MANAGING AGING EFFECTS ON DRY CASK STORAGE SYSTEMS FOR EXTENDED LONG-TERM STORAGE AND TRANSPORTATION OF USED FUEL

There is currently no designated disposal site for used nuclear fuel in the United States, which raises the prospect of extended long-term storage (i.e., >120 years) and deferred transportation of used fuel at operating and decommissioned nuclear power plant sites. Under U.S. federal regulations contained in Title 10 of the Code of Federal Regulations 72.42, the initial license term for an independent spent fuel storage installation (ISFSI) must not exceed 40 years from the date of issuance. Licenses may be renewed by the U.S. Nuclear Regulatory Commission at the expiration of the license term upon application by the licensee for a period not to exceed 40 years. Applications for ISFSI license renewals must include (1) time-limited aging analyses that demonstrate that structures, systems, and components (SSCs) important to safety will continue to perform their intended function for the requested period of extended operation and (2) a description of the aging management program for managing issues associated with aging that could adversely affect SSCs important to safety. This paper highlights issues related to managing aging effects on dry cask storage systems and ISFSIs for extended long-term storage and transportation of used nuclear fuel. In particular, it focuses on aging management issues related to the confinement boundary of bolted-closure and welded-closure storage casks and canisters. These highlights were largely extracted from a report prepared by Argonne for the U.S. Department of Energy’s Used Fuel Disposition Campaign for research and development on extended storage and transportation.