Abstract: A nuclear fuel powder production plant comprises a conversion installation (2) for the conversion of uranium hexafluoride (UF6) into uranium dioxide (UO2) having a hydrolysis reactor (4) for the conversion of UF6 into uranium oxyfluoride powder (UO2F2) and a pyrohydrolysis furnace (6) for converting the UO2F2 powder into UO2 powder. The nuclear fuel powder production plant also includes a packaging unit (20) for the UO2 powder comprising a filling station (22) having a chamber (26) for receiving a container (24) to be filled, a filling duct (28) supplied from the furnace (6) and a suction system (32) comprising a suction ring (34) disposed at the outlet (30) of the filling duct (28) for sucking an annular air flow (A) around a stream (P) of UO2 powder falling from the outlet (30) from the filling duct (28) into the container (24).

Abstract: A method to activate U3O8 for conversion of this uranium oxide to hydrated UO4 via reaction with hydrogen peroxide H2O2, wherein the following successive steps are performed: a) an aqueous suspension is prepared containing a powder of U3O8 and hydrogen peroxide; b) the aqueous suspension containing a powder of U3O8 and hydrogen peroxide is contacted with ozone, whereby an aqueous suspension is obtained of a powder of activated U3O8; c) optionally the powder of activated U3O8 is separated from the aqueous suspension. A method to convert U3O8 to hydrated UO4 of formula UO4, nH2O where n is 2 or 4, comprising at least one step at which hydrogen peroxide H2O2 is added to the aqueous suspension of a powder of activated U3O8 obtained at the end of step b) of the activation method or to an aqueous suspension prepared by placing in suspension in water the powder of activated U3O8 obtained at the end of step c) of the activation method.

Abstract: A method for converting UO3 and/or U3O8 into hydrated UO4 of formula UO4.nH2O wherein n is 2 or 4, comprising the following successive steps: a) preparing an aqueous suspension of a UO3 powder and/or a U3O8 powder; b) adding hydrogen peroxide H2O2 to the aqueous suspension of a UO3 and/or U3O8 powder, converting the UO3 and/or U3O8 into hydrated UO4 and precipitating, crystallizing the hydrated UO4 in the suspension; c) recovering the precipitate, crystals of UO4 hydrate; d) optionally, washing the recovered UO4 hydrate precipitate, crystal(s); e) optionally, repeating step d); f) optionally, drying the precipitate, the crystals; wherein the addition of H2O2 to the aqueous suspension is carried out so that the suspension contains a stoichiometric excess of H2O2 relatively to the stoichiometry of the reaction from UO3: UO3+nH2O+H2O2?UO4.nH2O+H2O??(1) or of the reaction from U3O8 UO2.67+1.33H2O2+nH2O?UO4.nH2O+1.

Abstract: The invention relates to a process for manufacturing an oxychloride or oxide of actinide(s) and/or of lanthanide(s) from a chloride of actinide(s) and/or of lanthanide(s) present in a medium comprising at least one molten salt of chloride type comprising a step of bringing said chloride of actinide(s) and/or lanthanide(s) present in said medium comprising at least one molten salt of chloride type into contact with a wet inert gas.

Abstract: A method for forming nanoparticles containing uranium oxide is described. The method includes combining a uranium-containing feedstock with an ionic liquid to form a mixture and holding the mixture at an elevated temperature for a period of time to form the product nanoparticles. The method can be carried out at low temperatures, for instance less than about 300° C.

Abstract: A method for forming nanoparticles containing uranium oxide is described. The method includes combining a uranium-containing feedstock with an ionic liquid to form a mixture and holding the mixture at an elevated temperature for a period of time to form the product nanoparticles. The method can be carried out at low temperatures, for instance less than about 300° C.

