Assessment of the Impact of a New Guanidine Suppressor In NGS on F/H Laboratory Analyses For DWPF and Saltstone MCU Transfers

Abstract

Implementation of the Next Generation Solvent (NGS) in the Modular Caustic-Side Solvent Extraction Unit (MCU) will now proceed with a new suppressor compound, 1,2,3-tris(3,7-dimethyloctyl)guanidine (TiDG), replacing the originally planned suppressor for NGS, 1,3-dicyclohexyl-2-(11-methyldodecyl) guanidine (DCiTG). The Savannah River National Laboratory (SRNL) was tasked with evaluating the potential impact to F/H Laboratory analyses supporting the Defense Waste Processing Facility (DWPF) Waste Acceptance Criteria (WAC) used to qualify transfers of MCU Strip Effluent (SE) into the facility and the Saltstone WAC used to qualify transfers of Tank 50 containing Decontaminated Salt Solution (DSS) from MCU into Saltstone. This assigned scope is covered by a Task Technical and Quality Assurance Plan (TTQAP). Previous impact evaluations were conducted when the DCiTG suppressor was planned for NGS and concluded that there was no impact to either the determination of MCU SE pH nor the analysis of Isopar® L carryover in the MCU SE and DSS streams. SRNL reported on this series of cross-check studies between the SRNL and F/H Laboratories. The change in suppressor from DCiTG to TiDG in the NGS should not impact the measurement of Isopar® L or pH in SE or DSS necessary to satisfy DWPF and Saltstone WAC (Tank 50) criteria, more » respectively. A statistical study of the low bias observed in Isopar® L measurements in both SRNL and F/H Laboratories may be necessary now that the final NGS composition is fixed in order to quantify the low bias so that a proper correction can be applied to measurements critical to the DWPF and Saltstone WACs. Depending upon the final DWPF WAC requirement put in place for SE pH, it could become necessary to implement an alternative ICP-AES measurement of boron. The current blended solvent system testing in SRNL should address any impacts to Isopar® L carryover into either the DSS or the SE. It is recommended that SRNL monitor the current blended solvent work underway with simulants in SRNL as well as any DWPF CPC testing done with the new SE stream to ascertain whether any need develops that could result in modification of any currently planned F/H Laboratory testing protocols. « less