This article presents the crucial role played by the French underground research laboratory (URL) in initiating the deep geological repository project Cigéo. In January 2023, Andra finalized the license application for the initial construction of Cigéo. Depending on Government’s decision, the construction of Cigéo may be authorized around 2027. Cigéo is the result of a National program, launched in 1991, aiming to safely manage high-level and intermediate level long-lived radioactive wastes. This National program is based on four principles: 1) excellent science and technical knowledge, 2) safety and security as primary goals for waste management, 3) high requirements for environment protection, 4) transparent and openpublic exchanges preceding the democratic decisions and orientations by the Parliament. The research and development (R&D) activities carried out in the URL supported the design and the safety demonstration of the Cigéo project. Moreover, running the URL has provided an opportunity to gain practical experience with regard to the security of underground operations, assessment of environmental impacts, and involvement of the public in the preparation of decisions. The practices implemented have helped gradually build confidence in the Cigéo project.

1. Introduction
2. Short Presentation of Cigéo, the FrenchDeep Geological Disposal Project
3. The Progressive Siting Process of theFacility
4. Andra’s Underground Research Facility(URL) in Bure
5. The Crucial Contribution of Andra’sURL to the Development of a SoundScientific and Technological ProgramSupporting Cigéo
6. The Crucial Contribution of Andra’sURL to the Safety Demonstration andto the Security of Cigéo
7. The Crucial Contribution of Andra’sURL for the Assessment of theEnvironmental Impact of Cigéo
8. The Crucial Contribution of the URL toPublic Information and Participationand to Building Confidence in theCigéo Project
9. Conclusion
Conflict of Interest
Acknowledgements

• Pascal Claude LEVERD(Institute for Korea Spent Nuclear Fuel, 111, Daedeok-daero 989beon-gil, Yuseong-gu, Daejeon 34057, Republic of Korea) Corresponding author