The Swiss program for the deep-geological disposal of radioactive waste: Status of site selection and concept demonstration

Introduction In order to select the sites for geological repositories for nuclear waste Switzerland follows a stepwise approach. After identification of 6 candidate sites in phase 1, in the ongoing phase 2 Nagra as the implementing organization has prepared the proposal for the selection of the candidate sites to be investigated in detail in the upcoming phase 3. For high-level waste the host rock is Opalinus Clay a 100 m thick shale that is intercalated in the Mesozoic sequence of clay rich rocks of Northern Switzerland. In this paper we describe the field activities and rock characterization program that is being assembled as a scientific base for the host rock and site selection. Secondly we depict a full scale emplacement experiment aiming at demonstrating the feasibility of the disposal concept at large scale. We focus on the current understanding of THM coupled effects and the feasibility of the highlevel waste repository concept.