Cigéo: Andra introduces the storage bridge and MLW-LL waste inspection robots

The National Agency for Radioactive Waste Management (Andra), in collaboration with Reel NFM Systems and Bouygues Construction Nuclear Expertise, has unveiled the demonstrator for its MLW-LL (Long-lived Medium-Level Waste, also known as “B” waste) storage bridge and an inspection robot. This presentation, which took place at a former industrial site in Le Creusot, is the culmination of several months of design, construction, and testing.

The future Cigéo storage site (Industrial Center for Geological Storage) is intended to host MLW-LL waste, among other things. This waste is packaged in cubic concrete containers weighing more than 16 tonnes (cylindrical, lighter ones weighing 2.6 tonnes). They will be stacked on top of each other in three layers in about twenty storage cells. Thanks to a laser system, a storage bridge will be used to move and install them with very high precision. If necessary, it will also be able to ensure their retrieval as part of the reversibility of storage.

Diagram of the MLW-LL waste storage principle ©Andra

The MLW-LL waste storage bridge validated

Andra has developed a demonstrator to validate the efficiency of the storage bridge under conditions similar to the future storage site. Designed by Reel NFM Systems, it takes the form of a large metal structure on two parallel rails, 5 meters wide and 7 meters tall, with a length of 40 meters (instead of 500 meters at Cigéo). In the final installation, access to the storage bridge will be prohibited due to the radioactivity of the waste. This is why it was designed to be fully automated [1].

Over ten months, Andra was able to perform various technical trials, from normal operation to incident scenarios. “The results are very positive and allow us to validate the efficiency of the bridge. Indeed, the positioning accuracy is twice as good as predicted,” says Yves Lorillon, mechanical process engineer at Andra. Other tests, with very positive feedback, were also conducted with deformations of the bridge’s track or in the event of a malfunction recovery.

“Rideau”, an inspection robot in a family of 11 siblings

Andra is also developing teleoperated inspection robots to monitor the cells during the package installation phase and after they are filled. There are 11 of these robots, capable of moving in confined spaces (between packages, for example) and performing a variety of measurements: visual tracking with cameras of concrete surfaces, temperature measurements, and radiation level readings, for example. Some can even intervene on defects that would block the storage bridge’s tracks.

Among these 11 inspection robots, Andra was able to showcase “Rideau”, a tracked inspection tool created by Bouygues Construction Nuclear Expertise. It can move very skillfully to inspect the environment between the concrete packages and carry measurement systems.

The development of these technological tools will continue in the coming years to increase in maturity, including the integration of artificial intelligence. Three robot patents have already been filed by Andra, and three others are under examination. ■

[1] All the tests and the demonstration were carried out without radioactive waste.

By François Terminet (Sfen)

Photo: Demonstrator of the MA-VL waste storage bridge, Credit: ©Andra