France’s Autorite de Surete Nucleaire (Nuclear Safety Authority – ASN) said on 19 July that it had suspended the serviceability certificate for one of the three steam generators at unit 2 of EDF's Fessenheim NPP, citing irregularities revealed by a quality audit. ASN launched an investigation after the audit by Areva at its Le Creusot site showed irregularities in the manufacturing tracking records of equipment for NPPs. A number of anomalies were discovered in the steel of the component's lower shell.

"The suspension follows the discovery of irregularities in the manufacture by Creusot Forge Areva," ASN said in a statement, adding that it had been informed by EDF that power generation at the reactor was stopped on 13 June and is due to restart on 29 August. ASN said the steam generator forging "had now been conducted in accordance with the technical dossier" submitted to it by Areva. These test certificates – issued following multiple inspections and hydraulic testing – are required for commissioning.

ASN added that, had it been aware of this non-compliance, it would not have originally issued the certificate. Areva said in a separate statement that it had taken note of ASN's decision and that technical analyses conducted have so far concluded that the irregularities did not affect operational safety.

EDF, however, has revised its nuclear electricity generation target for 2016 to reflect expected extended outages at some of its plants. EDF has revised its target down from 408-412TWh to 395-400TWh. The utility said output last month totalled 28.6TWh, down 2.1TWh compared with June 2015. Total output over the first half of 2016 was 205.2TWh, 5.2TWh less than in the first half of 2015.

EDF said it needs to demonstrate in the second half this year that "some components, mainly steam generators … can operate in a fully safe mode". It added, "Taking into account ASN's examination schedule, extensions of part of the outages are expected over the second half of 2016".