Rocks: custodians of radioactive waste

The aim of the Andra project, which involves the 3SR laboratory as part of a 20-year cooperation, is to store radioactive waste (primarily produced by the French electronuclear industries) in deep geological waste repositories. The “Callovo-Oxfordian” clay formation has been chosen as a disposal site for high-level waste and long-lived intermediate-level waste, as it is able to contain and retain radionuclides. At present, additional research is being done partly in the Meuse/Haute-Marne Underground Research Laboratory operated by Andra, composed of a network of tunnels 500 metres underground. The “packages” of high-level radioactive waste will be deposited in cylindrical boreholes drilled horizontally from the access tunnels and lined with steel tubes, to make it easier to install and remove the packages. “Our work is to assess the hydromechanical behaviour of the rock at the long- and short-term excavations in order to guarantee containment of the radioactive matter”, explained Jacques Desrues, CNRS Research Director at the 3SR laboratory. To this end, the researchers use complex numerical models stemming from the finite element method. “We aim to provide Andra with a robust, reliable and user-friendly tool”. It will take approximately one hundred and fifty years to build and fill the repository which will be monitored and which must be reversible for at least a century.

*French national agency for radioactive waste management