Thermodynamic assessment of the U–Y–O system

Abstract The CALPHAD methodology was used to develop a thermodynamic assessment of the U–La–O system. The solid solution and liquid phases are described with the compound energy formalism (CEF) and the partially ionic two-sublattice liquid model, respectively. Experimental thermodynamic and phase equilibria data published in the open literature were then used in optimizations to develop representations of the phases in the system that can be extended to include other actinide and fission products for multi-component models. The models that comprise this assessment very well reproduce experimentally determined oxygen potentials and the observed phase relations for the U–La–O system.