Washington is assessing a reported leak at China's Taishan Nuclear Power Plant, CNN reported on Monday (June 14).
But the Biden administration does not believe the facility is at a "crisis level" yet, following meetings of its National Security Council, CNN added, citing unnamed U.S. officials and documents it reviewed.
French power group EDF said on Monday it had been informed of a build-up of inert gases at its plant in China, and had called for a meeting with its Chinese partner.
CNN also reported that Framatome, the EDF unit which designed the reactor, had warned of an "imminent radiological threat."
Framatome said it was supporting efforts to resolve the situation, saying in a statement:
"According to the data available, the plant is operating within the safety parameters," adding that it was working with experts to assess the situation.
EDF said the build-up was a "known phenomenon, studied and provided for in the reactor operating procedures."
State-run China General Nuclear Power Group, the majority owner of the joint venture with EDF said in a statement on its website on Sunday (June 13) that operations at the nuclear power station met safety rules and the surrounding environment is safe.
The power from the plant serves the Guangzhou and Shenzhen areas, which have faced power shortages in recent weeks due to hot weather and lower than normal hydropower supplies from neighboring Yunnan province.
A Reuters call for comment to the National Nuclear Safety Administration went unanswered during a public holiday.