Tome Architecture and management of a geological repository - Andra

3 – Design study of a repository in a granite formationModular design of underground installations for flexible management and changes in designThe proposed architecture options are modular: they provide a flexible and gradual management of thedevelopment of a repository promote the staged management of the disposal process and allowdifferentiated management methods according to the various types of waste.Each package category (B, C and CU) is to be hosted in a dedicated repository zone, constructed,operated and closed independently. Each repository zone is designed to be built and operatedgradually as successive cell sub-assemblies. Closure designed in a gradual manner is organised intoseveral stages: closure of cell sub-assemblies, which can be carried out at the same time as the creationof new sub-assemblies, closure of access to this sub-assembly, and then of the repository installationsspecific to this waste category and lastly of all installations.As the repository is being developed in stages, new structures can be designed taking advantage of thelessons learnt and knowledge acquired during operation and observation of previous structures, as wellas of technical progress carried out otherwise. It is as well possible to incorporate data from social,technical and scientific backgrounds.• Technical feasibility of reversing the processAndra has studied the technical feasibility of reversing the process for the various repository stages:technological resources, operating conditions and necessary precautions.The repository is therefore designed to allow packages to be retrieved in the first stage by simplyreversing the process of their emplacement in the cell (as easily as in a storage facility). For laterstages, Andra has incorporated arrangements in order to access again to the installations which wereclosed and install the equipment required to retrieve the packages, would such a decision occur.• An observation programme supporting reversible repository managementKeeping options open during the repository process implies knowledge of its evolution and situation atall times: therefore it requires constant observation and implementation of the necessary measurementresources and systems. Andra has studied the possibilities of integrating measuring sensors in thestructures without disturbing repository operating and safety.Beyond the monitoring related to operational safety, this observation programme reinforcesunderstanding of the phenomenological evolution of the repository and provides important data fordecision-making. It also draws on feedback from the operation of the first structures in order toimprove repository design and management.Dossier 2005 Granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY49/228