Abstract: An actinide dioxide, e.g. uranium dioxide, plutonium dioxide, neptunium dioxide, etc., is prepared by reacting the actinide nitrate hexahydrate with sodium dithionite as a first step; the reaction product from this first step is a novel composition of matter comprising the actinide sulfite tetrahydrate. The reaction product resulting from this first step is then converted to the actinide dioxide by heating it in the absence of an oxygen-containing atmosphere (e.g. nitrogen) to a temperature of about 500.degree. to about 950.degree. C. for about 15 to about 135 minutes. If the reaction product resulting from the first step is, prior to carrying out the second heating step, exposed to an oxygen-containing atmosphere such as air, the resultant product is a novel composition of matter comprising the actinide oxysulfite tetrahydrate which can also be readily converted to the actinide dioxide by heating it in the absence of an oxygen-containing atmosphere (e.g. nitrogen) at a temperature of about 400.degree.

Abstract: Irradiated nuclear fuels consisting primarily of plutonium compounds and/or uranium compounds such as oxides, carbides, nitrides are converted in accordance with the method to plutonium hexafluoride and/or uranium hexafluoride. In a first step, the compounds are contacted within a first zone of an enclosure with a gas mixture containing at least one fluorination reagent. In a second step, the remainder of the compounds which have not been converted to fluorides during the first step is contacted directly within a second zone of the enclosure with a bed which has been fluidized by means of a gas mixture containing at least one fluorination reagent.

Abstract: A process for reducing plutonium is provided in which hydrazine is added as a reducing agent to a nitric acid solution of tetravalent plutonium in the presence of active carbon catalyst to thereby reduce tetravalent plutonium into trivalent plutonium.

Abstract: An effective method for purifying plutonium hexafluoride for the reprocessing of the spent nuclear fuel or for the recovery of fuel plutonium from the scrap by fluoride-volatility with high decontamination factors is presented using a selective adsorption of the fission products fluorides by letting the gas mixture flow through a layer of an adsorbent consisting of one or more of the specified compounds selected from hexafluoro sodium aluminate, zinc fluoride, nickel fluoride and ferric fluoride at an elevated temperature. The principle of the purification method is based on the fact that the fluorides of the fission products are easily adsorbed by the adsorbent but little plutonium hexafluoride is adsorbed. The fluorides of the fission products are easily removed from the adsorbent by heating and the recycling use of the adsorbent is possible.

Abstract: Flexible metal carbide fabrics are produced by a process that involves the steps of:(a) impregnating a preformed organic polymeric fabric with a solution of a metal compound;(b) heating the impregnated fabric to evolve volatile decomposition products and to leave a carbonaceous relic containing the metal in finely dispersed form; and(c) further heating the relic to 1000.degree.-2400.degree. C. in a non-oxidizing atmosphere to form the metal carbide. Boron carbide and silicon carbide fabrics produced by this process are attractive for high temperature structural applications.

Abstract: PuO.sub.2 -containing solids, particularly residues from incomplete HNO.sub.3 dissolution of irradiated nuclear fuels, are dissolved in aqueous HI. The resulting solution is evaporated to dryness and the solids are dissolved in HNO.sub.3 for further chemical reprocessing. Alternatively, the HI solution containing dissolved Pu values, can be contacted with a cation exchange resin causing the Pu values to load the resin. The Pu values are selectively eluted from the resin with more concentrated HI.

Abstract: The rate of reduction of Pu(IV) to Pu(III) in nitric acid solution containing a reducing agent is enhanced by exposing the solution to 200-500 nm electromagnetic radiation. Pu values are recovered from an organic extractant solution containing Pu(IV) values and U(VI) values by the method of contacting the extractant solution with an aqueous nitric acid solution in the presence of a reducing agent and exposing the aqueous solution to electromagnetic radiation having a wavelength of 200-500 nm. Under these conditions, Pu values preferentially distribute to the aqueous phase and U values preferentially distribute to the organic phase.

Abstract: The invention relates to a process for decontaminating or removing radionuclides from aqueous solution.

