Nuclear: Full power of the Flamanville EPR delayed until late autumn

EDF now expects the Flamanville EPR reactor to reach full power "before the end of autumn" , whereas the group had previously hoped to be able to reach this stage by the end of summer, according to a message on Friday, August 1.

The extension of a shutdown "to carry out a control and preventive maintenance operation on a protection valve of the main primary circuit" leads to a modification "of the date for reaching full power, now planned before the end of autumn" , the electricity group indicated in an information message on its website.

While the reactor had been shut down since June 19 for commissioning testing operations, standard for new nuclear installations, EDF decided on July 2 to keep it shut down to work on the valves.

The nuclear operator had in fact noted during the tests that two of the three valves placed at the top of the pressurizer which maintains the water in the primary circuit at a pressure of 155 bars "were not completely compliant" with the expectations in terms of "watertightness" .

Due to these "hazards" , EDF decided on Friday to extend this shutdown to carry out a preventive maintenance operation on the 3rd valve.

"The expertise carried out on the first two valves led EDF, in a proactive safety approach, to extend the checks to the third valve by taking advantage of the logistics already in place and mobilizing the available skills," explains EDF.

The reactor is now scheduled to restart on October 1, effectively delaying the transition to 100% reactor power. "There are 1,500 safety criteria that are tested during an initial (reactor) start-up," an EDF spokesperson emphasized. During these testing and inspection phases, it is sometimes necessary to "redo adjustments," it was explained. The new-generation reactor was connected to the electricity grid on December 21, 2024, 12 years behind schedule .

After a project marred by setbacks and technical hazards, the costs of Flamanville 3, the first nuclear reactor to start up in twenty-five years, have exploded compared to the initial estimate of 3.3 billion euros. According to a January report by the Court of Auditors, EDF now estimates its total cost at 19.3 billion euros under 2015 conditions, and even 22.6 billion euros under 2023 conditions, "including financing costs."