Evaluation of Ionsiv^™ IE-911 as a Cesium Removal Option for Ineel Acidic Tank Waste

Abstract:

Preliminary tests have been performed with a candidate ion exchange material in order to evaluate the efficacy for removing cesium from simulated Idaho National Engineering and Environmental Laboratory acidic tank waste. The ion exchanger being investigated is the inorganic material crystalline silicotitanate (CST). CST is available commercially in engineered form as IONSIV™ IE-911. Equilibrium and dynamic testing with the CST demonstrated it to have adequate selectivity and capacity for removing cesium from the complex acidic waste matrix. However, to improve the stability of the CST during a continuous column operation, it was necessary to reduce the acidity of the feed to approximately 0.5 M HNOj. This partial neutralization step was accomplished using 50 wt % NaOH. Formation of a visible precipitate was not observed during this process, and subsequent particle analysis confirmed the absence of any additional particle formation above 0.4 micron. CST was shown to exhibit reasonable, but relatively low, loading capacities for cesium based on a loading per unit mass of exchanger. However, the maximum allowable radiation dose for the spent ion exchanger shipping containers is expected to be the limiting value for cesium loading on the bed material. Therefore, it is anticipated that the candidate ion exchange material would provide acceptable or excess cesium removal capacity.