The objective of the "VE Experiment" is to evaluate "in situ" the consequences of desaturation in consolidated clay formations. Specifically, the design of the repository, in terms of drifts spacing and repository size, depends on the thermal load that the rock and the engineered clay barrier may accept, which depends directly on their degree of saturation. It is, therefore, vitally important that the desaturation - resaturation times of the rock be assessed, along with their impact on the future resaturation times of the engineered clay barrier, from the point of view of repository design optimisation. Furthermore, desaturation may give rise to cracking on drying, which would increase the area disturbed by excavation of the drifts (EDZ), in terms of a substantial increase in its hydraulic conductivity.
The main objectives of the project may be summarised as follows:
1. Estimation of desaturation and resaturation times in clay rock, produced by drift ventilation.
2. Estimation of the saturated hydraulic conductivity of the rock (macro-scale) and comparison with values obtained at smaller scales: laboratory testing, in-situ hydraulic testing. Evaluation of the scale effect impacting this important parameter.
3. Estimation of evolution of the EDZ, in terms of changes in hydraulic conductivity and of displacements caused by the generation of cracks on drying.
A set of scientific and technical reports including a final report, which should provide information of the "in situ" desaturation - resaturation consequences in consolidated clay formations during the operational and post-closure phases of a repository. The results will improve the scientific basis for the safety assessment of nuclear waste deep geological disposal.
Funding SchemeCSC - Cost-sharing contracts