Methodology to make a robust estimation of the carbon steel overpack lifetime with respect to the Belgian Supercontainer design

The Supercontainer (SC) design is the preferred option for the final disposal of vitrified high-level waste (HLW) and spent fuel (SF) in deep underground clay layers in Belgium. The SC consists of a 30 mm thick carbon steel overpack surrounded by a 70 cm thick concrete buffer, which is entirely encased in a 3 mm thick stainless steel envelope. In view of the Safety and Feasibility I Study (SFC I), an integrated strategy is developed to demonstrate and defend that the integrity of the carbon steel overpack can be ensured at least during the thermal phase. This presentation elaborates on how we propose to implement this methodology, which is based on three steps: lifetime prediction, validation and confidence building.