Crystalline Silicotitanate (CST) Ion Exchange Media Performance Evaluations in SRS Average Supernate Simulant and Tank 10H Waste Solution to Support TCCR

Savannah River Remediation (SRR) is deploying an "at-tank" ion exchange process to remove radioactive cesium from waste supernate which is referred to as the Tank Closure Cesium Removal (TCCR) system utilizing Crystalline Silicotitanate (CST) media. After being loaded with cesium, but before flushed and dried and sent to Interim Safe Storage (ISS), it is anticipated that the TCCR ion exchange columns will be taken off-line (stagnant) with the CST media still immersed in supernate. The currently designed columns include no active cooling system during processing (although no rmal process fluid flow through the column during operations provides significant cooling) or during off-line conditions and temperature increases are expected in the stagnant, loaded, and liquid-filled columns due to decay heat from the radionuclides absorbed to the CST. As a result, modification of the Tank 10H supernate composition has been considered through the addition of either NaOH or KOH reagents to decrease cesium loading.