LUCOEX / Work Package 2

Full Scale Emplacement Experiment (FE) Mont Terri

Task 2.1 Detailed experiment planning

The experiment has to be planned in detail to deliver a suitable work plan including all preparation, equipment development and field activities. The results have to be delivered about 6 months after the start of the project (Milestone and deliverable) to keep the tight schedule of the project.

Task 2.2 Tunnel construction and support

Evaluation of construction and support method

The construction of emplacement tunnels in Opalinus Clay requires a technology which permits mechanically excavating the tunnel and placing the support measures at a very early time just a few meters behind the face. It seems to be clear that we will generally rely on existing tunnelling equipment which has to be modified to comply with our needs. As the actual disposal site is not yet known, it may be necessary to modify the originally planned tunnel support (bolts and mesh) as it may be possible that the repository depth is as deep as 900 m or that the tunnels are placed in areas which are tectonically more disturbed than the Zürcher Weinland. First design studies have been carried out and will be the basis for further development.

Modification of tunnelling machine

Following the outcome of the design studies an evaluation of existing tunnelling machines will be carried out to find the most appropriate basic machine that can be modified in accordance with our needs.

Tunnel construction and ventilation period

The tunnel will be constructed at Mont Terri with a diameter of 2.5 – 2.8 m and an appropriate tunnel support (e.g. low pH shotcrete liner) to host 3 dummy canisters placed on bentonite blocks. Tunnel liner from cementitious material may cause axial transport paths after degradation of the cement. To avoid flow along the emplacement tunnel it is foreseen that certain sections in the tunnel will be constructed in a way that any axial flow path will be effectively interrupted (compartmentalisation). The applicability and the performance of such an “intermediate seal section” in the emplacement tunnel, probably consisting of a section with steel rips in conjunction with bentonite, will be tested in the experiment. After construction, the tunnel will be ventilated for about 1 year to simulate the expected duration prior to waste emplacement. The planned work in Task 2.2 will have two milestones – the decision on the excavation method and the start of tunnel construction. Reporting on the tunnelling activity including support work and modification of the used tunnelling machine will be described in the deliverable “Report on construction of the emplacement tunnel”.

Task 2.3 Preparation of the emplacement

Manufacturing of buffer blocks and the granular buffer Building on the experience gained in previous experiments funded by the European Commission (e.g. EB experiment at Mont Terri and ESDRED) bentonite blocks and granular bentonite will be manufactured from MX80 bentonite. The buffer material does not need further development but has to be delivered just before the actual emplacement task to avoid long storage times and possible alteration (milestone). A deliverable “Requirements, manufacturing and QC of the buffer components” will describe the techniques used and the physical parameters which are already defined in requirements set-up at Nagra within the Requirements Management Database.

Development of emplacement equipment

It is planned to design and construct equipment necessary to emplace the buffer blocks, the canister and the granular buffer. It is envisaged to construct rail-based emplacement equipment allowing placement of the canister together with the blocks in one working step. The preliminary design of the emplacement equipment for the granular buffer has been finalised and will be further developed. The system will consist of 5 auger systems which can be steered separately to improve the performance of the emplacement system in comparison of the original equipment used in the ESDRED project to produce an optimal homogeneity of the granular buffer. Do to the financial restrictions only the main emplacement equipment (multiple-auger device and necessary electronic control unit, testing of these parts) will be designed and constructed within this project. Additional supporting equipment (e.g. rails, crane, transport wagon) and additional equipment tests necessary to carry out the emplacement task will be funded outside this project because of the given financial restrictions. All equipment necessary to carry out the work will be ready for use at the milestone “Prototype of emplacement equipment tested and ready for use”. The construction of the main emplacement equipment, as defined above, will be reported in a deliverable “Report on construction of emplacement equipment”.

Task 2.4 Emplacement activity

The equipment, designed and manufactured in Task 2.3 will be used in the Rock Laboratory Mont Terri to emplace the canister, the bentonite blocks and the granular bentonite in the tunnel and sealing section. QC procedures will be developed and implemented to ensure adequate buffer density and homogeneity. Monitoring instruments will be placed in the buffer to monitor the subsequent heating and saturation of the buffer (instrumentation and monitoring is not part of this proposal but will be financed directly from Nagra). The emplacement section will finally be closed by a cement plug. The emplacement work will be finished at about 1 to 1.5 years after completion of the emplacement tunnel (milestone) and will be documented in the deliverable “Emplacement report”.

Task 2.5 Final reporting of WP 2

This task addresses the compilation of all WP 2 results in a final WP report (deliverable) and summarized in a peer reviewed scientific paper.

Task 2.6 Integration

This task is linked with WP1 in order to increase integration. The task addresses the following activities:

Expert advice of other participants on the WP test plan

Invitations to the other participants to participate in meetings and to attend installations and demonstrations during tunnel construction (month 10-12) and during emplacement of the heaters and the bentonite (month 25-27)) with the aim to give input to the WP Review of the WP final report by the other participants to verify relevant information is complete.

Networking for new scientists

Networking for new scientists will comprise the secondment of an employee of one of the partners to Nagra. Training of the scientist will include EDZ fracture mapping in clay rocks. Thereafter the scientist will take part in the geological mapping during the excavation of the experiment tunnel. The scientist needs to possess a PhD or a Master degree in Geology. The candidate has to deliver a report on his activities and findings (attachment to the final WP2 report).

  • Localization: Switzerland
  • Facility Mont Terri Underground Research Laboratory
  • WP-manager:Hanspeter Weber