Candidate waste forms for immobilisation of waste chloride salt from pyroprocessing of spent nuclear fuel

Sodalite/glass bodies prepared by hot isostatic pressing (HIPing) at ∼850 °C/100 MPa are candidates for immobilising fission product-bearing waste KCl–LiCl pyroprocessing salts. To study the capacity of sodalite to structurally incorporate such pyroprocessing salts, K, Li, Cs, Sr, Ba and La were individually targeted for substitution in a Na site in sodalite (Na vacancies targeted as charge compensators for alkaline and rare earths) and studied by X-ray diffraction and scanning electron microscopy after sintering in the range of 800–1000 °C. K and Li appeared to enter the sodalite, but Cs, Sr and Ba formed aluminosilicate phases and La formed an oxyapatite phase. However these non-sodalite phases have reasonable resistance to water leaching