Safety evaluation of MSF-type dual-purpose cask under severe accidents

Safety concerns about storage system for spent nuclear fuels have been increased. A dry cask storage system is considered as a realistic and feasible option for the safe management of spent fuels. Mitsubishi Heavy Industries, Ltd. (MHI) has established transportable storage (dualpurpose) casks, MSF-type cask. MHI performed several full-scale drop tests with the MSF prototype cask, and demonstrated compliance with the containment requirements specified in the IAEA Safety Standards (No.SSR-6). The MSF-24P dual-purpose cask for storage and transport of PWR spent fuel was designed by employing the structural evaluation method verified based on the full-scale drop test results. In order to establish severe accident management scenarios, we evaluated the safety of the MSF-24P cask against severe accidents in storage facilities. This paper describes the outline of preliminary evaluation results for the safety of the MSF-24P cask under severe accident conditions.