Can the nuclear industry's final waste, which we currently do not know how to reuse, be safely buried deep underground? In what kind of ground can this type of disposal be considered? How can we be sure that it will be safe for very long periods of time?
These are the kinds of questions being asked about deep geological disposal, which is considered by the IAEA and many countries – Belgium, Finland, Germany, Sweden, Switzerland and the US – to be the safest method of managing radioactive waste. It involves using an underground layer of rock, such as clay, granite, salt or tuff, as a 'safe', or at least a means of holding back this waste, for vitrified waste packages or for spent fuel assemblies.
To answer the questions being asked, in December 1998 the French government decided to build two underground laboratories to study the disposal of high-level and intermediate-level waste, one in the clay of the Paris basin (at Bure in Haute-Marne) and the other in granite.
Testing is being done at these laboratories prior to any decision being made about disposal. The main aim of the research is to ensure that long-lived radioactive nuclei do not return to the biosphere. The migration distances and the lengths of time to be taken into account, for the buried atoms that must be prevented from returning to the living world, are such that it is necessary to use experiments and models in order to make sure that there will not be any risk even in the distant future.
The research also aims to find out how long a disposal facility of this kind could be reversible. If by chance our descendants discovered a way of using the waste, or making it disappear, could we be sure they were able to remove it from the disposal facility?
For research area 2 under the Bataille Act and for the research being carried out by ANDRA, a laboratory has been built at the Bure site in Haute-Marne to test clay as a medium. The boring of the shafts began in December 2000. France now has facilities at this site where the necessary research can be carried out.
Plans to build a laboratory in granite in Haute-Vienne have been abandoned because of opposition from local communities. Mission Granite, set up in February 2000, stopped work 'pending further instructions'. The abandonment of this option prompted ANDRA to step up its collaboration with other countries engaged in this research (Sweden, Finland, Canada, etc.).
The results obtained have led to clay being chosen as a suitable environment for the site of a future French waste disposal facility. The 2006 Act sets out the conditions for installing a reversible waste disposal site in a deep geological stratum, which will be chosen in 2015. Waste could start being placed in it from 2025.
ANDRA video in french Tour of the Bure underground laboratory :