There are 9 dams of 15 to 65 m in height and 110 to 1,700 m in length but only one with the presence of a cover water (Bois Noirs Limouzat site). The dams are constructed using sand from the cycloning of tailings, or mining waste rocks.
In Niger, the dams, made of waste rocks, are lower in height. In Gabon, the remediated site is the only dam with a cover water.
Only the Bois Noirs dam (H max : 42 m, L: 508 m) is considered a type A dam subject to internal monitoring and regulatory monitoring.
The other dams in France are subject to internal monitoring by Orano and are inspected by an external expert every five years.
In addition, within the framework of the French National Plan for the Management of Waste and Radioactive Materials (PNGMDR), a working group is defining the criteria to be taken into account in order to conduct a study of their very long-term stability (3,000 years and sensitivity study up to 30, 000 years).
All of these dams meet regulatory requirements and are subject to internal monitoring by Orano, with certain structures undergoing inspection by an external expert.
A noticeable effort has been conducted in recent years on sites to improve their monitoring in operational and organizational terms. The general state of dams is satisfactory.
Orano Mining, with all the company members if the ICMM, is currently working on the definition an appropriate tailings storage facility governance framework. This should minimise the risk of catastrophic failures.