Stability and Buffering Capacity of the Geosphere for Long-term Isolation of Radioactive Waste

Application to Crystalline Rock

image of Stability and Buffering Capacity of the Geosphere for Long-term Isolation of Radioactive Waste
Geological settings selected as potential host formations for the deep geological disposal of radioactive waste are chosen for, among other assets, their long-term stability and buffering capacity against destabilising events and processes. These proceedings present the outcomes of a geosphere stability workshop, held in November 2007, that focused on crystalline and other types of hard, fractured rocks. The workshop underscored the fact that many such rocks are intrinsically stable environments that evolve extremely slowly and provide good buffering against external events and processes.

The proceedings show a good understanding of the processes and events that can affect crystalline rocks and, although there is less confidence in predicting exactly when and where such events will occur and the volume of rock that will be affected, the extent of the impacts on a geological repository can be confidently addressed using bounding approaches supported by geological information from similar sites around the world.



Arguments to Support Confidence in the Stability of Crystalline Rocks as Potential Host Formations

Nuclear Energy Agency

The Olkiluoto site has been chosen as a repository site for the high-level nuclear waste in 2001. Investigations in the site have been ongoing since 1987. The basic idea in the crystalline nuclear waste site still is that the solid repository block surrounded by deformation zones can host a safe repository. It is impossible to say that neither the major ductile nor large-scale brittle deformation zones are stable, but it is possible to say that the tectonic processes have been active in a stable way for billions of years by reactivating the old features time after time and there are no signs of new large features formed in the vicinity of the site during the present time including postglacial period. Understanding the geological history, especially the ductile deformation and over thrusting, begins from the understanding of the lithological features, mainly rock types, in the island. Vice versa, the occurrence and location of the lithological features are interpreted according to ductile deformation. In addition, you cannot study only present brittle deformation but you need to understand also older ductile and lithological features to be able to understand why these brittle features are where they are and to be able to predict them. 


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