Flamanville EPR Reactor Cleared to Operate Beyond 80% Power, EDF Aims for Full Capacity by End of Autumn

The French nuclear regulatory authority, the Autorité de sûreté nucléaire et de radioprotection (ASNR), has authorized the Flamanville EPR (European Pressurized Reactor) to operate at over 80% of its nominal capacity, marking a significant milestone for the project. This clearance allows EDF, the operator, to proceed with its plan to ramp up the reactor to full capacity of 1,600 megawatts by the end of autumn 2023.

The reactor first reached 80% power in mid-November 2025, and EDF promptly sought ASNR's approval to increase its output further. Previously, EDF had targeted reaching 100% capacity by summer 2025 but had to adjust this timeline due to technical difficulties. A sealing problem affecting valves in the primary circuit, crucial for heat transmission and pressure regulation, caused a three-month delay.

The Flamanville EPR project has faced enduring challenges, including significant delays totaling 12 years and an accumulated cost overrun exceeding 10 billion euros. Despite this, EDF remains committed to meeting the revised schedule and ensuring safe operations. A comprehensive inspection of the reactor is scheduled for late September 2026, involving mandatory routine checks by ASNR and replacement of the reactor vessel lid—a requirement dating back to 2017.

This authorization and the gradual power increase represent key steps in integrating the Flamanville EPR into France's nuclear infrastructure, underpinning the national energy strategy.