France’s first third-generation nuclear reactor will shut down for almost a full year. Starting Saturday, September 26, the European Pressurized Reactor (EPR) at the Flamanville plant in Normandy will stop producing for 350 days, according to operator EDF’s provisional schedule. This comes less than two years after connecting to the grid and less than a year after reaching full power.
This long shutdown is a required step for any new reactor, called an in-depth examination. EDF’s deputy director of nuclear production called it a very important step for the 1,600-megawatt EPR, the most powerful of France’s 57 reactors. Under rules from the Nuclear Safety and Radiation Protection Authority, the inspection must begin no later than thirty months after the reactor first loaded fuel. For older reactors, similar shutdowns at Chooz and Civaux lasted 130 and 282 days.
EDF will not say how long the cover replacement will take or how much it will cost, but describes the inspection as costing several hundred million euros. Despite the steel problem, the vessel bottom will not be replaced. An official explained that unlike the cover, the vessel bottom is smooth, allowing non-destructive checks during the reactor’s life.
The Flamanville EPR produced 7 terawatt-hours in the first nine months of 2026, in line with expectations. But not all goals were met. Since connecting to the French grid on December 21, 2024, total electricity produced is nearly 10 terawatt-hours, 4 terawatt-hours less than expected.
Reference
Le Monde, “L’EPR de Flamanville, dernier-né des réacteurs nucléaires français, au repos forcé durant près d’un an pour une vaste opération de maintenance,” published September 24, 2026. https://www.lemonde.fr/economie/article/2026/09/24/nucleaire-l-epr-de-flamanville-dernier-ne-des-reacteurs-francais-au-repos-force-durant-pres-d-un-an-pour-une-vaste-operation-de-maintenance_6781526_3234.html