Comparisons of Crystalline Silicotitanate and Resorcinol Formaldehyde Media for Cesium Removal by In-tank Column Processing

Chemical and thermal performance of crystalline silicotitanate (CST) and resorcinolformaldehyde (RF) ion exchange media were predicted for column configurations designed for installation in high level waste tanks and intended for cesium removal from radioactive waste supernates. Modeling predictions for the processing of a known Savannah River Site tank waste composition were generated. In a two column configuration under presumed nominal operating conditions (432 gallon packed bed, 10 gpm liquid flow, 25 oC, 45 nCi/g average breakthrough limit) with lead/lag column rotation between processing cycles, approximately two cycles were predicted to treat 1,000,000 gallons of radioactive waste with CST as compared to three cycles predicted for RF. However, this processing mode was shown to be highly unfavorable for RF due to the fact that the lead column is unnecessarily exposed to large radiation doses during movement of the cesium mass transfer zone into the lag column. Thermal modeling calculations indicated that maximum temperatures within stagnant, packed CST and RF columns containing the highest anticipated cesium loading and no active cooling will reach 128 and 78 oC, respectively, within 6 days. Active cooling maintains the cesiumsaturated CST and RF columns below 88 and 41 oC, respectively, under stagnant flow conditions. * author to whom all correspondence should be addressed email: [email protected]