France’s nuclear regulator finally approves Flamanville reactor vessel

Eleven years after work began on the Flamanville 3 nuclear reactor project in Normandy, France’s Nuclear Safety Authority (ASN) has given permission for EDF to commission its reactor pressure vessel.

The ASN had been concerned that the steel used to make parts of the vessel, including the lid, contained too much carbon. After carrying out tests the regulator is now satisfied the vessel will be safe, although it is requiring that the lid be replaced when the first fuel change occurs in 2024.

As well as the problem with metallurgy, the authority was concerned that between 130 and 150 welds did not meet its quality requirement. These are located between the steam generator and the turbine.

There is still some doubt about whether all of the welding will have to be redone. The ASN has said it believes that there is still “important technical work to do”, and there is particular concern over welds on the main steam discharge pipe.

Manufacturing operations at Le Creusot forge, where the components were made, were suspended in December 2015 and resumed in January this year after the implementation of an improvement plan.

Flamenville 3 is intended to be one of the first examples of a 1,650MW European Pressurised Reactor, developed by Areva, Siemens and EDF to be Europe’s flagship third generation product. A simplified version of the design will also be used for the UK’s first modern nuclear site, at Hinkley Point 3 in Somerset.

The first projects, at Flamanville and Olkiluoto 3 in Finland, have been plagued by delays and cost escalations, although two reactors at Taishan in southeast China, were relatively successful, with Taishan 1 going critical in June of this year, five years beyond its original deadline.

How late it was, a Flamanville timeline:

• September 2007  Work begin on site. EDF gives a cost estimate of €3.3bn and a commissioning date of 2012.
• December 2012  EDF’s cost estimate increases to €8.5bn and completion is pushed back to 2016.
• November 2014  EDF announces completion is delayed to 2017.
• April 2015  Aviva informs ASN that anomalies have been detected in the reactor vessel steel.
• January 2018  EDF found that some secondary cooling circuit welds did not meet specifications; ASN requests EDF to extend the welding checks to other systems.
• July 2018  EDF delays fuel loading to end of 2019 and increases the project’s cost estimate by €400m to €10.9bn, three times the original figure.

Image: Flamanville is located on Normandy’s Cotentin Peninsula (Manche Tourism)

Further reading:

• EDF’s Flamanville plant hit by “significant” problems with reactor welds
• After pain of Olkiluoto and Flamanville, world’s first EPR fires up in China
• French nuclear regulator highlights “anomaly” over steel forgings in 18 reactors