Cigéo (an acronym for Centre Industriel de Stockage Géologique, or Industrial Centre for Geological Disposal) is a French project to construct a deep geological repository for radioactive waste. It is designed to store approximately of high-level waste (HLW) and intermediate-level waste (ILW) produced by French nuclear facilities, including during their decommissioning, and by nuclear reprocessing of spent fuel.
The Agence nationale pour la gestion des déchets radioactifs (Andra) manages the project. After over thirty years of research, including at the Meuse/Haute Marne Underground Research Laboratory, Andra applied in 2023 to the French nuclear safety authority (ASN) for construction authorization. The facility is planned near the border of the Meuse and Haute-Marne departments, within the communes of Ribeaucourt, Bure, Mandres-en-Barrois, and Bonnet, in the drainage basin of the Seine, near the Meuse watershed. The waste will be stored in a layer of clay to ensure long-term containment.
The principle of geological disposal was enshrined in French law in 2006. A 2013 public debate concluded that disposal was not urgent and the project timeline required revision. The law also defines alternatives, such as long-term storage or transmutation of waste into radioisotopes with shorter half-lives.
Estimated costs range from 15 to 36 billion euros, with financing primarily the responsibility of waste producers but partly supported by the state budget. Social acceptability is a key challenge, with one billion euros spent to address public concerns. Two departmental Public Interest Groups (GIPs) support the project: the Haute-Marne GIP, chaired by Nicolas Lacroix, and the Meuse GIP, chaired by Jérôme Dumont, presidents of their respective departmental councils.
Since 1996, Cigéo has faced controversies over funding, the reversibility of disposal, uncertainties about containment over , the volume of waste, and the perceived legitimacy of public debates.
Storage of long-lived radioactive waste
Objectives of storage
The activities of nuclear facilities generate fission products with very high levels of radioactivity and lifetimes in the tens of millennia. Additionally, there are actinides that are less radioactive but have lifetimes in the millions of years, such as neptunium-237, which has a half-life of 2.1 million years, fission products with lower activity such as iodine-129 (half-life of 16 million years), and activation products such as chlorine-36 (half-life of ). These elements are non-reusable nuclear wastes. In nuclear reprocessing, they are separated from uranium and plutonium, which are potentially reusable.
The strategy for management of long-lived HLW (whether fission products, actinides or activation products) consists of isolating them in places inaccessible to humans for long enough for their radiotoxicity to reduce, the principal challenge residing in the capacity of the facility to contain the radionuclides for a sufficiently long time by means of different barriers placed between the waste and ecosystems on the surface. One of the options currently retained consists of storing the waste at a depth of 300–500 meters in vaults dug out in a geological layer that is stable, dense and as impervious as possible (e.g. granite, volcanic tuff, or clay, as is envisaged in France). The radiation from a large proportion of these wastes will be reduced by a factor of 1,000 in roughly a thousand years.
The dangers of irradiation are poorly quantified for low doses, but according to the international authorities on radioprotection (United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), International Commission on Radiological Protection (ICRP)), the effect is negligible for doses at similar levels to natural background radiation (on the order of a micro-Sievert per hour, or 5mSv/year). On the other hand, according to the IRSN, the radiological impact on people and ecosystems should be evaluated equally in the short or very long term. Underground storage allows the containment of radioactivity over the very long term: groundwater flow being very weak in the impermeable region, only certain mobile radionuclides are able to migrate over a period of tens of millennia, potentially reaching the surface only in extremely small quantities.
Two doctoral theses in 2008 and 2011 on archeological glasses and obsidians estimate that the vitrification process used to immobilize HLW should by itself be capable of assuring containment of radioactive materials for . Nevertheless, for the evaluation of performance of geological disposal, migration models do not take credit for artificial confinement (the containers); only the natural rock is considered. The example of the natural nuclear fission reactors in the Oklo Mine, where non-volatile fission products have only migrated some centimeters in nearly 2 billion years, was used in preparatory works for Yucca Mountain nuclear waste repository to show that confinement over such timescales is possible.Yucca Mountain: The Most Studied Real Estate on the Planet, U.S. Senate Committee on Environment and Public Works, March 2006.
According to a 2017 thesis in the history of science at the School for Advanced Studies in the Social Sciences (EHESS), Andra has had to retreat little by little from attempting to produce a formal proof of the absolute safety of disposal to instead presenting a body of arguments demonstrating that the evolution of Cigéo is controlled in the very long-term.
