Paul Bossart, Earth Scientist, Switzerland

„It’s about credibility and transparency“

Paul Bossart studied earth sciences at the ETH Zurich and received a PhD in structural geology. In 1989 he began conducting research in various rock laboratories (Grimsel in Switzerland, Kamaishi in Japan and Äspö in Sweden). In 1996 he established the Mont Terri rock laboratory and has been director of the rock laboratory since 2006. Mont Terri is operated by swisstopo.

"I feel like I'm in my element in the mountains, which is why I studied geology. I’m fascinated by the dynamics of the Earth: continents moving over huge periods of time, mountains rising and levels being razed. I dealt with this subject in my dissertation, namely the question of why the Himalaya mountain range in Pakistan changed its east-west orientation to a north-south one. It has to do with the opposing pressure of the continental plates. After my PhD at the ETH Zurich, I worked in the private sector, where I was able to establish the Mont Terri rock laboratory in the canton of Jura. I was involved in a project in the Grimsel rock laboratory five years ago, where I became familiar with the National Cooperative for the Disposal of Radioactive Waste (Nagra) and its work. At this time granite was considered the ideal medium for containing radioactive waste. The first exploratory drilling in northern Switzerland sought to determine if this was the ideal terrain for disposing radioactive waste. The Scandinavians and Japanese had also researched granite. At the beginning of the 1990s, I worked in a rock laboratory in northern Japan and in Äspö in Sweden between 1993 and 1995. During this time, Belgian geologists had examined a clay for its suitability as a containment medium, the so-called Boom Clay – with encouraging results.
Unlike other countries, the bedrock in Switzerland is young, lively in the sense of active movements, complex and multi-stoned. It’s precisely for this reason that several possible types of rocks were tested for their suitability as a containment medium, including Opalinus Clay. Nagra is still committed to granite, but increasingly more Swiss geology experts are calling for studies into disposing highly radioactive waste in impermeable sedimentary rocks. Unlike granite, Opalinus Clay has far less difficulties with water because it's practically watertight and therefore encased, i.e. stagnant. This is a decisive advantage in long-term disposal because radionuclides trapped in clay cannot be transported into the biosphere with water. At Mont Terri, a horizontal tunnel in the mountain was formed when a motorway was constructed, which means that a layer of potential host rock is ready to be explored. It presents the ideal conditions for a laboratory since the question of disposing radioactive waste is not at issue here.
For the canton of Jura, it was clear from the outset that managing this should not be placed in the hands of Nagra. The federal government had to assume responsibility for the Mont Terri rock laboratory whether it wanted to or not. At first, the Federal Office for Water and Geology was the responsible authority and afterwards swisstopo, who I work for. swisstopo has been operating the laboratory since 1996 with its own staff, and it's growing quickly: 44 experiments are in progress and more are planned – just like the expansion of the entire rock laboratory. This is because increasingly more countries are exploring the possibility of using clay as a containment medium. As director, I actively participate in planning the experiments and also have the opportunity with our team to conduct my own experiments. In something as important as disposing highly radioactive waste, we have to try to refute every hypothesis until we can establish that they correspond to the facts. We cannot afford any mistakes: we have to uncover every weakness in a disposal concept and be credible and transparent until the very last point. Only then is there the chance to convince the population living in the region where the repository will be built that they should consent to this."

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A struggle over trust