Architecture and management of a geological repository - Andra

Figure 10.3.17Wireless transmission system passing through a C cell plug, currently understudyData transmission from the cell may be complemented by the monitoring of the swelling clay plug. Itcould be carried out by installing a set of sensors, similar to that described for the monitoring of theclay core of a B cell seal (cf. 10.3.7.3). So as not to diminish the long-term hydraulic efficiency of thecell plug, this monitoring equipment would be positioned in an instrumented section near to a concreteretaining plug. This equipment would make it possible to monitor resaturation and localiseddeformation of the plug due to the combined effect of settlement , rock deformation and the swellingof the clay. It would provide useful information if it were necessary to revert to the previous stage, andwould enable us to confirm the evolution of the plug as regards the expected long-term hydraulicperformance.In summary, the monitoring of the evolution of the near-field in bore-holes is not affected by thisstage. The lifetime and the reliability of the sensors embedded in the sleeve or in the cell are notdegraded to a greater extent as a result of the fitting of the cell plug. Wired or wireless transmissionoptions can be envisaged, which allows the acquisition of certain measurements to continue after cellclosure.10.3.8.4 The evolution of the C cell observation system after the drift is backfilledThe backfilling of the access drifts does not impose additional constraints on the reliability or thelifetime of the sensors. The only way of transmitting signals from the cells is to make use of wirelesstransmission to the drifts. As for the case of B modules, the concrete lining in the drifts and thebackfill allow the presence of wired equipment. It can thus carry out transmissions from the entranceof a cell up to the accessible connecting drift.In addition, the evolution of cells can be determined indirectly by the monitoring of the near-field ofthe operating unit. The measurements in instrumented section of the access drifts and the temperaturemeasurements obtained via fiber optic distributed along the whole length of all the drifts can becontinued without interruption, until the following stage when the connecting drifts are closed.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM412/495