Closure of the disposal facility
As final disposal progresses, the repository will be expanded by excavating more deposition and central tunnels. According to current estimates, the final disposal operations will continue until the 2120s.
When the operations of the disposal facility end, the open central tunnels, the associated vehicle connections and auxiliary rooms at the deposition depth will be closed first. After that, the other tunnels are closed and, lastly, the access connections to the ground level, i.e. the vehicle tunnel, shafts and test holes drilled in the damage zone of the disposal facility.
In the interests of long-term safety, it is essential that the repository is backfilled and closed in such a way that the bedrock situation returns as close as possible to the natural state prior to the excavation of the repository.
The objective of the closure is to isolate the repository from terrestrial conditions and to prevent people from accessing the facilities. The closure prevents the formation of direct flow paths between the ground level and repository and ensures that backfill of the deposition tunnels remains in place. Natural materials compatible with surrounding rock and having poor hydraulic conductivity have a beneficial effect on the long-term functioning and safety of the final disposal solution.