Russia's meteorological service has confirmed there were "extremely high" concentrations of the radioactive isotope ruthenium-106 (Ru-106) in several parts of the country in late September, AFP reported on November 20.
The reported findings from Russia appear to confirm reports from Europe earlier this month that a cloud containing the radioisotope Ru-106 drifted over Europe last month, which European meteorological agencies had said likely originated in either the southeastern Urals region of Russia or Kazakhstan.
"Probes of radioactive aerosols from monitoring stations Argayash and Novogorny were found to contain radioisotope Ru-106" between September 25 and October 1, Russia's Rosgidromet service said, according to AFP.
AFP cited the Russian weather service as saying the highest concentration was registered at a monitoring station in Argayash, a village in the Chelyabinsk region in the southern Urals, which was reported as having "extremely high pollution" of Ru-106, exceeding natural background pollution by 986 times.
The isotope was then detected in Tatarstan and then in southern Russia, eventually reaching "all European countries starting in Italy and toward the north of Europe" from September 29, AFP cited Rosgidromet as saying.
Evgeny Savchenko, the Chelyabinsk region’s minister of public security, said that the regional administration had not received any official information about dangerous levels of radiation in September.
“When the media got hysteric about some accident and cloud of ruthenium-106, we asked for explanations” from Rosgidromet and Rosatom, Russia’s nuclear energy corporation, Savchenko wrote on his Facebook page.
The Russian meteorology agency did not point to any specific source of the pollution, AFP said.
The Argayash station is about 30 kilometers from the Mayak nuclear facility, which in 1957 was the site of one of the worst nuclear accidents in history. Today, Mayak is a reprocessing site for spent nuclear fuel.
On November 9, France's Institute for Radioprotection and Nuclear Safety issued a report saying Ru-106 had been detected in France between September 27 and October 13.
It said that the source of the pollution was probably an accident somewhere between the Volga River and the Ural Mountains, adding that the concentrations measured in Europe were not a danger to public health.
Ruthenium-106 is a product of splitting atoms in a reactor and is also used in certain medical treatments. It does not occur naturally.
The French report said a nuclear reactor accident could not have been the source of the Ru-106 since other radioactive elements would also have been detected in the cloud.
In mid-October, in response to the earliest European reports about the radioactive cloud, the Russian nuclear energy company Rosatom issued a statement cited by Russian media outlets as saying, "In samples tested from September 25 to October 7, including in the southern Urals, no trace of Ruthenium-106 was found, except in St. Petersburg."
Rosatom later said in response to the French agency's report that "radiation around all objects of Russian nuclear infrastructure are within the norm and are at the level of background radiation."
But Rosatom suggested that a discharge from an installation linked to the nuclear fuel cycle or which produces radioactive materials could be the cause of the radioactive cloud.
Greenpeace Russia on November 20 called on Rosatom to open "an in-depth inquiry and publish the results about the incidents at Mayak."
"Greenpeace will send a letter asking prosecutors to open an inquiry into potential concealment of a nuclear incident," it said in a statement.