nuclear-news

The Flamanville EPR nuclear reactor will not be able to deliver its full power without major works.

According to our information, EDF has still not been able to identify the cause of the malfunction of the turbine in the Normandy reactor.

 La Tribune Juliette Raynal, 04/07/25

After a doomed construction site, the Normandy reactor of the Flamanville EPR started up on December 21, twelve years behind schedule. Its entry into service does not signal the end of the problems, far from it. According to our information, the difficulties encountered with the turbo-alternator unit, the centerpiece of a nuclear power plant, will prevent the first French EPR from delivering its full electrical power without major intervention requiring the assembly of scaffolding inside a room that is difficult to access.

Contacted by La Tribune , EDF did not wish to comment on this information and indicated that it was maintaining its provisional schedule with the transition to 100% of its nominal power in the summer of 2025. “While technically the reactor could well reach its full thermal power in the coming months, the electrical power will be reduced by 10 to 20% due to the partial vacuum,”  qualifies a well-informed source.

As we reported on March 13, EDF teams had to deal  with abnormal heating in the turbo-generator unit. Located in the heart of the engine room, the 70-meter-long Arabelle turbine, manufactured by General Electric,  but now owned by Arabelle Solutions, a subsidiary of EDF, 
transforms the thermal energy contained in the steam into mechanical energy to drive the alternator that produces electricity.
 The Arabelle turbine, the centerpiece of the power plant

In a technical document published  following a general meeting, organized on February 25th within the framework of the Local Information Commission (CLI), the electrician revealed a malfunction:  “The temperature increases beyond the authorized limit on stages 7 and 8 of the turbo alternator group when trying to reach the expected condenser vacuum . “

…………………………………….. the 57th reactor in the French fleet is still shut down due to a maintenance operation on equipment located in the nuclear part of the plant.

After several postponements, its start-up is expected on April 11. “While these adjustments allow the reactor to be restarted without exceeding the authorized heating levels, they will not allow it to operate at full power,” a well-informed source cautions. “The reactor will only be able to continue its tests at a partial vacuum,” the same source specifies.

……………………………..With  the vacuum reduced, the turbine’s efficiency will be mechanically reduced and could therefore be between 10 and 20% below its nominal operating temperature.

The cause of the malfunction has not yet been identified.

“The work that has been carried out on the bearings is corrective work. It helps to reduce the fault that is causing excessive heating, but the teams involved do not expect this to completely resolve the problem. In short, it helps to treat the symptoms, but not the cause, which remains unidentified ,” reports  this source.

According to our information, to attempt a diagnosis, EDF teams will have to install scaffolding inside the condenser itself. A room that is difficult to access since it is located just below the turbine.  “It is an intrusive operation that requires a complete shutdown of the reactor for at least several weeks ,” according to this well-informed source.

“A nightmare to cope with”

Unlike a conventional shutdown for refueling, which lasts on average 30 to 40 days, this first break should last  “at least 250 days ,” said Régis Clément, deputy director of EDF’s nuclear fleet division, during a press briefing on December 20. In other words, more than eight months.  EDF also intends to take advantage of this interruption to replace the defective tank cover, required by the nuclear regulator.

While waiting for this operation, the various components of the turbine, due to its abnormal operation, could well be damaged. And for good reason, even if by lowering the vacuum level the defect becomes acceptable, it does not disappear. As a result, the bearings wear unevenly and mistreat the turbine. “This machine risks being a nightmare to operate ,” fears a person close to the case.

April 12, 2025 - Posted by Christina Macpherson | France, technology