Effect of alpha radiation on the leaching behaviour of nuclear glass

The behaviour of nuclear glass subjected to the stress loading expected in a repository must be investigated to demonstrate that it is capable of durably confining radioactive elements. Because of the minor actinides (Np, Am, Cm) contained in the glass, alpha radiation is one of the stresses that could affect the glass properties. This study focuses on the effect of alpha radiation on the chemical reactivity of R7T7 glass with pure water. Various glass samples doped with 237Np, 238Pu, 239Pu, 241Am or 244Cm were fabricated in the CEA facilities at Marcoule. The content of each actinide was adjusted to cover a range of alpha activity varying from 105 to 1011 Bq g−1 and a range of alpha decay doses up to 4 × 1018 g−1. Inactive glass samples were also subjected to multiple-energy external irradiation by heavy ions to simulate the impact of alpha damage. The initial glass alteration rates, which reflect the chemical reactivity between the glass matrix and pure water, were determined by standard Soxhlet tests together with analysis of the leaching solution by ICP-AES. Comparing the glass leaching rates is indicative of the impact of alpha radiation. The experimental data show that neither the alpha activity nor the alpha decay dose has a significant impact on the initial alteration rate of R7T7 glass.