French utility EDF said on 9 October repairs of faulty welds at unit 3 of the Flamanville nuclear plant in western France would boost the project’s cost by 14% to EUR12.4 billion ($13.6 billion).

Construction of the 1650MWe Flamanville 3 EPR started in December 2007, and it was initially expected to begin operation in 2013 at the cost of EUR3bn.

 Flamanville 3 will be unable to load nuclear fuel before the end of 2022 as EDF needs to repair 66 welds, it said.

EDF’s preferred repair plan includes using remote-operated robots to conduct high-precision operations inside piping for eight welds. This would push net investment to EUR15.5 billion in 2020 and would trim net income by a projected EUR400 million next year, EDF said.

According to Bloomberg, EDF aims to secure regulatory approval for its repair plan by the end of next year. It also has a fallback option, which would involve extracting the piping to repair the welds. However, that would “probably lead to an extra delay of one year and an extra cost of 400 million euros,” EDF’s head of nuclear new build, Xavier Ursat, said on a conference call.

The French government has asked EDF to prove by the middle of 2021 that it can build competitively priced nuclear plants to replace some of its 58 ageing reactors.

EDF recently raised its cost estimate for two similar reactors at Hinkely Point C in the UK. The EPR being built at Olkiluoto 3 in Finland is ten years behind schedule and vastly over budget.