Termination of Safeguards on ULWBR Material

The Department of Energy (DOE), Office of Environmental Management, has approved the disposition of 31 metric tons of Unirradiated Light Water Breeder Reactor (ULWBR) material in canisters stored within dry wells of the Underground Fuel Storage Facility at the Idaho Nuclear Technology and Engineering Center (INTEC). This unirradiated material consists primarily of ceramic pellets of thorium oxide in stainless steel cladding, but it also contains 300 kilograms of uranium that is 98 wt% U-233. The ULWBR material was not processed at the INTEC because it was incompatible with prior chemical separation schemes. Other economical recovery options were not identified, and expressions of interest for consolidating the material with existing projects at other DOE sites were not received. The U-233 might be used for producing the medical isotope Actinium-225, but the proof-of-principle demonstration and follow-on pilot program were not developed to the point of requiring production quantities of U-233. Consequently, the selected disposition of the ULWBR material was burial as Low-Level Waste at the Nevada Test Site (NTS), which required terminating safeguards controls for the contained Category II quantity of Attractiveness Level D special nuclear material (SNM). The requested termination followed the twelve point evaluation criteria of the Historical Defense Program Discard Guidance and included a security vulnerability analysis for evaluating the risks of theft, diversion, and radiological sabotage associated with the material. Continuity of knowledge in the book inventory was assured by documenting that the original shipper’s measurements reflected the quantities of materials received and that the ULWBR materials had remained under adequate physical protection and had been subject to periodic physical inventories. The method selected for confirming the book values as the basis for terminating safeguards was the nondestructive assay used during physical inventories. Shipping arrangements included refurbishing a licensed Department of Transportation Type B cask to be reused over the duration of the disposal process. A corresponding batching plan and shipping schedule were developed to accommodate multiple commercial shipments of Category III quantities of SNM in the selected cask, such that all canisters would be received at NTS prior to the expiration of the nonrenewable cask license.