Architecture and management of a geological repository - Andra

5 – Repository Modules• Thrust frameThe thrust frame is anchored to the drift lining. Its length inside the drift is approximately 5 m(compatible with 2.5 m long sleeve components).• Boring tool and drill stringThe boring tool proposed is equipped with carbide teeth.The three peripheral bits are pivotal and canbe retracted at the end of the drilling (see Figure 5.2.20)The thrust and rotation of the boring tool are transmitted by a drill string. It seems preferable to equipthe drill string with a helicoidal screw ensuring centring and broken rocks removal. Other brokenrocks removal solution can also be considered. A drive shoe installed at the end of the sleeve and leftin place enables allows for bore finishing operations.The head excavation diameter is adjustable and can be set according to the penetrability of the sleeveand the quality of the boring. The manufacturers recommend accommodating a centimetric radiusannular space between the sleeve and the terrain. This annular space can be obtained with the driveshoe or through adjustment of the drill bits (to be optimised via in situ tests).Figure 5.2.20Tool used for C waste disposal cell excavation• Installation of sleeve tubes (permanent and temporary parts)The standard sleeve components are positioned at the end of the tube already engaged, and they arewelded immediately before their insertion in the disposal cell (MIG or MAG welding, for example).The temporary sleeve tube components can be connected via mechanical locking, allowing fasterinstallation and subsequent recovery upon closure of the disposal cell.The temporary sleeve is connected to the permanent sleeve via a remotely removable shank (simpleshrink-on or bayonet fixing).• Welding of the sleeve bottom sealing plate and cleaningAfter withdrawing the boring tool, a metal plate is welded on the bottom of the sleeve. This operationis performed with a welding robot of similar design to those used in the petroleum industry (see Figure5.2.21).DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM220/495