloy powder and of said composition of powders. The alloy powder comprising uranium and molybdenum in ?-metastable phase according to the invention is formed of particles comprising a nucleus which consists of said alloy, and which is covered with a layer of alumina positioned in contact with this nucleus. Applications: manufacture of nuclear fuel elements and, in particular, of fuel elements for experimental nuclear reactors; manufacture of targets intended for production of radioelements, which are useful in particular for medical imaging, such as technetium 99m.

Abstract: Compositions are provided that include nuclear fuel. Methods for treating nuclear fuel are provided which can include exposing the fuel to a carbonate-peroxide solution. Methods can also include exposing the fuel to an ammonium solution. Methods for acquiring molybdenum from a uranium comprising material are provided.

Abstract: UO2 nuclear fuel pellets are fabricated by adding additive powder comprising Mn compound and Al compound into UO2 powder.

Abstract: Compositions are provided that include nuclear fuel. Methods for treating nuclear fuel are provided which can include exposing the fuel to a carbonate-peroxide solution. Methods can also include exposing the fuel to an ammonium solution. Methods for acquiring molybdenum from a uranium comprising material are provided.

Abstract: Neutron source comprising a composite, said composite comprising crystals comprising BeO and AmBe13, and an excess of beryllium, wherein the crystals have an average size of less than 2 microns; the size distribution of the crystals is less than 2 microns; and the beryllium is present in a 7-fold to a 75-fold excess by weight of the amount of AmBe13; and methods of making thereof.

Abstract: Among fuel rods constituting a fuel assembly, Gd compound oxide is added to low Gd containing fuel rods that containing uranium dioxide of which enrichment exceeds 5 wt %. The Gd compound oxide is oxide of gadolinium and rare earth element A except for gadolinium and is expressed as a chemical formula A1-xGdxO2-0.5x or a chemical formula A1-xGdxO1.5. As the rare earth element A, cerium Ce, lanthanum La or erbium Er can be used.

Abstract: A composition is prepared by heating particles of a nuclear fuel material in a metal salt that decomposes below 1000° C. to form a metal oxide. Magnesium nitrate hexahydrate is an example of such a metal salt. A resulting composition includes the particles homogeneously dispersed in a matrix of magnesium oxide. After the composition is used in a nuclear reactor, the now spent composition is removed, cooled, and the matrix is dissolved away from the spent particles, which can be reused in another nuclear fuel composition. The recovered fuel particles also contain some fission products that provide a radiation barrier that discourages theft of the recovered fuel particles.

Abstract: A process for reprocessing a spent nuclear fuel and for preparing a mixed uranium-plutonium oxide. The process: a) separates the uranium and plutonium from fission products, americium, and curium that are present in an aqueous nitric solution resulting from dissolution of the fuel in nitric acid, the separating including at least one operation of coextracting the uranium and plutonium from the solution by a solvent phase; b) partitions the coextracted uranium and plutonium to a first aqueous phase containing plutonium and uranium, and a second aqueous phase containing uranium but no plutonium; c) purifies the plutonium and uranium that are present in the first aqueous phase; and d) coconverts the plutonium and uranium to a mixed uranium/plutonium oxide.

Abstract: The invention relates to a method for producing a radioactive brachytherapy source material comprising indium-114m in radioactive equilibrium with indium-114 as main radioactive isotopes. A new radioactive brachytherapy source material comprises indium-114m in radioactive equilibrium with indium-114 as main radioactive isotopes. A new encapsulated radioactive brachytherapy source comprises the new radioactive brachytherapy source material.

Abstract: A ceramic waste immobilizing material for the encapsulation of high level radioactive waste (HLW), e.g. resulting from the reprocessing of irradiated nuclear fuel. The ceramic waste immobilising material enables waste ions from at least fission products in irradiated nuclear fuel to be dissolved in substantially solid solution form. The ceramic waste immobilising medium has a matrix comprising phases of hollandite, perovskite and zirconolite in which the waste ions are dissolved. The invention also includes a method of immobilizing HLW from reprocessed nuclear fuel assemblies comprising the steps of mixing a liquor containing the HLW with a precursor material comprising oxides or oxide precursors of at least titanium, calcium and barium to form a slurry, drying the slurry, and calcining the dried slurry under a reducing atmosphere to form a powder comprising 30–65 weight % waste.

