Crystalline Silicotitanate Ion Exchange Column Sizing and Sensitivity Study in Support of the Hanford Test Bed Initiative

Abstract

The Environmental Management Office of the Department of Energy (DOE) is spearheading a Test Bed Initiative a (TBI) to treat and dispose 2,000 gallons of tank waste from Hanford. One step in the process is to remove radioactive 137 Cs from the waste using Crystalline Silicotitanate b (CST) ion exchange media. This report describes the modeling performed to provide an estimate of the volume of a bed of CST required to meet the design requirements. Sensitivity studies were also performed to help provide project guidance. This modeling effort assumed 2100 gallons of waste to be processed (i.e., entire 2000 gallon campaign plus a 100 gallon margin).The Savannah River National Laboratory (SRNL) has extensive experience in the testing and modeling of ion exchange columns using CST for the explicit removal of 137 Cs from highly caustic feed solutions. This analysis effort uses SRNL's modeling methodology for CST based on extensive testing for Savannah River Site (SRS), Hanford Site, and other DOE Complex-wide applications. This methodology has been used to assess primarily waste streams with typically lower potassium concentrations than that expected for the TBI waste stream and with CST manufactured into a smaller bead size than planned for use in TBI. However, while applying the existing model methodology to recent CST testing of Hanford simulant and actual tank waste, it was found capable of adequately predicting measured Cs breakthrough performance at high potassium and with larger bead size media. As the results provided in this report indicate, a reliable calculational scheme has been achieved that can provide design guidance on the sizing and expected performance for the upcoming TBI ion exchange column.