Simulation of high temperature, non-congruent phase transitions in uO 2+X

A detailed model of UO2+X undergoing non-congruent melting at very high temperature is being developed to help support the design and analysis of experimental work being conducted as part of nuclear safety research. This work includes the simulation of nuclear fuel under upset conditions where centreline melting may occur. The Phase Field model has been implemented for this purpose using recently published material properties and compares well with experimental data. The versatility and robustness of this modelling technique is demonstrated with a simulation of centreline melting in a CANDU fuel element as a consequence of fission heating.