Tome Architecture and management of a geological repository - Andra

6 – C waste repository zoneElectron beam welding and the welding inspection methods have been used for the spent fuelcontainer demonstrators studied for the clay medium using the same grade of steel as envisaged here.6.4 The disposal cellsIn the granite medium, the orientation and distribution of minor fracturing likely to locally affect thevery low permeability of the rock govern whether horizontal or vertical cells are chosen for thegranite.The analysis of minor fracturing in the French geological context shows that it is more oftenrepresented by sub-planar structures and generally sub-vertical or vertical.Also in reference it has been decided to study the vertical disposal borehole design, which as it is closeto the line of the highest dip of most of these structures, statistically limits the number intersected bythe disposal cells.These disposal boreholes are installed in handling drifts. This chapter describes both these twostructures.Figure 6.4.1View of a C waste disposal boreholeHowever for a site where the geometries of minor fracturing are predominantly horizontal, ahorizontal tunnel cell design could be applied. It would be based on the same broad design principles,with primarily a steel over-pack inserted in a sleeve and a clay engineered barrier placed between thesleeve and the wall of the horizontal tunnel.Dossier 2005 granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY175/228