This task is aimed at advancing techniques for evaluating the key processes of relevance to the long-term near-field system performance. Particular concern focusses on the coupled thermal-hydrological-mechanical-chemical (T-H-M-C) behaviour of the engineered barrier system (EBS) and the solute transport process in the EBS and its near-field. To these ends, the subtask (i) "full-scale EBS performance experiment" launched in 2014 is continued and then expanded with the dismantlement of the entire experimental setup and the subtask (ii) "solute transport experiment with model testing" is extensively carried out.

*View the location of the 350 m Niche No.4 in the Locations & Facilities page.

In situ demonstration experiments show the engineering feasibility of a range of technical options that would allow flexibility in designing a repository for a variety of geological environments. Relevant concepts / criteria, methodologies and techniques are established in two subtasks: (i) the "demonstration of engineering feasibility of repository technology" addressing the 'development and testing of operation, retrieval and closure technologies' and the 'systematic integration of technologies towards EBS emplacement' and (ii) the "evaluation of EBS behaviour over 100°C".

*View the location of the 350 m Niche No.2 in the Locations & Facilities page.

This task is dedicated to gain a better understanding of the hydro-mechanical buffering behaviour of sedimentary rocks against natural perturbations such as fault reactivation and uplifting. In situ experiment and field investigation programmes involve two subtasks: (i) the "evaluation of intrinsic buffering against endogenic and exogenic processes" focussing on the 'evaluation of hydro-mechanical responses of fault to water pressure changes' and the 'improvement of techniques for characterising groundwater stagnant domain' and (ii) the "development of techniques for evaluating excavation damaged zone (EDZ) self-sealing behaviour after backfilling".