Thermal conductivity is one of the most important properties of fuel and cladding material. In this study, the thermal conductivity of uranium and T91 steel were measured using the transient plane source (TPS) method. Results showed that the thermal conductivity of T91 increased gradually to a point, then decreased. Fast reacting cladding materials require high thermal conductivities, and T91 was found to have higher conductivities than other commercial materials. As ...