Design and Performance Assessment of High‐Level Waste Disposal Canisters

ABSTRACT The current Swiss concept for the disposal of high‐level waste involves the emplacement of carbon steel disposal canisters in a deep geological repository in Opalinus Clay. The development of canister designs able to provide complete containment of radionuclides for at least 10 000 years follows a design‐by‐analysis approach that involves advanced analysis to evaluate the response and performance of a design under various conditions. The preliminary canister design is made of carbon steel, and the closure is completed by electron beam welding. Assessment of the canister lifetime is done by evaluating the degradation mechanisms that can take place in the repository and bounding the possible damage to the canister under conservative assumptions. Structural assessments and fracture mechanics are then employed to demonstrate that the degraded canister remains unbreached.