Abstract: This invention relates to the integration of ammonium carbonate leach processes with established acid and alkaline uranium leach processes as multifunctional industrial processes for the extraction, high degree purification and conversion of processed or semi-processed uranium as U3O8, UO2, or most tetra or hexa-valent forms of uranium, and where applicable, for the recovery of uranium from uranium ores, using advanced multiple stage membrane based technologies for the separation and concentration of uranium in solution from heavy metals and lighter elements that may be present in the solution, and the selective leach and precipitation properties of an ammonium carbonate leach.

Abstract: A method for manufacturing a porous fuel comprising uranium, optionally plutonium and at least one minor actinide is provided. The method may comprise the following successive steps: a) a step for compacting as pellets a mixture of powders comprising uranium oxide, optionally plutonium oxide and at least one oxide of a minor actinide, at least one portion of the uranium oxide being in the form of triuranium octaoxide U3O8, the other portion being in the form of uranium dioxide UO2; b) a step for reducing at least one portion of the triuranium octaoxide U3O8 into uranium dioxide UO2.

Abstract: Method for producing a uranium concentrate in the form of solid particles, by precipitation from a uranium-containing solution using a precipitating agent, in a vertical reactor comprising a base, a top, a central part, an upper part, and a lower part, the solid particles of the uranium concentrate forming a fluidized bed under the action of a rising liquid current which circulates from the base towards the top of the reactor successively passing through the lower part, the central part and the upper part of the reactor, and which is created by introducing a liquid recycling current (flow) at the base of the reactor, said liquid recycling current being tapped at a first determined level (A) in the upper part of the reactor and sent back without settling to the base of the reactor, excess liquid being also evacuated via an overflow located at a second determined level (B) in the upper part of the reactor; a method in which the upper limit (C) of the fluidized bed of solid particles is controlled so that it is

Abstract: Porous metal oxides are provided. The porous metal oxides are prepared by heat treating a coordination polymer. A method of preparing the porous metal oxide is also provided. According to the method, the shape of the particles of the metal oxide can be easily controlled, and the shape and distribution of pores of the porous metal oxide can be adjusted.

Abstract: A method for converting UO3 and/or U3O8 into hydrated UO4 of formula UO4.nH2O wherein n is 2 or 4, comprising the following successive steps: a) preparing an aqueous suspension of a UO3 powder and/or a U3O8 powder; b) adding hydrogen peroxide H2O2 to the aqueous suspension of a UO3 and/or U3O8 powder, converting the UO3 and/or U3O8 into hydrated UO4 and precipitating, crystallizing the hydrated UO4 in the suspension; g) recovering the precipitate, crystals of UO4 hydrate; h) optionally, washing the recovered UO4 hydrate precipitate, crystal(s); i) optionally, repeating step d); j) optionally, drying the precipitate, the crystals; wherein the addition of H2O2 to the aqueous suspension is carried out so that the suspension contains a stoichiometric excess of H2O2 relatively to the stoichiometry of the reaction from UO3: UO3+nH2O+H2O2?UO4.nH2O+H2O??(1) or of the reaction from U3O8 UO2.67+1.33H2O2+nH2O?UO4.

Abstract: There is provided a method of producing U3O8 powder having large surface area and small particle size by oxidizing defective UO2 pellets and manufacturing nuclear fuel pellets which are stable in a pore structure and high in density through the use of a mixture comprising UO2 powder and U3O8 powder. The method includes producing an U308 powder having a surface area of at least 1 m2/g by oxidizing defective UO2 pellets at a temperature of 300 to 370° C. in such a way that a maximum weight increase rate per 1 g of the UO2 pellets is up to 0.06 wt %/min; producing a mixed powder by mixing the U3O8 powder with an UO2 powder by 2 to 15 wt %; producing a compact by compression molding the mixed powder; and sintering the compact in a reducing gas atmosphere at a temperature of 1600 to 1800° C. In addition, a small amount of an Al-compound may be added to the oxidized U3O8 powder before the U3O8 powder is mixed with the UO2 powder.

