Architecture and management of a geological repository - Andra

5 – Repository ModulesIn Japan, two generic geological media are considered: granite and clay. Report H12 (1999) [51]presents a concept in which the primary package (CSD-V) is protected by a low-alloy steel over-pack.The over-packs are placed in horizontal or vertical cells about 2.20 m in diameter. A buffer ofprefabricated blocks of swelling clay (with 30% sand) is placed between the disposal package and theterrain (see Figure 5.2.5). The thickness of the swelling clay buffer varies according to the geologyconsidered and the specified strength of the over-pack. This thickness is in any case somewherebetween 30 and 70 cm.Figure 5.2.5JNC (Japan) concepts for disposal of C packages, according to the H12 reportIn Switzerland, the Nagra's "Project Opalinus Clay" report [44], presents concepts for disposal inrelatively stiff clay located at a depth of less than 600 m.The disposal packages are placed on compacted swelling clay bases in a lined repository drift (seeFigure 5.2.6). The distance between two adjacent packages is about 3 m. The spaces between andaround the packages are then filled in with pulverulent swelling clay, lightly compacted in-situ.Figure 5.2.6Nagra (Switzerland) concept for disposal of C packagesThe three examples presented above highlight the similarities with the Andra concept. The foreignconcepts generally adopt the principle of over-packs and the cells are usually horizontal. Furthermore,in nearly all cases, the packages are spaced a distance apart for thermal reasons.5.2.3 Description and sizing of the cell and access drift during the operating periodThis section is devoted to a description of the structures in the operating configuration. A descriptionof the "sealed cell" configuration is given in section5.2.6. The main characteristics of the cell and itsassociated access drift are presented in Figure 5.2.7. Figure 5.2.8 gives a more detailed presentation ofthe various components described below [65].DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM200/495