Architecture and management of a geological repository - Andra

5 – Repository Modules• Disposal cell design and constructionA functional clearance of 30 mm in diameter has been included in the disposal cell design to enablepackage and pusher robot displacement. This functional clearance is understood with respect to theoutside dimensions of the packages including sliding runners. It has been minimised as far as possibleat this stage so as to limit the mechanical degradation of the argillite on a very long-term basis in caseof sleeve collapse. It is intended to enable the transfer of packages without risk of jamming (forexample, due to sleeve section alignment defects or the presence of rough or jagged edges inconnections). In order to minimise these risks, several technical measures can be considered:- Controlling the alignment of the sleeve sections. Misalignments may result from angular defects,or from lateral displacements of correctly oriented sections. A preliminary inspection with anoptical sighting device prior to welding the tube components can prevent angular alignmentdefects during the installation of the sleeve. Likewise, misalignments due to lateral displacementscan be controlled using optical sighting and centring devices.- Obtaining a good running surface. This mainly depends on the quality of the connections. Theabove-mentioned connections without internal sleeves satisfy this requirement.In addition, the radiological protection calculations show that a cylindrical plug without shoulder isenough to ensure radiological protection. The absence of shoulders on the metal plug (and therefore onthe sleeve) simplifies the installation of the packages.All of these design factors facilitating package installation also favour reversibility. The passage ofpackages during a possible removal operation does not entail specific difficulties with respect toinstallation. The removal operation even provides additional advantages associated with the possibilityof exerting significant tensile forces on the packages.• Access drift designThe effective cross-section of the access drift is dimensioned based on transfer cask displacement anddocking. The transfer cask travels in transverse position inside the drift (without rotation for docking).The figure below shows the docking of the transfer cask in front of a disposal cell.Figure 5.2.16Docking of C waste transfer cask in front of disposal cellDOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM215/495