Impacts of glaciation, permafrost and tectonic conditions on far-field radionuclide evolution following a potential repository failure case

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Geological disposal of waste must be located in areas that remain sufficiently isolated from groundwater flow. Otherwise, in case of repository failure, fluid flow processes may favor migration of radionuclides into the biosphere. Few studies address the consequences of far-field waste transport in such worst-case scenarios. However, the hydrogeological conditions of the entire system will eventually differ from those encountered at the time of the repository construction as they are strongly controlled by both external factors (e.g. climate change) and intrinsic basin features. This environmental risk proposal aims to investigate the impacts of (i) glaciation, (ii) permafrost and (iii) tectonic events on the hydrological and hydromechanical boundaries that control large-scale groundwater flow near hypothetical waste repositories. For this purpose, the Yeniseisky site (YS) in Russia, a potential deep geological repository of radioactive waste in crystalline rock, serves as a case study encompassing in a unique way all three of the above features of the geological setting. Multiphysics simulations of Thermal-Hydraulic-Mechanical-Chemical (THM-C) coupled processes will be applied in order to provide scenarios of far-field radionuclide evolution in the worst-case scenario of a repository failure. The novelty of the THM-C models and the access to a unique database of the YS will broaden the classical understanding of anomalous fluid, heat and mass migration within tectonically active basins. Accordingly, while the proposed topic relates to radionuclide fate, the physical and numerical concepts underlying the developed models can be applied to a multitude of geosphere utilization-scenarios (e.g. CO 2 storage, waste remediation, seismic nucleation). Furthermore, related benchmark studies in similar crystalline geological formations are planned.