[en] The Materials Interaction Test is designed to provide early scoping data on host rock performance and interaction between nuclear waste canister materials and host repository media under conditions representative of expected disposal environments. Capsules containing these materials were put in a spent fuel assembly and subsequently placed in a disposal test to study behavior in a low-level radiation environment at temperatures expected to range between 300 and 400⁰F. Thermal control capsules are being exposed in laboratory furnaces to allow a determination and separation of thermal and radiation effects. Post-test specimen examinations are planned to determine material property changes and interaction effects and provide data for understanding the effectiveness of host rock, canister, and cladding materials in long-term waste isolation