Phase Equilibria in the Uranium-Plutonium-Oxygen Ternary Phase Diagram at (U0.55,Pu0.45)O2-x and (U0.45,Pu0.55)O2-x

In the present experimental study, after studying the impact of phase separation on (U1-y,Puy)O2-x MOX fuel at y=0.45 and.0.55 at room temperature, phase equilibria has been investigated at high temperature up to 1700K by High Temperature X-Ray Diffraction measurements. We provide new data on the phase separation temperature, demonstrating that phase equilibria are highly influenced by fuel composition. In addition, data on Linear Thermal Expansion Coefficient have been calculated for corresponding hypo-stoichiometric solid solution at high temperature and compared to literature. We believe these results might further assess the description of U-Pu-O phase diagram.