Nagra News – June 2026

“Stay calm in the event of an alarm.” Ourcolleague Michèle Vaterlaus hears this phrase just as she is getting ready fora tour of the Mont Terri Rock Laboratory – donning a helmet, fluorescentwaistcoat and a tracking device – and then she already finds herself being driveninto the mountain. What she hopes to encounter at a depth of 300 metres:something mysterious. What she finds instead: artificial light, concrete, 13degrees. And a 175-million-year-old, grey-brown stone thatcan self-seal fissures.

The Opalinus Clay is the centrepiece ofSwitzerland’s deep geological repository, not because it is particularly hardor impenetrable, but because it is particularly tight, because it swells whenwater penetrates it, and because radioactive particles attach themselves to itsclay minerals. Nagra plans to construct Switzerland’s deep geologicalrepository in the Opalinus Clay. Scientists from Switzerland and many othercountries have been researching the Opalinus Clay atthe Mont Terri Rock Laboratory for 30 years. More than any otherbarrier, this rock can help to contain radioactive waste until it will nolonger pose a hazard to humans and the environment.

Anyone who has ever tried to clear outtheir basement, garage or attic will know that not everything considered“waste” has to be tossed out immediately. Some things can be recycled, somemight even have to be disposed of as hazardous waste, but some items will bepacked away again, sometimes even for decades, until we really know what to dowith them. To a certain extent, the same applies to radioactive waste, but withone major difference: how we decide to dispose of it is not left up to personaljudgement, but to objective measurements. This is important because not all radioactive waste has to go into adeep geological repository.

In the May newsletter, we presented the Full-Scale Emplacement experiment. The question “What is a submarine doing deep inside amountain?” interested many readers.

Stay curious and keep in touch. We lookforward to connecting with you on Instagram, Facebook, YouTube and on LinkedIn.

Yours sincerely