A 175-million-year-old clay rock, formed when ammonites swam in Jurassic seas, could become the ultimate solution to Germany’s nuclear legacy.
It’s not science fiction: it’s applied geology, circular economy and a lesson in humility in the face of Earth’s deep time.
The clay named after a fossil
By: Gabriel E. Levy B.
There is something almost poetic about the fact that the solution to the most complex nuclear problem of our time has the name of fossil.
Opalinus clay owes its name to Leioceras opalinum, a shelled ammonite with iridescent reflections that swam in the seas of central Europe about 175 million years ago. When that animal existed, dinosaurs dominated the continents. The sea was shallow, warm, and layers of mineral mud were accumulating at its bottom that, million by million years, became one of the most impermeable rocks we know.
What makes this rock extraordinary is not its age, but its behavior. First: it hardly allows water to pass through, with permeability values so low that they are difficult to imagine on an everyday scale.
Second: if it cracks, it seals itself. The clay absorbs moisture, swells, and closes the crack. Third, their microscopic particles have a negative electric charge, and radionuclides, which are positively charged metals, are trapped like magnets. Rock not only contains, but actively retains.
In other words, nature spent 175 million years making the perfect safe before humans had the problem it needed to keep.
DEBORAH drills into a Swiss mountain at 800 meters
The article published by Xataka on March 22, 2026 describes a project that deserves attention: DEBORAH (Deep Borehole to Resolve the Mont Terri Anticline Hydrogeology). In the Swiss canton of Jura, near Saint-Ursanne, there is an underground laboratory that is reached through the safety gallery of a motorway tunnel, between 150 and 200 metres underground. From there, a drilling rig moves downwards extracting intact rock columns for analysis.
The project is led by Germany through the Centre for Research in Geosciences (GFZ) and the Federal Institute for Geosciences and Natural Resources (BGR), together with the UK Nuclear Waste Service and the University of Bern. In total, 22 partners from 9 countries participate. The first 55 meters have already been drilled with a sample recovery rate of 100%. The final goal is 800 meters deep, where the temperature and pressure are very different from those of the surface layers already studied.
Each column extracted is like reading a geological diary: it reveals age, composition, fractures and, above all, how the rock behaves in the face of water. Switzerland has already opted for this formation for its definitive repository, choosing the Nördlich Lägern region. Germany and the United Kingdom observe the results before making decisions of their own.
Germany and a legacy that does not disappear
On April 15, 2023, Germany shut down its last three nuclear power plants. It was the official end of more than six decades of atomic energy. However, the legacy is still there, spread over 16 temporary warehouses throughout the country: around 27,000 cubic metres of high-level waste in some 1,900 CASTOR-type containers. They account for only 5% of the total volume of German nuclear waste, but they concentrate 99% of the radioactivity.
Finding a deep geological repository for this material has been a legal obligation since 2017. The search includes three types of rock: salt, clay and granite. The experiences with salt were not good: Gorleben was discarded after spending 1,500 million euros, and the Asse II repository has been filtering contaminated brine since 1988. Given this history, Jurassic clay has gained prominence.
The selection of the final site, initially scheduled for 2031, has been postponed to some extent between 2046 and 2074. In March 2025, the responsible agencies proposed measures to speed up the process and reach a decision before mid-century. The price of error, in this case, is not paid by one generation: it is paid by all those who come.
Circular economy on a geological scale
This is where the topic becomes really interesting for those working in the circular economy. We usually talk about this model in terms of months or years: a product that is repaired, a material that is reused, a waste that returns to the production process. But Opalinus Clay forces you to extend your mental horizon to millions of years.
The first level of circularity is almost philosophical: the same sedimentary processes that underpinned the dinosaur ecosystem created the structures that today can isolate our most hazardous waste for a million years. The Konrad mine, near Salzgitter, is a concrete example: an ancient Jurassic iron deposit, protected by hundreds of meters of Cretaceous clay, will be a repository for more than 300,000 cubic meters of low- and medium-level waste. The planet manufactured the solution before the problem existed.
