EPR Reactor: Information Letter n°4: ASN continues to implement its inspection programme on the Flamanville 3 EPR site

ASN continued its inspection activities at the Flamanville 3 construction site during the 3rd quarter of 2008. The most significant points relating to these inspections are as follows.

Sampling and testing concrete samples from the Flamanville 3 site

During concrete pouring operations on the reactor building platform, ASN had concrete samples taken by an independent laboratory to verify the properties of the concrete used on the site.
 Tests on these samples demonstrated that the mechanical strength of the concrete used for these operations was satisfactory.

Analysis of the action taken to remedy the reinforcement problem reported to ASN on 21 May 2008

On 21 May 2008, EDF informed ASN of a problem concerning the rebars in a part of the foundation raft of a building designed to house some of the reactor safeguard systems (see information letters 2 and 3). At ASN's request, concrete pouring operations concerning safety-related buildings were interrupted for 23 days after the problem had been discovered.
 As part of the technical action taken to remedy the problem, EDF sent ASN a copy of the impact study carried out. The study demonstrated that the lack of stirrups in some isolated spots had no effect on the mechanical strength of the structure given the margins allowed at the design stage.
 ASN nevertheless asked EDF to implement corrective action and make the necessary repairs. This was done last July.

Liner manufacture (the liner refers to the metal lining the reactor building)

Following its inspection on 5 June 2008, ASN asked EDF for an impact analysis on the use of a different liner plate welding method from that referred to in EDF technical specifications. EDF replied by sending a document setting out the technical aspects of the problem and suggested performing additional tests to guarantee weld quality using this method.
 After reviewing with its technical support organization, IRSN, ASN informed EDF on 28 August 2008 that it had no objection to liner manufacturing continuing under the present conditions, provided the proposed additional tests were performed.