Comments on 'Thermal treatment of uranium oxide irradiated in pressurized water reactor: swelling and release of fission gases' by I. Zacharie, S. Lansiart, P. Combette, M. Trotabas, M. Coster and M. Groos

In analysing their detailed post-irradiation results on UO(2) Zacharie et al. interpret the diffusion of fission gases to grain boundaries in terms of atomic gas atom diffusion. In this comment, the basis for this conclusion is questioned and when other evidence is considered, it is suggested that there is little support for the mechanism; On the other hand, calculations using the model based on the directed bubble diffusion up induced vacancy gradients towards grain boundaries show that gas release and intragranular swelling, and their response to annealing temperature, are of the right magnitude to lit the experimental data. (C) 1999 Elsevier Science B.V. All rights reserved.