Leaching Behavior of Glasses With High Level Liquid Waste From Power Reactor Under Simulated Deep Geological Disposal Conditions

During the disposal process of high-level radioactive waste(HLLW) liquid glass solidified body in deep geological media, groundwater intrusion into protective barriers may expose glass wasteforms to corrosive environments, leading to structural degradation and radionuclide release. This paper systematically investigates the leaching behavior of nuclear waste glass under various simulated disposal conditions. The primary elements analyzed include Si, B, Na, Cs, and U, both on the surface and within the glass matrix. The findings indicate that elevated temperatures accelerate network dissolution by enhancing molecular and ionic mobility, thereby increasing the kinetic energy of water molecules and dissolved ions. When Na⁺ is added to the glass, the radio of Si to O is reduced, and non-bridging oxygens(NBOs) appear. The emergence of non-bridging oxygens causes the silicate network to fracture, leading to the gradual breakdown of the network structure. The above reasons lead to significant leaching of elements from the bulk glass into the aqueous solution. At temperatures of 25 ℃ and 90 ℃, the particle sizes of the glass wasteform measured in the two leaching liquids were found that after filtration through a 220 nm filter membrane, a large amount of micron-sized precipitate was removed from both leaching solutions, and no stable colloids were formed. This prevents the probability of radionuclides migration in the form of colloids. In 90 ℃ atmospheric environment, corrosion was noted on the surface of the glass solidified bodies immersed in deionized water and Beishan groundwater during the 60-day testing period; however, the morphology and composition of the resulting corrosion layer aredifferent between the two immersion liquids. SEM-EDS and XRD analyses demonstrate that corrosion layers formed on glass surfaces after 60-day immersion at 90 ℃ exhibit distinct morphologies depending on the leaching solution. In Beishan groundwater, the presence of Mg²⁺ induces the formation of a magnesium silicate(MgSiO₃) repair layer, enriching the corrosion layer in Si and O(silicon-oxygen ratio increased to 23.31%) and the repair layer acts as a natural barrier to mitigate further corrosion. In contrast, deionized water immersion results in alumina(Al₂O₃) impurities and amorphous silica(SiO₂) as primary corrosion products. Filtration experiments(220 nm membrane) confirm the absence of stable colloids, indicating negligible colloid-facilitated radionuclide migration. The findings elucidate the synergistic effects of temperature and geochemical conditions on glass durability, highlighting the critical role of Mg²⁺ in mitigating corrosion through reparative mineralogical phase formation.