Geological Repositories for Radioactive Waste in Switzerland
For high-level radioactive waste (HLW), deep geological storage is the preferred option in many countries. Depending on societal acceptance and nuclear programs, national site selection processes are more or less advanced. In Switzerland, a site selection process has been started in 2008, and a final decision is expected to be taken by 2027. Starting from entire Switzerland and based on a variety of safety criteria, suitable host rocks and siting regions have been proposed in 2008 and confirmed by the government in 2011. Since radionuclide transport is prone to groundwater, hydrogeological considerations form a key issue. On a regional scale, the existence of different groundwater regimes (hydraulic heads, groundwater chemistry and age) below and above the host rocks provides confidence in the long-term barrier efficiency of the host rocks in-between. Favorable host rocks are low-permeability, clay-rich sedimentary formations, since they are able to act as long-term barriers due to inherent self-sealing and radionuclide retardation capacity. Homogeneous low-porosity rocks are preferred over fractured rocks, because they can be explored much easier and the results are more reliable in a safety analysis. However, not all fracture zones may be detected in advance. Since they may potentially act as preferential flow paths, disposal may be avoided in tectonically affected regions. The disposed waste and the buildings will interact with the host rock. Induced processes are e.g. the generation of corrosion gases, the formation of excavation damaged zones around the tunnels, the alteration of cement materials and heat-induced mineral reactions. Such processes are focus of ongoing research to verify our understanding in quantitative modelling. The construction of a geological repository may raise conflicts with the use of other underground resources. Mineral and thermal springs may be affected, and the extraction of hydrocarbons, geothermal energy or water resources may undergo restrictions. The presentation will highlight some milestones on the long road towards radioactive waste disposal. The present situation and major challenges are discussed from the viewpoint of the Swiss safety authority.
https://www.munich-geocenter.org/events/seminars/frontiers-in-earth-sciences-14/geological-repositories-for-radioactive-waste-in
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Geological Repositories for Radioactive Waste in Switzerland
Speaker
Martin Herfort
(
Swiss Federal Nuclear Safety Inspectorate ENSI)
Abstract
For high-level radioactive waste (HLW), deep geological storage is the preferred option in many countries. Depending on societal acceptance and nuclear programs, national site selection processes are more or less advanced. In Switzerland, a site selection process has been started in 2008, and a final decision is expected to be taken by 2027.
Starting from entire Switzerland and based on a variety of safety criteria, suitable host rocks and siting regions have been proposed in 2008 and confirmed by the government in 2011. Since radionuclide transport is prone to groundwater, hydrogeological considerations form a key issue. On a regional scale, the existence of different groundwater regimes (hydraulic heads, groundwater chemistry and age) below and above the host rocks provides confidence in the long-term barrier efficiency of the host rocks in-between.
Favorable host rocks are low-permeability, clay-rich sedimentary formations, since they are able to act as long-term barriers due to inherent self-sealing and radionuclide retardation capacity. Homogeneous low-porosity rocks are preferred over fractured rocks, because they can be explored much easier and the results are more reliable in a safety analysis. However, not all fracture zones may be detected in advance. Since they may potentially act as preferential flow paths, disposal may be avoided in tectonically affected regions.
The disposed waste and the buildings will interact with the host rock. Induced processes are e.g. the generation of corrosion gases, the formation of excavation damaged zones around the tunnels, the alteration of cement materials and heat-induced mineral reactions. Such processes are focus of ongoing research to verify our understanding in quantitative modelling.
The construction of a geological repository may raise conflicts with the use of other underground resources. Mineral and thermal springs may be affected, and the extraction of hydrocarbons, geothermal energy or water resources may undergo restrictions.
The presentation will highlight some milestones on the long road towards radioactive waste disposal. The present situation and major challenges are discussed from the viewpoint of the Swiss safety authority.
