Considerations for Disposition of Dry Cask Storage System Materials at End of Storage System Life

Dry cask storage systems are deployed at nuclear power plants for used nuclear fuel (UNF)
storage when spent fuel pools reach their storage capacity and/or the plants are decommissioned. An important consideration arising from the increasing use of these systems is management of the dry cask storage systems’ materials after the UNF proceeds to disposition. Thermal analyses of repository design concepts currently under consideration indicate that waste packages for certain geologic media may be significantly smaller in size than the canisters being used for on- site dry storage by the nuclear utilities. Therefore, at some point along the UNF disposition pathway, there could be a need to repackage fuel assemblies already loaded into the dry storage canisters currently in use.

In the United States, there are already over 1850 of these dry storage canisters deployed and approximately 200 canisters per year are being loaded at the current fleet of commercial nuclear power plants. About 10 cubic meters of material from each dry storage canister system is not UNF. The concrete horizontal storage modules or vertical storage overpacks will need to be reused, repurposed, recycled, or disposed of in some manner. The empty metal storage canister/cask will also have to be decontaminated for possible reuse or recycling or disposed of as low-level radioactive waste. These material disposition options can have an impact on the cost of the overall used fuel management system. This paper explores some of the considerations associated with managing the dry cask storage system materials.