Tome Architecture and management of a geological repository - Andra

4 - General architecture of the repository in a granite mediumA reversible repository comprises both underground repository infrastructures and installationsconstructed on the surface.This chapter starts by presenting the surface installations. It provides a succinct description of theirmain characteristics and the general principles of organisation. It describes the still preliminary lay-outof the nuclear zone, at this very early design stage, based on the hypothesis that primary packagereception and disposal package conditioning operations will be carried out on the repository site. Ithighlights the analogies between the planned installations and other existing nuclear installations.A presentation of underground installations follows. The modularity of the architecture adapted to thefracturing of each repository zone is shown to be based on current and proven technical undergroundconstruction work solutions. While aiming at adapting the repository design to the variousconfigurations of French granites, the principle of functional redundancy between the disposalpackages and the engineered barrier has been adopted in the absence of a designated site. Thisarrangement limits the required criteria of the geological medium to those common to granites:slightly permeable rock that has retention capability and mechanical strength.Lastly this chapter presents how the disposal process is implemented through the construction andoperation aspects of the structures. It emphasises that these processes are based on proven nuclearindustry and underground construction work practices (mines and underground infrastructures). Itdemonstrates that repository architecture allows these activities to be carried out simultaneously whileprocess phasing offers flexible management according to the reversibility rationale.4.1 Surface installationsThe essential functions of the surface installations are: receiving the primary waste packages,conditioning the disposal packages and supporting the underground installation construction operations.These installations are not specific to a repository: hence there are no new technical feasibility issues.They are very similar to existing industrial installations, which explains why at this stage, the descriptionof them is limited to a preliminary outline.Potential surface installation lay-outs are only given in this section by way of illustration. Likewise itshould be noted that these lay-outs do not allow for site-related constraints such as topography.However the order of magnitude of the surface installation dimensions can be assessed from them,especially the footprint, and an overall estimate of their sensitivity to possible waste managementscenarios.4.1.1 General organisation of surface installationsThe surface installations are divided into four main zones:- the nuclear zone, with a surface area of around 25 ha, where the primary waste packages arereceived and the disposal packages are prepared,- the industrial zone, with a surface area of around 35 ha, grouping the workshops and facilitiesrequired in support of the work underground,- the administrative zone, with a surface area of around 20 h, consisting of offices, car parks andpersonnel related buildings (canteens, etc),- the broken rock storage dump, with a surface area of between 120 and 250 ha depending on thescenarios.Note that the surface area allocated to the industrial and administrative zones (55 ha) is around thesame size as the area occupied by the surface installations for a major underground works site, such asthe Channel Tunnel.Dossier 2005 Granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY52/228