Architecture and management of a geological repository - Andra

6 – Overall underground architecture6.1.3 Taking account of operational safety and the diverse nature of the activitiesThe design of the repository’s architecture must include the capability to construct repository subassembliesat the same time as other sub-assemblies are in use or being closed. This leads to the coexistenceof nuclear operation activities (transfer and placing of packages) and civil engineeringactivities (construction and closing of repository structures). These activities are characterised bydifferent safety and security requirements and different physical flows. Safety and efficiency requireinstallations to be designed so as to separate these activities in either space or time.6.1.3.1 Construction activitiesConstruction activities include the excavation, support, lining and fitting out of undergroundstructures. They fall within the scope of a conventional underground work site or mining operation.6.1.3.2 Repository placement or “nuclear operational” activitiesRepository placement or “nuclear operation” activities concern the receipt of primary packages andthe preparation of disposal packages in surface installations, the transfer of these disposal packages tounderground installations and their placement in the disposal cells.They also concern the observation of the installations for a period during which they are accessible,within the context of reversible repository management.These nuclear activities are characterized by constraints similar to those of conventional nuclearinstallations.The repository's siting underground entails additional constraints and particular attention must begiven to the management of ventilation and the mechanical stability of underground structures(adaptation of their dimensions to the geomechanical characteristics of the ground, surveillance ofunderground structures).6.1.3.3 Closing activitiesThese activities concern the sealing of the cells, the sealing and back-filling of the drifts and thesealing and backfilling of the shafts.The sealing of the cells requires civil engineering techniques in the immediate vicinity of a “nuclear”structure; it will therefore be subjected to constraints similar to those of nuclear operations.The sealing and back-filling of the drifts are possible using civil engineering techniques outside the“nuclear” context as they are located at a significant distance from the disposal cells.6.1.3.4 Ventilation of underground installationsVentilation is an essential element of the hygiene and safety of all underground structures. As such, itis an dimensioning element which must be considered from the structure’s design stage. It enablespersonnel to work in constantly renewed fresh air and makes it possible to evacuate personnel andcontrol smoke in the event of a fire.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM255/495