By RFI
“14 December 2025 marks a key step: the Flamanville 3 reactor reached 100% nuclear power at 11:37am and generated 1,669 MW of gross electrical power,” EDF said in a statement, a few days after receiving clearance from the Nuclear Safety and Radiation Protection Authority (ASNR).
Flamanville 3, the first new nuclear reactor to start up in France in 25 years, was connected to the national grid on 21 December 2024 — 12 years later than originally planned. Its costs have soared from an initial estimate of €3.3 billion to as much as €23.7 billion in 2023 prices, according to France’s Court of Auditors.
Nuclear energy, which makes up a major share of France’s electricity production, remains central to the country’s efforts to maintain a low-carbon power mix. But its implementation continues to face technical and political challenges, from waste management to costs.
President Emmanuel Macron announced an ambitious nuclear revival in 2022, including plans to build six new-generation EPR2 reactors, with an option for eight more. However, the government has yet to finalise its long-term energy roadmap, known as the third Multiannual Energy Programme (PPE), amid sharp political divisions over the balance between nuclear and renewables. The far-right National Rally (RN) has opposed further development of renewable energy projects.
Macron takes stock of France’s nuclear projects with focus on energy transition
Testing phase
EDF said reaching full power would allow operators “to test equipment at maximum output, take measurements and verify proper operation.” In the coming weeks, as part of the reactor’s commissioning programme, power levels will fluctuate to support tests at different stages, with maintenance also planned on an internal electrical substation.
Specifically, teams will “completely replace a 400kV feedthrough connecting overhead lines to underground cables running down the cliff to the auxiliary transformer of Flamanville 3,” an EDF spokeswoman told French press agency AFP. The procedure will be carried out while the reactor remains synchronised to the grid, she added.
The ASNR on Friday authorised EDF to raise the reactor’s power output beyond 80%. EDF said at the time that teams were “mobilised to bring the reactor to 100% power by the end of autumn,” in line with previous commitments.
The gross output cited on Sunday differs from the net power delivered to the national grid, as part of the energy generated is used by the reactor itself.
Built on the Normandy coast next to two older reactors, Flamanville 3 is now the most powerful unit in France’s nuclear fleet, capable of supplying electricity to two million households.
Other EPR reactors are already operating in China (Taishan 1 and 2) and Finland (Olkiluoto 3), while two more are under construction at Hinkley Point in south-west England.
Source: Newswire @ France’s Flamanville nuclear reactor reaches full power for first time – RFI
