Phase equilibria in the BaUO3-BaZrO3-BaMoO3system

The phase equilibria in the pseudo-ternary BaUO3-BaZrO3-BaMoO3 system were studied to understand the thermochemical properties of the perovskite type gray oxide phase in high burnup MOX fuel. Thermodynamic equilibrium calculation for the system was performed by using a ChemSage program under the various oxygen potentials. Solid solutions existing in the system were treated by an ideal solution model. The present calculation results well agreed with the previous reported post irradiation examination results, showing that BaMoO3 was scarcely included in the gray oxide phase.