France’s Institute for Radiological Protection and Nuclear Safety (IRSN) said on 4 July that the project to construct an underground radioactive waste repository, the Centre Industriel de Stockage Géologique (Cigéo), has achieved "satisfactory technical maturity", but four issues could potentially affect the design and timeline.

Cigeo,  an underground system of disposal tunnels is planned for construction in a natural layer of clay near Bure, in the Meuse/Haute Marne area. Waste management agency Andra has submitted a "safety options dossier" for Cigéo project to the Autorité de Sûreté Nucléaire (ASN), settings out the objectives, concepts and principles of ensuring safety. ASN asked its technical arm, IRSN, to examine the dossier and provide feedback.

The IRSN has submitted a report to ASN on its conclusions based on numerous technical meetings and more than 600 questions to which Andra responded. It also organised meetings with stakeholders. The four issues which need to be addressed include optimisation of the facility’s architecture to avoid radiation leakage into the environment; risk monitoring during operations; the possibility of intervention to prevent contamination; and fire preparedness.  IRSN said fire preparedness is the "most sensitive" issue because Andra’s concept "does not provide sufficient safety guarantees". Some 40,000 packages (18%) of the packages to be stored at Cigéo are at risk of thermal runaway if their temperature rises, especially during a fire, IRSN said.

IRSN recommends that Andra and the waste generators should either consider pre-treating such waste to eliminate its thermal reactivity, or reconsider the disposal concept to remove the risk of a fire spreading into the storage cavity.

The International Atomic Energy Agency (IAEA) team, which conducted a peer review last November of Cigéo's "safety options dossier", said it considers Andra's methodology for evaluating operational safety is "comprehensive and systematic". However, the review team encouraged ASN, Andra and IRSN to use its review of the dossier as a basis to make more precise expectations for the licence application. It added, "This is especially important as the planned Cigéo facility is one-of-a-kind." ASN’s opinion on Andra's safety options dossier, which is expected soon, will provide the framework for drawing up the application for authorisation.

Cigeo is financed by radioactive waste generators, including EDF, Areva and the French Alternative Energies and Atomic Energy Commission. The project is being managed by Andra.

The construction licence application for Cigéo should be submitted by the end of 2018, with construction starting in 2020. The pilot phase of disposal could begin in 2025.