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: The invention provides an improved method of manufacturing fuel by blending fuel from different sources in a way which accounts for the isotopic variation in the fuel from different sources. In particular, the invention provides a method for producing nuclear fuel, the method comprising defining one or more reference composition for fuel to be produced; providing two or more amounts of feed fuel material from which to produce the fuel, defining the deviation of each of the amounts of feed fuel material from a reference composition; selecting and mixing masses of feed fuel material from two or more of the amounts of feed fuel material, the masses being selected to give a lower deviation between the mixed feed fuel material and the selected reference composition than between the feed fuel material amounts, and the selected reference composition, the deviation being defined by a function based on the isotopic composition of the feed fuel material amounts.

Abstract: Improved method of sintering for the manufacture of nuclear fuel comprising a fissionable ceramic material including a silica containing additive. The method includes controlling the sintering atmosphere to impede loss through vaporization of the silica.

Abstract: A method of producing mixed oxide fuel pellets. The method uses oxides of at least two fissile elements and includes a mixing, milling, spheroidising and sintering step to produce a fuel pellet incorporating a neutron poison.

Abstract: This invention relates to a composite nuclear fuel material and method of manufacture of said material.The purpose of the invention is a composite nuclear fuel material comprising a matrix inert under irradiation and particles of nuclear fuel offering good resistance to fissure propagation under irradiation and high retention of volatile fission products.This purpose is achieved using a method which allows the creation of a clearance of a few microns between the particles and the matrix.

Abstract: The improved oxide, once-through plutonium fuel compound that can be used for nuclear fission in currently operating light-water reactors and fast reactors has a composition in the range defined by the lines that connect the three compositional points of a three-component system consisting of plutonium dioxide (PuO.sub.2), a plutonium host phase and alumina (Al.sub.2 O.sub.3). The compound also has such a phase structure that two phases, the plutonium host phase having plutonium dioxide dissolved therein and the alumina phase, are in equilibrium.

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 preparing active, sinterable, finely-divided plutonium oxide (PuO.sub.2) powder from plutonium metal is disclosed. The process yields plutonium fissile material which can be easily blended to form a uniformly homogeneous powder for the fabrication of high-quality light water reactor ceramic fuel pellets. Such homogeneous fuels are required to prevent hot spots from developing in a reactor using the fuel.

Abstract: A method for producing UO.sub.2 or (U/Pu)O.sub.2 powder includes obtaining ammonium uranyl carbonate or ammonium uranyl plutonyl carbonate by treating a starting oxide selected from the group consisting of uranium oxide, plutonium oxide and uranium plutonium mixed oxide, with at least one solution selected from the group consisting of aqueous ammonium carbonate solution and aqueous ammonium hydrogen carbonate solution. The ammonium uranyl carbonate or ammonium uranyl plutonyl carbonate is then heated and in particular calcined.

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 element comprising sintered pellets based on uraniferous oxide which are surrounded by a metallic sheath and permitting trapping of the fission products which appear in the course of irradiation characterized in that the pellets contain or are coated with or that the sheath is internally coated with an agent for trapping said fission products based on mixed metallic oxide comprising SiO.sub.2 and one at least of the oxides ZrO.sub.2 or CeO.sub.2.

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: 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: ADU (ammonium diuranate) is prepared in particle form directly by reacting ammonium gas with liquid droplets of atomized uranyl compound solutions. Generation of liquid filtrate is prevented by using concentrated solutions of uranyl compounds as feed solutions, or drying the wet ADU particles formed before their settlement when a feed of low concentration is used. The ADU particle thus prepared is finely divided and easy-handling. No filtration operation is necessary in the preparation. The UO.sub.2 powder consequently obtained after calcining and reduction has consistent quality from batch to batch and has good pelletizing and sintering properties. Uranium dioxide with low fluorine content can be prepared from uranyl fluoride solution. Gadolinium-uranium oxide can also be prepared with the present method using an aqueous mixture of gadolinium nitrate and uranyl nitrate as a feed solution.

