(242a) Cesium Removal from Tank Waste Simulants Using Crystalline Silicotitanate at 12% and 100% Bed Heights

Augmented pretreatment is planned near the Hanford waste tanks in skid-mounted platforms termed Tank Side Cesium Removal (TSCR). A promising Cs ion exchange material, crystalline silicotitanate (CST) in an engineered bead form is under investigation to support the TSCR pretreatment flow sheet for Cs removal from the tank waste supernate. Pacific Northwest National Laboratory has been tasked with demonstrating the unit operations for the Low Activity Waste Pretreatment System with actual Hanford tank waste. Testing was requested by Washington River Protection Solutions to better define IX processing using Low-Activity Waste Pretreatment System (LAWPS) prototypic IX unit operation process steps at full height and medium height. Column testing at both the medium (12% of the full bed height) and full height scales was conducted to evaluate process variables and scale up performance of Cs exchange onto the CST. Nominal process conditions used 5.6 M Na simulant processed at 1.8 BV/h at 20 °C. Process variables included 1) increased process temperature to 35 °C, 2) increased Na concentration to 6.0 M, 3) added organics to the 5.6 M Na simulant, and 4) flowrate changes. The kinetics of Cs exchange were examined for each of the variable simulant test matrices. These studies were intended to provide results and experience using the CST in a full height column format and assess impacts of multiple process variabilities.