Abstract: A method for converting depleted uranium tetrafluoride (UF4) to triuranium octaoxide (U3O8), and producing sulfur tetrafluoride, using a two step process. The first step uses heat and a mixture of the uranium tetrafluoride and an alkaline compound, either an alkaline oxide or an alkaline hydroxide, to produce U3O8 and a water-soluble metal halide. The second step uses heat, sulfur and a halogen to produce sulfur tetrafluoride and triuranium octaoxide.

Abstract: A method for making a metal-titania pulp and photocatalyst is provided, including firstly acidically hydrolyzing a titanium alkoxide solution in presence of an alcohol solvent to get a colloidal solution; then, adding at least one metal salt solution into the colloidal solution to produce a nano-porous metal/titania photocatalyst under appropriate conditions by appropriate reaction. The nano-porous metal/titania photocatalyst thus prepared has excellent optical activity and is applicable in research of water decomposition with light to improve production efficiency of hydrogen energy. In addition, the photocatalyst is further processed in the form of powder or film to facilitate industrial application in wastewater treatment.

Abstract: Catalyst for oxidation reactions which comprises at least one constituent active in the catalysis of hydrogen chloride oxidation and support therefor, which support is based on uranium oxide. The catalyst is notable for a high stability and activity.

Abstract: A method for converting depleted uranium tetrafluoride (UF4) to triuranium octaoxide (U3O8), and producing sulfur tetrafluoride, using a two step process. The first step uses heat and a mixture of the uranium tetrafluoride and an alkaline compound, either an alkaline oxide or an alkaline hydroxide, to produce U3O8 and a water-soluble metal halide. The second step uses heat, sulfur and a halogen to produce sulfur tetrafluoride and triuranium octaoxide.

Abstract: The invention relates to a process for reprocessing a spent nuclear fuel and for preparing a mixed uranium-plutonium oxide, which process comprises: a) the separation of the uranium and plutonium from the fission products, the americium and the curium that are present in an aqueous nitric solution resulting from the dissolution of the fuel in nitric acid, this step including at least one operation of coextracting the uranium and plutonium from said solution by a solvent phase; b) the partition of 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) the purification of the plutonium and uranium that are present in the first aqueous phase; and d) a step of coconverting the plutonium and uranium to a mixed uranium/plutonium oxide. Applications: reprocessing of nuclear fuels based on uranium oxide or on mixed uranium-plutonium oxide.

Abstract: Fluorine extraction systems and associated processes are described herein. In one embodiment, a fluorine extraction process can include loading a mixture containing a uranium fluoride (UxFy, where x and y are integers) and an oxidizing agent into a reaction vessel. The reaction vessel has a closed bottom section and an opening spaced apart from the bottom section. The fluorine extraction process can also include heating the mixture containing uranium fluoride and the oxidizing agent in the reaction vessel, forming at least one uranium dioxide and a non-radioactive gas product from the heated mixture, and controlling a depth of the mixture in the reaction vessel to achieve a desired reaction yield of the non-radioactive gas product.

Abstract: Multi-step metal compound oxidation process to produce compounds and enhanced metal oxides from various source materials, e.g. metal sulfides, carbides, nitrides and other metal containing materials with metal oxides from secondary reaction steps being utilized as an oxidation agent in the first reactions.

Abstract: Process for manufacturing an electrochemical device including a cathode, an anode and at least one electrolyte membrane disposed between the anode and the cathode, wherein at least one of the cathode, the anode and the electrolyte membrane, contains at least a ceramic material.

Abstract: A method of declogging at least one filter of a plant for manufacturing uranium oxide from uranium hexafluoride, including separating, from the wall of the filter, uranium oxyfluoride particles deposited, by a stream of inert gas such as nitrogen, injected into the filter, in a counter-currentwise direction to the flow of hydrofluoric acid.