Study of Callovo-Oxfordian clay
The region proposed by Andra for the location of Cigéo is in the East of France, at the boundary of the departments of Meuse and Haute-Marne.
Safety performance of a geological disposal site is dependent, among other factors, on the characteristics of the host rock. The geological layer planned for the location of the wastes is the "Callovo-Oxfordian." It consists of a layer of clay rock, about 160 million years old, situated at a depth of around in the East of the Paris basin (between 420 and depth at the site of the Bure laboratory. The argilites (a mix of clay and quartz from the Callovo-Oxfordian stages of the Jurassic) possess physico-chemical characteristics which tend to limit the migration of radionuclides. The clay layer, with a thickness of more than and at a depth of has revealed excellent containment properties: stable for at least 100 million years, homogenous over several hundred km, the region has very low permeability and is resistant to groundwater flow (the principal cause of degradation of waste containers and dispersion of radionuclides), and the clay has an elevated retention capacity (capacity for sorption of radioactive elements).
During operation of the facility, Andra is aiming at a maximum acceptable dose of for the public and for monitored workers, which is a quarter of the current regulatory limit. Andra Reference Documents: Le dossier 2005 For long term, the objective is that the committed dose must remain lower than for the most affected reference group. Modelled estimates of the dose peak at the at the end of (dominated by iodine-129 and chlorine-36, which are both soluble); while staying significantly under the objective the dose would be higher () in the case of hypothetical disposal of "CU1" and "CU2" spent fuel from EdF.
The goal of the Meuse/Haute Marne Underground Research Laboratory was the study of the clay layer, with a view to determining if its characteristics are consistent with the safety objectives of a disposal facility located in the transposition zone.« La zone de transposition est la zone au sein de laquelle la couche du Callovo-Oxfordien présente des propriétés physiques et chimiques similaires à celles observées au niveau du laboratoire souterrain de recherche. Sa superficie est d'environ .» C.RP.ADP.09.0035.A
Andra's work has permitted to show evidence that the properties of the Callovo-Oxfordian argillites will strongly reduce the mobility of actinides and thus the activity flux out of the host rock formation, by confining them in the near field. The ASN nevertheless underlined the necessity of taking into account the residual uncertainties regarding the homogeneity of the clay layer. These uncertainties have been cited by the France Nature Environnement association in justifying its opposition to the project.
Description of the project
General description
The planned facility is composed of surface facilities, notably for receipt and preparation of waste packages or support services for excavation and construction works.
It is envisaged that the wastes will be placed in underground stores situated at a depth of around , in a layer of clay rock which should be impermeable and have properties which support confinement over the very long term. A funicular railway should enable the waste packages to be taken underground or returned to the surface.Labalette, T., Harman, A., & Dupuis, M. C. (2011, January). The Cigéo industrial geological repository project. In ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management (). American Society of Mechanical Engineers. The design and eventual construction, maintenance and operation of the funicular have been entrusted to the Grenoble-based Poma, a specialist in cable lifts, for a cost of 68 M€ and with a potential start of operations in 2025 (if the facility is constructed by that point).
Having entered the pre-industrial phase in 2011, the Cigéo project could accept its first waste packages in 2025, after a series of stages and a calendar defined by law. It is planned to operate Cigéo for at least 100 years. The underground disposal tunnels will be constructed progressively, as and when needed. Their footprint will extend to around after about 100 years of operations.
The law requires that the waste disposal will be reversible for a minimum of 100 years. in order to allow future generations the possibility of modifying or adjusting to disposal process, for example by removal of the stored packages if another "mode of management" is planned or if the safety of the site is called into question. It is not, however, planned to make financial provision to cover some or all of the cost of such a reversal operation.
Wastes destined for Cigéo Cigéo was conceived for the disposal of high-level waste, and long-lived intermediate-level (LL-ILW) waste which could not be disposed of in surface or near-surface disposal facilities for reasons of nuclear safety or radiation protection. For high-level wastes, the dose rate at 1 meter from an unshielded package can be multiple Sieverts per hour at the time of disposal.
The wastes are conditioned in "parcels" by their producer before being placed in a disposal container. The estimated volumes of wastes for disposal at Cigéo are: approximately conditioned HLW (approx. parcels), on the order of containers; approximately LL-ILW (approx. parcels), on the order of containers.