(Bloomberg) -- Electricite de France SA discovered new defects at two of its nuclear reactors that were halted for maintenance and repairs, raising fresh concerns that its electricity output will remain largely constrained this year after plunging in 2022.

Flaws tied to so-called thermal fatigue have been found on the pipes of the Penly-2 and Cattenom-3 reactors, the utility said in a statement. The pipes have been replaced as part of broader repairs related to “stress corrosion” cracks — a different type of faults — that are affecting emergency cooling pipes of some of the EDF’s atomic plants, according to the nuclear safety authority.

The nuclear giant has been forced to halt more than a dozen of its 56 reactors for months of repairs since it first found signs of such stress corrosion phenomenon in late 2021. 

The announcement comes just days after the country’s nuclear safety authority asked EDF to revise its program of reactor checks following the utility’s discovery of a “significant” stress corrosion crack earlier this year on its Penly-1 reactor. EDF said it will propose an update of its reactor check strategy to the watchdog in the coming days.

The fresh setbacks could force EDF to carry out more extensive checks on its atomic plants, reviving concern that France will have to import large amounts of power this year. Last year, worries about electricity shortages combined with dwindling deliveries of Russian gas pushed European energy prices to records.  

French power for delivery in 2024 jumped as much as 9% to 176.50 euros a megawatt-hour, the biggest increase since Jan. 20 on EEX. 

(Updates to say that reactors have been repaired in second and third paragraphs)

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