Abstract: A substance in a condensed state, for example a powdered solid, is in continuous movement in the longitudinal direction (6) of a furnace (4, 5). A reactive gas mixture is brought into contact with the substance in the condensed state. A plurality of samples of the gaseous mixture are removed at a plurality of reference points (14) spaced apart from one another along the longitudinal direction (6) of the furnace (4, 5); each of the gas samples is analyzed outside the furnace to determine the composition of the gas mixture and for each point (14), the extent of a chemical reaction between the condensed substance and the reactive gas mixture is deduced from the composition of the gas mixture at each of the reference points (14). In particular, the apparatus comprises a sampling and injection rod (10) introduced into the furnace (4, 5) and disposed in its longitudinal direction (6).

Abstract: Method for producing metal oxide nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone into metal vapor. The metal vapor is directed away from the hot zone and into the cooler plasma afterglow where it oxidizes, cools and condenses to form solid metal oxide nanoparticles.

Abstract: A two-cycle countercurrent extraction process for recovery of highly pure uranium from fertilizer grade weak phosphoric acid. The proposed process uses selective extraction using di-(2-ethyl hexyl) phosphoric acid (D2EHPA) and tri-n-butyl phosphate (TBP) with refined kerosene as synergistic extractant system on hydrogen peroxide treated phosphoric acid, and stripping the loaded extract with strong phosphoric acid containing metallic iron to lower redox potential. The loaded-stripped acid is diluted with water back to weak phosphoric acid state and its redox potential raised by adding hydrogen peroxide and re-extracted with same extractant system. This extract is first scrubbed with sulfuric acid and then stripped with alkali carbonate separating iron as a precipitate, treated with sodium hydroxide precipitating sodium uranate, which is re-dissolved in sulfuric acid and converted with hydrogen peroxide to highly pure yellow cake of uranium peroxide.

Abstract: A depleted UF6 processing plant including a first fluidized bed reactor configured to react depleted UF6 with steam to produce UO2F2 and hydrogen fluoride, a second fluidized bed reactor connected to the first fluidized bed reactor and configured to react the UO2F2 with steam to produce U3O8, hydrogen fluoride and oxygen, a gas cooler configured to cool the hydrogen fluoride generated in the first and second fluidized bed reactors down to 150 to 300° C., and a fluorine fixing reactor containing granular calcium carbonate and connected to the gas cooler to receive the hydrogen fluoride cooled down to 150 to 300° C. from the gas cooler. The fluorine fixing reactor is configured to form granular calcium fluoride from the granular calcium carbonate and the hydrogen fluoride passing through the fluorine fixing reactor.

Abstract: A metal oxide powder except &agr;-alumina, comprising polyhedral particles having at least 6 planes each, a number average particle size of from 0.1 to 300 &mgr;m, and a D90/D10 ratio of 10 or less where D10 and D90 are particle sizes at 10% and 90% accumulation, respectively from the smallest particle size side in a cumulative particle size curve of the particles. This metal oxide powder contains less agglomerated particles, and has a narrow particle size distribution and a uniform particle shape.

Abstract: A gas siphon type reactor (10) is used to carry out a three phase chemical reaction under pressure, such as the reduction of uranyl nitrate to uranous nitrate by hydrogen, in the presence of a catalyst made up of platinum on a silica carrier. The control of the pressure in the reactor (10) is provided by regulating the liquid and gas flow rates from a high pressure separator (52), into which the liquid and the gas leaving the reactor (10) are routed. The liquid in the reactor (10) is tapped from a lateral branch pipe (32) fitted with a filter (36) and emerging in the upper area (30), behind a profiled wall (34).

Abstract: A method for producing mixed oxide nuclear fuel pellets comprises the steps of preparing an U-Pu oxide blend powder having a Pu content in excess of the finally desired value, preparing uranium oxide powder, mixing adequate quantities of both powders in order to achieve the desired plutonium content and compacting and sintering the mixture for obtaining the pellets. The step of preparing the uranium oxide powder involves the following sequence of substeps: a) preparing an aqueous solution of uranyl nitrate to which between 0.5 and 2 wt % of organic thickeners are added such that the viscosity of the solution is adjusted to values between 20 and 100 centipoise, b) dispersing of the solution into droplets, c) introducing the droplets into a hydroxide bath, d) washing the resulting beads, e) drying the beads by azeotropic distillation using an immiscible organic solvent, f) thermally treating the beads in an oxidizing atmosphere and g) thermally treating in a reducing atmosphere.

