Rock laboratories provide researchers with the opportunity to carry out experiments on a large scale.
This allows the rock and its behaviour to be investigated under relevant conditions and technical procedures and methodologies to be tested. Such experiments provide key input for constructing geological repositories.
Nagra has its own rock laboratory on the Grimsel pass in Canton Bern and is involved in the programme at the Mont Terri Rock Laboratory in Canton Jura; the latter is managed by the Federal Government (Federal Office of Topography, swisstopo).
The rock laboratories can also be visited by interested groups, allowing the research activities to be experienced first-hand.
Information on suitable host rock formations, the functioning of the engineered safety barriers and the transport of toxic substances in the safety barrier system and the geosphere can be obtained through research projects in rock laboratories such as Nagra's facility on the Grimsel pass in Canton Bern.
International collaboration and exchange of know-how, projects covering all areas of geosciences and engineering and active dialogue with scientists during visits by the public and politicians are all aspects of the activities at the Grimsel rock laboratory – one kilometre deep inside the Swiss Alps.
- Grimsel rock laboratory
- Grimsel lake
Geology of the Grimsel area
Some 300 million years ago, magma penetrated from the earth's interior and solidified at a depth of around 13 kilometres to form crystalline rocks. The volume of the rock was reduced during cooling and deep fracture systems were formed. Rocks in liquid form rose through these fractures to form so-called dyke rocks (lamprophyres and applies).
During the next 200 million years, the rocks of the Aar Massif remained virtually unchanged. During the alpine mountain-building phase around 40 million years ago, the Massif was subjected to strong loading. As a result of transport of the alpine nappes towards the north, the Aar Massif subsided and was overlain. At the time of the maximum overburden (around 12 km), the rocks were exposed to high temperatures (around 450°C) and pressures (around 300 MPa). This phase saw the formation of schistosity and shear zones. In the subsequent phase of uplift around 16 million years ago, tension joints or fissures formed in the rock; these are partly filled with beautiful crystals. Uplift is still ongoing today at a rate of around 0.5 to 0.8 millimetres per year.
Geological-tectonic profile along the Grimsel pass road
- Sediments of the Wildhorn nappe (Jurassic, Cretaceous)
- Autochthonous and parautochthonous sediments (Triassic to Lower Tertiary)
- Innertkirchen Crystalline
- Mittagfluh Granite
- Central and Southern Aare Granite
- Grimsel Granodiorite
Experiments at the Grimsel rock laboratory
The geological situation at the Grimsel rock laboratory (fractured, water-bearing and homogeneous rock zones) offers ideal conditions for carrying out a wide range of experiments. Today, the focus is on the performance and safety of the engineered and geological barriers of a deep repository. Projects at the GTS are investigating disposal concepts on a 1:1 scale. A controlled zone in the laboratory allows radionuclides to be used to test models of the transport of radioactive substances.
The tunnel system of the Grimsel rock laboratory
The abbreviations indicate a selection of test locations.
- FEBEX 1:1 Demonstration of the emplacement concept for high-level waste (brochure, pdf 980 KB)
- PSG Determining pore space geometry in the rock matrix
- GMT Gas transport through the engineered barriers and surrounding geosphere (brochure, pdf, 1.9 MB)
- CRR Retardation of colloids and radionuclides (brochure, pdf, 544 KB)
- HPF Hyperalkaline plume in fractured rock (brochure, pdf, 1 MB)
- CFM Formation and transport of colloids and radionuclides
- LTD Long-term diffusion of radionuclides
An international research project is running at Mont Terri in Canton Jura under the lead of the Federal Office of Topography (swisstopo).
Nagra has been involved in the experiment programme since 1996.
Experiments are carried out in the Mont Terri rock laboratory to investigate the hydrogeological, geochemical and rock mechanical properties of the Opalinus Clay formation and to evaluate the behaviour of engineered barrier systems. The results provide input to assessments of the feasibility and safety of waste repositories constructed in clay formations (the Opalinus Clay in particular).
The laboratory is open all year for visits by interested groups.
|The facilities of the Mont Terri rock laboratory are reached through the safety gallery of the Mont Terri motorway tunnel. Image: DesAir|
The Geology of Mont Terri
During the Jurassic period some 175 million years ago, fine mud particles were deposited on the bed of a shallow sea. Over the next millions of years, these formed a layer of claystone up to 150 metres thick – the Opalinus Clay.
The Mont Terri anticline (a large fold) formed some 10 million years ago during the folding of the Jura mountains and was thrust towards the north-west over the Tabular Jura of the Ajoie. In the area where the rock laboratory is located, the rock strata dip with an angle of around 45 degrees towards the south-east.
Experiments in the Mont Terri rock laboratory
The geological conditions in the Mont Terri rock laboratory include both fractured and undisturbed areas of rock and offer ideal conditions for a wide range of experiments. Today, the focus is on the performance and safety of the engineered and geological barriers of a deep repository. Projects at the laboratory are investigating disposal concepts on a 1:1 scale. A controlled zone allows radionuclides to be used to test models of the transport of radioactive substances in the rock.
The current programme consists of a total of 46 different experiments, many of which are long-term projects extending over several research phases. The project partners hold regular meetings to discuss results and to consider the initiation and financing of new experiments.
The tunnels of the Mont Terri rock laboratory
The abbreviations indicate a selection of test locations.
- EB Engineered barriers (demonstration of emplacement technology)
- EZ-B Fracture formation in the excavation damaged zone
- DR Diffusion and retention of radionuclides
- FE 1:1 emplacement experiment for investigating the tunnel environment
- HG-A Gas flow paths through the rock and along sealing structures
- VE Ventilation experiment