Russian nuclear facility denies playing any role in that big radioactive cloud

The Mayak Production Association, one of the biggest nuclear facilities in Russia, categorically denies any involvement in the “extremely high” concentrations of the radioactive isotope ruthenium-106 that spread across parts of the country and Europe earlier this year.

The Mayak plant says it hasn’t produced ruthenium-106 from spent nuclear fuel “for many years,” claiming that its air emissions have been within regulated levels in 2017. According to the website Znak.com, the radioisotope could have reached the atmosphere from nuclear waste brought to Mayak for processing.

On November 20, citing a recent study by Russia's meteorological service, Greenpeace reported that “extremely high” concentrations of ruthenium-106 were detected in late September in populated areas throughout the Chelyabinsk region, not far from the Mayak plant, which reprocesses spent nuclear fuel, making tritium and radioisotopes.

The Russian nuclear energy company Rosatom has disputed international reports suggesting that a radioactive cloud originated in Russia, saying that radiation levels at all Russian nuclear facilities have been within norms and “at the level of background radiation.”

In September 1957, in what’s known as the Kyshtym disaster, a cooling system error at the Mayak plant caused a chemical (non-nuclear) explosion, contaminating almost 9,000 square miles with radiation. At the time, roughly 270,000 people lived in the radiation zone. More than 10,000 locals closest to the disaster were resettled and their homes were demolished. For decades, Soviet officials kept information about the incident a secret.