(224b) Development and Implementation of the Next Generation Solvent Flowsheet at the Salt Waste Processing Facility

The Salt Waste Processing Facility (SWPF) was recently deployed at the Savannah River Site (SRS) in Aiken, SC. to accelerate the decontamination of salt waste contained within the 51 High-Level Waste (HLW) tanks at SRS. Within the SWPF, the Caustic Side Solvent Extraction (CSSX) process is employed to remove soluble, radioactive cesium from aqueous streams in order to divert the waste streams with the highest radioactivity to the Defense Waste Processing Facility (DWPF) for vitrification. Several potential improvements have been identified in the solvent system currently employed in the CSSX process, leading to the generation of a Next Generation Solvent (NGS) flowsheet to support higher decontamination factors and faster cycle times. Researchers at the Savannah River National Laboratory (SRNL) have performed extensive testing to assess the benefits of this NGS flowsheet. SRNL researchers have also performed the necessary investigations into safety-related aspects of the NGS flowsheet to ensure a successful implementation.

The research presented here will discuss the catalog of SRNL experiments to develop and support the NGS flowsheet as well as recent testing to investigate potential technical and safety-related gaps, such as flammable gas generation, chemical degradation, and differences in physical properties. Additional discussion will be given to the importance of an NGS solvent and the implications of faster salt waste processing across the SRS.