A build-up of xenon and krypton is being investigated at a nuclear plant in China following claims of a potential leak.

US news network CNN reported earlier this week that the US government is looking into a report of a leak at the Taishan power plant in Guangdong province run by a joint venture between French power group EDF Energy and China General Nuclear Power Group (CGN), which has denied claims of a leak.

EDF has reportedly said that a build-up of krypton and xenon had affected the primary circuit of Taishan Unit 1.

EDF said there was a build-up of the noble gases in the primary circuit of reactor number 1 of the Taishan plant, but that it was a “known phenomenon” and that it had procedures for dealing with such a build-up of gases.

French engineering company Framatome, which is owned by EDF, designed the plant’s reactor and is still involved in its operations. Framatome wrote to the US government warning of an “imminent radiological threat” at the plant, according to CNN.

Framatome said in a statement, “Framatome is supporting resolution of a performance issue with the Taishan Nuclear Power Plant in Guangdong Province, China. According to the data available, the plant is operating within the safety parameters. Our team is working with relevant experts to assess the situation and propose solutions to address any potential issue.”

The gas leaked after the coating on some fuel rods had deteriorated, according to reports.

As for how this situation impacts on the rare gases market, Dick Betzendahl, of Betzendahl Gas Consultants LLC, told gasworld, “Most of the gas would be krypton-85 [a radioisotope of krypton]. Krypton-85 is radioactive with slightly more than a 10-year half-life. As far as I know, the krypton-xenon mixture could not be economically purified as the technology is not available to separate the krypton-85. Also, the mixture would have a dangerous level of radioactivity. The xenon would be mostly xenon with some isotopes of xenon and some would be radioactive with short half-lives. If it were to be released into the atmosphere, which is done at some nuclear plants, it could increase the Kr-85 and xenon isotopes in the crude mixture if a steel mill with a rare gas column was close by. This could cause problems with the electronic industry. As long there is no crude rare gas extraction near the release it would have very little effect on the purified product.”