Fugro assesses safe site for French nuclear repository

Challenge

The complex project needed a multidisciplinary team of experts equipped with specialist skills in ground characterisation to choose the preferred location to isolate and store radioactive waste. Our Geo-data were crucial in proving the suitability of the proposed site under the scrutiny of national and nuclear industry regulators, and the local community.

Solution

Using innovative methods, our multidisciplinary team identified the ideal location for the Centre Industriel de Stockage Géologique (CIGEO), France’s future deep geological disposal facility, 500 m below the surface in Bure, north-east France.

Our team of experts in sedimentology and structural geology provided geological assessments before drilling access galleries and small storage tunnels at the 500 m deep test site, which is a precursor to the eventual repository. Working both above ground and in the underground research laboratory, we delivered a range of advanced and specialist services to provide comprehensive data for assessing ground risk and identifying the best location for the repository.

Having examined the quality of claystone underground, we developed a robust structural model, which included fracture network characteristics, to assess the risk of any radioactive substances migrating from the future repository. We verified that the rock at the selected location was easy to excavate, and that the claystone provided an effective natural barrier to block and limit the migration of radioactive substances – ideal for a repository that has to provide a safe solution for the long-term isolation of radioactive waste.

Many tasks were completed above ground to characterise the underground facility zone, including geological mapping, seismic reflection surveys and evaluation programmes. We also executed some critical tasks underground, such as sedimentological, structural and geotechnical surveys of drift excavations, detailed studies of stratigraphic markers, and microstructure analysis.

Innovation highlight

Our team developed a unique 3D scanner-based methodology in the underground research laboratory. This ground-breaking approach enabled us to quickly digitise highly accurate, 3D textured models of the rock faces, providing unprecedented visuals of the ground formation at the assessment depth. The technology allowed non-intrusive, remote and safe characterisation of the host formation in situ, which was quickly implemented every 5 m during the drilling of the galleries. In short, our innovation was quicker than conventional methods and provided more detailed results.

Impact

Based on the high degree of accuracy of our detailed data, ground-modelling and risk characterisation, Andra was able to select a smaller zone (30 km2 rather than 250 km2) for the development of the CIGEO. We efficiently delivered critical data while enhancing quality and integrity, thanks to our underground research laboratory for 3D scanning and ongoing in situ assessments. This enabled the French National Radioactive Waste Management Agency to provide robust answers regarding site feasibility and risk management to meet the approval of regulators, planning authorities, and agencies representing the interests of regional communities.