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Stepwise development of Cigéo and timeline of the associated decisions

Reversibility of disposal  throughout its service life is one of the principles guiding the design of Cigéo, the geological disposal facility project for the most hazardous radioactive waste. Gradually defined as from 1991, disposal reversibility was endorsed by Parliament in 2006, then clarified by a new law in 2016. Considering that the disposal facility is to be operated by 5 successive generations, the aim is to avoid freezing its development at the design stage and imprisoning future generations in the decisions taken at the outset.

Reversibility relies in particular on the gradual development of Cigéo, punctuated by decisions which form opportunities to re-appraise and re-direct the project, if necessary, in light of the data and experience feedback acquired during the operation of the repository.


The development of the disposal facility is organised in several successive phases:
• The initial design, which also comprises the prior development work and will end in the granting of the license to build the facility;
• The initial construction, during which facilities will be built for receiving and disposing of the first waste packages;
• The operating phase, during which the packages will be disposed of and the infrastructures will be gradually extended;
• The dismantling and closure phase;
• The monitoring phase.

A pilot industrial phase covering the initial construction and the first years of operation is also planned. Cigéo will be built in several parts, called “stages”, which correspond to the construction of a group of surface buildings and/or underground structures.
On this basis and after the initial construction, the infrastructures of the disposal facility will be gradually extended, in successive stages, to accommodate new waste packages, while benefiting from the improvements arising from operational experience feedback and technological development.Cigéo timeline

Cigéo timeline


Cigéo is designed to dispose of the reference inventory waste, corresponding to the HLW and ILW-LL waste which is already generated and will be generated by the licensed nuclear facilities.

The adaptability of the repository and its gradual expansion will enable future generations, if they so wish, to modify the project, particularly to take into account any inventory variations caused by energy policy changes. Andra is conducting studies to ensure that other waste could be safely disposed of in Cigéo, if such a decision were taken: it constitutes the spare inventory.

The flexibility of its operation also helps to accommodate any variations in inventory. In the event of variations, the disposal operations will be adjustable to fit the rise in radioactive waste volume

New waste conditioning modes will be able to be developed and the corresponding packages received, after licensing, without substantial modification of the infrastructures or equipment. 

Lastly, by gradually expanding the repository, the improvements caused by scientific and technological progress or experience feedback can be integrated.


During or between each phase, or even before starting a new stage of construction, decisions on the Cigéo project are expected. Today, a first survey of these decisions results in an overview of the deployment, forecast to be centuries-long, of the disposal facility.The first, fundamental, decision is whether or not to start the construction of Cigéo and to determine the terms of Cigéo governance. Andra is currently preparing an application for a license to build the waste repository (DAC). If, when the application has been processed, Cigéo is licensed, the initial construction phase may begin.

Afterwards, as the deployment phases proceed, several decisions have been identified by Andra. As each new decision is taken, it will be possible to re-appraise the soundness of the previous ones and, if necessary, adapt them in line with the reversibility principle. Decision postponement or backtracking is also possible.


What is governance?

Governance is the way in which decisions are prepared, taken and followed up. As project owner and future operator of the Cigéo repository, Andra bears responsibility for its industrial facility and takes the decisions on its development, in compliance with the requirements and licenses issued by the authorities. Andra has started consultations to collect the opinion of the stakeholders and the public on how citizens can be involved in the preparation and follow-up of the decisions on the Cigéo project.

What will happen if a decision modifies the progress of the Cigéo project?

Reversibility throughout the service life of the disposal facility, together with its design principles (robustness, sustainability) will allow any changes to be integrated.

In particular, any major project change will require a new license to be granted by the French safety authorities on the basis of the disposal facility safety demonstration (founded on new studies).

What is the pilot industrial installation?

The pilot industrial installation of the disposal facility corresponds to Cigéo’s first years of construction and operation. It will provide in situ confirmation of the design and safety of the repository, together with the data acquired during more than 20 years of research, and will also allow testing of the retrievability of the packages and the reversibility of the facility. This phase will also be the opportunity to acquire experience feedback on the operation of the repository. Beyond these technical issues, the pilot industrial phase will allow testing of the governance of the Cigéo disposal facility.

The pilot industrial phase was made a part of Cigéo’s development process. Andra intends it to begin after the decree licensing the construction of the repository’s nuclear facility. On the basis of the lessons learned during this phase, Andra will generate a summary report which will be processed by the authorities and serve as the input for the Parliament’s decision on whether or not to continue with the Cigéo project.

What is the spare inventory waste? What kind of studies is Andra conducting on this waste?

A change of national energy policy could mean that some materials are considered as waste, which would then have to be disposed of. These include spent fuels or waste arising from the extension beyond 50 years of the service life of the existing reactors. The spare inventory also contains some of the long-lived low-level radioactive waste (LL-LLW) inventory, in order to take into account the uncertainties caused by
the development of a new management stream for this waste.

The studies conducted by Andra aim to ensure the absence from Cigéo’s design of any obstacles to the disposal of the spare inventory waste and to identify any necessary adaptations.

A change in the inventory would require a new license.