The discovery of a major crack on a reactor at the Penly nuclear power plant (Seine-Maritime) will lead to the extension of shutdowns of other sites for checks, said Thursday March 8 Julien Collet, the deputy director general of the Nuclear Safety Authority (ASN), with Agence France-Presse (AFP). However, this should not result, he said, in "mass shutdowns" of reactors.
A larger than expected crack has been detected by EDF at Penly-1 on an emergency pipe used to flood the reactor with water in the event of a nuclear accident. It "did not have any consequences on the personnel or on the environment, however [it] affects the safety function linked to the cooling of the reactor", underlines the ASN in an information note. This corrosion-related phenomenon has already been identified since the end of 2021 on several sites, but generated smaller cracks and on other types of pipes.
This new damage is on a system "deemed non-sensitive but on a weld that underwent major repairs at the time of construction" of the reactor. According to Mr. Collet, "the fact that a weld has been repaired can in itself be a generator of stress corrosion, but these repairs can concern all the reactors".
The fortuitous discovery of the phenomenon of stress corrosion in October 2021 had forced EDF to shut down many reactors for large-scale inspection and repair operations, contributing to the colossal losses recorded by the electrician in 2022. EDF had decided to carry out inspections sometimes coupled with repairs for 16 of the 58 reactors in its nuclear fleet, the most recent and considered the most sensitive to the phenomenon.
The discovery of the new Penly crack prompted ASN to ask EDF to review this strategy. "We are asking him to reprioritize the checks on the welds repaired on all the reactors", specifies Mr. Collet, including those of 900 MW, the largest and oldest series in the French fleet.
This incident "is beyond what is acceptable from a safety point of view", estimated with AFP Karine Herviou, deputy director general of the Institute for radiation protection and nuclear safety (IRSN), the police nuclear safety scientist. According to her, however, it is necessary to “remain extremely careful about what can be at the origin of the stress corrosion at EDF. (…) Is the problem at Penly unique? We can't tell, so we have to go check it out."