[en] Fabrication defects detected at the end of 2014 in upper and lower heads of the Flamanville-3 reactor pressure vessel are, by size and characteristics, very serious mechanical defaults. These phenomena strongly put into question the safety case of the EPR (European Pressurized Water Reactor) currently under construction in Normandy. The reason why a well-known material heterogeneity problem was not solved during the forging of the pieces at Areva's Le Creusot plant has yet to be investigated. The reason why the defects were detected or publicly released so late, at a moment when the pressure vessel was already in place in the reactor building, also needs to be scrutinised. Areva will face a very difficult challenge in justifying the safety case for the flawed pressure vessel. The only alternative to demonstrating safety in spite of the defects would be to repair or replace the faulty components, which appears hardly feasible and particularly expensive in the case of the bottom piece. Therefore the future of the entire Flamanville-3 project is at stake. The problem has also international implications, since at least some of the upper and/or lower heads of the Taishan-1 and -2 EPRs, under construction in China, are apparently also affected. It is also not clear whether components destined for the Hinkley Point-C have been fabricated yet and could be concerned. (author)