Solidus and liquidus of plutonium and uranium mixed oxide

Solidus and liquidus of mixed oxides of plutonium and uranium were measured as a function of Pu-content and oxygen-to-metal ratio using the thermal arrest technique. The solidus and the liquidus were observed to decrease with increasing Pu-content and to slightly increase with decreasing oxygen-to-metal ratio in the region of hypo-stoichiometric composition. The solidus of UO2.00, (Pu0.12U0.88)O2.00 and (Pu0.2U0.8)O2.00 were determined as 3128, 3077 and 3052 K, respectively. The solidus and the liquidus of the mixed oxides with 29 and 40 at% Pu were also measured. It was observed that a reaction with the tungsten capsule occurred during the measurement. Therefore, the solidus and the liquidus of the oxides with 29 and 40 at% Pu could not be obtained.