A Re-examination of Thermodynamic Modelling of U-RU Binary Phase Diagram

Abstract

Ruthenium (Ru) is one of the more abundant fission products (FPs) both in fast breeder reactors and thermal reactors. Post irradiation examinations (PIE) show that both "the white metallic phase" (Mo-Tc-Ru-Rh-Pd) and "the other metallic phase" (U(Pd-Rh-Ru)₃) are present in spent nuclear fuels. Todescribe this quaternary system, binary subsystems of uranium (U) with Pd, Rh, and Ru are necessary. Presently, only the U-Ru system has been thermodynamically described but with some problems. As part of research on U-Ru-Rh-Pd quaternary system, an improved consistent thermodynamic model describing the U-Ru binary phase diagram has been obtained.