Abstract: A substance in a condensed state, for example a powdered solid, is in continuous movement in the longitudinal direction (6) of a furnace (4, 5). A reactive gas mixture is brought into contact with the substance in the condensed state. A plurality of samples of the gaseous mixture are removed at a plurality of reference points (14) spaced apart from one another along the longitudinal direction (6) of the furnace (4, 5); each of the gas samples is analyzed outside the furnace to determine the composition of the gas mixture and for each point (14), the extent of a chemical reaction between the condensed substance and the reactive gas mixture is deduced from the composition of the gas mixture at each of the reference points (14). In particular, the apparatus comprises a sampling and injection rod (10) introduced into the furnace (4, 5) and disposed in its longitudinal direction (6).

Abstract: A depleted UF6 processing plant including a first fluidized bed reactor configured to react depleted UF6 with steam to produce UO2F2 and hydrogen fluoride, a second fluidized bed reactor connected to the first fluidized bed reactor and configured to react the UO2F2 with steam to produce U3O8, hydrogen fluoride and oxygen, a gas cooler configured to cool the hydrogen fluoride generated in the first and second fluidized bed reactors down to 150 to 300° C., and a fluorine fixing reactor containing granular calcium carbonate and connected to the gas cooler to receive the hydrogen fluoride cooled down to 150 to 300° C. from the gas cooler. The fluorine fixing reactor is configured to form granular calcium fluoride from the granular calcium carbonate and the hydrogen fluoride passing through the fluorine fixing reactor.

Abstract: The object of the present invention is to simplify the depleted UF6 processing plant and processing method and to prevent calcium fluoride to be a fine powder, wherein the processing plant comprises a first fluidized bed reactor for forming UO2F2 and hydrogen fluoride by allowing depleted UF6 to react with steam, a second fluidized bed reactor for forming U3Oa, hydrogen fluoride and oxygen by allowing UO2F2 to react with steam, a gas cooler for cooling hydrogen fluoride at 150 to 300° C., and a fluoride fixing reactor for forming calcium fluoride by allowing cooled hydrogen fluoride to contact calcium carbonate; and wherein the processing process comprises a dry vapor-phase reaction step for forcing UO2F2 and hydrogen fluoride by allowing depleted UF6 to react with steam at a temperature of 230 to 280° C.

Abstract: A method of dissolving in an ionic liquid a metal in an initial oxidation state below its maximum oxidation state, characterized in that the ionic liquid reacts with the metal and oxidizes it to a higher oxidation state. The initial metal may be in the form of a compound thereof and may be irradiated nuclear fuel comprising UO2 and/or PuO2 as well as fission products. The ionic liquid typically is nitrate-based, for example a pyridinium or substituted imidazolium nitrate, and contains a Bronstead or Franklin acid to increase the oxidizing power of the nitrate. Suitable acids are HNO3, H2SO4 and [NO+]. Imidazolium nitrates and certain pyridinium nitrates form one aspect of the invention.

Abstract: The invention relates to a method for recovering products from the defluorination of uranium hexafluoride. Recovered are a commercial grade anhydrous hydrogen fluoride and triuranium oxide through the use of two distinct reactors.

Abstract: Uranium trioxide Is reduced to uranium dioxide using microwave radiation or radiofrequency radiation directed in such a way that the radiation encounters an Interface between uranium trioxide and the uranium-containing reduction product without first having passed through that product. By this method, and also using a reducing gas, it is possible to obtain UO2 with an O:U ratio less than 2.04:1.

