High-level waste generates heat and when placed in a repository it will cause the clay around the disposal galleries to heat up temporarily. The PRACLAY experiment is a large-scale experiment designed to study the impact of this heat on the deep clay layer. It will also look at how excavation affects the behaviour of the clay.
This knowledge is essential for determining how the construction of a repository can influence the ability of clay to physically contain radioactive waste. It is vital to ascertain that this ability will not be impaired in order to confirm that disposal of heat-emitting high-level waste in a deep clay formation is a safe solution in the long term.
The PRACLAY experiment is being carried out on a large scale, over a long period of time and at the temperatures that would be expected in an actual high-level waste repository.
Phase 1: Construction of the PRACLAY gallery (2007)
Phase 2: Installation of the heating system and sealing of the PRACLAY gallery (2008-2011)
Phase 3: Heating phase (from 2014)