Radioactive waste under conditions of future ice ages

The evolution of the landscape and the behavior of the groundwater system are key concerns for the long-term management of radioactive waste in deep geological repositories. At time scales relevant for repository safety assessments (i.e., 1 Ma), future ice ages are an important external perturbation to repository integrity in mid-latitudes and northern latitudes. Ice ages result in the alteration of the landscape by glacial erosion and sedimentation; lead to the formation of periglacial permafrost; and impose significant transient hydraulic, mechanical, thermal, and chemical changes that can influence groundwater flow and radionuclide mobility. Four case studies are presented: (1) discussing the processes involved in the formation of deeply incised troughs and overdeepened valleys in the Swiss Plateau; (2) outlining the occurrence and dimensions of tunnel valleys in the North German Plain and their impact on repository host rocks; (3) illustrating the integration of techniques and geoscientific evidence, as applied in assessing the stability and resilience of a deep-seated groundwater system in the Great Lakes Basin of North America; and (4) detailing results of a numerical modeling study of the impact of periglacial and glacial climate conditions on groundwater flow in the Fennoscandian Shield.