Theories of fission gas behaviour

A review is presented of the theoretical developments and experimental evidence that have helped to evolve current models used to describe the behaviour of inert fission gases created during the irradiation behaviour of reactor fuel materials. The phenomena which are stressed relate primarily to steady state behaviour of fuel elements but are also relevant to an understanding of transient behaviour. The processes considered include gas atom solubility; gas atom diffusivity; bubble nucleation; and bubble growth, by bubble coalescence. (U.K.)