A 10.9-L volume of AP-105 tank waste (diluted to 5.6 M Na) was processed through the Direct Feed Test Platform (DFTP) system at the Radiochemical Processing Laboratory. The DFTP incorporates a small-scale ion exchange unit operation mimicking the Tank Side Cesium Removal (TSCR) system operation. The ion exchange system used 10-mL crystalline silicotitanate (CST) beds (Honeywell UOP, LLC product IONSIVTM R9140-B, Lot 2002009604). The CST was sieved to screen out >30-mesh particles to provide an appropriate scaling factor to TSCR. The CST was placed in 1.5-cm-inner-diameter columns. Feed was processed at 1.83 bed volumes (BV) per hour at ambient hot cell temperature (~28 °C). The Cs breakthrough profiles were determined for the lead, lag, and polish columns. The Waste Acceptance Criterion (WAC) for 137Cs was reached from the lag column after processing 560 BVs; the WAC limit from the polish column was reached after processing 974 BVs. The AP-105DF composite feed and composite effluent were characterized to understand the fractionation of selected metals and radionuclides.
Batch contact testing with the diluted AP-105 tank waste was also conducted to develop the Cs loading isotherm. The Cs load capacity at the equilibrium Cs concentration of 5.66E-5 M Cs was 0.0420 mmoles Cs/g dry CST; this was ~15% lower than observed of AP-107 tank waste. Additionally, the predicted 50% Cs breakthrough, 760 BVs, was ~15% lower than observed during the column run (647 BVs).
Revised: January 26, 2021 |
Published: January 12, 2021