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 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: The invention relates to a nuclear fuel cladding totally or partially made of a composite material with a ceramic matrix containing silicon carbide (SiC) fibers as a matrix reinforcement and an interphase layer provided between the matrix and the fibers, the matrix including silicon carbide as well as at least one of the following additional carbides: titanium carbide (TiC), zirconium carbide (Zrc), and ternary titanium silicon carbide (Ti3SiC2). When irradiated and at temperatures of between 800° C. and 1200° C., said cladding can mechanically maintain the nuclear fuel within the cladding while enabling optimal thermal-energy transfer towards the coolant. The invention also relates to a method for making the nuclear fuel cladding.

Abstract: A process for joining, by spark plasma sintering, at least two refractory ceramic parts, each of the parts having at least one surface to be joined by spark plasma sintering, in which surfaces to be joined are brought into contact without addition of any sort between the surfaces. Then, a joining pressure of 1 to 200 MPa is applied to the ceramic parts. A pulsed electric current having an intensity of 500 A to 8000 A is applied to the ceramic parts so as to raise the temperature of the parts to a joining temperature of at least 1300° C. Then, the electric current is terminated simultaneously with the pressure, and the parts are cooled, and the joined parts are recovered.

Abstract: The invention relates to a nuclear fuel cladding totally or partially made of a composite material with a ceramic matrix containing silicon carbide (SiC) fibers as a matrix reinforcement and an interphase layer provided between said matrix and said fibers, the matrix including at least one carbide selected from titanium carbide (TiC), zirconium carbide (ZrC), or ternary titanium silicon carbide (Ti3SiC2). When irradiated and at temperatures of between 800° C. and 1200° C., said cladding can mechanically maintain the nuclear fuel within the cladding while enabling optimal thermal-energy transfer towards the coolant. The invention also relates to a method for making the nuclear fuel cladding.

Abstract: A process for joining, by spark plasma sintering, at least two refractory ceramic parts, each of the parts having at least one surface to be joined by spark plasma sintering, in which surfaces to be joined are brought into contact without addition of any sort between the surfaces. Then, a joining pressure of 1 to 200 MPa is applied to the ceramic parts. A pulsed electric current having an intensity of 500 A to 8000 A is applied to the ceramic parts so as to raise the temperature of the parts to a joining temperature of at least 1300° C. Then, the electric current is terminated simultaneously with the pressure, and the parts are cooled, and the joined parts are recovered.

Abstract: The invention relates to the conditioning or packaging of radioactive iodine, particularly iodine 129, using an apatite as the confinement matrix. Having the iodine, said apatite corresponds to the formula:M.sub.10 (XO.sub.4).sub.6-6x (PO.sub.4).sub.6x I.sub.2 (I)in which M represents Cd or Pb, X represents V or As, I is the radioactive iodine to be conditioned and x is such that 0.ltoreq.x<1. This iodoapatite (1) can be surrounded by an apatite (3) not containing iodine serving as a physical barrier.The iodoapatite can be obtained from a solid compound of the iodine, e.g. an iodide such as silver iodide or lead iodide, by reaction with a compound of formula:M.sub.3 (XO.sub.4).sub.2-2x (PO.sub.4).sub.2x (II)orM.sub.10 (XO.sub.4).sub.6-6x (PO.sub.4).sub.6x Y.sub.2 (III)in which M, X and x are as defined hereinbefore and Y can represent OH, F, Cl or O.sub.1/2.