By Benjamin Mallet
PARIS (Reuters) - French nuclear safety watchdog ASN said on Thursday power group EDF (EPA:EDF) may have to stop some of its reactors for corrosion checks earlier than currently planned after new cracks were detected at three reactors this month.
The ASN deputy chief, Julien Collet, said a revised maintenance and repair plan presented by EDF after the discovery of new problems at the Penly and Cattenom reactors "goes in the right direction". But he added that the watchdog had doubts about the timing of some of the additional checks envisaged under the plan, particularly those scheduled for 2024.
"There are around five reactors where we still have questions regarding the schedule," Collet said, without identifying the reactors concerned.
EDF has been dogged by corrosion problems at several of its reactors that first emerged at the end of 2021 and forced it to shut down an unprecedented number of plants last year, pushing nuclear output to a 34-year low.
Earlier this month, it revealed it had found new corrosion-related cracks on the Penly 1 and Penly 2 reactors in Normandy and the Cattenom 3 reactor in Moselle, leading the ASN to request an updated maintenance plan.
On Thursday the ASN said EDF's revised strategy should make it possible to control, by the end of 2023, more than 90% of the repaired welds identified as priorities.
But it said that the recent discovery of "thermal fatigue" defaults at Penly and Cattenom required further analysis.
Thermal fatigue happens when very hot and cold water meet inside pipes, causing the steel to dilate, contract and become more fragile over time.
The ASN said it would pursue its dialogue with EDF to ensure the envisaged schedule is appropriate.
The deputy director of EDF nuclear fleet, Regis (NYSE:RGS) Clement, told reporters the group did not see a need to change its forecasts for 2023 nuclear production at this stage.
Sources have told Reuters that EDF's plan for additional checks on pipe weldings would incorporate them into already-planned reactor stoppages so as to minimise additional disruption.
That would allow EDF to maintain its 2023 power production goal of between 300 Terawatt-hours (TWh) and 330 TWh this year.