Security Designs for Geological Repository of Nuclear Spent Fuel

Security designs for geological repositories of nuclear spent fuel incorporate a number of measures to prevent the reciprocal action between the stored wastes and the surrounding rocks. Since the level of nuclear wastes storage safety depends directly from its depth below the surface, contemporary storage standards require using available mining techniques to drill repositories at the depth of no less than 500 to 900 meters (Kollar 49).

The most common method of geological repositories building amounts to drilling a vertical shaft along with the access tunnels to reach the planned depth (Kollar 34). At the planned depth, further provisions are made to facilitate horizontal disposal galleries for placing SNF and HLW (IAEA 11). At that, the used fuels are put there entombed and then, they are surrounded by the chosen butter materials and backfilled and sealed afterwards (IAEA 18).

To put off the threat of radionuclides migration, storage areas are equipped with multiple barriers (IAEA 11). These berries can be of two types: geological and engineered. Both types of barriers form the multi barrier system (IAEA 18). All these procedures are performed only in the areas with the selected host rocks that match the requirements for storing every particular type of nuclear spent fuels because rocks are the most important isolation barriers (Okko 15). Important characteristics of host rocks are medium, and presence of ground waters (Kollar 52). The engineering shielding system has three elements: the waste matrix, initial package such as fuel rod cladding, and bentonite clay. The final barrier in the multi barrier system is the geological one and it is the rock formation (Okko 5).