A Model for the High Temperature Swelling of Clad Oxide Fuel

A fuel-specimen model is developed to describe the diametral swelling behavior of W-Re clad, oxide fuel specimens irradiated at a clad surface temperature in excess of 1200°C. The model is based on experimental observations at elevated fuel temperatures that fission-gas bubbles form to expand the fuel but that bubble and lenticular void movement, as a result of vaporphase transport, provide a mechanism for redensifying the fuel so that swelling is a continuous steady-state process. Good agreement with experimentally measured diametral changes is obtained by application of the model.