French nuclear regulator Autorite de Surete Nucleaire (ASN) said 5 April that weak spots have been found in steel at the EPR reactor Areva is building for utility EDF in Flamanville. Areva and EDF said in a joint statement a new series of tests will be conducted on the EPR, but construction work would continue – the project is already years behind schedule and billions of euros over budget.

Areva had informed ASN tests conducted at the end of 2014 had shown that in certain zones of the reactor vessel and cover of the EPR there was a significant concentration of carbon, which weakens the mechanical resilience of the steel and its ability to resist the spreading of cracks. French Energy Minister Segolene Royal said in a statement that results of the new tests are expected in October. It is unclear whether the tests would lead to further delays for Flamanville or whether they would affect three other EPRs under construction, one in Olkiluoto, Finland, two in Taishan, China. ASN said it has has informed nuclear regulators in those countries.

The cost of the EPR projects in France and Finland are currently put at around €9bn ($9.8bn) – up from an initial estimate of some €3bn. In November, EDF announced a new one-year delay for the Flamanville reactor which it now expects to be connected to the grid in 2017, a decade after construction started. It had initially been scheduled to start in 2012. Construction on the Olkiluoto reactor began in 2005 and it is not expected to be connected to the grid before 2018, nearly a decade later than scheduled.