A reversible, flexible project
Cigeo is designed to be reversible for at least 100 years. To comply with this parliamentary requirement, Andra has taken technical measures that can be implemented for retrieval of stored packages while leaving Cigeo flexible so that it can adapt to change without jeopardizing the safety of the repository.
Reversibility: Andra's proposals
Responding to a strong demand by society, the Parliament required in 2006 that disposal be reversible for at least 100 years. The conditions for reversibility will be set by a new law that will be passed before Cigeo licenced. Andra's proposals are intended to respond to the expectations related to reversibility that were identified as part of an extensive dialogue that has taken place since 2006. This process took place on all levels: local (commission on reversibility of the local information and oversight committee, meetings with the public and local stakeholders), national (scientific colloquia, exchanges with review bodies, meetings with organisations), and international (international project sponsored by the OECD's Nuclear Energy Agency, and an international conference in Reims in December 2010).
1. Technical concepts for entirely safe retrievability of waste packages
Equipment designed to place waste packages in disposal cells is also designed to retrieve them if necessary. To facilitate retrieval, packages are designed with specific handling interfaces (for example, ceramic runners for sliding HLW packages in the disposal cell). Space will be left around packages after the emplacement in the cell. The waste packages and disposal cells are designed using best industrial practices to ensure durability and robustness. Systems for monitoring disposal cells will provide the information on technical conditions necessary for a retrieval operation. Andra has already created prototype equipment for package handling. Full-scale removal tests have already been performed with mockups to simulate situations in which the disposal cell is deformed. Retrieval tests will also be performed in Cigeo before it receives its operating license. Tests will continue once Cigeo is in operation. If the decision is taken to retrieve a large number of waste packages, special facilities would need to be built on the surface to manage them (for storage, onward shipping, processing, etc.).
2. A repository that can be adapted
Cigeo is designed so that the architecture of the underground facility can evolve over its operating lifetime. It will be built in successive phases that could take into account:
- possible changes in the inventory of waste to be disposed, e.g., in accordance with changes to France's energy policy,
- scientific and technical evolutions,
- operating experience feedback, particularly from monitoring repository.
3. Gradual closure
The deep radioactive waste repository is a facility intended to be closed definitively to limit exposure of future generations. Closure of the repository will occur gradually, from closure of disposal cells to shafts and ramps sealing. Each step in the closure process will add additional "passive" safety systems and reduce the need for human actions to monitor safety.
The retrievability scale published by the OECD's Nuclear Energy Agency shows the progress of passive safety in the repository through the steps of the closure process. It also shows retrieval of waste packages will be increasingly complex with the completion of these steps, which will constitute the most significant decisions of Cigeo's operation.
A reference schedule of the closing steps will be established as part of Cigeo's repository licence. The decision calendar will thus available to all organisations involved. This schedule may be changed during operation, since with Cigeo's design, each closing step can be delayed.
4. Milestones for regular meetings after commissioning
Andra has proposed to continue the step-by-step process initiated by the 1991 Bataille Act by organising milestones for regular meetings with all groups concerned to prepare decisions concerning plans for development and closure of the repository and reassessing reversibility conditions.
During these meetings, which may take place every ten years, a report will be prepared on the operation of the repository. It will take into account periodic safety reviews, lessons drawn from observations of the repository and its environment, and economic and social outcomes. Evolutions in scientific and technical knowledge as well as the orientations of the French National Radioactive Materials and Waste Management Plan will also be presented. Andra is proposing that the first of these meetings be held five years after Cigeo is commissioned.
Even-handed generational sharing for financing reversibility
Current generations shall finance the resources required for final, safe disposal of their radioactive wastes (construction, operation and closure of Cigeo). This includes the cost of technical measures taken to ensure reversibility. Current generations are thus offering future generations options for acting on the disposal process. If future generations decide to modify this process, particularly by retrieving packages, they will assume the cost.
Documents for downloading
Conferences and colloquia organised on the topic
- October 2008 study days
- June 2009 interdisciplinary colloquium
- December 2010 international conference