The effect of grain size on the swelling and gas release properties of uo2 during irradiation

Abstract Uranium dioxide specimens of two different grain sizes have been irradiated at 1750°C up to 0.4% FIMA and measurements made of fission-gas release and dimensional changes. The results show a significant reduction of both these effects with increasing grain size. Also, at swelling values around 10%, the major contribution to swelling was due to grain-edge tunnels which were extensively interlinked to the free surface. The consequence of this is discussed regarding models for both gas release and swelling.