France's nuclear regulator, the Autorité de Sûreté Nucléaire (ASN), has defined the preconditions for the resumption of forging operations at Areva's Le Creusot forge. The facility has been out of operation since December 2015 following the discovery of quality assurance issues.
ASN announced in April 2015 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. The detection of this anomaly led ASN to ask Areva NP and EDF to "learn all possible lessons from this event".
In May 2016, the French nuclear safety regulator said an ongoing quality audit at Areva's Le Creusot forge - which Areva bought in 2006 - had identified "irregularities" in paperwork on some 400 plant components produced there since 1965. The issues "comprise inconsistencies, modifications or omissions in the production files, concerning manufacturing parameters and test results", it said.
There are three processes currently under way, ASN said. Firstly, the search for technical anomalies on other EDF reactor components similar to those detected on the Flamanville EPR vessel, which has enabled EDF to identify similar anomalies on the channel heads of certain steam generators. Secondly, manufacturing quality reviews on parts at Areva NP manufacturing plants, which enabled Areva NP to detect irregularities in the manufacturing files from Creusot Forge. Thirdly, initiation of a review of basic nuclear installation licensee monitoring of their contractors and subcontractors, of ASN oversight and of alert mechanisms.
Areva submitted an action plan to ASN on 1 August 2016 aimed at guaranteeing the quality of future production at the Le Creusot facility. The company has informed ASN of its intention to resume forging operations there.
ASN has conducted several inspections of the forging facility, including a multinational inspection carried out in accordance with the inspection protocol of the Multinational Design Evaluation Program (MDEP). The aim of this inspection - carried out from 28 November to 2 December 2016 - was to examine the review method for the component files already assessed and those currently undergoing assessment. It examined the organisational and technical changes, as well as the changes in terms of quality and nuclear safety culture implemented within the Creusot Forge plant.
In a 31 January letter to Areva, ASN said the inspectors noted Areva's action plan is "in the process of being implemented". The inspectors considered a certain number of subjects needed to be adapted and supplemented, such as management of change, human resources, exhaustiveness of root cause analyses, detection of irregular practices, reviews of manufactured component files, management of current manufacturing processes, internal monitoring by Creusot Forge and the quality and nuclear safety culture.
ASN has now written to both Areva and EDF informing them of the preconditions required for resumption of forging of components for use in French nuclear power plants.
"Prior to the restart of manufacturing, ASN will check that the action plan is complete and that the actions already taken have proved to be effective," ASN said. "Subsequently, ASN will maintain increased oversight and monitoring of Areva's Creusot Forge plant."
Researched and written
by World Nuclear News