Abstract: The invention relates to a process for preparing a castable powder of uranium dioxide UO2, for use in the manufacture of MOX fuel. This process comprises the following stages: 1) to prepare an aqueous suspension of a powder of UO2 obtained by dry process from uranium hexafluoride, said suspension comprising 50 to 80% by weight of UO2 and at least one additive chosen among deflocculation agents, organic binders, hydrogen peroxide H2O2 and a powder of U3O8, in such a quantity that the viscosity of the suspension does not exceed 250 mPa.sec, and 2) to atomise this suspension and dry it in a hot gas, at a temperature of 150 to 300° C., to obtain a castable powder of UO2 with an average particle size of 20 to 100 &mgr;m.

Abstract: The invention relates to a process for thermal etching under oxidizing conditions of a ceramic, more particularly with the aim of revealing its grain boundaries and for the study of its granular microstructure. The invention applies to technical and nuclear ceramics and in particular UO2 and to (U, Pu) O2 mixtures. The thermal etching is performed in a furnace or kiln under a controlled atmosphere constituted by an oxidizing gas supplying a chemical oxygen potential of −75 to −125 kJ/mole and comprises the following successive stages: rapid rise in the temperature of the furnace to a rate of 900 to 1500° C./h from the initial temperature to a temperature plateau, maintaining the temperature at said plateau at a value of 1250 to 1450° C. for between 30 and 15 minutes, lowering the temperature to the final temperature.

Abstract: Process for the production of nuclear fuel pellets based on mixed uranium and plutonium oxide having a specific plutonium content from a charge of UO.sub.2 and PuO.sub.2 powders by lubrification, pelletizing and sintering, in which a solid, sulphur, organic additive of the zwitterion type is incorporated into the mixture during the co-milling stage for the powders.