Abstract: A method for producing uranium oxide includes combining uranium tetrafluoride and a phyllosilicate mineral containing a solid oxidizing agent within the mineral's structure having a lower thermodynamic stability than the uranium oxide; heating the combination below the vapor point of the uranium tetrafluoride to sufficiently react the uranium tetrafluoride and the oxidizing agent to produce uranium oxide and a non-radioactive fluorine compound; and removing the fluorine compound.

Abstract: The conversion apparatus comprises in succession: a reactor provided with injectors of UF.sub.6, steam, and nitrogen so as to cause UO.sub.2 F.sub.2 to be formed by hydrolysis; a rotary tubular pyrohydrolysis furnace for transforming UO.sub.2 F.sub.2 into uranium oxide, and provided with heaters distributed in at least five zones; and a tail end for conditioning the oxide powder. The injectors comprise three concentric nozzles connected respectively to inlets for UF.sub.6, nitrogen, and steam, UF.sub.6 being fed to the central nozzle and nitrogen being injected between UF.sub.6 and steam.

Abstract: A thermal decomposition method useful in the nuclear industry for preparing a powdered mixture of metal oxides having suitable reactivity from nitrates thereof in the form of an aqueous solution or a mixture of solids. According to the method, the solution or the mixture of solids is thermomechanically contacted with a gaseous fluid in the contact area of a reaction chamber, said gaseous fluid being fed into the reaction chamber at the same time as the solution or mixture at a temperature no lower than the decomposition temperature of the nitrates, and having a mechanical energy high enough to generate a fine spray of the solution or a fine dispersion of the solid mixture, and instantly decompose the nitrates. The resulting oxide mixtures may be used to prepare nuclear fuels.

Abstract: A method for producing uranium oxide includes combining uranium oxyfluoride and a solid oxidizing agent having a lower thermodynamic stability than the uranium oxide after "oxide"; heating the combination below the vapor point of the uranium oxyfluoride to sufficiently react the uranium oxyfluoride and the oxidizing agent to produce uranium oxide and a non-radioactive fluorine compound; and removing the fluorine compound after "compound".

Abstract: A method for producing uranium oxide includes combining uranium oxyfluoride and silicon and heating the combination below the vapor point of the uranium oxyfluoride to sufficiently react the uranium oxyfluoride and silicon to produce uranium oxide and a non-radioactive fluorine compound; and removing the fluorine compound, e.g. silicon tetrafluoride.

Abstract: A method for producing silicon tetrafluoride includes combining uranium oxyfluoride and silicon dioxide; heating the combination below the melting point of the uranium oxyfluoride to sufficiently react the uranium oxyfluoride and the silicon dioxide to produce non-radioactive silicon tetrafluoride and an oxide of uranium; and removing the silicon tetrafluoride.

Abstract: A multicomponent fluid feed apparatus is disclosed that independently preheats and then mixes two or more fluid streams being introduced into a high temperature chemical reactor to promote more rigorous and complete reactions using assemblies of inert tubular elements and an integral mixing orifice plate. The design allows use of ceramic and speciality alloy materials for high temperature service with particularly corrosive halide feeds such as UF.sub.6 and HF. Radiant heat transfer to the tubular elements from external means gives the necessary system high temperatures without excessive temperatures to cause material failure. Preheating of the gaseous reactants in a separate step prior to mixing and injecting the gaseous reactants into a high temperature chemical reactor was found to provide an improved thermal conversion of UF.sub.6 to uranium oxides.

Abstract: A method for producing uranium oxide includes combining uranium tetrafluoride and a solid oxidizing agent having a lower thermodynamic stability than the uranium oxide; heating the combination below the vapor point of the uranium tetrafluoride to sufficiently react the uranium tetrafluoride and the oxidizing agent to produce uranium oxide and a non-radioactive fluorine compound; and removing the fluorine compound.

