(486d) Impact to Savannah River Site Processing Facilities from Combining Fuel Spent Nuclear Fuels with High-Level Waste

The Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) near Aiken, South Carolina, processes and immobilizes the legacy waste from the production of nuclear weapons materials (along with smaller quantities of nuclear isotopes, Pu for space missions and research materials). The Salt Waste Processing Facility (SWPF) will process approximately 100 million gallons of soluble radioactive waste and produces two additional waste streams that are processed through DWPF. In addition to SRS produced nuclear waste, Spent Nuclear Fuel (SNF) from reactors outside SRS is being stored in a former reactor disassembly basin at SRS. Changes to waste composition require a thorough facilities evaluation as unexpected changes to processing conditions can result in costly equipment failure and schedule impacts.

In this paper, we discuss the studies that were performed to assess the impact of adding the neutralized SNF with SRS high-level waste (HLW). The SNF comes from various US reactors along with a number of foreign reactors. SRS used aluminum cladding for its fuel and targets whereas the SNF has a variety of claddings including aluminum, stainless steel, Zircaloy, Hastelloy, etc. These difficult to dissolve SNFs all require more aggressive dissolution flowsheets, requiring electrolytic dissolution and HF. The neutralized slurries can be very different than historical SRS HLW, many high in fissile uranium and plutonium.

This paper discusses the impact of combining the non-SRS SNFs with SRS sludge and the impacts on processing in DWPF and SWPF. The emphasis in the paper will be the impact of added fluorine and fissile actinides (particularly U-235, Pu-239 and Pu-241) on downstream processing facilities. In order to combine the non-SRS SNF without negatively impacting sludge processing, the SNF will be dissolved in nitric acid without actinide recovery. The solution will be neutralized with sodium hydroxide and added to high level waste (HLW) tanks for processing in DWPF and SWPF.