Tome Architecture and management of a geological repository - Andra

5 – B waste repository zoneFigure 5.5.13D view of a module of non-exothermic waste cellsIn the case of two-level architecture, the module refers to disposal cells located at the same depth andsharing common connecting infrastructures.Disposal module dimensioning primarily depends on the definition of rock volumes to be preservedaround each cell. The previous section introduced a "hydraulic" buffer distance between a disposalchamber and potentially water-conducting faults that delimit the host block. Two other types of bufferneed to be defined in order to control the disturbance to the medium induced by the medium:- "thermal" buffer, between disposal chambers of slightly exothermic packages ;- "mechanical" buffer, between disposal chambers (pillar), and between a chamber and faults at theedge of the blocks.• Dimensioning of a "thermal" bufferThe compactness of the repository with modules that accommodate slightly exothermic waste (typesB1 and B5) depends on a defined buffer distance to limit thermal disturbance between the disposalcells.Accordingly an analysis has been made of the design sensitivity to the various clearance values for thethree types of granite modelled using preliminary disposal cell dimensioning calculations (§ 5.4.2.3).For buffer values close to 60 m, thermal interference is not perceptible at the core of the pillar betweentwo cells until after a few centuries. When this interference is observed, the temperature of thepackaging concrete is less than 50°C.• Dimensioning of a "mechanical" clearanceTaking into account mechanical criteria for dimensioning disposal modules plays a part in defining thepillars between two large diameter tunnels, and in the buffer distance between a cell and a faultdelimiting the module host block.Dossier 2005 Granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY137/228