Architecture and management of a geological repository - Andra

This operation is complete when a boring tool on the micro tunnel borer comes into contact with thehead of the cell’s permanent sleeve. The boring head may then be retracted to finish pushing thesupport casing and withdraw the micro tunnel borer.Once the support casing is installed, the temporary sleeve may be connected to the permanent sleeve(Figure 10.4.15). The inside diameters of both sleeves shall be chosen identical in order to minimizejunction discontinuity. The temporary sleeve is brought into contact by the tube pusher of theequipment used previously. Proper alignment between both sleeves is made possible by a tapered-endcentring tool pushed by a string of rods. Correct alignment between both sleeves is ensured by aconnecting collar placed at the end of the temporary sleeve. This collar is placed on top of thepermanent sleeve end and mechanically connects both sleeve sections.Figure 10.4.15Reconstructing C cell headThe temporary sleeve is then aligned on the permanent sleeve using the laser optical appliance. Theaxis of this 9-m long tube shall be aligned on the permanent sleeve’s axis in order to avoid all risks ofjamming in the blend. Then, it is welded on the support casing at the entrance to the cell head section.Re-equipping the cell head sectionRe-equipping consists in re-installing the shielded trap door following a procedure similar to that usedfor installation. Now the cell is ready to permit the package retrieval process (Figure 10.3.16).Theduration of the cell reconditioning process is estimated at about one week.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM431/495