Architecture and management of a geological repository - Andra

6 – Overall underground architecture6.5.4.3 Secondary infrastructure of a repository zone of spent fuel packages (CU1)In the case of a repository zone of spent fuels (CU1 types), the construction flows are more importantand the package transfer flows less important than for the repository zone of C waste packages. Thetransport vehicles used for the construction 113 and the package transfer vehicles would have largersizees which would be incompatible with the presence of large section ducts. The infrastructureconsists of five drifts, comprising one reserved for ventilation, three for construction and one forpackage transfers.6.6 Adaptation of the underground architecture to the various scenariosThis section focuses on the architecture’s flexibility with respect to the inventory assumptions madeevident by the scenarios described in chapter 3. For the same scenario, the architecture can also beadapted according to how long it takes to receive the various package categories.6.6.1 GeneralA distinction is made between the repository zones according to the exothermal or non exothermalcharacter of the packages to be disposed :- The B and C0 wastes are hardly or only moderately exothermal and can be disposed without a predisposalstorage time. The package repository zones represent footprints and relatively smallconstruction work volumes. The sizing of these zones and the connecting drifts which allow themto be served seems hardly sensitive either to the start date of the disposal or the construction andoperation rates.- The C wastes other than the C0 waste and possibly the spent fuels CU1 and CU2 are characterisedby a high exothermicity, which implies within the studied concepts a pre-disposal. Thecorresponding repository zones represent larger footprints and construction work volumes. Thesizing of these repository zones and their connecting drifts is sensitive to the disposal dates and theconstruction and operation rates. Finally, the package inventories corresponding to these zonesmay be highly different from one scenario to another (see chapter 3).- After the initial construction phase, which includes the shafts, a portion of the infrastructures ofthe shaft zone and of the connecting infrastructures, as well as the initial waste respository cells,the construction of the repository underground structures can be progressively pursued. Thus, foreach repository zone, an additional infrastructure needed for the construction of the said zone canbe constructed. The design of the infrastructures must therefore be a trade-off between flexibility,which tends to favour connecting infrastructures specific to each zone and minimisation ofexcavations, which tends to favour common infrastructures.6.6.2 Presentation of the overall architecture of a repository for the scenario S1aAn example of an architecture corresponding to the scenario S1a is shown in Figure 6.6.1 below. Thepre-disposal storage time of the highly exothermal packages corresponds to a disposal ″as reasonablyearly as possible″ with the proposed concepts, such as indicated in chapter 5 (that is, 60 and 70 years,respectively, for the reference packages C1/C2 and C3/C4).113 In particular, the transports of engineered barrier (EB) elementsDOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM281/495