Abstract: The disclosed invention consists of a ceramic form of fuel for a nuclear reactor comprising an oxide of a fissionable element and containing therein a consumable neutron absorbing agent. The ceramic fissionable fuel product provides longer fuel performance in nuclear reactor service.

Abstract: A process is disclosed for producing sintered mixed metal oxide nuclear f pellets containing UO.sub.2 and the oxide of at least one other fissionable or rare earth element M, the pellets being directly soluble in nitric acid without nitric acid additive or prior treatment of the pellets. The process comprises the steps of mixing together nitrate solutions of the elements, concentrating the mixture of solutions, thermally denitrating the concentrated nitrate mixture without additives, to obtain an intermediate mixed oxide powder, calcining the intermediate mixed oxide powder, reducing the calcined mixture, stabilizing the uranium oxide UO.sub.2 in the reduced oxide mixture, shaping and pressing the resulting stabilized, reduced oxide mixture to obtain pellets of green material, sintering the pellets of green material and grinding the sintered pellets.

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: A sintered nuclear fuel compact of UO.sub.2 or the mixed oxides (U, Pu)O.sub.2 and (U, Th)O.sub.2, with which reactivity losses in a nuclear reactor having relatively long fuel element cycles are avoided, has in its sintered matrix neutron poison in the chemical compound form UB.sub.x with x=2; 4 and/or 12 and/or B.sub.4 C. A sintered nuclear fuel compact of this kind is produced by sintering from a compact comprising a mixture of at least one of the mixture components UO.sub.2, PuO.sub.2, (U, Pu)O.sub.2 and (U, Th)O.sub.2 powder with UB.sub.x powder, where x=2; 4 and/or 12 and/or B.sub.4 C powder.

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 method and binder composition for prolonging the induced plasticity of a particulate ceramic material admixture comprising uranium dioxide and a fugitive binder, and product thereof, for subsequent compaction by compression molding in the manufacture of nuclear fuel pellets. The fugitive binder comprises a reaction product of an amine carbonate or amine carbamate and ammonium oxalate reacted with uranium dioxide at a temperature of at least 65.degree. C. The uranyl oxalate-carbonate reaction product has the composition of (UO.sub.2 (CO.sub.3) (C.sub.2 O.sub.4). 2H.sub.2 O). 2H.sub.2 O.

Abstract: Process for the preparation of pulverulent metallic oxides with predetermined reactivity which is adjusted by the specific surface area, which are intended to be subjected to subsequent conversions, by thermal treatment of corresponding nitrates in the form of an aqueous solution or of a solids material, consisting of hydrated uranyl nitrate, on its own or in admixture with at least one of thorium nitrate, cerium nitrate and plutonium nitrate, which process is characterized in that it consists of two treatment stages:(a) the first stage essentially consisting of incompletely dehydrating the hydrated uranyl nitrate.(b) the second stage essentially consisting of decomposing the product resulting from the first stage by calcination under controlled steam pressure.The process is used for obtaining uranium oxide on its own or in admixture with thorium oxide, cerium oxide and plutonium oxide, with a view to subsequent chemical conversions and/or sintering.

Abstract: UO.sub.2 base powder exhibiting any specific surface and crystallite diameter properties is mixed with rare earth (SE) oxide-containing powder, the particles of which exhibit at least in one surface layer, a crystal lattice of the fluorite type, with the stoichiometric composition (SE.sub.0.5, U.sub.0.5) 0.sub.2.00 and/or form it in sintering; and is compacted to form compacts which are sintered in a gas atmosphere with reducing action at 1500.degree. C. to 1750.degree. C. to form high-density sintered bodies.

Abstract: A reproducible method and stable binder composition for preserving the induced plasticity of a particulate ceramic material admixture comprising uranium dioxide and a fugitive binder, and product thereof, for subsequent compaction by compressing molding in the manufacture of nuclear fuel pellets.

