Abstract: A process is provided for preparing a powder of an oxide of at least one metal, each metal having an oxidation number between (III) and (VI). This process comprises successively and in this order: (a) reacting, with a compound comprising a hydroxide, an aqueous solution comprising, for each metal, at least one salt of the cation of said metal, (b) separating the precipitate obtained, (c) contacting the separated precipitate with an organic protic polar solvent, (d) removing the organic protic polar solvent by vacuum drying the precipitate. A process is further provided for manufacturing a pellet of an oxide of at least one metal as well as to a powder and to a pellet obtained according to these processes and to uses thereof.

Abstract: A method for processing a spent nuclear fuel is disclosed which includes a step for decontaminating uranium(VI) from one or more actinides(IV) and more specially from neptunium and/or plutonium, by complexing this (these) actinide(s)(IV). This method includes a step for decontaminating uranium (VI) from at least one actinide(IV), which decontaminating step comprises at least one operation for stripping the actinide(IV) from an organic phase, not miscible with water, and wherein uranium(VI) and the actinide(IV) are present, by putting the organic phase into contact with an aqueous phase comprising nitric acid and at least one complexing agent which more strongly complexes actinides(IV) than uranium(VI), and then separating the organic phase from the nitric aqueous phase, wherein the at least one complexing agent is a diglycolamide.

Abstract: A method for measuring dosage by means of a radiation detector, especially an X-radiation or gamma-radiation detector, used in the spectroscopic mode, and a dosage measurement system using said method. A range of energies and a dose type H is chosen, a radiation detector of a given type is used, spectra measured by the detector are established for various radiations of the given type, the energies of which are within the chosen range and the respective doses of which are known, and from the spectra, a weighting function is established, that is a correspondence between a mean dose increment and a mean energy, deposited into the detector. This enables a person provided with a dosimeter identical to the detector to know at any time the mean absorbed dose rate, expressed in the amount H.

Abstract: A process is described for synthesizing a mixed peroxide or hydroxo-peroxide of an actinyl and at least one cation X1, wherein the actinyl is a uranyl or neptunyl and the at least one cation X1 is a di-, tri- or tetra-charged metal cation. This process includes the reaction in a solvent of a salt of the at least one cation X1 with a compound C2 selected from mixed peroxides and hydroxo-peroxides of the actinyl and of at least one singly charged cation X2, whereby compound C2 is converted to the peroxide or hydroxo-peroxide by replacement of the at least one cation X2 by said at least one cation X1. Also disclosed is a process for synthesizing a mixed oxide of an actinide selected from uranium and neptunium, and of at least one metal able to form a di-, tri- or tetra-charged cation, which implements the preceding synthesis process.

Abstract: A method for preparing a powder of a solid solution of dioxide of uranium and of at least one other actinide and/or lanthanide element comprising combusting a solution that comprises uranyl nitrate and at least one nitrate of the other actinide and/or lanthanide element and glycine, with the glycine being used in a predetermined amount so as to form, at the end of the combustion, the solid solution.

Abstract: The present invention relates to a process for sintering a compacted powder of at least one oxide of a metal selected from an actinide and a lanthanide, this process comprising the following successive steps, carried out in a furnace and under an atmosphere comprising an inert gas, dihydrogen and water: (a) a temperature increase from an initial temperature TI up to a hold temperature TP, (b) maintaining the temperature at the hold temperature TP, and (c) a temperature decrease from the hold temperature TP down to a final temperature TF, in which the P(H2)/P(H2O) ratio is such that: 500<P(H2)/P(H2O)?50 000, during step (a), from TI until a first intermediate temperature Ti1 between 1000° C. and TP is reached, and P(H2)/P(H2O)?500, at least during step (c), from a second intermediate temperature Ti2 between TP and 1000° C., until TF is reached.