Phase Separation Challenges in Borosilicate Nuclear Glasses and Strategies for Vitrification Improvement

This review highlights three main topics: advancements in vitrification technology and associated issues like melter corrosion in global facilities, the chemistry and networking of glassy and frit forms of waste, and improvements in vitrified structures that enhance the properties of glass formulations. Borosilicate glass formulations offer various technical advantages for nuclear waste management, including effective bonding with fission products and actinides, resistance to radiation, simple and safe technology, and low leaching tendencies in aqueous environments. The maximum results indicate that the vitrification facility in Tarapur, India, 43.8% waste loadings with 6.4% B2O3 in the glass composition, while Savannah River Site in the USA processes waste loadings of up to 50 wt% with 6% B2O3 in the glass composition. In the IAEA-TECDOC, it is stated that considering spent fuel borosilicate glasses are suitable matrices for the immobilising up to 13 wt % of UO2 or 6 wt % of PuO2. However, borosilicate glasses may face issues when the molybdenum ratio in the waste exceeds certain limits, potentially leading to phase separation in the vitrified network. This review covers the importance of waste management policies and provides a historical overview of nuclear waste glass in different countries.