Jun 12, 2025
Potential defects identified in French nuclear reactors.
France's EdF has identified potential defects in the piping of the 1.5GW Civaux 2 reactor, as reported by the nuclear safety authority ASNR. Tests showed two "signs," likely echoes from ultrasound assessments, that may indicate defects. These tests are ongoing as part of a strategy to address stress corrosion, though ASNR has not yet confirmed whether these signs represent actual stress corrosion issues.
Stress corrosion occurs when mechanical stress combined with certain chemicals leads to cracks in piping. The French reactor fleet experienced significant stress corrosion problems from 2021 to 2023, with about a third of the reactors taken offline for inspections and repairs.
Civaux 2 is an N4 reactor, one of four such reactors in France, and was among the last built before the Flamanville 3, entering service between 2000 and 2002. It has been offline since April 5 for maintenance and is expected to return by July 31 after undergoing defueling, inspections, and a fuel swap of one-third of its inventory.
Civaux 1 was the first reactor to reveal stress corrosion faults in August 2021, with subsequent tests confirming similar issues in the other three N4 reactors. The N4 and several 1.3GW P4 reactors are notably susceptible to stress corrosion, as stated by EdF's Cedric Lewandowski to a parliamentary commission in 2022.
Following reports of the potential defects, the French power market experienced a sharp increase on Wednesday morning, with the front-year contract rising from €62.30/MWh to over €68/MWh before settling around €66/MWh by mid-afternoon. Market reactions varied, with some deeming the price movement an overreaction due to limited confirmed information, while others argued the potential return of stress corrosion justified the increased prices, anticipating lasting effects.
As of Wednesday evening, Civaux 2 is still expected to return to service on July 30, with the four N4 reactors forecasted to provide 3GW of availability for most of this month, increasing to 4.5GW in early July and then to 6GW for the first three weeks of August, before reducing back to 3GW from mid-September. Chooz 2 has been offline since mid-April for economic reasons, halting output on April 18 to conserve fuel for peak demand periods, according to EdF.
Stress corrosion occurs when mechanical stress combined with certain chemicals leads to cracks in piping. The French reactor fleet experienced significant stress corrosion problems from 2021 to 2023, with about a third of the reactors taken offline for inspections and repairs.
Civaux 2 is an N4 reactor, one of four such reactors in France, and was among the last built before the Flamanville 3, entering service between 2000 and 2002. It has been offline since April 5 for maintenance and is expected to return by July 31 after undergoing defueling, inspections, and a fuel swap of one-third of its inventory.
Civaux 1 was the first reactor to reveal stress corrosion faults in August 2021, with subsequent tests confirming similar issues in the other three N4 reactors. The N4 and several 1.3GW P4 reactors are notably susceptible to stress corrosion, as stated by EdF's Cedric Lewandowski to a parliamentary commission in 2022.
Following reports of the potential defects, the French power market experienced a sharp increase on Wednesday morning, with the front-year contract rising from €62.30/MWh to over €68/MWh before settling around €66/MWh by mid-afternoon. Market reactions varied, with some deeming the price movement an overreaction due to limited confirmed information, while others argued the potential return of stress corrosion justified the increased prices, anticipating lasting effects.
As of Wednesday evening, Civaux 2 is still expected to return to service on July 30, with the four N4 reactors forecasted to provide 3GW of availability for most of this month, increasing to 4.5GW in early July and then to 6GW for the first three weeks of August, before reducing back to 3GW from mid-September. Chooz 2 has been offline since mid-April for economic reasons, halting output on April 18 to conserve fuel for peak demand periods, according to EdF.