Riiiight people are protesting for no reason...

The French government has yet to authorize Cigéo's construction, and now the French Nuclear Safety Authority (ASN) and the Institute for Radioprotection and Nuclear Safety (IRSN) have raised concerns about the design. Although it acknowledges overall progress, IRSN questions whether the sealing would be a strong enough barrier and says ANDRA needs to do more to reduce the risk of radioactive leaks. The agency also needs to improve its strategies to monitor risks and to rehabilitate the facility in case of radioactive spills, IRSN says. Perhaps the biggest problem, however, is medium-level radioactive sludge immobilized in bitumen, or tar, a technique introduced in the 1960s that has now been abandoned. IRSN says that in case of fire in a tunnel, bituminized waste could rapidly overheat and burn. “We would risk creating a phenomenon that we don't know how to stop,” and trigger “a very substantial” release of radioactivity into the environment, says François Besnus, director of IRSN's Environment Division in Fontenay-aux-Roses. Both agencies say ANDRA and the producers of nuclear waste need to study treatments that prevent overheating; if that fails, a major redesign of the facility may be needed.

...

Others say the risks are simply too high. Radiation will break down water in the rock and cause corrosion of metal structures, leading to the release of explosive hydrogen gas, says biologist and engineer Bertrand Thuillier, an associate professor at the University of Lille. ANDRA plans to ventilate the tunnels, but that could exacerbate fires by providing oxygen, he says. A failure could be catastrophic, Thuillier warns: The area around Bure helps provide eastern Paris with water and is close to one of the world's most cherished wine regions, Champagne.

https://www.science.org/doi/10.1126/science.357.6354.858

Edit: and just so we're clear, this is "the biggest, most complex and costliest nuclear decommissioning and radioactive waste management programme on earth." With planned cost between 23 and 54 bilion €