Effects of vapor hydration and radiation on the leaching behavior of nuclear glass

International audience; •Chemical durability of nuclear glass was studied by considering combined effects of vapor hydration and radiation.•No significant impact of ionizing effect was observed on the leaching behavior of hydrated glass.•The presence of pre-hydrated layer, especially the secondary phases, showed major impacts on glass chemical durability. During the long-term disposal of high-level nuclear waste glass in the geological disposal facility, the nuclear glass could be exposed to an unsaturated vapor environment prior to the direct contact with groundwater. Additionally, glass will experience damages due to self-irradiation. In this study, experiments were performed to investigate the chemical durability of glass after being hydrated and irradiated. This study proposes an attempt to investigate the impact of ionizing effect by applying alpha or gamma radiations to the pre-hydrated glass. The impact on chemical durability is evaluated by leaching the hydrated and irradiated glass samples. With the studied doses, 8 Giga Gy of alpha radiation or 100 kGy of gamma radiation, no significant modification of chemical durability is observed upon irradiation. On the other hand, leaching of pre-hydrated glass shows the increase of the initial release of Si, which is considered to be related to the dissolution of secondary phases. Furthermore, the total dissolution of hydrated layer is observed, which would result in the release of radionuclides at the same rate as Si does and thus needs further investigation.