The Long Term Rock Buffer Monitoring (LTRBM) in situ test, assessing under realistic conditions the performances of monitoring devices developed in Modern2020
Résumé
The demonstration of monitoring technologies in repository like conditions is hence essential to assess the quality of engineering design and determine safety strategies. This study offers a summary of the design and field operations that have led to the construction of a dedicated in situ test called “Long Term Rock Buffer Monitoring” (LTRBM) experiment which aims at testing new monitoring technologies developed in and outside the Modern2020 project. A preliminary evaluation of the new and innovative technologies, including new sensors and wireless transmitting devices is also proposed. The design setup allows an engineered barrier composed by a 4 meter long bentonite buffer and 2 meter long cement plug to be saturated by synthetic water composition in equilibrium with the COx claystone (pH = 7.2), through 5 independent hydration mats. The new sensors and wireless devices were placed in and around the engineered barrier to monitor chemical parameters, pressure and saturation variations during the buffer hydration. Though a large majority of the sensors are working and react immediately to the evolving bentonite structure, some of the new prototypes have failed to measure or transmit data from the buffer. The failure of these prototypes is generally connected to handling and preparation issues prior to their installation. The first 6 months of monitoring has demonstrated that LTRBM experiment offers a reliable, cost effective and reproducible setup to assess the performance of a wide range of monitoring technologies.
Domaines
Sciences de l'environnement
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