Abstract: A method for producing uranium oxide includes combining uranium tetrafluoride, silicon and a gaseous anhydrous oxidizing agent having a lower thermodynamic stability than any oxide of uranium produced; heating the combination below the vapor point of the uranium tetrafluoride to sufficiently react the uranium tetrafluoride, silicon and the oxidizing agent to produce uranium oxide and a non-radioactive fluorine compound; and removing the fluorine compound.

Abstract: A method for producing silicon tetrafluoride includes combining uranium tetrafluoride and silicon dioxide; heating the combination below the melting point of the uranium tetrafluoride to sufficiently react the uranium tetrafluoride and the silicon dioxide to produce non-radioactive silicon tetrafluoride and an oxide of uranium; and removing the silicon tetrafluoride.

Abstract: The present invention provides a method for varying and controlling the chemical composition and physical properties of the uranium oxide solids produced by the thermal conversion of UF.sub.6. The method allows the production of predominantly UO.sub.2, U.sub.3 O.sub.8, or UO.sub.3 interchangeably from the same reactor simply by controlling the hydrogen and oxygen contents of the feed relative to uranium. The temperature profile of the thermal reactor is established by specifying the preheat of the feed prior to mixing, the feed composition, and the reactor wall temperature to thus vary and control the physical properties of the resulting solids according to the end use of the uranium product.

Abstract: The present invention provides a process for the oxidation of uranium hexafluoride by injecting the uranium hexafluoride and an oxidant gas together into a reaction vessel to form a plume characterized in that a plurality of the said plumes are formed together in the same vessel, the plumes mutually contributing to a circulating product formation stream in the said vessel. The process may include the establishment of three or more plumes simultaneously contributing to the reaction between the gases in the reaction vessel. The oxidant gas may comprise steam. The process may be one in which the product is formed as a particulate solid. The product particles may initially be formed as dentritic particles which may be recirculated in the reaction vessel to promote seeding, growth, agglomeration and aggregation of the required product particles, the plumes thereby contributing to the product formation process in the vessel.

Abstract: A single-step process for producing solid uranium oxide and gaseous HF from UF.sub.6 which comprises bringing together two gaseous reactant streams, one of said streams comprising UF.sub.6 optionally admixed with oxygen as O.sub.2, and the second reactant stream comprising a mixture of hydrogen as H.sub.2 or as a hydrogen-containing compound and oxygen as an oxygen-containing compound, said gaseous reactant streams being brought together at a temperature and composition such that the UF.sub.6 is converted rapidly by flame reaction into readily separable solid uranium oxide and a gaseous HF product.

Abstract: A method for purifying metallic alloys of uranium for use as nuclear reactor fuels in which the metal alloy is first converted to an oxide and then dissolved in nitric acid. Initial removal of metal oxide impurities not soluble in nitric acid is accomplished by filtration or other physical means. Further purification can be accomplished by carbonate leaching of uranyl ions from the partially purified solution or using traditional methods such as solvent extraction.

Abstract: Process for obtaining uranium trioxide from a uranyl nitrate solution, the trioxide obtained having to have a specific surface between 12 and 15 m.sup.2 /g, consisting of producing in a zone of the reaction chamber called the contact zone, a thermomechanical contact between the uranyl nitrate solution, atomized into fine droplets according to a given axis in the contact zone, and a gaseous fluid introduced into the contact zone, the gaseous fluid being at a sufficiently high temperature and having a sufficiently high mechanical energy to carry out, within the contact zone, the dehydration and calcination of the uranyl nitrate.

Abstract: Finely powdered urania scrap materials are subjected to sintering conditions (greater than 1600.degree. C.) in a hydrogen atmosphere for about 4 to 8 hours in order to remove impurities (such as Si, Fe, Ni, Sn, Cu, Na and Pb). The process upgrades the quality of the urania powder to where it can be used directly as clean scrap makeup, thereby avoiding expensive decontamination and recovery steps like solvent extraction. The novelty of the process is in the use of sintering conditions (greater than 1600.degree. C.) in a hydrogen atmosphere on finely divided powder to decontaminate urania materials.