Architecture and management of a geological repository - Andra

• Instrumented bore-holesAn option which is complementary to that of instrumentation of a cell consists in burying sensors inbore-holes parallel or lateral to the cell as illustrated in Figure 10.3.16.Figure 10.3.16Monitoring of a C cell on the sleeve and in bore-holesThis type of system enables monitoring of the rock near to the cell. Bore-holes parallel to each controlcell are distributed in the same way as the monitoring units on the sleeve. They are carried out fromthe access drift. The lateral bore-holes are distributed in the same way as the instrumented sections,with an additional bore-hole beyond the bottom of the cell. They are carried out from theinterconnecting drift.Several extensometers, thermometers and interstitial pressure cells can be incorporated into thesebore-holes. They complement the deformation and temperature measurements carried out on thesleeve. In particular, they make it possible to determine the thermal field in the wall and near to thecell and the field of stresses in the rock and in the sleeve. Also, the monitoring of reductions ininterstitial pressure near to the head of the cell provides a more accurate basis for developing modelsof prediction of any desaturation of the rock near the temporary sleeve.Instrumentation in bore-holes has several advantages in relation to instrumentation in the sleeve.Firstly, the near-field of the control cell can be monitored, without being curtailed by the fitting of thecell plug. Moreover, the environmental conditions in the rock, and particularly the dose rate from thecell, do not constitute great limitations on the reliability or the lifetime of the monitoring equipment.10.3.8.2 The evolution of the C control cell monitoring system after the packages are put inplaceThe mechanical and hydraulic evolutions and possible corrosion, initiated during the construction ofthe cell, continue after the packages are put in place. Moreover, this insertion of the packages causesheating in the structure and the near-field.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM410/495