Flamanville EPR reactor shuts down to replace defective vessel lid

The Flamanville EPR nuclear reactor in Normandy has been shut down for a 350-day maintenance period. A primary objective of this shutdown is the replacement of the reactor pressure vessel lid.

The 100-ton steel component, measuring approximately six meters in diameter, was originally forged at the Creusot facilities. The replacement was mandated by the French Nuclear Safety Authority (ASN) due to a defect discovered in 2014. The original lid contained excessive carbon concentrations in the steel, which posed a risk regarding its ability to resist crack propagation.

Following the replacement, the defective lid will be stored on-site for two years in a dedicated facility before being transported to a radioactive waste storage center managed by Andra. This maintenance occurs less than two years after the EPR's initial connection to the power grid.