A company that jointly operates a French-built nuclear reactor at Taishan in the southern Chinese province of Guangdong said on Monday it is working to resolve a "performance issue" following reports of a radioactive leak at the plant.
"Framatome is supporting resolution of a performance issue with the Taishan Nuclear Power Plant in Guangdong province, China," the company said in a statement on its website.
"According to the data available, the plant is operating within the safety parameters," it said.
"Our team is working with relevant experts to assess the situation and propose solutions to address any potential issue," the statement said.
The Taishan Nuclear Power Plant issued its own statement on Sunday, in response to media inquiries.
"At present, continuous monitoring of environmental data shows that the environmental indicators of Taishan Nuclear Power Plant and its surroundings are normal," the plant, which is jointly run by Framatome and China General Nuclear (CGN), said.
"All operating indicators of the two units have met the requirements of nuclear safety regulations and power plant technical specifications," it said.
It said Unit 1, which began operation on Dec. 13, 2018, is currently operating on full power, while Unit 2 was undergoing a "planned overhaul."
"Taishan Nuclear Power Plant Unit 2 ... was successfully connected to the grid on June 10," the company said on its website. “The overhaul has been completed, and met all safety, quality and scheduling targets."
French power group EDF said it had been informed of a build-up of inert gases at its nuclear power station in China, and had called for a meeting with its Chinese partner to review data on the plant, Reuters reported.
It said the build-up of noble gases had affected the primary circuit of Unit 1 of the Taishan plant, was a "known phenomenon, studied and provided for in the reactor operating procedures."
Calls by Reuters to China's National Nuclear Safety Administration rang unanswered on Monday, which was a public holiday in China.
CNN reported on Monday that the U.S. government had spent the past week assessing a report of a leak at the Taishan power plant in Guangdong province run by a joint venture between EDF and China General Nuclear Power Group (CGN).
Gamma radiation levels in Hong Kong, 135 kilometers (85 miles) from the plant were within normal range on Monday, data displayed on the Hong Kong Observatory website showed.
The plant operators' statements came after CNN reported that the company had written to the U.S. Department of Energy warning of an "imminent radiological threat."
The Chinese authorities had responded by raising levels of radiation considered officially acceptable, rather than by shutting the plant down, the network cited a letter from the company to the department as saying.
It added that U.S. officials believed that the current situation at the plant does not present a severe safety threat.
The U.S.$8.3 billion Taishan plant was among the first in the world to use European pressurized reactors (EPR) designed by French nuclear firm Areva, but has been plagued by delays and technical problems.
Hong Kong's crowd-funded investigative news agency FactWire reported at the end of 2017 that cracks had been found in some of the reactor parts, but that the authorities had decided to go ahead with a final test-firing of the reactor on June 6, 2018 without making the move public.
It said the reactor would be used with the problematic reactor cover in place until April 2025.
Reported by Fong Tak Ho for RFA's Cantonese Service, and by the Mandarin Service. Translated and edited by Luisetta Mudie.