Investigation of Plutonium and Uranium Uptake into MCU Solvent and Next Generation Solvent

At the request of the Savannah River Remediation (SRR) customer, the Savannah River National Laboratory (SRNL) examined the plutonium (Pu) and uranium (U) uptake into the Next Generation Solvent (NGS) that will be used at the Salt Waste Processing Facility (SWPF). SRNL examined archived samples of solvent used in Extraction-Scrub-Strip (ESS) tests, as well as samples from new tests designed explicitly to examine the Pu and U uptake. Direct radiocounting for Pu and U provided the best results. Using the radiocounting results, we found that in all cases there were <3.41E-12 g Pu/g of NGS and <1.17E-05 g U/g of NGS in multiple samples, even after extended contact times and high aqueous:organic volume phase ratios. These values are conservative as they do not allow for release or removal of the actinides by scrub, strip, or solvent wash processes. The values do not account for extended use or any increase that may occur due to radiolytic damage of the solvent.