Deep Geological Repository Concept in the Czech Republic

The Czech concept for a deep geological repository is similar to those of several other countries. The underground and surface layouts are shown in Fig. 1 and Fig. 2. The Figures refer to a situation in which the repository is fully operational, i.e. radioactive waste and spent nuclear fuel is being accepted, loaded into transport containers and transported to the underground facility in which it is finally disposed of. At the same time, the construction of further underground disposal chambers continues. In addition to the structures shown in the Figures, an operations building, buildings to house workers, an administration building, an information centre, roads etc. will be necessary to service the repository most of which will be located in the so-called non-active zone; the active zone is provided with special sophisticated safety protection.

Fig. 1. Model of the planned Czech deep repository

The above-ground area covers 29.5 hectares of which 3 hectares serve for the handling of spent nuclear fuel and high-level waste. The remaining reserve and handling area will be used for the construction of service buildings; a railway spur will be constructed on part of this area. For security reasons, i.e. so that the area can be closed following the arrival of a train carrying spent nuclear fuel, this area will form an integral part of the repository’s above-ground area even though no important handling functions will be performed there.

Fig. 2. Repository above-ground area

The underground area comprises access and ventilation shafts, tunnels and disposal chambers. A major part of the underground area is made up of a complex network of galleries in which spent nuclear fuel containers will be placed. The containers will be arranged both vertically beneath the disposal gallery and horizontally in the gallery walls. The access galleries will gradually be sealed to prevent any contact between the underground chambers in which the waste is emplaced and the biosphere.

A system of multiple barriers will be constructed; repository safety must be at such a level that the system will function even in the event that one of the barriers loses its isolation capability. Spent nuclear fuel and high-level waste containers will be surrounded by sealing materials (bentonite) and placed in chambers excavated in the host rock at a depth of approximately 500 metres.