Abstract: This invention relates to a novel method and a novel generator, or source, for providing gaseous negative ions of selected metal hexafluorides. The method is summarized as follows: in an evacuated zone, reacting gaseous fluorine with an actinide-metal body selected from the group consisting of uranium, plutonium, neptunium, and americium to convert at least part of the metal to the hexafluoride state, thus producing gaseous negatively charged metal-hexafluoride ions in the evacuated zone, and applying an electric field to the zone to remove the ions therefrom. The ion source comprises a chamber defining a reaction zone; means for evacuating the zone; an actinide-metal body in the zone, the metal being uranium, plutonium, neptunium, or americium; means for contacting the body with gaseous fluorine to convert at least a part thereof to the hexafluoride state; and means for applying an electric field to the evacuated zone to extract gaseous, negatively charged metal-hexafluoride ions therefrom.

Abstract: A nitric acid solution having a nitric acid concentration within the range of 0.01 to 15 M and containing plutonium(IV) ions and/or plutonium(III) ions is reacted with a formic acid solution in order to obtain a precipitate of plutonium(III) formiate.

Abstract: A method is disclosed for the selective separation and sequestering of plutonium from uranium which comprises contacting a gas stream containing uranium hexafluoride [at a partial pressure of 26 torr or less] and plutonium hexafluoride at any pressure with graphite whereby PuF.sub.6 is selectively intercalated into the graphite while UF.sub.6 is left unreacted in the gas stream. Preferably, the contacting of UF.sub.6 and PuF.sub.6 with graphite is conducted in the presence of excess fluorine.In another embodiment the graphite is first reacted with a chemical oxidant. Such pretreatment of the graphite renders it inert to UF.sub.6 intercalation at partial pressures over 26 torr, the pressure above which UF.sub.6 normally intercalates with graphite. Such pretreatment will have less effect on PuF.sub.6 intercalation into the prereacted graphite compound and therefore will permit the separation of UF.sub.6 -PuF.sub.

Abstract: In the recovery of plutonium from irradiated nuclear fuel elements especially those coming from fast nuclear reactors, the improvement consisting in that the spent nuclear fuel elements are subjected to the action of a molten nitrate bath (mixed nitrates of alkali metals or alkaline earth metals), whereafter the plutonium thus obtained is further decomposed in a nitrate bath at a higher temperature, then the plutonium is recovered and a further thermal decomposition of the remaining material at a still higher temperature enables the uranium to be recovered. The recovery of plutonium requires the action of the nitric vapors, the recovery of uranium does not. Molten nitrates can likewise be recovered and recycled.

Abstract: A nitrided alloy of uranium and zirconium is provided which consists of a single-phase UN structure containing a dissolved amount of Zr as ZrN, effective to inhibit dissociation of the UN phase.

Abstract: Process for enriching .sup.238 PuO.sub.2 with .sup.16 O and forming sintered fuel pellets therefrom comprising the steps of compressing a mass of .sup.238 PuO.sub.2 containing .sup.16 O, .sup.17 O and .sup.18 O into a pellet; exposing the pellet to an atmosphere of .sup.16 O and an inert carrier gas at an increasing temperature up to about 1400.degree. C with varied gas flow to obtain an exchange of .sup.17 O and .sup.18 O and the simultaneous sintering of the pellet; and cooling the sintered and exchanged pellet.

Abstract: A method is provided for producing a selected metal nitride utilizing a salt bath. The selected metal is introduced into the salt bath in the presence of gaseous nitrogen and at least a certain amount of a halide of the selected metal. The salt bath is maintained at a temperature above its melting point for time sufficient to form a precipitate of the desired amount of a nitride of the selected metal. In accordance with a preferred embodment, the pressure is thereafter reduced to less than atmospheric and the temperature increased above the boiling point of the salt for a time sufficient to volatilize the molten salt which is removed to leave a precipitate of the selected metal nitride. The method is particularly applicable to the production of the mononitrides of uranium, plutonium, thorium, and mixtures thereof.

Abstract: A method for separating specific isotopes present in an isotopic mixture by aerodynamically accelerating a gaseous compound to form a jet of molecules, and passing the jet through a stream of electron donor atoms whereby an electron transfer takes place, thus forming negative ions of the molecules. The molecular ions are then passed through a radiofrequency quadrupole mass filter to separate the specific isotopes. This method may be used for any compounds having a sufficiently high electron affinity to permit negative ion formation, and is especially useful for the separation of plutonium and uranium isotopes.

