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French nuclear watchdog calls discovery of new weld defects at Flamanville “serious”.

13 April 2018

The President of the French Nuclear Safety Authority (ASN), Pierre-Franck Chevet, told a Senate committee that new defects unearthed on April 10 at the Flamanville nuclear power station being built on the Normandy coast were “serious”. This follows the latest discovery of faulty welds in critical pipework at the plant.

The Flamanville EPR - Image: EDF
The Flamanville EPR - Image: EDF

Chevet had already used the same qualifier in February about the first 38 faulty welds in pipes connecting the four steam generators to the turbine. At that time, Flamanville operator EDF said these were deviations from a high quality standard, more demanding than the standard standards applied to nuclear pressure equipment, so the welds would still be safe.

At the end of March, however, in an inspection prior to the commissioning of the plant, the company discovered further "quality deviations". And this time, not in relation to increased safety requirements, but compared to the normal regulations for this type of equipment.

These defects relate to the entire main secondary circuit of the reactor - 150 welds in 350 metres of pipes - in the system that brings condensed water to the steam generator.

ASN said an inspection on April 10 revealed critical problems, and Chevet told the Senate committee there was clearly a lack of supervision by EDF and Framatome, formerly Areva NP, which is building key sections of the Flamanville plant.

"For some welds, we do not understand how the anomalies were not detected before," he said.

In a Le Monde interview, Thierry Charles, Deputy Director General of the Institute for Radiation Protection and Nuclear Safety (IRSN), said there were three serious failures: poor quality welds, poor manufacturing controls and quality monitoring by EDF being carried out too late. This, he said, led to there being an "abnormal situation".

ASN is now waiting for the results of the additional checks announced by EDF on the 150 potentially suspect welds, which are expected by the end of May. The operator will then have to detail the corrective measures that it will implement. According to IRSN, in the best case the welds would be redone, and in the worst, the whole secondary circuit would need to be replaced.

Nuclear fuel was scheduled to be loaded into the Flamanville reactor at the end of 2018, with a view to the plant becoming operational in the course of 2019. These newly-identified problems might put back this timetable.

The cost of the Flamanville plant, which will have a new generation EPR reactor, has tripled after a series of technical problems and delays, from 3.3 billion euros in 2005 to 10.5 billion euros today.
Flamanville was the second EPR reactor to be constructed after Olkiluoto in Finland, which has suffered comparable delays and cost overruns, and which is also due to enter service in 2019.

This means that the first EPR to enter production will probably be at the Taishan nuclear plant in China. Work on Taishan 1 and 2 reactors have also suffered repeated delays, but not on the scale of the French and Finnish plants. At least one of the Chinese reactors is expected to be commissioned this year. 

The UK plans to build two EPRs at Hinkley Point in Somerset and these could be further delayed if the new problems at Flamanville prove serious. The UK EPRs are already mired in controversy over the high cost of the project.

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