Impact of precipitates on the removal of cesium from Hanford waste tank simulants


Steven M. Serkiz, Kimberly R. Powell, and A.L. Pishko. Savannah River Technology Center, Westinghouse Savannah River Company, 773A rm B121, Aiken, SC 29808
The Savannah River Technology Center has been investigating ion exchange methods for removing radio-cesium and technetium from alkaline wastes currently stored at the Hanford Site. In the current process flow sheet, including a precipitation and ultrafiltration step, the baseline technology for the Waste Treatment Plant removal of cesium is an elutable cesium-specific resin prepared by IBC Advanced Technologies. Recent work has shown the formation of a post-filtration precipitation and concerns have been raised on the impacts of these precipitates on cesium ion exchange. Data were collected on the development of post-precipitates from a range of alkaline waste simulants designed to represent the chemical composition of Hanford waste tanks. Digestion and elemental analysis, x-ray diffraction, scanning electron microscopy (SEM), and energy dispersive x-ray analysis (EDX) characterized these precipitates. Changes in resin performance were evaluated using batch contacts of the resin with stable cesium. Attempts were made to evaluate the relationship between the physicochemical properties of the precipitates formed and cesium sorption to the resin.