Lithium Chloride Influences the Properties of Borophosphate Glass During the Immobilization of Radioactive Waste Generated from Pyrochemical Processing of Spent Nuclear Fuel

Abstract

This study investigates the properties of a borophosphate glass (BPG) matrix incorporating lithium chloride (LiCl) as a simulated spent electrolyte, a type of radioactive waste (RAW) generated during the pyrochemical reprocessing of spent nuclear fuel (SNF). X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the amorphous structure and homogeneity of the synthesized material. The thermal properties of the glass were characterized using differential scanning calorimetry (DSC) and thermal conductivity measurements. The incorporation of LiCl had no significant effect on the glass transition temperature, which remained at approximately 410°C; however, it influenced the electrical conductivity, as determined by electro-chemical impedance spectroscopy. Mechanical strength and hydrolytic stability tests were carried out in accordance with established requirements for RAW immobilization matrices. The analysis of surface morphology revealed the formation of a diffusion layer due to the leaching of sodium ions into the solution. The results demonstrate the feasibility of using the selected glass composition as an immobilization matrix for LiCl-based spent electrolytes.