The emergence of problems in a new-generation nuclear reactor in China threatens to undermine efforts by its French designer to sell it elsewhere, and could hurt Beijing's nuclear industry, analysts said.

French energy giant EDF and the Chinese government have sought to ease concerns about a gas build-up at the Taishan Nuclear Power Plant in southern Guangdong province after a CNN report of a potential leak at the site.

Chinese nuclear safety and environmental authorities said Wednesday there has been an increase in radioactivity in one of the two power units due to five damaged fuel rods, but that it was a "common phenomenon" that doesn't warrant concern.

But it is the latest snag to hit EDF's much-vaunted EPR reactor.

The Taishan power station became in 2018 the first site worldwide to use the pressurised water design, which has been subject to years of delays in similar projects in Britain, France and Finland.

A second EPR reactor was launched at Taishan a year later. The facility is partly owned by EDF along with state-owned China General Nuclear Power Group, the majority stakeholder and operator of the plant.

EDF said this week it was first informed about the problem with the fuel rods in October, but only learned about the gas build-up on Saturday, according to EDF.

French energy giant EDF and the Chinese government have sought to ease concerns about a gas build-up at the Taishan Nuclear Power Plant after a CNN report of a potential leak at the site
French energy giant EDF and the Chinese government have sought to ease concerns about a gas build-up at the Taishan Nuclear Power Plant after a CNN report of a potential leak at the site AFP / PETER PARKS

The problem and the silence of Chinese authorities triggered criticism of EDF, whose EPR reactor is supposed to be safer, last longer and produce more electricity than previous versions.

"It seems that both the Chinese nuclear regulators and the French nuclear corporations may have acted in bad faith," said Paul Dorfman, a researcher at the University College London's Energy Institute.

"If so, this new EPR debacle should have important consequences for any further plans for new EPR builds in France, the UK, and internationally," he added.

But for Nicolas Mazzucchi, a research fellow at the Paris-based Foundation for Strategic Research, it is too early to draw any conclusions.

"Is it due to inadequate actions by the (Chinese) safety regulator? Or is it a problem of a nature whose impact upon the reactor needs further evaluation? For the moment, all these questions remain unanswered," Mazzucchi said.

The Taishan incident comes as EDF, which is currently struggling to finish the Flamanville EPR in France after more than a dozen years of work, is hoping to win new contracts.

China's Taishan nuclear power plant
China's Taishan nuclear power plant AFP / Patricio ARANA

France, which must eventually decide whether to renew its park of ageing nuclear reactors, is holding off on making a decision until Flamanville comes online, which is now expected in late-2022 at best.

"All energies have advantages and disadvantages, let's look at them but not react to them in a hurry," the minister responsible for France's green energy transition, Barbara Pompili, told France Inter radio.

EDF is also in discussions with European countries such as Poland and the Czech Republic.

Britain, where two EPR reactors are under construction, is considering ordering another two.

EDF is also in talks with India about building a giant plant at Jaitapur with six EPR reactors.

But EDF faces competition internationally from Russia as well as China, which has developed its own reactor.

A perceived lack of transparency in China's handling of problems at Taishan could undermine confidence in its own reactor, according to experts.

"It's really very bad news for the Chinese nuclear sector", which "could end up with a bad image internationally," Mazzucchi said.

That outcome will not displease the United States, which has been looking to counter China's growing influence internationally, and "has a vested interest in bashing them whenever possible", he added.

Taishan could also undermine the development of nuclear energy within China.

While the nation has the world's third-largest park of reactors, nuclear energy remains a relatively small part of China's energy mix.

After the Fukushima disaster in 2011, Chinese authorities have become prudent in further developing nuclear power in the face of sceptical public opinion.

"The events at Taishan therefore challenge Beijing to explain the facts to its population, even as China has in recent weeks very publicly criticised Japan's handling of its management of the Fukushima waste water cleanup," said Mark Hibbs, a senior nuclear policy fellow at the Carnegie Endowment for International Peace.

The Chinese government statement on Wednesday denied claims in the earlier CNN report that it was raising the acceptable limit of radiation detection around the plant.