France:The Chooz nuclear power plant has fully restarted after a long shutdown

Reactor No. 1 of the Chooz nuclear power plant, one of the first concerned by the discovery of corrosion problems, restarted on Wednesday night, after more than 500 days of shutdown and almost a month after reactor No. 2.

Stopped since December 18, 2021, the reactor No. 1 of this plant was reconnected to the network Wednesday evening and has gradually entered into production, said a spokesman for EDF, contacted by AFP. “The rise to 100% power will last at least 48 hours,” he said. With a capacity of 1,450 MW each, the two reactors, both commissioned in 2000, are among the most recent and most powerful of EDF’s 56 nuclear power plants.

These two units had to be shut down shortly after the detection in October 2021, during a ten-yearly inspection, of micro-cracks in a portion of the emergency piping of the Civaux plant, the last of the French nuclear fleet to be commissioned, in 2002. The design of the reactors of both plants is identical. The risk of cracks was then identified on other sites, leading EDF to extend controls and shutdowns, resulting in a record number of reactors shut down last winter and a nuclear production level at its lowest.

EDF’s expert assessments had revealed the presence of an unprecedented phenomenon of stress corrosion on emergency pipes that are crucial for the cooling of the power plants, mainly on the most recent and most powerful reactors, those of 1,300 and 1,450 MW. “A total of 60.5 linear meters of piping have been replaced and inspected on the two Chooz reactors, including 33 meters on reactor No. 1,” EDF management said. As of May 11, 20 out of 56 reactors were still shut down, due to scheduled maintenance visits or the continuation of the crack treatment program.