A Full-Scale Test (FST) program was performed by Parsons and its team members General Atomics and Energy Solutions to assess the performance of full-scale centrifugal contactors specified for the Department of Energy Salt Waste Processing Facility (SWPF). The SWPF, to be located at the Savannah River Site (SRS) in Aiken, South Carolina, will remove highly radioactive waste constituents, principally actinides, strontium (Sr), and cesium (Cs) radionuclides, from salt waste solutions currently stored in SRS high-level waste tanks. Caustic-side Solvent Extraction (CSSX) removes Cs from waste feed that has been treated upstream to remove actinides and Sr. CSSX uses a custom solvent to extract Cs from the salt solution in a series of single stage centrifugal contactors. The test system comprised (a) eleven 25.4 cm (10") full-scale contactors (versus 36 in SWPF) for the extraction, scrub, strip, and wash stages; (b) two solvent recovery coalescers; and (c) the associated hardware and control system, packaged in four skid mounted modules. This paper describes the results of tests performed to define both hydraulic performance parameters (maximum hydraulic capacity and phase carryover) and solvent extraction performance parameters (Cs mass transfer efficiencies) using simulated SWPF waste and actual CSSX solvent. The test results confirmed key design features of the CSSX process and, as a consequence, the use of CSSX in the SWPF.
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