The Mont Terri Rock Laboratory. Photo/Foto: TES.

The Mont Terri Rock Laboratory

Switzerland is known for its excellent research institutes, scientific research and universities. The topics and themes vary from climate change, glaciers, medicine, pharma, and CO2 reduction to technologies and other fields. The country is one of the world’s champions of innovation and patents. They have one thing in common: they occur at or above the earth’s surface.

Mont Terri Rock Laboratory

However, 300 metres below the earth’s surface, close to Saint-Ursanne (Canton Jura) is an innovative research project. The Mont Terri Rock Laboratory celebrated its 25th birthday in 2021. What began in 1996 as a small research facility in the Opalinus Clay of the Mont Terri motorway tunnel is an internationally renowned research laboratory today.

The last 25 years have shown that claystone like the Opalinus Clay can safely contain radioactive waste over very long periods. Claystones and mudstones have the function of confinement but also prevent gases such as CO2 from penetrating the biosphere from deeper layers.

Opalinus Clay

The Opalinus clay was formed in the Jurassic period, some 180 million years ago. A subtropical sea then covered the region. The underground water still contains salt for this reason. The clay is almost impregnable, making it interesting to store radioactive materials and CO2.

The website gives an excellent overview of the history of the last 25 years, the development of the Mont Terri rock laboratory, the experiments and their research results, and an outlook on future research priorities. 

The Mont Terri Rock Laboratory has a total length of 1 280 meters. It started in 1996 with small niches and continuously expanded until 2018. 


More than five hundred people from twenty-two Partner organisations from governments, universities, and research institutes in Europe, Japan, Canada and the United States. Two petroleum companies are involved as well.

The Project has three main objectives: to research and develop new methods that can be applied in claystone such as the Opalinus Clay, but which are also transferrable to other argillaceous formations worldwide, to characterise the Opalinus Clay, which means to acquire knowledge of the physical, chemical and biological properties of this clay formation, and to carry out demonstration experiments. Young scientists from all over the world contribute to the many experiments. 

The latter primarily demonstrates the long-term behaviour ( hundreds of thousands of years) and the construction feasibility of a disposal system. The main question is always the same, be it for radioactive waste or CO2 storage: is a deep repository system safe in that it does not threaten the operators in the short term and the geosphere and the biosphere in the long run term? 

Legal basis and funding

The legal basis between the research partners and the Swiss operator Swisstopo defines the rights and obligations of the Project Partners. The Swiss Federal Office of Topography swisstopo is the geo-information centre of the Swiss Confederation. Since 2010, swisstopo has been running the Mont Terri Visitor Centre with NAGRA (National Cooperation for the Disposal of Radioactive Waste/ Nationale Genossenschaft für die Lagerung radioaktiver Abfälle) and ENSI (Swiss Federal Nuclear Safety Inspectorate/Eidgenössisches Nuklearsicherheitsinspektorat).

As the facility owner, the Canton of Jura supervises the operator SWISSTOPO and grants it annual authorisation to conduct the experiments. The Canton of Jura has implemented a monitoring commission, the Commission de suivi. 

To date, around 180 experiments have been performed in the rock laboratory. Of these, 75% have been completed, analysed and published. Currently, approximately 45 experiments are running. The Swiss government covers around 40% of the budget.

Research and experiments

The research and development sector is concerned with matters of testing and further development of investigative technologies, e.g. drilling and excavating technologies, continual sampling of pore water, geochemical and microbiological experiments, earthquakes, ascertaining ground pressure, development of suitable hydro-tests in highly impermeable formations, measurement of geological changes in host rock and pore water in a deep storage system, methodologies for long-term monitoring.


The Project is a so-called rock laboratory. It means that it is used exclusively for research. There will never be a deep geological repository. An important feature is that the partners can choose their research priorities. The central theme will continue to be a repository for the deep storage of radioactive waste. But increasingly, the laboratory will also make an essential contribution to energy strategies and CO2 experiments.

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