Cracks in nuclear power plants: EDF wants to control 90% of the riskiest welds by the end of 2023

EDF has identified 320 welds believed to be at risk of cracking in its nuclear power plants, and wants to have 90% of the “priority” welds checked among these by the end of the year, according to the strategy communicated to the Safety Authority (ASN) after the recent discovery of a large crack in the Penly 1 reactor (Seine-Maritime). “ASN takes note of this change of strategy and believes that it is EDF’s responsibility to implement it”, indicates the nuclear policeman in a press release sent on Thursday 16 March.

Several major cracks have been found and revealed in recent days, including a never-before-seen size at Penly 1, on an emergency pipe used to flood the reactor with water in the event of a nuclear accident. This is the same “stress corrosion” phenomenon, identified since October 2021 at several sites, but which has so far generated minor cracks and other areas of these pipes. In this case, this crack of unprecedented depth was in a pipe that had undergone special repairs during the construction of the plant in the 1980s.

“Additional Analysis”

From this discovery, 320 line welds were identified as being subject to repair at the time of reactor construction. EDF’s revised strategy will make it possible to control, by the end of 2023, more than 90% of the welds it deems to be a priority among these 320, the ASN indicated on Thursday. Their exact number was not immediately disclosed. “90% are the welds on which there have been the most important repairs,” Julien Collet, deputy general manager of ASN, explained in a telephone call.

Other so-called “thermal fatigue” cracks have also been identified on emergency pipelines “considered susceptible to stress corrosion cracking” at Penly 2 and Cattenom 3. The ASN therefore believes that “the discovery of a thermal fatigue defect among the recently characterized large , on a weld for which this degradation mode was not foreseen, requires further analysis”.