Optimization of Cesium Ion Exchange Performance with Hanford Tank Waste Feed Dilution

Crystalline silicotitanate (CST) ion exchanger is currently used to remove cesium (Cs-137) from the aqueous phase of Hanford tank wastes in preparation for vitrification at the Waste Treatment and Immobilization Plant (WTP). The CST is a non-elutable inorganic ion exchanger targeted to maintain a decontamination factor of >= 1,000 prior to the column effluent reaching a waste acceptance criterion. In an effort to reduce costs generated by ion exchange processing, system optimization of the waste treatment has been conducted. Decreasing the tank waste supernate sodium molarity prior to processing through the ion exchange columns showed that it can significantly reduce the number of columns used while maintaining the necessary sodium throughput. Optimization of this process can result in significant cost savings and ultimately result in less waste production.