Update on the Flamanville EPR: the reactor has reached 100% of nuclear thermal power
14 December 2025 marks a major milestone: the Flamanville 3 reactor reached 100% nuclear thermal power at 11:37am and generated 1,669MW of gross electrical power*.
The ramp-up to 100% nuclear thermal power follows the approval by the French nuclear safety and radiation protection authority (ASNR) on 12 December 2025, to go beyond the 80% threshold.
Reaching the 100% mark for the first time enables testing of equipment at full power, taking of measurements and verifying that everything is functioning properly. Over the coming weeks, and as part of the start-up program, the power of the reactor will vary to continue testing at different power levels and an operation will be carried out on an internal electrical substation.
This milestone reflects the commitment and expertise of the teams of EDF and of its industrial partners over the past months to ensure the safe start-up of the reactor.
*The nuclear thermal power of a nuclear reactor corresponds to the heat produced in the reactor core by nuclear fission. This is the total amount of heat produced by the reactor. This heat is used to produce steam that will turn the turbine. It is expressed in thermal MW (MWth). Gross electrical power is the maximum power delivered by the turbine which drives an alternator to convert mechanical energy into electricity. A nuclear reactor consumes part of the electricity it produces for its own operating needs (pumps, ventilation systems, safety systems, etc.). Net electrical power refers to the power injected into the national electricity grid. It is equal to the gross power minus its internal consumption. The maximum electrical power of the reactor may vary according to operating conditions (cooling water temperature, environmental constraints, network settings).
About EDF
The EDF Group is a key player in the energy transition, as an integrated energy operator engaged in all aspects of the energy business: power generation, distribution, trading, energy sales and energy services. The Group is a world leader in low-carbon energy, with an output of 520TWh 94% decarbonised and a carbon intensity of 30gCO2/kWh in 2024, a diverse generation mix based mainly on nuclear and renewable energy (including hydropower). It is also investing in new technologies to support the energy transition. EDF's raison d'être is to build a net zero energy future with electricity and innovative solutions and services, to help save the planet and drive well-being and economic development. The Group supplies energy and services to approximately 41.5 million customers (1) and generated consolidated sales of €118.7 billion in 2024.
(1) The customer portfolio consists of electricity, gas and recurring service contracts
