THE future of the multi-billion pound Hinkley Point C project has again been put into doubt after nuclear reactors designed for the plant were discovered to have “very serious” faults.

A reactor vessel already installed at the huge Flamanville plant in Normandy was found to have weak spots in the lid and the bottom which could reduce the resistance of the metal.

The company which has designed the vessels, Areva, had orders for five more including two for China, one for America and two for Hinkley. It is not certain whether the Hinkley ones have already been manufactured.

The head of the French nuclear regulator, Pierre-Franck Chevet, warned any defects could be very costly to rectify.

He explained: “This is a serious, even a very serious anomaly as it affects an absolutely crucial reactor component on which no risk of rupture can be taken.”

This latest set-back for Hinkley was greeted with derision by Alan Jeffery, spokesman for the Stop Hinkley campaign group.

He said: “In recent months, we’ve seen legal action from a number of sources including the Austrian government and German Greenpeace.

“Now we hear about these very serious defects in the Flamanville reactors. It’s one disaster after another.

“EDF Energy should cut its losses and give up on Hinkley C now, so the South-West can get on with developing a sensible sustainable energy strategy.

“To tackle climate change effectively we need to get started on energy efficiency and renewable energy programmes now, not waiting around for the nuclear industry to sort out its problems first.”

A spokesman for the UK regulator, the Office for Nuclear Regulation, said: “ONR is aware of ASN’s concerns with the reactor pressure vessel at Flamanville 3.

“The UK currently has no EPR reactors but expects that learning from Flamanville 3 will be taken into account in the manufacture of components intended for the planned new reactor at Hinkley Point C “ONR has been liaising with ASN and the Hinkley Point C licensee, NNB GenCo and will continue to do so.”

In a statement, EDF added: “The manufacturing processes used on Flamanville 3 reactor vessel are compliant with the mechanical requirements implemented and validated for the French nuclear reactor program. The robustness of this process is demonstrated through the 1,700 nuclear reactor years of good operations.

“However, since the 2005 new Order on nuclear pressure equipment (“ESPN Order”), the French nuclear safety authority (ASN) is requesting for Flamanville 3 equipment to comply with new mechanical specifications.

“AREVA and EDF are currently preparing the work on a new series of tests aimed at demonstrating the compliance of Flamanville 3 equipment to these new standards. In accordance with the regulation, this programme will be submitted to ASN for approval.

“On the basis of the information available at this stage, EDF can confirm that work can continue on Flamanville’s EPR site.”