EVALUATION OF PHASES IN PU-C-O AND (U,PU)-C-O SYSTEMS BY X-RAY-DIFFRACTOMETRY AND CHEMICAL-ANALYSIS

Preparation and characterisation of the carbides of uranium, plutonium and mixed uranium and plutonium form a part of advanced fuel development programs for fast breeder reactors. In the present study, the compositions of the phases of Pu-C-O and (U,Pu)-C-O systems have been determined by chemical analysis and lattice parameter measurement. The carbide samples have been prepared by vacuum carbothermic synthesis of tabletted oxide-graphite powder mixture. Dependence of stoichiometry of Pu2C3 phase on the oxygen content of Pu(C,O) phase in Pu(C,O)+Pu2C3 phase mixture has been evaluated. Stoichiometry and oxygen solubility of (U0.3Pu0.7)(C,O) phase in multiple phase mixture have been determined. Segregation of plutonium in (U,Pu)(2)C-3 phase of (U,Pu)(C,O)+(U,Pu)(2)C-3 phase mixture and its dependence on the oxygen content of (U,Pu)(C,O) phase have also been determined from the measurement of the lattice parameter of (U,Pu)(2)C-3 phase.