RSC-Programme - Interim Report. Approach and Basis for - Posiva

23be mechanically instable especially during glaciations or they are main groundwaterflow routes and thus of importance for transport of solutes and chemical stability at thesite. Between these features the host rock properties are such that is suitable for hostingdeposition holes with local exceptions.Tunnel scale criteria address the selection of suitable rock volumes within each panellocated in the rock volume between the layout determining features. The rock volumeconsidered suitable based on the repository scale classification may still contain featureslike local scale deformation zones and large and highly transmissive fractures whichaffect the suitability of the host rock locally (see Section 5.3 for a more detaileddiscussion). These are addressed by the tunnel and deposition hole scale criteria. Theapplication of the repository and tunnel scale criteria consider also whether in the givenvolume there is enough potential locations for the deposition holes so that excavatingthe tunnel(s) is economical. The final acceptance of the deposition hole, is based on theassessment of the suitability of the host rock defined by the deposition hole scaleclassification, but also on quality assurance of the engineering for example holestraightness. Figure 3-3 presents the scaled approach for identifying potentially suitablerock volumes and canister positions.