Advances in Simulating Non-congruent Melting of Hyperstoichiometric Uranium Dioxide Fuel

Abstract

A model is being developed to simulate UO₂ at very high temperatures incorporating the effects of non-congruent phase transitions. In particular, the melting transformation and the possible ‘Λ- transition’ is being investigated to help support the design and analysis of experimental work being conducted as part of nuclear safety research. This work includes the interpretation of the behaviour of operating CANDU fuel under upset conditions, where centerline melting may potentially occur (particularly if the fuel is oxidized). The model presented here numerically solves a system of coupled nonlinear differential equations as derived from fundamental principles. The results of the model present here compare well against laser flash experiments in recently published literature.