Abstract: An actinide dioxide, e.g., uranium dioxide, plutonium dioxide, neptunium dioxide, etc., is prepared by reacting the actinide nitrate hexahydrate with sodium dithionite as a first step; the reaction product from this first step is a novel composition of matter comprising the actinide sulfite tetrahydrate. The reaction product resulting from this first step is then converted to the actinide dioxide by heating it in the absence of an oxygen-containing atmosphere (e.g., nitrogen) to a temperature of about 500.degree. to about 950.degree. C. for about 15 to about 135 minutes. If the reaction product resulting from the first step is, prior to carrying out the second heating step, exposed to an oxygen-containing atmosphere such as air, the resultant product is a novel composition of matter comprising the actinide oxysulfite tetrahydrate which can also be readily converted to the actinide dioxide by heating it in the absence of an oxygen-containing atmosphere (e.g., nitrogen) at a temperature of about 400.degree.

Abstract: Uniform microspheres substantially or completely free from internal cavities and voids are prepared by spraying an aqueous hydrated metal oxide solution onto the surface of a water-immiscible organic liquid containing from 0.04 to 2.0 percent by volume of a surface active agent, the viscosities of each of the organic and inorganic phases plus the amount of surface active agent within the above range being selected such that there is sufficient surface active agent present to prevent the globules from adhering to each other yet an insufficient amount to prevent deformation from the substantially spherical shape.

Abstract: Salts or materials containing plutonium and americium are dissolved in hydrochloric acid, heated, and contacted with an alkali metal carbonate solution to precipitate plutonium and americium carbonates which are thereafter readily separable from the solution.

Abstract: The preparation of metal and metalloid carbides, borides, nitrides silicides and sulfides by reaction in the vapor phase of the corresponding vaporous metal halide, e.g., metal chloride, with a source of carbon, boron, nitrogen, silicon or sulfur respectively in a reactor is described. Reactants can be introduced into the reactor through a reactant inlet nozzle assembly. Inhibition and often substantial elimination of product growth on exposed surfaces of such assembly is accomplished by introducing the corresponding substantially anhydrous hydrogen halide, e.g., hydrogen chloride, into the principal reactant mixing zone.

Abstract: Pure monocarbides, or pure mononitrides or carbonitrides of metals are prepared by first forming a mixture of carbon with an oxalate of the metals and thermally decomposing the metal oxalate in the presence of the carbon by a stream of hydrogen. The hydrogen is removed and monocarbides are then formed by heating the decomposition products in vacuo to carbothermally reduce them. Mononitrides and carbonitrides can be formed by replacing the hydrogen with nitrogen and heating the decomposition products in the nitrogen.

Abstract: A method for dissolving plutonium dioxide comprises adding silver ions to a nitric acid-hydrofluoric acid solution to significantly speed up dissolution of difficultly soluble plutonium dioxide.

Abstract: For use as a power source in heart pacers, plutonium dioxide having a naturally-occurring oxygen isotope composition is converted into solid phase PuCl.sub.3 which is subsequently oxidized to form plutonium dioxide of the desired isotope composition by means of water vapor, the oxygen component of which consists essentially of the isotope .sup.16 O. Apparatus suited for this purpose is also described.

Abstract: A process for preparing actinide-nitrides from massive actinide metal which is suitable for sintering into low density fuel shapes by partially hydriding the massive metal and simultaneously dehydriding and nitriding the dehydrided portion. The process is repeated until all of the massive metal is converted to a nitride.

Abstract: Fast breeder fuel elements which have been highly burnt-up are reprocessed by extracting uranium and plutonium into an organic solution containing tributyl phosphate. The tributyl phosphate degenerates at least partially into dibutyl phosphate and monobutyl phosphate, which form stable complexes with tetravalent plutonium in the organic solution. This tetravalent plutonium is released from its complexed state and stripped into aqueous phase by contacting the organic solution with an aqueous phase containing tetravalent uranium.

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.