A simple fuel performance code, SESAME, has been developed to analyze the steady-state irradiation behavior of metallic fuels. Important characteristics of metallic fuels such as fission product gas release, swelling, material redistribution, bonding sodium infiltration, and axial elongation are studied. Simple models have been developed for the SESAME code, which have been found to be successful in predicting irradiation data and useful in investigating the basic mechanisms that contribute to these particular irradiation behaviors of metallic fuels.