Autumn event of the VECS Chemistry Alumni at the Grimsel rock laboratory of NAGRA
On 16 September, VECS Alumni and some Bio Alumni visited the NAGRA rock laboratory. The visit could not have been of more current interest, as the decision on the site of the Swiss deep geological repository in the Nördlich Lägern region had been announced a few days earlier.
Cozy prelude
VECS Alumni and a few Bio alumni and alumnae visited the rock laboratory of the National Cooperative for the Disposal of Radioactive Waste (NAGRA) in the Grimsel region on September 16 and learned a lot about the history of radioactive waste and the lengthy process of finding a long-term solution for the storage of this waste. The goal is, after all, a safe storage period of 1,000,000 years!
Journey into the tunnel
A group of just over 20 alumni and alumnae gathered at the Gasthaus Bären in Guttannen in the Bernese Oberland on September 16. Only one alumnus had braved all weather adversities and tackled a crossing of the Aare Gorge in the morning. Strengthened by a good lunch and entertaining conversations, we were picked up by two buses of NAGRA and transported towards Grimsel. Normally, one could reach the rock laboratory directly by postal bus. However, this will not be possible until at least 2025 due to the large construction site in connection with the installation of the new Grimsel dam.
Why a laboratory in the rock?
Some of the tunnels in the granite of the Grimsel have existed since 1910 and were excavated with the construction of the various reservoirs and power plants in the area. Since the crystalline material granite was highly favored during the initial phase of the search for a site for a Swiss deep geological repository, the establishment of a research facility in the rock of the Grimsel proved to be ideal. In the meantime, there is another underground laboratory in Mont Terri in the Jura, where the subsoil contains a layer of Opalinus Clay, i.e. the material that is currently intended as a carrier for the repository. There however, it is not NAGRA that is in charge but Swisstopo. In the meantime, NAGRA maintains another underground laboratory in Mont Terri in the Jura. There, the subsoil contains a layer of Opalinus Clay, i.e. the material that is currently intended as a carrier for the repository. Even if the granite is now no longer relevant for Switzerland itself, there are still some other countries that are interested in a repository in granite and therefore support the Grimsellabor with appropriate financial contributions.
A great tour guide
We were shown through the tunnels by geologist Dr. Florian Kober, the deputy director of the rock laboratory and also an ETH alumnus. Extremely knowledgeable and eloquent, he gave us insight into the history and activities of the rock laboratory and spiced the whole thing up with a good pinch of humor. Thanks a lot!
The actual experiments are, of course, hidden invisibly in the stone - so in that respect there is little to see. But various exhibits and illustrations show very nicely what is being researched inside the rock. We were able to take a look at a model waste container and could see how it would be stored in a tunnel in the future, isolated from a layer of the material bentonite. Bentonite swells and seals when it gets wet, which is a desirable property for long-term storage.
What's being researched?
A recently launched 20-year experiment is addressing the question of how bentonite behaves under elevated temperature. After all, the waste is constantly heated by radioactivity. This waste heat must be taken into account when planning a facility, but also when filling the containers with individual fuel rods. If the insulation layer is stable even under higher temperature, containers could be stored more densely and the dimension of the required plant could be reduced considerably. Other experiments are investigating how radioactive material is distributed in granite by water. However, the facility does not conduct research with real radioactive waste, but with artificial radio cocktails.
Breathtaking final banger
Towards the end of the tour, we were allowed to board the buses once again and drove half a kilometer further into the tunnel. There, the final banger awaited us: an impressive crystal chasm, the likes of which most of us had never seen before. And here, too, the component of caution had been wisely incorporated into the planning: The fissure is indeed protected by a thick glass pane from the access of greedy visitors.
A visit to the rock is well worth it!