The second level is more tangible. According to the International Atomic Energy Agency, up to 90% of a nuclear power plant’s non-radioactive materials – metals, concrete, equipment – can be reused or recycled during decommissioning. Germany has more than 30 installations to be dismantled. In Grenoble, France, six decommissioned nuclear facilities were transformed into a research center for renewable energies: batteries, hydrogen, electric vehicles. The waste of one industry ends up being the cradle of another.
The third level is more speculative, but points in a direction worth pursuing. Germany’s Federal Agency for Disruptive Innovation (SPRIND) commissioned a study proposing to use accelerated neutron sources to reduce the hazard period of high-level waste: from one million years to less than 1,000 years, with a potential volume reduction of 90%. The federal regulator considers the technology still premature, and there is an open debate among scientific institutions about its feasibility. But the circular logic is impeccable: transform the most dangerous waste into something manageable within human timescales.
What the Jurassic Rock Teaches Us
There is an irony that deserves to be named. Germany decided to abandon nuclear energy precisely because it did not want to live with its risks. And now, to solve the problem that energy left behind, he has to learn to think like a Jurassic geologist, on timescales that far exceed the duration of any known civilization.
The Opalinus Clay demonstrates something that the contemporary circular economy is still learning to articulate: cycles are not only economic or industrial, they are also geological and biological. Nature does not generate permanent waste. Everything comes back, transforms, is integrated. What we call nuclear waste, the Earth treats as a temporary containment problem, as long as we find the right training to manage it.
The DEBORAH project will not only drill rock. It will also pierce our certainties about the temporal limits of human responsibility. If it takes a million years for a waste to become harmless, the question isn’t just where to store it. It’s how to pass that information on to generations that don’t even speak our language.
Conclusions
The German case of Jurassic clay as a nuclear repository is not only scientific news. It is a living argument for a circular economy that takes its own principles seriously to the ultimate consequences. If the circular model requires closing cycles and eliminating definitive waste, then the management of the nuclear legacy forces us to think in cycles of millions of years and to use the resources that the Earth has already produced, because the most effective ones are not manufactured by us. They were made by the Jurassic.
Germany has a generational task before it: to decide where to deposit forever the remains of an energy gamble that lasted seven decades. The answer lies, paradoxically, in a rock named after an extinct cephalopod. Perhaps that is the most circular thing of all: that nature, which produced uranium and the organisms that will one day become fossil fuels, has also unknowingly prepared the place to keep its consequences.
The future of German nuclear waste depends on us being able to listen to what a 175-million-year-old rock has to say. And to have the patience, responsibility and humility to act accordingly.
Sources consulted
- Xataka (March 22, 2026). Nuclear waste is a problem, so Germany is looking for the solution on a Jurassic rock in Switzerland. xataka.com
- Nagra (2024). The Opalinus Clay: indispensable to the safety of the deep geological repository. nagra.ch
- Interesting Engineering (2024). Scientists dig 2,600 feet underground to test ancient clay for nuclear waste storage. interestingengineering.com
- Clean Energy Wire (2023). After the phase-out: Germany grapples with nuclear legacy as waste challenge remains. cleanenergywire.org
- Clean Energy Wire (2023). German state institutions at odds over options for treating nuclear waste with transmutation. cleanenergywire.org
- World Nuclear News (2025). Germany proposes accelerating search for repository site. world-nuclear-news.org
- IAEA Bulletin (2023). How the circular economy is transforming nuclear decommissioning. iaea.org
- IAEA (2023). Mission says Germany committed to safe, responsible waste management. iaea.org
- World Nuclear Association. Storage and Disposal of Radioactive Waste. world-nuclear.org
- Asse II mine / Gorleben / Deep geological repository. wikipedia.org
