Crystallinity study of rare earth waste glass as function of composition and temperature

Abstract

Pyroprocessing is an alternative reprocessing method for managing and reusing spent nuclear fuel while avoiding wet reprocessing. Pyroprocessing produces several waste streams, including metals, salts, and rare earth (RE) oxides, that need to be immobilized in a suitable waste form for disposal. Borosilicate glass has been chosen as the waste form because of its durability and ability to dissolve almost any RE waste component into the matrix. Crystallization that occurs in waste glasses as the waste loading increases may complicate glass processing and affect the product quality. This work investigates several borosilicate glasses in terms of liquidus temperature (TL) and product durability (using the product consistency test method established by the American Society and Testing Materials [ASTM] procedure). The present study shows that a high waste loading can be achieved at melting temperatures below 1400°C without affecting glass durability. More than two crystalline phases were observed in heat-treated glasses with high waste loadings. The effect of composition to the TL was carried out for high waste loading glass.