A senior executive at the Russian nuclear-processing plant suspected of being behind a spike of radioactivity over Europe in September-October has admitted that the facility emits the isotope that was recorded above the Ural Mountains.
Russian officials last month reported high levels of Ruthenium-106 in areas close to the Mayak plant but the plant insisted it could not have been the contamination source because it doesn't extract the isotope or conduct any operations that may lead to its release.
Yury Mokrov, adviser to Mayak's director general, said in a webcast press conference on December 13 that the plant does routinely process Ruthenium-106. Mokrov insisted, however, that the plant cannot be the source of any major leak, saying the emissions from the plant are so insignificant "we can only see it in the [plant's] chimney."
Mokrov's statement came after members of a commission led by Rosatom, the state corporation in charge of Russia's nuclear energy industry, said on December 8 that the spike in radioactivity over Europe could have come from a falling satellite.
The French nuclear-safety institute, IRSN, said on November 9 that the ruthenium-106 probably came from a facility such as a nuclear-fuel-treatment site or radioactive medicine center in that part of Russia or to the south in Kazakhstan.
It said the pollution did not pose health or environmental risks, but the lack of a warning from Moscow raised concerns -- in Russia and abroad -- that the government could be withholding information about accidents involving radioactivity.
France's IRSN initially believed the radioactive material might have come from a satellite equipped with a generator containing ruthenium.
But IRSN health director Jean-Christophe Gariel, said in November that the institute no longer believed that was the case.
He cited an investigation by the UN's International Atomic Energy Agency (IAEA), which found that no satellites powered by ruthenium had reentered the atmosphere during the time period in question.
Mayak, in Russia's Chelyabinsk region, saw one of the world's worst nuclear accidents in September 1957, when a waste tank exploded.
That contaminated 23,000 square kilometers of territory and prompted authorities to evacuate 10,000 residents from neighboring regions.