In the country's first acknowledgement of a radioactive cloud over Europe, Russia's meteorological service has confirmed "extremely high" concentrations of ruthenium 106 in the country last month. Rosgidromet said Monday that the radioactive isotope formed in nuclear reactors was detected at monitoring stations in Argayash and Novogorny between Sept. 25 and Oct. 1, before reaching Tatarstan, more than 500 miles west, reports the AFP. Ruthenium 106 was eventually detected as far away as Denmark, Spain, and Cyprus, reports NPR. Though Rosgidromet doesn't identify the source of the isotope, it notes that Argayash, in the southern the Ural Mountains, had "extremely high pollution" at 986 times the natural background level.
That draws eyes to the Mayak nuclear facility, where spent nuclear fuel is reprocessed 20 miles from Argayash. France's Institute for Radioprotection and Nuclear Safety previously suggested the radioactivity indicated a nuclear accident at a facility dealing with spent nuclear fuel or a facility for radioactive medicine between the Ural Mountains and the Volga River in late September. However, Russian state nuclear company Rosatom, which owns the Mayak facility, denies it's the source of the radioactivity, per Reuters. Previously, Rosatom denied that ruthenium 106 had even been detected in the region between Sept. 25 and Oct. 7. Greenpeace Russia is now calling for "an inquiry into potential concealment of a nuclear incident," per the AFP. (Read more Russia stories.)