Anomaly in the carbon concentration of the steel: after inspection, ASN has authorised restarting of the reactors concerned
ASN has authorised restarting of the twelve reactors1 concerned by the anomaly in the carbon concentration of the steel of the channel heads of the steam generators manufactured by JCFC2.
On 18th October 2016 ASN had instructed EDF to perform additional inspections of the steam generator channel heads of certain reactors within three months. In view of the results of these inspections and the proof EDF provided regarding the serviceability of these steam generators, ASN authorised restarting of the last reactor concerned - reactor 1 of the Civaux nuclear power plant (NPP) - on 24th February 2017.
ASN has published a chronological record of its exchanges with EDF concerning this anomaly. It has also made the correspondence it sent to EDF available to the public.
On 7th April 2015, ASN made public the discovery of an anomaly in the composition of the steel in certain zones of the vessel closure head and the vessel bottom head of the Flamanville EPR reactor. Detection of this anomaly led ASN to ask Areva NP and EDF to draw all the lessons to be learned from this event. Three processes are currently in progress:
- the search on other EDF reactor components for technical anomalies similar to those detected on the Flamanville EPR reactor vessel. As a result of this search, EDF has identified similar anomalies on the channel heads of a number of steam generators;
- reviews of the quality of fabrication of the parts in the Areva NP manufacturing plants which have enabled Areva NP to detect irregularities in the Creusot Forge manufacturing files;
- the initiation of reflection on the way in which basic nuclear installation licensees monitor their service providers and subcontractors, on ASN oversight and on the alert mechanisms.
- Consult the chronological record of exchanges between ASN and EDF regarding the anomaly in the carbon concentration in the steel of the steam generator channel heads (in French)
- Consult the letters sent by EDF to ASN on 21st April 2015, 10th December 2015, 22nd April 2016, 27th May 2016, 13th June 2016, 22nd July 2016, 7th October 2016, 14th October 2016, 2nd November 2016, 4th November 2016, 18th November 2016, 5th December 2016, 12th January 2017 and 17th January 2017 (in French)
- Consult ASN resolutions 2016-DC-0572 of 18th October 2016 (in English), CODEP-DCN-2016-048322 of 9th December 2016, 2017-DC-0578 of 12th January 2017, CODEP-BDX-2017-001988 of 17th January 2017 and 2017-DC-0580 of 17th January 2017 (in French)
- Consult the page containing the information published to date by ASN on the lessons learned from the anomaly affecting the Flamanville EPR reactor vessel.
1. Bugey NPP, reactor 4; Civaux NPP, reactors 1 and 2; Dampierre NPP, reactor 3; Fessenheim NPP, reactor 1; Gravelines NPP, reactors 2 and 4; Saint-Laurent-des-Eaux NPP, reactor B1; Tricastin NPP, reactors 1, 2, 3 and 4.
2. Japan Casting and Forging Corporation