Reactivity of Crystalline Silicotitanate (CST) and Hazardous Metal/Actinide Loading During Low Curie Salt Use

Crystalline Silicotitanate (CST) in its engineered form (IONSIV (registered) IE-911) continues to be studied for possible use for removing radioactive cesium from several types of waste solutions at the Savannah River Site. This study involved deriving information about spent CST that assists in determining possible disposition alternatives. Results for this work include: After passing 3000 column volumes of a dissolved saltcake simulant containing RCRA hazardous metals, the spent CST passed a TCLP test and is RCRA nonhazardous. The spent CST was found to have transuranic concentrations greater than the TRU limit of 100 nCi/g. The triplicate measurement showed TRU levels greater than 4000 nCi/g. Studies involving simulating storage of ground CST in sludge slurries indicated no detrimental effects on the measured yield stress or viscosity of the slurries when stored for up to 4 months at 50 degrees C. During the storage testing, there was no indication of significant degradation of the C ST as measured by in growth of CST-specific elements in the liquid phase of the slurry. Also, during storage tests minor desorption of cesium from the ground CST material was observed