Testing a new cesium-specific ion exchange resin for decontamination of alkaline high-activity waste

摘要

Radioactive Cs-137 is a fission produce found in wastes produced by reprocessing fuels from nuclear reactors. The highest concentrations of this isotope in wastes from the reprocessing of defense production reactors are found in the alkaline high-activity waste, a mixture primarily of sodium nitrate and sodium hydroxide called the supernate. In recent years, much research has been directed at methods for the selective removal and concentration of Cs-137 during waste processing. The approach to the ultimate management of high-activity waste at the Savannah River Site (SRS) is to remove cesium from the supernate, combine it with insoluble sludge formed on neutralization of acidic waste, and convert them both to glass by vitrification in a joule heater melter. A cesium-specific ion exchange resin that will adequately decontaminate the supernate but will not introduce excessive amounts of organic material into the melter has been developed at SRS. The resin has been tested with simulated, both at SRS and at Battelle's Pacific Northwest Lab, and with actual supernate at SRS. It has consistently shown reliable performance and high selectivity than other organic ion exchangers for cesium ion in those solutions. Repeated cycles on 200 mL. columns using simulated supernate feed and formic acid eluent have established operation parameters for the resin.