French radioactive waste management agency Andra has applied to the department of Aube in north-eastern France for environmental permission to increase the current authorised storage capacity of Cires, the country's dedicated disposal facility for very-low-level radioactive waste (VLLW).

The three tranches at Cires (Image: Andra)

Opened in Morvilliers in 2003, Cires (the Centre Industriel de Regroupement, d'Entreposage et de Stockage) was designed and authorised to receive 650,000 cubic metres of VLLW - primarily weakly contaminated rubble, earth, scrap metal, etc - in three storage areas, called tranches 1, 2 and 3. By the end of 2022, Cires had reached 69.4% of its total authorised storage capacity. In view of the VLLW delivery forecasts announced by the producers of waste for the coming years, the site - covering 46 hectares - is expected to reach its authorised storage capacity around 2028/2029.

The national inventory of radioactive materials and waste, published by Andra, predicts that between 2,100,000 cubic metres and 2,300,000 cubic metres of VLLW will be produced by 2050-2060, mainly during the dismantling of nuclear facilities currently in operation.

"In the medium term, the aim is to increase the authorised storage capacity of Cires, without changing the current footprint of the repository zone and while maintaining its level of safety," Andra said. "The Acaci (Increasing the CApacity of CIres) project can be envisaged thanks to the optimisation of storage implemented at Cires over several years. Adaptations to cell design and disposal arrangements have saving a third of the storage area initially planned."

When Cires was commissioned in 2003, the disposal cells for VLLW were 80 metres long and could contain 10,000 cubic metres of waste. From 2007, cells 176 metres long were built, increasing the capacity of each cell to 25,000 cubic metres. In 2010, steepening of the slopes and deepening the cells made it possible to reach disposal capacity of 27,000 cubic metres of VLLW per cell. In 2016, a new optimisation was implemented, which involved raising the height of the above-ground part of the repository. This increased the storage capacity of each cell to about 30,000 cubic metres.

"In concrete terms, these successive optimisations have made it possible to save more than 50% of the area initially planned to accommodate the 650,000 cubic metres of VLLW in the authorised storage capacity," Andra said. "Only two areas out of the three planned will be used by 2028/2029.

"The third tranche will, if the Acaci project is authorised, handle 250,000-300,000 cubic metres of additional waste, thus achieving a storage volume of more of 900,000 cubic metres, over the same area."

Andra submitted the environment authorisation application file to the Aube department on 7 April. This file includes several documents explaining the purpose of the project as well as the work and arrangements necessary for its implementation.

"An impact study and a risk study in particular present the implications of increasing the authorised storage capacity of Cires and all the reduction, avoidance and compensation measures put in place to mitigate these effects as much as possible," Andra noted.

The environmental authorisation procedure comprises three phases, expected to take more than a year to complete. During the first phase, the project will be reviewed by the State services, including the Environmental Authority. In the second phase, the public and local authorities will be consulted. In the third phase, the department will make a decision based on the report and reasoned conclusions of the investigating commissioner.

"The objective is to make the first disposal cell of tranche 3 available before the end of operation of tranche 2, in order to ensure the continuity of VLLW disposal," Andra said. "Thus, according to the provisional schedule, work could begin in 2024-2025, after obtaining the environmental permit."

It said developing tranche 3 to operate it once tranche 2 is filled with waste would give 10 or even 15 years of additional storage capacity and "would have the advantage of allowing more time to evaluate, in parallel, the relevance of other VLLW management solutions".