French utility EDF said on 10 September that it had discovered problems with the weldings and other components in some of its reactors, causing its shares to fall more than 8% as a result of concerns about possible reactor closures.

EDF said its subsidiary Framatome (formerly Areva) had informed it of “a deviation from technical standards” in manufacturing of certain components on reactors in operation, notably the weldings on some of the reactors’ steam generators.  

EDF said it was too early to say whether the problems could lead to reactor closures, but acknowledged that several reactors were affected by welding anomalies, adding that further information would be released in the coming days. An EDF spokesman said not all of France’s 58 reactors were affected as EDF also had other suppliers including Westinghouse and MHI, and that Framatome had not always used the same welding procedure.  
 
France’s Autorité de Sûreté Nucléaire (ASN - Nuclear Safety Authority) has been informed of the problem and will rule later on any possible closures, EDF said.

Frederic Menage, head of nuclear safety at L'Institut de Radioprotection et de Sûreté Nucléaire, ASN’s technical arm, told Reuters the weldings problems affected mainly older 900MWe reactors whose steam generators had ,” since 2008. The steam generators are produced by welding steel rings together to form a large cylinder. After the weldings cool, they need to be reheated to 600 degrees Celsius to remove any tension that could lead to cracks. Menage said a new procedure introduced from 2008 had not reheated the components evenly and that EDF and the ASN now needed to investigate this.
 
EDF has experienced similar issues in the past. In 2016, the French regulator ordered EDF to close up to a third of its 58 reactors for safety checks and repairs following problems with Areva-made components. EDF has also faced new delays of up to three years on the EPR reactor under construction at Flamanville 3 following the discovery of problems with weldings on the reactor’s cooling circuit pipes. In June ASN said EDF would have to repair eight faulty pipe welds in the secondary main cooling loops before Flamanville 3 could begin commercial operation. In August EDF said it had found more than 200 irregularities in materials supplied by the alloys division of Eramet for its nuclear plants.  ASN said the irregularities required “specific management”, but did not make any of the materials unfit for use.
 
Adding to EDF’s problems, ASN said on 11 September that it had put units 1 and 2 at the Flamanville nuclear plant under increased surveillance following a series of shortcomings in maintenance and contractor oversight. Flamanville 1&2 are 1330MW pressurised water reactor units that began commercial operation in 1986 and 1987.
 
ASN said it had summoned the station’s director and ordered him to submit an action plan to improve plant operation. ASN noted a high number of significant shortcomings in plant maintenance, the oversight of contractors in the plant, as well as the insufficient quality of documentation. “Reinforcing surveillance by ASN will result in additional controls and special attention to the implementation of the action plan defined by EDF following the convening of the plant manager. ASN will regularly monitor, through inspections, the effectiveness of the improvement actions deployed by EDF.”
 
ASN identified three areas for scrutiny: the control of maintenance and operating activities and associated documentation; the management of experience feedback, in particular, the reporting of significant events to ASN; and the priority given to safety issues in decision-making.  The two-unit  Belleville station has been under increased surveillance since 2017.