Interstitial sites for He incorporation in nuclear glasses and links to the structure: Results from numerical investigation

To investigate rare gases incorporation in glasses in relation with nuclear waste confinement, a wide range of borosilicate glasses have been studied by means of molecular dynamics simulations. The rare gases solubility is related to the number of interstitial sites accessible for these gases. To elucidate any relation between the number of interstitial sites and the glass composition, a large set of glass compositions that contain the most representative components in nuclear glasses is considered. We are mainly interested in SBN glasses (SiO2–B2O3–Na2O). A composition dependent force field was used to model the interactions between the atoms. Delaunay tessellation method was used to characterize the different topologies accessible for rare gases and analyze the interstitial sites distribution. In order to investigate irradiation effects by nuclear energy deposition on the number of interstitial sites accessible for He, disordered glasses representative of structures submitted to series of displacement cascades, were prepared by modifying the preparation procedure and the number of interstitial site changes were analyzed.