Abstract: There is provided a process for the production of pourable, directly compactable uranium dioxide powder by continuous precipitation of uranium peroxide from a stirred uranyl nitrate solution at a pH of 1 - 2.5 with hydrogen peroxide, calcining of the peroxide at 500.degree.- 800.degree. C. and subsequent reduction at 550.degree.- 750.degree. C. The precipitation solution contains 70 - 150 g/l of uranium and 0.80 g/l of ammonium nitrate and is treated with 15 - 20% aqueous hydrogen peroxide solution in the ratio of U:H.sub.2 O.sub.2 from 1:1.5 to 1:3 and there is led through the solution a mixture of ammonia and air having an air-ammonia volume ratio of 1:0.3 - 0.6. An apparatus for carrying out the process is also described. SUBACKGROUND OF THE INVENTIONThe present invention is directed to a process and apparatus for the production of directly pressable (moldable) uranium dioxide powder from uranium peroxide (UO.sub.4.xH.sub.

Abstract: An improved process for the conversion of gaseous uranium hexafluoride to a uranium oxide rich composition in the presence of an active flame in a reaction zone is achieved by introducing a first gaseous reactant comprising a mixture of uranium hexafluoride and an oxygen-containing carrier gas and a second gaseous reactant comprising a reducing gas, the reactants being separated by a shielding gas as introduced to the reaction zone. The shielding gas temporarily separates the gaseous reactants and temporarily prevents substantial mixing and reacting of the gaseous reactants. The flame occurring in the reaction zone is maintained away from contact with the inlet introducing the mixture to the reaction zone.

Abstract: A process of recovering uranium values as uranium peroxide from an aqueous uranyl solution containing dissolved vanadium and sodium impurities by treating the uranyl solution with hydrogen peroxide in an amount sufficient to have an excess of at least 0.5 parts H.sub.2 O.sub.2 per part of vanadium (V.sub.2 O.sub.5) above the stoichiometric amount required to form the uranium peroxide, the hydrogen peroxide treatment being carried out in three sequential phases consisting of I, a precipitation phase in which the hydrogen peroxide is added to the uranyl solution to precipitate the uranium peroxide and the pH of the reaction medium maintained in the range of 2.5 to 5.5 for a period of from about 1 to 60 minutes after the hydrogen peroxide addition; II, a digestion phase in which the pH of the reaction medium is maintained in the range of 3.0 to 7.0 for a period of about 5 to 180 minutes and III, a final phase in which the pH of the reaction medium is maintained in the range of 4.0 to 7.

Abstract: A novel process and an apparatus are herein disclosed for separating molybdenum-99 from irradiated uranium.

Abstract: An improved process for the conversion of gaseous uranium hexafluoride to a uranium oxide rich composition in the presence of an active flame in a reaction zone is disclosed and comprises introducing a first gaseous reactant comprising a mixture of uranium hexafluoride and an oxygen-containing carrier gas and a second gaseous reactant comprising a reducing gas, the reactants being separated by a shielding gas as introduced to the reaction zone. The shielding gas temporarily separates the gaseous reactants and temporarily prevents substantial mixing and reacting of the gaseous reactants. The flame occurring in the reaction zone is maintained away from contact with the inlet introducing the mixture to the reaction zone.

Abstract: A process for converting uranium hexafluoride (UF.sub.6) to uranium dioxide (UO.sub.2) of a relatively large particle size in a fluidized bed reactor by mixing uranium hexafluoride with a mixture of steam and hydrogen and by preliminary reacting in an ejector gaseous uranium hexafluoride with steam and hydrogen to form a mixture of uranium and oxide and uranium oxyfluoride seed particles of varying sizes, separating the larger particles from the smaller particles in a cyclone separator, recycling the smaller seed particles through the ejector to increase their size, and introducing the larger seed particles from the cyclone separator into a fluidized bed reactor where the seed particles serve as nuclei on which coarser particles of uranium dioxide are formed.

Abstract: This invention presents a process for conversion of gaseous uranium hexafluoride to an oxide product of uranium by introducing to a reaction zone in the presence of an active flame maintained in the reaction zone a first gaseous reactant comprising a mixture of uranium hexafluoride and an oxygen-containing gas and a second gaseous reactant comprising a reducing gas and temporarily separating the first and second gaseous reactants with a shielding gas which temporarily prevents substantial mixing and reaction between these gaseous reactants. The first and second gaseous reactants ultimately react in a primary flame to give a particulate uranium dioxide rich composition and residual reducing gas. An oxygen-containing gas as a third gaseous reactant is introduced through multiple downstream inlets with the inlet closest to the primary flame being at a location in the reaction zone where the uranium hexafluoride conversion to the uranium dioxide rich composition is substantially complete.

Abstract: A method of dehalogenating a particulate composition in a calciner having a heating zone and a cooling zone is presented in which a dehalogenating atmosphere flows through the calciner, including a constricted zone in the calciner, countercurrent to the movement of the composition through the calciner. There is practiced a step of constricting the passage of the controlled atmosphere to a zone of greater flow velocity so that the flow of the dehalogenating atmosphere through the constricted zone substantially minimizes diffusion into the cooling zone of the gaseous impurities removed from the particulate composition in the heating zone.

Abstract: Uranium is separated from contaminating cations in an aqueous liquor containing uranyl ions. The liquor is mixed with sufficient recycled uranium complex to raise the weight ratio of uranium to said cations preferably to at least about three. The liquor is then extracted with at least enough non-interfering, water-immiscible, organic solvent to theoretically extract about all of the uranium in the liquor. The oganic solvent contains a reagent which reacts with the uranyl ions to form a complex soluble in the solvent. If the aqueous liquor is acidic, the organic solvent is then scrubbed with water. The organic solvent is stripped with a solution containing at least enough ammonium carbonate to pecipitate the uranium complex. A portion of the uranium complex is recycled and the remainder can be collected and calcined to produce U.sub.3 O.sub.8 or UO.sub.2.

Abstract: A fluorine containing heavy-metal oxide powder, particularly UO.sub.2 powder, is subjected to a pyrohydrolysis treatment under the most complete exclusion of hydrogen.

Abstract: The invention relates to a method for the preparation of aniondeficient actinide nitrate solutions. Anion deficient actinide nitrate solutions are used for the preparation of ceramic spherical ceramic nuclear fuel.According to the invention one or more actinide oxides selected from the group of PuO.sub.2, UO.sub.2, U.sub.3 O.sub.8, UO.sub.3 of oxides ranging between UO.sub.2 and UO.sub.3 are dissolved in one or more actinide nitrates which are molten in their water of crystallination. The obtained mixture is subsequently diluted with water.

Abstract: Concentrated anion-deficient salt solutions are prepared of the actinide oxides, PuO.sub.2, UO.sub.2, UO.sub.3 and U.sub.3 O.sub.8 by dissolving one or more oxides in an aqueous solution of thorium nitrate at a concentration of 4 molar or greater and at a temperature of 60.degree. C. or more. Anion-deficient salt solutions of actinide metals so produced are useful as starting materials for the manufacture of ceramic nuclear fuel particles by the sol-gel process.