PNNL

Abstract

Crystalline silicotitanate (CST) ion exchanger is planned to be used to remove cesium (137Cs) from the aqueous phases of Hanford tank wastes in preparation for vitrification at the Waste Treatment and Immobilization Plant (WTP) Pretreatment Facility. Column scale up testing was conducted to evaluate performance of Cs exchange onto the CST. Batch contact testing was conducted to assess exchange kinetics of Cs exchange at four different CST PSDs. Column testing was conducted at three column sizes, small (2.5% full height), medium (12% full height), and full height, to assess Cs load performance behavior. Testing at the small scale was compared to actual Hanford tank waste testing to verify the validity of simulant tests to accurately represent full height column performance. A change in CST particle size was essential in scaling the small column dynamics up to full scale. Based on these results, a determination of intraparticle and film diffusion impacts on overall mass transfer coefficients will allow future modeling of the breakthrough performance at a range of process conditions.