The Nuclear Safety Authority has ordered EDF to “revise its strategy” when a major crack was discovered on a weld in an emergency circuit of a shutdown reactor, Penly 1, in Seine-Maritime. EDF mentions a “significant stress corrosion defect” on an emergency pipe used to cool the reactor in the event of an emergency.
The defect was brought to light during “metallurgical expertise” on “a weld deposited in January”, according to a note published on February 24 on the group’s website. EDF specifies that “the analysis is continuing” and “will be submitted to the Nuclear Safety Authority (ASN) for examination and approval”.
The fault concerns Penly 1, one of the reactors shut down as part of the extensive stress corrosion control programme. The fortuitous discovery of this phenomenon in October 2021 had forced EDF to shut down many reactors for large-scale inspection and repair operations.
The P’4 reactors question
According to several sources interviewed by Context, “the crack discovered by EDF is massive: 23 millimeters on a 27 millimeter pipe”. “What is new (…) is the depth of the crack”, indicates to AFP Yves Marignac, energy expert and member of the permanent groups of experts of the ASN.
The piping could have been weakened by a repair operation aimed at “realigning” the circuits, when the reactor was built. According to EDF, “this weld had been repaired twice during the first assembly of the circuit during construction”.
“This significant stress corrosion defect was probably generated by these targeted ‘double repair’ operations during the first assembly of the pipes”, admits the operator in his note.
For Yves Marignac, “the fact that larger cracks are possible raises the question of maintaining the operation of the 6 reactors” of the P’4 type, such as Penly, pending their preventive repair, announced in December by EDF for current 2023.