[EPR Flamanville series] Flamanville 3 reaches 100% of its nominal power

The Flamanville 3 EPR officially reached 100% of its nominal power on 14 December 2025. Numerous tests are still scheduled before the reactor’s first shutdown, planned for September 2026.

25, 80 … and now 100%! The Flamanville EPR has finally reached full power. On 14 December 2025 at 11:37 a.m., EDF announced in a press release that the reactor achieved its full output, displaying 1,669 MWe of gross electrical power [1]. This historic milestone for the French nuclear fleet followed the authorisation granted on 12 December 2025 by the Nuclear Safety and Radiation Protection Authority (ASNR), allowing the unit to exceed the 80% power level.

A collective achievement

The nuclear sector has welcomed this success for Flamanville 3. Cédric Lewandowski, EDF Group Executive Director in charge of Nuclear and Thermal Generation, notably praised the extensive collaborative effort carried out across the group.
“It is the result of the relentless work and expertise of the teams responsible for the project, from EDF’s Nuclear Generation Division, the Flamanville site itself of course, as well as the engineering teams of the National Centre for Power Generation Equipment (CNEPE), the Fleet Engineering and Environmental Division (DIPDE), the Technical Directorate, the former Industrial Directorate, and Edvance. This is a historic day for EDF, for the French nuclear fleet, for the entire nuclear sector, and for all those who believed in this ambitious project.”

“Congratulations to all the teams mobilised over recent months to ensure the safe start-up of the reactor. This milestone reflects the commitment and expertise of EDF’s teams and its industrial partners,” also welcomed Bernard Fontana, CEO of EDF.

Many tests still ahead

The EPR’s journey is not yet over, as it will still undergo several tests at this power level in the coming weeks. “The reactor’s power will be adjusted to continue testing at different power plateaus, and work will be carried out on an internal electrical substation,” EDF adds.
“A complete replacement will be carried out on a 400 kV bushing of an electrical substation that connects overhead lines to underground cables running down to the foot of the cliff and supplying the auxiliary transformer of the Flamanville 3 reactor,” an EDF spokesperson told AFP.

In addition, starting on 26 September 2026, the EPR will undergo its first comprehensive inspection, involving a shutdown scheduled to last 350 days. Mandatory for all new reactors, this phase will provide an opportunity to conduct a number of tests and maintenance operations after nearly one year of operation at full power. ■