Examination of Crystalline Silicotitanate and Applicability in Removal of Cesium from SRS High Level Waste

摘要

The In-Tank Precipitation (ITP) Process decontaminates radioactive waste by precipitating cesium with tetraphenylborate (TPB) and adsorbing strontium on monosodium titanate (MST). Alternative methods for cesium removal may offer improvements over the ITP process. One method studied is adsorption onto crystalline silicotitanate (CST), a material developed as a fine powder by Sandia National Laboratory and Texas A(ampersand)M University. The material has recently been made into an engineered form by UOP. Preliminary examination of the material indicates it is an effective cesium ion exchanger for Savannah River Site High Level Waste (HLW) with an overall average distribution coefficient at 23 degrees C of 1500 (std. dev. 171) mL/g. Unlike organic-based ion exchangers, elution is not feasible and the material would likely need to be disposed directly in glass.To determine if further testing is warranted, estimates of waste processing rates and glass solubility were completed. Based on calculated TiO(sub 2) limits in the current glass formulation, the cesium capacity of CST is sufficient to allow the same loading in the glass as the current process. The material would need to be in a column configuration to permit full saturation and sufficient decontamination. The radiation associated with a fully saturated CST column is extremely high and poses a significant processing concern.