System-wide impacts of resolution options for a nonconforming dry storage system

Approximately 90% of the dry storage systems (DSSs) currently in use consist of welded stainless-steel canisters placed in concrete or metal overpacks. The remaining 10% of dry storage systems are bolted-lid metal casks. Although the sizes and configurations of DSSs can vary significantly, confinement is ensured by a pressure boundary consisting of metallic gaskets (e.g., bolted-lid metal casks) or metallic components that are welded together (e.g., welded steel canisters). As part of a robust, integrated waste management system, previous work identified and evaluated resolution options for addressing potential future regulatory nonconformancies associated with welded stainless-steel canisters or bolted-lid metal casks and their components that are part of the confinement boundary. Five resolution options were identified: • Use-As-Is: Licensing or other administrative actions to enable continued storage or transportation offsite without conducting any repair operation. • Overpack: Use of a new overpack container to contain the nonconforming DSS component. This new overpack would be licensable for continued storage or transportation offsite. • Repair: Activities to restore the DSS component to a condition that enables safe and reliable transportation or continued storage but does not restore the component to its original design requirements and specifications. • Rework: Activities to restore the DSS component to a condition that enables safe and reliable transportation or continued storage and at the same time conforms to its original design requirements and specifications. • Replace: Transfer of spent nuclear fuel to a new storage container. This paper provides a system-wide comparison of the identified resolution options that may be used to address a postulated nonconformance in a welded steel canister or bolted-lid metal cask. Three reference scenarios are analyzed, and cost and schedule metrics are then used to compare and evaluate the effect of each option at different stages throughout the DSS's lifetime: storage, transportation, and disposal. Different options are shown to have different downstream impacts, and an option that may be cost-effective in the short term could have a significant impact over the long term. The end goal of this effort is to provide an informed impact assessment of possible future technical concepts and approaches to be used in system analysis efforts.