The long-term safety of humans and the environment will be guaranteed by means of a system of engineered safety barriers in deep geological repositories. Radioactive waste must be permanently disposed of without burdening coming generations with unreasonable encumbrances and duties. During the disposal process the maximum level of radionuclides released from a deep geological repository into the environment may not exceed the individual dose of 0.1 millisieverts per year. This level corresponds to a very small percentage of the average natural exposure to radiation.
The long-term safety of the deep geological repository is guaranteed by a number of different barriers. Waste is completely shut away because of the combination of technical barriers and the choice of host rock (natural barriers). A substantial part of the remaining radioactive material decays while the receptacles are still intact. The clay-containing minerals used to backfill the caverns (bentonite) and the rock layer absorbs any further radioactive particles that might be released.