China officials said Wednesday radiation levels at its Taishan nuclear reactors were normal.
Earlier this week French utility company Électricité de France S.A., or EDF, said it was investigating reports of a possible leak at one reactor.
EDF, one of the project's largest shareholders, launched an investigation after it received reports of abnormal levels of radiation. A CNN report said it received information from Framatome - an EDF unit that designed the reactors - that one reactor presented an "imminent radiological threat" as a result of a buildup of dangerous gases including xenon and krypton.
China foreign ministry representative Zhao Lijian said at a news briefing all of the nuclear reactors were fully compliant with requirements. He said there were no signs of abnormalities or leaks.
"So far China's nuclear power plants have maintained a good operating record, with no incidents affecting the environment and public health," Zhao said.
EDF said the likely reason for the leak might be some of the fuel rods supplied by Framatome.
"Under normal operating conditions it is true some gases like krypton and xenon will escape and be detected but in this case the concentrations are much higher - so something is happening," a former vice chairperson of the Japan Atomic Energy Commission Tatsujiro Suzuki said.
Environmental groups said krypton and xenon at high levels could cause serious environmental issues. If the problem gets worse, it could result in an ecological disaster.
"Once radioactive gas is leaking to the environment it is a serious issue. It could get worse. I think there could be problems with the fuel. It is unusual," Suzuki said.
Hong Kong chief executive Carrie Lam said this week she had asked the Hong Kong Observatory and the Water Supplies Department to monitor radiation near the facility. Lam said so far the agency hadn't detected anything abnormal.
The Taishan nuclear reactor project, which was completed and put into full operation in 2019, consists of two French-designed nuclear reactors. The facility is located around 200 kilometers from Hong Kong.