Operations at Cigeo

Last update on : Friday 30 August 2013
 

Cigeo will consist of surface facilities for operations such as waste package receipt, inspection and preparation, an underground disposal facility and infrastructure that will connect the underground facility with the surface. The repository will operate for more than 100 years and be expanded as needed. To guarantee its role and ensure that wastes are contained over very long time periods without the need for human intervention, the underground structures at Cigeo will be closed up little by little.

 


Route of a HL waste package inside the facilities


Route of a IL-LL waste package inside the facilities

The Cigeo project is now in the industrial design phase, which draws on the results and evaluation of 20 years of R&D efforts. Andra and its contractor, the Gaiya joint venture formed by Technip and Ingerop, investigated several options in 2012. This industrial outline is reviewed in 2013 by a group of experts and evaluated by the ASN and the National Review Board. The recommendations stemming from these evaluations, the avenues for optimisation identified by Andra and any changes made to the project following the public debate will be taken into account in the following study phase before the construction licence application is submitted. The technical description presented on this website is based on the technical options preferred by Andra at this phase of the studies.

Construction of Cigeo

The repository will be built very gradually. The first structures to be built will be the facilities needed to conduct the excavation work and start operations at the repository. Once operations are under way, work on building the underground facility will occur on an as-needed basis in a series of phases. Zones under construction will be physically isolated from operating zones. Likewise, the ventilation shafts for the package transfer drifts will be separated from the shafts for the working drifts. The rock removed during the digging of the underground facility will represent a volume in the order of 10 million cubic metres produced over more than 100 years.

Operation of CigeoConstruction of Cigeo.© Andra

The broken rock will be regulated by special provisions to protect the environment and allow a portion of the rock to be used to close up Cigeo (around 40% will be reused to backfill the underground structures). For comparison, the same volume of rock is excavated during large tunnel projects, but over a period of a dozen years (around 7 million cubic metres for the Channel Tunnel and around 15 million cubic metres for the base tunnel of the future Turin-Lyon high-speed railway).

Operation of Cigeo

Production of waste packages on producers' sites

Waste is conditioned and the packages produced under the responsibility of their producers. The quality of the packages is verified by the producers during conditioning and before shipment to Cigeo. The producers' facilities are subject to inspection by the relevant safety authorities (the ASN or the Nuclear Safety Authority for Defence-related facilities and activities, ASND). Andra monitors producers to ensure that they implement a quality assurance programme for waste packages.

Receipt of waste packages at Cigeo

Waste packages will not be allowed in the facility until they have undergone a process to ensure that they meet the technical criteria for repository safety set by Andra and approved by the ASN. Producers will thus have to file an acceptance application to Andra. This application will have to demonstrate that the waste packages in question meet these technical criteria. After waste acceptance by Andra, the packages may be sent to Cigeo.

Waste package disposal

Upon arriving at Cigeo, waste packages will be transferred to buildings where they will be taken out of their transport casks and inspected (absence of contamination, dose rates, etc.). These buildings will also be used to manage flows of packages prior to their transfer into the underground facility. These facilities are not intended to replace producers' own storage facilities, particularly those used to allow wastes to cool sufficiently prior to their emplacement in the repository.
Waste packages will then be placed in disposal containers.

Some waste packages from producers may arrive ready for emplacement in the repository. Disposal packages will be placed in a cask to shield against radiation. The cask will be loaded onto a funicular that will descend all the way to the cells at the same speed as a person walking on foot. Emplacement of waste packages in the cells may be remotely controlled. The transfer cask will dock with the door of the cell in order to create a seal while the door is open. The door will not be able to open until the transfer cask is correctly docked. The handling system will then transfer the packages into the cell and the door of the cell will be closed. Radiation protection will be ensured during each operation.

Pilot zone for HLW

HLW are characterised by radioactivity concentrations that make them highly irradiating and cause them to generate more heat than ILW-LL. The conditions of their disposal are being tested in full-scale experiments in the URL (such as cell excavation and thermal loading).
Their handling has been studied and full-scale prototypes have been created using dummy packages fitted with radiation shielding. These prototypes are on public display at the technological exhibition facility in Saudron. These results will be used to support the safety demonstration to be presented as part of the repository licence application that will be submitted in 2015. Starting in 2025 the first batches of HLW packages will be placed in a pilot zone of the repository. The waste to be emplaced there will represent 5% of the total amount of HLW. The pilot zone will be monitored for 50 years or so before the remaining 95% are disposed of in the repository.

Closure of Cigeo

To guarantee its role and ensure that waste is confined over very long time periods without the need for human intervention, the underground structures at Cigeo will be closed up progressively according to a decision-making process that is expected to be defined in the future act that will lay down the reversibility conditions of the disposal.

The underground facility will be closed up zone by zone:

  • plugging of disposal cells;
  • sealing will be put in place (swelling clay structure designed to give the backfilled drifts a high degree of impermeability) and backfilling of disposal cells access drifts and later of main drifts;
  • backfilling and sealing of shafts and later of ramps.

The structures will be backfilled with the clay removed during the excavation of the repository and stored at the surface. The seals will be made of swelling clay and concrete to limit the flow of water through the drifts and the surface-underground connections over the long term.

The surface facilities will be dismantled at the same time as the underground facility is closed up.