Abstract: A method is disclosed for making a fuel pellet for a nuclear reactor. A mixture is prepared of PuO.sub.2 and UO.sub.2 powders, where the mixture contains at least about 30% PuO.sub.2, and where at least about 12% of the Pu is the Pu.sup.240 isotope. To this mixture is added about 0.3 to about 5% of a binder having a melting point of at least about 250.degree. F. The mixture is pressed to form a slug and the slug is granulated. Up to about 4.7% of a lubricant having a melting point of at least about 330.degree. F. is added to the granulated slug. Both the binder and the lubricant are selected from a group consisting of polyvinyl carboxylate, polyvinyl alcohol, naturally occurring high molecular weight cellulosic polymers, chemically modified high molecular weight cellulosic polymers, and mixtures thereof. The mixture is pressed to form a pellet and the pellet is sintered.

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: Method for dissolving hard-to-dissolve thorium and/or plutonium oxides, especially dioxides such as ThO.sub.2, PuO.sub.2 or (U/Pu)O.sub.2 mixed oxides by heating the oxides in a hermetically sealed vessel in fluoride-free nitric acid. The use of a gas atmosphere containing oxygen in the sealed vessel is advantageous.

Abstract: Method for the manufacture of oxidic sintered nuclear fuel bodies by compacting UO.sub.2 -starting powder or a mixture of UO.sub.2 -and PuO.sub.2 starting powder which contains up to 10% by weight rare-earth oxide, especially Gd.sub.2 O.sub.3, as an additive into blanks and subsequent densification of these blanks by a heat treatment in a sintering atomsphere with reducing action. The UO.sub.2 -starting powder used for compacting has a specific surface in the range of 2 to 4.5 m.sup.2 /g and/or a mean crystallite diameter in the range of 80 nm to 250 nm, and the heat treatment in the sintering atmosphere with reducing action is carried out at a temperature in the range of 1,500.degree. C. to 1,750.degree. C.

Abstract: A method of producing an oxide fuel pellet having a low density is provided which comprises adding a manganese compound to an oxide fuel powder selected from a group consisting of uranium dioxide powder and a mixed powder of uranium dioxide and plutonium dioxide, in an amount of 0.01 to 5.0% by weight based on the weight of the oxide fuel powder, molding the resulting mixture into a pellet form, and sintering the pellet-formed mixture at a temperature of 1,200.degree. to 1,700.degree. C.

Abstract: Manufacture of very dense oxidic fuel bodies of UO.sub.2 with rare earth oxides in which pressed blanks are subjected to sintering in an oxidizing atmosphere at relatively low temperature and are sintered in a reducing atmosphere at a higher temperature. This avoids sintering-inhibiting phases and permits very dense bodies with greater content of rare earth oxides to be produced.

Abstract: A method for improving the physical properties of pressed bodies or pellets formed of particulate nuclear fuel material containing uranium dioxide. The green or unfired pressed bodies comprise a fugitive binder dispersed through the particulate fuel material.

Abstract: A nuclear fuel material green body of density from about 30 to 70% of theoretical density having tensile strenght and plasticity adequate to maintain the integrity of the body during processing leading to ultimate sintered condition is produced by adding an amine carbonate or carbamate or mixture thereof to a particulate mass of the nuclear fuel material under conditions resulting in reaction with the amine compound to form a water-soluble compound effective as a binder for the particulate material.

Abstract: The grain size of particulate uranium oxides is increased and adjusted by the application thereto of hydrogen peroxide. The procedure is useful in the manufacture of nuclear reactor fuel from powdered fissionable materials.

Abstract: A nuclear fuel material green body of density from about 30 to 70% of theoretical density having tensile strength and plasticity adequate to maintain the integrity of the body during processing leading to ultimate sintered condition is produced by adding one or more amines to a particulate mass of the nuclear fuel containing about five percent of ammonium uranyl carbonate under conditions resulting in reaction of the amine with the ammonium uranyl carbonate, liberation of ammonia and formation of a water-soluble uranyl compound more effective as a binder than the ammonium uranyl carbonate.

Abstract: A process for imparting increased strength and physical durability in green bodies or pellets formed of particulate oxides of uranium, plutonium and the like in the production of pelletized fissionable nuclear fuel. The green or unfired pellets comprise a fugitive binder dispersed through the particulate oxide fuel material.