The Melting Behaviour of Oxide Nuclear Fuels: Effects of the Oxygen Potential Studied by Laser Heating

The present work highlights the importance, in nuclear fuel safety and performance, of the very high oxygen potentials of actinide oxides (ThO2, UO2, NpO2, PuO2) at temperatures close to melting (around 3000 K), i.e. a tendency to oxidize their environment and chemically react with it.Laser heating coupled with fast pyrometry constitutes an effective approach of studying the melting behaviour of these materials under a controlled atmosphere. Novel results reported in this work show that earlier data are confirmed, with the current technique, only for compounds with a relatively low oxygen potential, such as ThO2 and UO2 and their mixed compositions.