Abstract
The management option of fission products and minor actinides originating from fuel reprocessing from the French nuclear industry is vitrification of this high-level long-lived radioactive waste. The planned outlet is deep geological disposal of these radioactive glass packages with the objective of long-term radionuclides confinement, reducing and controlling their radiological impact on the environment. After several thousand years, and the corrosion of the steel overpack, the groundwater will encounter the glass, causing it to deteriorate. It is therefore necessary to understand the alteration behavior of the glass and evaluate its alteration rate to assess the release and transport of radionuclides contained within it. The impact of self-irradiation of nuclear glass on its structure and properties must be determined to estimate its long-term chemical and physical durability. In the short term, the energy deposited in the glass, also called dose, is mainly due to beta decays and gamma transitions of fission products but in the long term, alpha decays become the main source of radiation from minor actinides. These different types of decay, however, continue to occur simultaneously, leading to a complex irradiation scenario. Given the difficulty associated with studies on radioactive materials, ion and electron irradiations are used to simulate the effect of irradiation damage caused by two types of interactions, nuclear or electronic, depending on the decay involved. In this work, the structural changes for different irradiation scenarios of a complex SON68 type glass as well as its equivalent simple glass ISG are studied. The effect of different couplings between nuclear and electronic interactions for different electronic stopping power Se are simulated by Au and He ions and electron irradiations. 2 MeV electron irradiations simulate the damage of beta and gamma radiations at saturation of effects. 7 MeV Au irradiations and 2 MeV He simulate the damage of the recoil nuclei of alpha decays and alpha particles respectively. Au irradiations induce mainly nuclear interactions with matter while the electron and He irradiations lead to electronic interactions, except at the end of the path for He, but correspond to different stopping powers (higher for He than for electrons). Sequential irradiations are performed to reproduce the coupling effect of these different interactions on the structure and properties of the glass. These modifications are determined by Raman, FTIR, NMR, optical interferometry, contact angle measurement and TEM observation.