Scientists dig 2,600 feet underground to test ancient clay for nuclear waste storage

A team of international researchers led by Germany’s GFZ Helmholtz Centre for Geosciences has begun deep drilling beneath a mountain in Switzerland to evaluate the suitability of Opalinus clay (OPA) formations for long-term nuclear waste storage. The project, part of the DEBORAH initiative, targets the Mont Terri underground rock laboratory, where the team has completed the first 55 meters of drilling and plans to reach a depth of approximately 800 meters. Opalinus clay, dating back 175 million years to the Jurassic Period and found in Southern Germany and Switzerland, is considered a promising natural barrier due to its potential to isolate radioactive waste safely for thousands of years. The researchers are extracting cylindrical rock cores to analyze the interaction between the clay and surrounding rock layers with underground water systems, a critical factor for assessing the long-term stability of nuclear waste repositories. The Mont Terri site, operational since 1966 and used by multiple international partners, provides a unique environment to study these hydrogeological