LONG-TERM STORAGE OF SPENT FUEL IN JAPAN - RESEARCH PERSPECTIVE -

In Japan, interim storage period using dual purpose metal cask was assumed for 40 to 60 years in the safety examination guideline by the Nuclear Safety Commission. Integrity of the metal cask and its internals are essential for the safe transport after the long term storage. A report developed by the Japanese governmental working groups on “Long-term integrity of metal dry cask and the internals in interim storage facility using metal dry cask” is introduced in this paper. In order to evaluate and secure the long-term integrity, it is necessary to accumulate knowledge on the metal cask and the internals to establish methods for pre-shipment inspection after the long-term storage. This paper outlines the pre-shipment inspection methods. In addition, research activities by CRIEPI are described on long-term containment of metal gasket used for metal cask and stress corrosion cracking of stainless steel canister used for concrete cask, etc.