AGEING MANAGEMENT AND POST-STORAGE TRANSPORT OF DUAL PURPOSE CASK FOR SPENT FUEL

Ageing management of spent fuel storage facility may follow lessons learned from literature for nuclear power plant and a review for spent fuel dry cask storage system by US NRC, DOE, by German BAM, that by Japan NISA, etc. Namely, the essence of systematic approach to ageing management includes Understanding ageing, Plan (Development and optimization of activities for ageing management), Do (Managing ageing mechanisms), Check (Monitoring, inspection and assessment), and Act (Maintenance). The PDCA cycle will optimize the systematic approach to the ageing management. An ageing management programme (AMP) for the storage system over the period of extended storage will address uncertainties in the safety-relevant functions of the system that may otherwise be impaired by ageing mechanisms. The AMP identifies SSCs (System, Structure and Components) that need specific actions to mitigate ageing and ensures that no ageing effects result in a loss of their intended function of the SSCs, during an intended licensed period. AMPs generally include Prevention, Mitigation, Monitoring, Inspection, and Maintenance programmes. Ageing management plans should ensure compliance with transportation requirements after extended storage. Potential issue would be a significant change of the transport regulations in the future. If the regulations changed significantly, a gap analysis should be performed to identify any impact to the cask safety. Compensating arrangements, if necessary, should be proposed at that time. Assuming that the regulations will not change significantly after longterm storage, we will be able to renew the license both for transport and storage of the cask during the storage period. For example, in Japan, a holistic approach was established for the license of a 50-year storage and transport. In this approach, we can evaluate integrity of spent fuel, basket, etc. with respect to chemical, thermal, mechanical, and radiation factors. With this approach we will not have to open the cask lid for visual inspection of the spent fuel, basket, etc. prior to the post-storage transport.