(Bloomberg) -- Electricite de France SA said repairs of faulty welds at a nuclear plant under construction in western France will boost the project’s cost by 14% to 12.4 billion euros ($13.6 billion), adding further financial strain to the cash-strapped atomic power giant.

The almost-completed plant, which is already seven years behind schedule, won’t be commissioned until the end of 2022, Paris-based EDF said Wednesday in a statement. The previous estimate for the project was for 10.9 billion euros.

EDF favors the proposed use of “remote-operated robots, designed to conduct high-precision operations inside the piping concerned,” it said.

The latest cost overrun for the Flamanville-3 reactor, whose budget has more than tripled since construction started in 2007, comes weeks after the French state-controlled utility raised its estimate for the cost of two similar reactors it’s building in the U.K.

The repeated setbacks, which have forced EDF to sell assets to curb its debt in recent years, contrast with swiftly falling costs for solar and wind projects. While nuclear energy can provide low-carbon electricity round the clock, spiraling costs may make it harder for the utility to convince the French and British governments to introduce regulations and financial support to help it fund new atomic plants.

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 aging reactors. It has also been reluctant to approve new nuclear projects before Flamanville-3 is online. Like in the U.K., France is working to step up the pace of building offshore wind farms.

The new setback at Flamanville also comes at a critical juncture, with EDF seeking to sell as many as six similar reactors in India. It’s competing with Russian, Chinese and U.S. builders in other markets such as Saudi Arabia.

EDF has repeatedly blamed the delays at Flamanville on a lull in reactor construction in France at the turn of this century, which has led to a loss of knowhow. Two similar reactors built by a venture between EDF and China General Nuclear Power Corp. in southwest China successfully started up in recent months.

The delay in starting the 1.6 gigawatt Flamanville project is likely to put some strain on France’s power supply in the event of unexpectedly cold winters. EDF is being forced by the government to close two 900-megawatt reactors along the German border next year, and it also wants utilities to shutter 3 gigawatts of coal-fired capacity in 2022.

To reduce the risk of any blackouts, the government has said it may keep two EDF coal-power stations in western France running for a limited number of hours from 2022.

To contact the reporter on this story: Francois de Beaupuy in Paris at fdebeaupuy@bloomberg.net

To contact the editors responsible for this story: James Herron at jherron9@bloomberg.net, Amanda Jordan

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