Tests are underway this month on a model of a reactor used at the Flamanville nuclear plant in northern France.
Areva and EDF told French nuclear safety authority ASN that work was underway to ensure the reactor was compliant with requirements.
It follows initial tests that showed carbon content in the reactor was greater than recommended.
Areva said: “EDF and Areva teams are working to perform the additional tests as soon as possible, following approval by the ASN on the test conditions, and to provide the safety authority with all the necessary information to demonstrate the safety and quality of the corresponding equipment.”
The UK’s Office for Nuclear Regulation said it expected any lessons from Flamanville to be useful at the proposed new nuclear plant in Somerset.
“ONR is aware of ASN’s concerns with the reactor pressure vessel at Flamanville 3,” it said in a statement.
“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.”
EDF said the manufacturing processes used on the Flamanville 3 reactor vessel were compliant with the mechanical requirements implemented and validated for the French nuclear reactor program.
It added: “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, 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 program 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.”