EDF was summoned on Tuesday March 7 by the nuclear policeman of “revise your strategy” to solve the problems which have been seriously disrupting its power plants since the end of 2021, after the discovery of a new crack on an emergency circuit of a shutdown reactor, Penly 1, in Seine-Maritime.
Unnoticed until its media coverage on Tuesday by the Context site, an EDF note published on February 24 indicates that it detected in Penly 1 a “significant stress corrosion defect” on an emergency line used to cool the reactor in the event of an emergency.
In the process, the Nuclear Safety Authority (ASN), nuclear watchdog in France, asked EDF to “revise your strategy” on the treatment of stress corrosion in some of these reactors. “This event had no impact on the staff or the environment. However, it affects the safety function related to reactor cooling”underlines the ASN in an information note published Tuesday at the end of the day.
Dark year for EDF
While EDF believed that it was out of crisis on the treatment of this phenomenon, this announcement casts new uncertainties on the electrician’s prospects for 2023, after a dark year weighed down by the setbacks of its nuclear fleet, which contributed to deepen its losses and debt.
EDF’s nuclear fleet (56 reactors) has indeed suffered an unprecedented crisis since the discovery in October 2021 of a stress corrosion phenomenon on the most recent reactors. This problem had forced EDF to shut down many reactors for large-scale control and repair operations, contributing to the colossal losses recorded by the electrician in 2022.
In 2022, France thus experienced its lowest level of electricity production since 1992 and had to import electricity from its European neighbors.
Crack close to a relief pipe
In the Seine-Maritime reactor, the new fault was detected during“metallurgical expertise” on “a weld deposited in January”according to the note posted on the group’s website.
Until now, it was only about microcracks, of the order of a few millimeters. But the new crack is near a weld of an emergency pipe used to cool the reactor in an emergency. She “extends 155mm, or about a quarter of the circumference of the pipe, and its maximum depth is 23mm, for a pipe thickness of 27mm”according to ASN.
The piping could have been weakened by a repair operation aimed at “realign” circuits, at the very moment of the construction of the reactor. “This line was considered by EDF as not susceptible to stress corrosion cracking, in particular due to its geometry. However, this weld was the subject of a double repair during the construction of the reactor, which is likely to modify its mechanical properties and the internal stresses of the metal at the level of this zone.explains the ASN.
The Penly power station, made up of two reactors, was commissioned between 1990 and 1992. It is part of the series of the most powerful reactors, says « P’4 », with a capacity of 1,300 MW. Six of them are due for preventive repair in 2023 according to an EDF announcement in December.