Computer simulations of non-congruent melting of hyperstoichiometric uranium dioxide

Detailed models of UO2+x at very high temperatures incorporating the effects of non-congruent melting have been developed to support the design and analysis of experimental work related to nuclear safety. Models based on both the Stefan formulation and phase field approach are implemented using recently published material properties. Simulations compare well with laser flash experiments performed on UO2+x. This work has application in modelling centreline melting of defective fuel which may occur due to the reduced thermal conductivity and lower incipient melting temperature associated with fuel oxidation.