(66a) Testing and Startup of the Savannah River Site Integrated Salt Disposition Process

The Savannah River Site (SRS) is currently removing liquid radioactive waste from the tanks in its Tank Farm. To treat waste streams that are low in 137Cs, 90Sr, and/or actinides, SRS developed the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction (CSSX) Unit (MCU). The ARP contacts SRS salt solution with monosodium titanate (MST) to sorb strontium and select actinides. After MST contact, the resulting slurry is filtered to remove the MST (and sorbed strontium and actinides) and entrained sludge. The filtrate is transferred to the MCU for further treatment to remove cesium. The solid particulates that are removed by the filter are concentrated to ~ 5 wt %, washed to reduce the sodium concentration, and transferred to the Defense Waste Processing Facility (DWPF) for vitrification. The CSSX process extracts the cesium from the radioactive waste using a DOE EM developed solvent to produce a Decontaminated Salt Solution (DSS), and strips/concentrates the cesium from the solvent with dilute nitric acid. The DSS is then incorporated in grout and the strip solution is transferred to DWPF for vitrification.

SRNL personnel performed tests using actual radioactive samples of the first waste batch for processing prior to start of operation. Testing included MST sorption to remove strontium/ actinides and CSSX batch contact tests. This paper describes the tests conducted and compares results from initial facility operations. The results include strontium, plutonium, and cesium removal, cesium concentration, and organic carryover/recovery. Additionally, the paper describes some related lessons learned during commissioning of the facility.