EPR Reactor: Information Letter n°6: ASN remains vigilant and is pursuing its inspection programme at the Flamanville 3 EPR site

Published on 31/07/2009 at 17:52

Information notice

During the first six months of 2009, ASN continued its inspection activities at the Flamanville 3 EPR construction site. Highlights of this work included:

Manufacturing of the liner (metal lining designed to seal the containment)

As a result of several inspections carried out in 2008 at the construction site, ASN found deficiencies in liner manufacturing, requiring a high rate of repairs on welds (see Newsletter No.5). In compliance with ASN's request of 4 February 2009, EDF carried out a full inspection of certain welds that had already been completed and proceeded with the repair work required to ensure that the defects found would not have any impact on the containment function provided by the liner.

Secondly, EDF and the Contract Holder carrying out the liner welds submitted an action plan to ASN on 15 April 2009 designed to significantly improve the quality of these welds. The key points of this action plan involve optimising the weld process and the conditions in which welding is performed, improving training for welders and stricter monitoring on weld operations. Pending assessment of how effective this action plan turns out to be, radiographic tests have been performed on 100% of the welds already done.

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View of site (bottom of liner)
 © EDF

 Implementation of the action plan was examined as part of the inspection of 22 April 2009 (see next Newsletter). The inspectors thought that this action plan should serve to improve weld quality. However, there has not yet been enough feedback to assess the relevance and effectiveness of the actions implemented in concrete terms.
 Monthly reviews of the action plan have been sent to ASN since 15 May 2009.

In July 2009, EDF submitted evidence to ASN of controls performed on weld operations. The results of the radiographic shots performed over a period of one month of welding mainly showed acceptable repair rates (less than 10%). On this basis, EDF has decided to suspend radiographic tests, while maintaining closer monitoring over weld operations.

ASN believes that the actions implemented by EDF are likely to improve control over weld operations. ASN will nonetheless continue to monitor these operations closely.

ASN inspections

 During the first six months of 2009, ASN inspectors carried out 16 inspections at the Flamanville 3 construction site, focusing on:

  • Civil engineering
  • Safety management
  • Impact of the worksite on reactors in operation
  • Emergency response organisation and resources
  • Management of sources of ionising radiation
  • Services
  • Workplace inspections
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Thanks to these inspections, it has been ascertained that the action plan, implemented by EDF following the identification, in 2008, of several anomalies related to civil engineering operations, has resulted in a significant improvement in the quality of the works, as well as in monitoring concreting and reinforcement activities.

Nonetheless, during the inspection performed on 28 May 2009 regarding preparatory work for the concreting work on the foundation raft for the internal structures of the Reactor Building, the inspectors and their technical support agency alerted EDF to the fact that a significant number of tasks still had to be completed before going ahead with the concreting operation under the best conditions. Following this inspection, and after the concreting work had been carried out, ASN found that a number of nonconformance files had been opened. ASN considers that the problems found by EDF and the Contract Holder, notably an insufficient volume of concrete poured in places and modifications to the formwork during concreting operations, do not impact on the safety of the structure. These problems do, however, highlight a major source of pressure related to satisfactory progress on the schedule and that is liable to have a negative impact on the quality of the works. ASN has asked EDF to take adequate measures to avoid repeating this type of problem-generating situation.

 International relations

 ASN maintains close relations with foreign nuclear safety authorities. To this end, there were several visits by its counterparts during the first six months of 2009. Visitors included Mr Laaksonen, Director-General of Finland's Radiation and Nuclear Safety Authority, STUK, Mrs Svinicki and Mr Lyons, commissioners from the US safety authority, NRC.

Such regular contact provides an opportunity to discuss the problems encountered in different countries and reap the benefits of feedback on past or current construction projects, regarding worksite activities and factory-manufactured components as well as the detailed design for the reactor.

Regarding examination of detailed design work, in June; ASN met with a delegation from the Chinese safety authority, accompanied by its technical support agency, to discuss the conclusions drawn by each safety authority prior to granting licences to construct nuclear reactors.

Within the framework of multilateral meetings, ASN is also actively involved in the studies carried out by the EPR working group as part of the Multinational Design Evaluation Programme.

News regarding the standing group of experts on nuclear reactors

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To make its most important decisions, ASN draws on the opinions and recommendations of standing groups of experts, which are made public on its website, together with its final decisions. These standing groups are made up of experts from a variety of backgrounds (universities, associations, industry, auditing) appointed on the strength of their expertise.

Commissioning the Flamanville 3 INB 167, involving the first implementation of radioactive substances at the installation, is subject to authorisation by ASN, in application of Article 20 of Decree 2007-1557 of 2 November 2007.

The standing group of experts for nuclear reactors will be asked to examine the industrial operating licence application for the Flamanville 3 reactor. In addition, prior to commissioning, the group will submit opinions on issues of major concern, such as the overall I&C architecture for the future Flamanville 3 reactor.

With a view to preparing the group for these various tasks, ASN suggested keeping it informed, at annual meetings for this purpose, on the construction supervision actions carried out by ASN and IRSN. The first such session was held on 7 May 2009, preceded, on 23 April, by a visit to the Flamanville 3 site. At the information session, the members of the standing group were presented with the major regulatory steps in the commissioning process, the policy deployed by ASN to monitor construction, and a progress report on the Flamanville 3 project (site, design, manufacturing and qualification) together with the inspections carried out by ASN and its support agency, IRSN.

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Date of last update : 26/11/2021