Pollucite Ceramics and Glass-Ceramics as Advanced Wasteforms for the Immobilization of Cs-Loaded IONSIV Wastes

IONSIV R9120-B is a commercial inorganic ion exchange material used in the nuclear industry for the removal of Cs-137 from contaminated liquids. Once IONSIV is loaded with radioactive species, it is considered waste and requires treatment by incorporation into a stable wasteform to prevent radionuclide release during disposal. This work presents a promising, novel candidate glass-ceramic wasteform based on pollucite for the immobilization of cesium-loaded IONSIV. The tailored glass-ceramic provides chemical and processing flexibility through the addition of small amounts of glass formers, with cesium partitioned predominantly to the more chemically durable ceramic phase. A high waste loading of ∼70-80 wt % was achieved, along with a consistent phase assemblage of pollucite, srilankite, rutile, and glass. The chemical durability of the candidate wasteform was assessed using the ASTM C1285 standard method, with the results indicating high chemical durability relative to other candidate materials for cesium immobilization. A single preferred pollucite glass-ceramic design with a 70 wt % waste loading was selected and validated using unloaded and Cs-loaded IONSIV. Importantly, the design ensures consistent phase formation irrespective of Cs-loading on IONSIV, demonstrating tolerance to accommodate compositional variations in the waste.