In many countries with nuclear programmes which produce considerable quantities of radioactive waste and spent fuel assemblies, research and development programmes for the final disposal of radioactive waste have been initiated. The underground laboratories play an important role because the future conditions of disposal are reconstructed in these laboratories. Theoretical approaches and newly developed methods can be confirmed by practical experience. Computer programmes which forecast the future conditions in a repository can be reviewed with the help of practical tests. Apart from gaining experience concerning the characterisation of a site and the technical design of a repository, it is also possible to gather information on the operation of machinery and equipment to be used in a repository.

Depending on the existing geological conditions in the respective countries, different host rocks are examined with regard to their suitability for the final disposal of radioactive waste. There are therefore underground laboratories in salt, granite and also in clay. The largest and most intensively used underground laboratories are in rock salt at the Asse (Germany), in granite at Grimsel, in clay at Mont-Terri (both in Switzerland) and in granite at Äspö (Sweden). In France, another underground laboratory is currently being built in a clay formation at the Bure site.

See also: ASSE (Germany), GRIMSEL (Switzerland) and ÄSPÖ (Sweden).