Failure Modes and Effects Analysis (FMEA) of Welded Stainless Steel Canisters for Dry Cask Storage Systems

Due to the delayed opening of a final geological repository for spent nuclear fuel, the lifespan of dry cask storage systems may be increased to 120 years or longer. To ensure safety over this extended period of interim storage, degradation mechanisms that have the potential to cause penetration of the canister confinement boundary must be evaluated and understood. To address this issue, the Electric Power Research Institute (EPRI) performed a failure modes and effects analysis (FMEA) to identify credible degradation mechanisms and their consequences during on-site storage prior to eventual transport to a final repository or reprocessing facility.

The majority of nuclear plants have constructed an independent spent fuel storage installation (ISFSI) to relieve crowding in the spent fuel pool using dry cask storage systems (DCSSs). As a result of concerns that corrosion of the DCSS’s inner stainless steel canisters may occur at some sites over an extended life of 120 years or longer, the Electric Power Research Institute (EPRI) is developing an Aging Management Plan. The Plan includes susceptibility criteria to identify conditions that may lead to a loss of the confinement function of stored DCSSs.