Fig. 5
An example of the multi-barrier concept for vitrified HLW (high-level waste) developed in Switzerland and Japan (e.g. JAEA 2000). The vitrified waste is poured into a steel fabrication container which is in turn placed in a thick metal canister (typically carbon-steel but, in some designs, the container is copper) and emplaced axially in a tunnel which is backfilled with compacted bentonite clay. The EBS (engineered barrier system) is protected by a stable host rock, which also acts to retard any radionuclides which are released by the EBS. Image courtesy of Nagra