Modelling oxidising perturbations in argillaceous material

This paper presents the results of a numerical investigation of transient redox conditions in argillaceous material in the context of HLW deep geological disposal. The redox state is a crucial parameter not only for the lifetime of the canisters but also for the migration of radionuclides after canister failure. Since reducing redox conditions prevail in deep underground porous media, the digging of excavations to build the repository will induce an oxidising perturbation in the vicinity of the galleries and tunnels. After emplacement of waste packages and closure of galleries, other processes will control the evolution of the redox conditions such as the corrosion of steel canisters and structures, or the radiolysis of water close to the waste packages. Since reducing conditions are considered favourable for the confining function of the repository, the purpose of this study is to quantify the persistence in time and space of the initial oxidising atmospheric perturbation. (authors)