Radiations effects in ISG glass: from structural changes to long-term aqueous behavior

The aim of the studies about the stability of nuclear glasses is to predict as accurately as possible their behavior over geological timescale. It requires the development of experimental methods to accelerate their irradiation and leaching ageing. This study focuses on the International Simple Glass behavior under irradiation by evaluating its structural and macroscopic property evolutions, and also its long-term chemical durability. Two irradiation ageing scenarios are considered: an alpha self-irradiation of a 244Cm-doped-ISG glass and an external irradiation with few MeV gold ions of non-radioactive ISG glass coupons. The results obtained from the Raman spectroscopy, density, and hardness measurements led to the conclusion that ballistic effects from the recoil nuclei are responsible of the changes with dose observed under alpha self-irradiation and that the ISG glass is a good surrogate of the French nuclear SON68 complex glass under such irradiation conditions. The assessment of the structural evolution with dose of this glass reinforces the mechanistic concepts about the glass response under alpha self-irradiation damage, where the glass response to a recoil nucleus event is the result of a very fast quenching of the damaged zone in the displacement cascade. Furthermore, the irradiation damage induced by gold ions does not fully mimic the 244Cm-doped glass evolution with nuclear dose, since the results of this simulation method overestimates the amplitude of the irradiation damage in the glass because the effects of the alpha particle are not included. Finally, this study demonstrates that the ISG glass water alteration at high-reaction progress is impacted by the glass damage, which indicates that the long-term glass chemical durability will depend on the glass structure when water arrives in contact.