DUAL-PURPOSE METAL CASK INTEGRITY AFTER LONG-TERM INTERIM STORAGE (Activities for the verification test of a dual-purpose metal cask)

The purpose of the verification test is to demonstrate structural integrity and functional safety of a dual-purpose metal cask for transport and storage of spent fuel. The test focuses on integrity under transport conditions after long-term interim storage and includes a survey study and testing which is subdivided into two tests, material property tests and system verification tests. The Purpose of the material property tests is to evaluate the degradation of cask materials during long-term storage. The tests include (1) Corrosion and SCC tests of the metals of cask body and basket, (2) Thermal aging tests of the aluminum alloys of basket, (3) Neutron and gamma irradiation tests of neutron shielding materials (resin), (4) Thermal aging tests after irradiation of neutron shielding materials, (5) Thermal relaxation tests of metal seal and (6) Corrosion test of metal seal and its contact surfaces. The cask system verification tests focus on the leak tightness of the cask containment system. The 9 meters free drop test and the thermal test based on the IAEA regulations might result in severe damage to the containment system. A full-scale lid section model composed of metal seals and double lids is appropriate for the tests. This paper presents the general plan and the current technical topics concerning the verification test.