Spent nuclear fuel dry packaging facility - Design concept, cost, and throughput analysis

Spent nuclear fuel (SNF) assemblies are stored in pools or dry casks at commercial reactor sites awaiting transfer to an interim storage facility (ISF) or a geologic repository for disposal. To meet acceptance criteria for repository waste package loading, fuel in dry storage may require repackaging into smaller canisters. A modular packaging facility design has been developed to receive and package 1, 500 metric tons of uranium (MTU) of fuel annually. This fuel may arrive in welded canisters previously stored at reactor sites or in bolted lid bare fuel transportation casks (TCs) that would typically be shipped directly from spent fuel pools at reactor sites. Three outgoing sizes of storage, transportation, aging, and disposal (STAD) canisters were evaluated against 8 possible inflows of SNF canisters and casks to determine the effect on facility throughput. Cost estimates have been developed for the packaging facility, and operating costs have been determined for packaging 1, 500 MTU of SNF per year. Transfer of SNF from (TCs) or dual-purpose canisters (DPCs) would be performed in a dry hot cell environment. When compared to a wet packaging method, a dry packaging method could improve throughput by eliminating the need for quenching the fuel prior to immersion in the pool, and the time required for drying canisters in preparation for shipment. The dry packaging process could also reduce the contamination levels on the outer surface of the transfer cask for DPC system or the outer surface of the TC depending on the scenario, resulting in lower personnel exposure and reduced waste treatment costs for cask decontamination. The newly loaded canisters would be sealed, dried, and leak tested prior to loading in TCs for transport to a geologic repository or to an ISF. Additional facilities would be provided for decontamination of the TCs and transfer casks for reuse, as well as decontamination of the empty DPCs for disposal as low-level radioactive waste. Layout and elevation drawings have been developed for the facility, which would provide a process area on two levels for cask and canister handling operations, two fuel transfer cells for dry fuel transfer to STAD canisters, STAD canister closure, handling, and shipment area; and railcar receipt and dispatch bays. A remediation pool is also provided for unloading and packaging of damaged SNF. Results from system modeling indicate that the desired throughput of 1, 500 MTU/year can be attained for 16 of the 18 throughput cases examined. The two cases that were lower than the target rate of 1, 500 MTU/year were associated with repackaging the contents of medium canisters (capacity of 12 PWR/32 BWR SNF assemblies) into small canisters (capacity of 4 PWR/9 BWR assemblies), because more canisters would have to be handled before and after SNF transfer compared to other canister sizes. Estimates for both capital and annual operating costs have been developed and are in the range of $2.1B-$2.3B for capital costs and $207M-$275M for annual operating costs depending on the sizes of the incoming and outgoing canisters.