French nuclear safety authority Autorité de Sûreté Nucléaire ((ASN) said on 5 May that "irregularities" had been found in documents relating to manufacturing checks of around 400 components produced at Areva's Le Cruesot forge plant in France since 1965. Some 50 of the parts "would appear to be in service in French nuclear power plants", ASN said, citing information provided by Areva.
ASN has now asked Areva and the licensees concerned to submit a "list of parts concerned as rapidly as possible", along with an "assessment of the consequences for the safety of the facilities".
The findings are the result of an ongoing quality review at Le Creusot, launched in April 2015 at the instigation of the ASN, following the detection of an anomalies in the reactor pressure vessel (RPV) of the European pressurised water reactor (EPR) at unit 3 of the Flamanville NPP. This raised questions over quality control and carbon content of steel in the RPV.
The upper and bottom head of the reactor pressure vessel for the Flamanville EPR were manufactured at the Le Creusot facility in September 2006 and January 2007. A subsequent change in regulations concerning carbon content of steel was applied to them and last April Areva informed the ASN that chemical and mechanical tests conducted in late 2014 on a vessel head similar to that of the Flamanville EPR had revealed an area with carbon concentration beyond the new limits. This, ASN said, has led to "lower than expected mechanical toughness values".
Although the initial findings of the review were sent to the ASN in October 2015, ASN said it "considered that this relatively superficial review, which only went back as far as 2010, was insufficient and did not give a complete picture of the organisation and practices at Creusot Forge, the quality of the parts produced and the safety culture prevailing within the plant".
At the end of 2015, ASN asked Areva to take the process further and go back to at least 2004, which was when the first parts intended for the EPR were manufactured. The latest findings indicate "inconsistencies, modifications or omissions in the production files, concerning manufacturing parameters or test results".
ASN said: "The review process will need to be seen through to completion in order to assess all the anomalies which may have affected past manufacturing operations and draw any relevant conclusions regarding the safety of the facilities."