Architecture and management of a geological repository - Andra

7 – The shafts and the driftsThe grooves are filled with swelling clay (type MX80, like the core). The aim is to have a swellingpressure at installation in the order of 3 MPa on the groove faces. The density of the clay and theinstallation voids are adjusted to this purpose.The liner is removed over around 1.30 m perpendicular to each groove, leaving 0.5 m either side; thedistance thus separating the concrete and the clay from the grooves limits a potential alkalinedisturbance in the clay, which thus retains sufficient swelling capability.• Construction of hydraulic cut-offsThe liner is removed locally. The grooves are excavated using a saw fitted with picks, with a cuttingtool similar to the cutters used in salt and coal mines to create grooves in the rock massifs.The technological feasibility of creating a groove has been tested in the Mont Terri laboratory (EZ-Atest) and in the Meuse/Haute Marne laboratory (KEY test). These tests have confirmed that it ispossible to create such grooves and has checked their effectiveness in interrupting the fractured zonein the rock.The grooves may be filled by assembling pre-compacted bentonite blocks. These blocks are set inplace mechanically using erectors: they can weigh individually a few hundred kilograms to severaltonnes depending on methods implemented. Injections of bentonite powder fill the interstices.Figure 7.7.5Groove excavation for the KEY test at the Meuse/Haute Marne laboratory7.7.2.6 Special case of B waste disposal cell sealsThe seal design presented for the connecting drift is adapted slightly to close a B waste disposal cell(Figure 7.7.6).DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM315/495