Architecture and management of a geological repository - Andra

To monitor the corrosion of metal components, visual inspection methods either employed directly orremotely using miniaturised cameras, followed by sampling or ultrasound measurement can be carriedout as long as the object or the monitoring area is accessible or at a distance accessible by remotecontrol. Corrosion indicators (sacrificial anodes, etc.) can be used, either to indicate an absence ofsignificant corrosion, or to detect a high corrosion rate. This type of indicator is used in the monitoringof pipelines and reinforced concrete structures in marine environments.In the nuclear industry, possible contamination is monitored regularly by mass spectrometry systems.They analyse samples obtained by suction from the atmosphere to be checked, through a filter, toidentify the isotopes and to quantify their activity. This principle is used, for example, for themonitoring of α-β radioactive aerosols in the atmosphere in nuclear installations. The restrictions foruse are similar to those for hydrogen detectors and they therefore require regular re-calibration.• Transmission and centralisation equipmentMore an more data acquisition and monitoring is centrally managed, due in particular to the risingnumber of measurements performed. Centralised management facilitates the acquisition andexploitation of measurements.For around ten years, conventional electrical signal type measurement equipment have beencomplemented by fiber optic sensor technologies. This latter type of technology is easily integratedinto a fiber optic type transmission system. Optical means have a number of advantages as comparedwith electrical cables. They are not sensitive to electromagnetic disturbance and the signals can betransmitted without amplification over several tens of kilometres.It is also possible to use low or very lowfrequency electromagnetic transmissiontechnology which obviates the need forphysical connections between the sensorand the reception system. This wirelesstransmission technology has been used foraround twenty years in the petrol refiningindustry for the control of directionalboring and for the observation of oilaccumulations. Just such a system is usedon the Meuse/Haute Marne laboratory sitefor in-situ pressure and temperaturemonitoring (Figure 10.3.7). Piezometricprobes installed 420 m under the groundtransmit information to the surface withoutany wire connections. The lifetime of thisequipment depends on the lifetime of thebatteries that power the sensors and thefrequency of measurements.Their lifetime is approximately ten yearsfor normal use [87]. One of the objectivesof current developments is to increase thislifetime.420 m80 mReceptionEPG sensor10 mFigure 10.3.7 Wireless surface transmission to theLaboratory in the Meuse/Haute-Marne siteDOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM398/495