EPR Reactor: Information Letter n°1

Anomalies have been reported, which is to be expected on such a large construction site (examples are given below). In ASN's opinion, these anomalies have been

Lightbox Stacks under construction around cranes Vue du chantier (fond du liner) © EDF

properly remedied. The Authority nevertheless considers that EDF should reinforce the leading and the monitoring of subcontractors' activities on the site and, when their technical skills are found satisfactory, action should be taken to develop their safety culture.

Since work began, ASN has examined the following anomalies in particular:

1. Not enough consideration has been given to the consequences of a site crane falling on a reactor 2 auxiliary building. After discussing the problem with ASN, EDF decided to build stacks around the cranes located on the site to prevent them from falling on nearby facilities.
 (see photo on right)

2. Cracks observed in a concrete block making up the foundation raft of the Flamanville 3 EPR nuclear island. The concrete was poured on 3-5 December 2007.

The cracking was due to shrinkage as the concrete hardened. This type of phenomenon is frequently observed in large-scale concreting operations. EDF remedied this problem by injecting pressurised resin into the cracks.

After considering IRSN's opinion, ASN accepted the solution proposed by EDF.

3. During the inspection of 5 March 2008, ASN found that certain rebars were not arranged as indicated in drawings. In ASN's opinion, this shows that the group of contractors in charge of concrete structural work did not exercise adequate technical supervision and that EDF monitoring was insufficient. In response to these observations, EDF defined the corrective action to be taken to prevent any recurrence of the situation. These nonconformances were remedied before the concrete was poured.