Transient fission gas release during fast reactor transients

This paper presents modelling work performed at BELGONUCLEAIRE in order to understand the processes by which fission products are released from oxide fuel during fast reactor transients, for heating rates up to 1000 K/s. After a review of available experimental data, a model based on transient equiaxed grain growth is proposed which provides a simple interpretation of observed facts, including gas release, denuded zones and fuel swelling. Application of this model shows that fission gas release is quite important in case of solid fuel, and stresses the impact of fuel burnup and stoichiometry on the fission gas release and swelling phenmomena. (author)