Geotechnical site investigations to prove the rock stability of large cavities and the barrier efficiency of the rock mass

Nuclear power plants may be sited in underground caverns, on slopes, or in pits. When a possible site is being considered, geoengineering and rock mechanical factors must be considered with respect to the feasibility of construction and the protective effect of the surrounding rocks as a barrier against internal accidents and external hazards.

The Federal Institute for Geosciences and Natural Resources carried out a preliminary evaluation of suitable sites in Germany in the 1980's using geoengineering and rock mechanical criteria. Three suitable rock types were defined: quartzite, schist and New Red Sandstone. These theoretical studies must be supplemented byin situ measurements, especially with respect to the efficiency of the rock as a geological barrier.