Back in September 2017, an unusually large amount of radiation was detected hovering over central and eastern Europe, Asia, the Arabian Peninsula, and the Caribbean. At the time, news outlets reported that European nations were citing a nuclear incident in Russia as the cause, but Russia denied knowledge of such an incident.
Now, just two years later, an international team of scientists have studied more than 1,300 measurements from Europe and around the world to determine the true source of the radioactive cloud, and it seems original reporting was likely correct.
A recent article on LiveScience.com titled “Mysterious radiation cloud over Europe traced to secret Russian nuclear accident,” by Tom Metclafe, explains the new research. The team of scientists concluded that the cloud “could only have been caused by a nuclear-fuel reprocessing accident at the Mayak Production Association, a nuclear facility in the Chelyabinsk region of the Ural Mountains in Russia, sometime between noon on Sept. 26 and noon on Sept. 27,” he reported.
In fact, between 250 and 400 terabecquerels of radioactive ruthenium-106 were released in that timeframe, according to Georg Steinhauser, nuclear chemist, Leibniz University, lead author of the research.
Although Russia still has never admitted to a nuclear accident at that location in 2017, it’s this ruthenium-106 that has convinced the team that the cloud came from a nuclear accident in that area. The isotope is produced as a byproduct of nuclear fission, and is typically separated and placed in long-term storage with other radioactive waste byproducts, Metclafe reports.
This led experts to conclude that the large release into the atmosphere could only be a result of a nuclear fuel reprocessing accident, and Mayak was one of only a few nuclear fuel reprocessing plants in the world at the time, Steinhauser told Live Science in the article. This is supported by meteorological studies from the research that show that the cloud could only have come from this facility.
Steinhauser told Life Science that the accident was likely a fire or an explosion that left workers exposed to high levels of radiation. However, the cloud was diluted enough to avoid harm to the people beneath it, despite having a radiation level between 30 and 100 times that which was released after the Fukushima accident, he says in the article.
The research was published in the journal Proceedings of the National Academy of Sciences.