A European group of scientists has recently published their conclusions on the radioactive cloud that moved throughout Europe in September 2017, one of the most serious radioactive material leaks since Fukushima in 2011 Even though it happened two years ago, the population did not even know that it was there, as media coverage was insignificant.
The study, published in the journal ‘Proceedings of the National Academy of Sciences‘, has analyzed more than 1,300 measurements from all over Europe and other regions of the world to find out the cause of this incident. The result: it was not a reactor accident, but an accident at a nuclear reprocessing plant.
Although the exact origin of radioactivity is difficult to determine, the data suggests a point of release in the southern Urals.
This is precisely where the Russian nuclear facility Majak is located. The Mayak Production Association is one of the biggest nuclear facilities in the Russian Federation, housing a reprocessing plant, where scientists were trying to produce the isotope cerium–144, for subsequent use in neutrino experiments at the Gran Sasso National Laboratory in Italy, as has previously been speculated.
To date, no one has assumed responsibility for this considerable leak in the fall of 2017. It is noteworthy to mention that the incident never caused any risks to the health of the European population.
Among the 70 experts from all over Europe who contributed data and experience to the current study are Dieter Hainz and Dr. Paul Saey, from the Institute of Subatomic and Atomic Physics of TU Wien (Vienna).
The data were evaluated by Professor Georg Steinhauser, of the University of Hannover (who is closely associated with the Atomic Institute) together with Dr. Olivier Masson, of the Institute of Radioprotection and Sûreté Nucléaire (IRSN) in France.
“We measured radioactive ruthenium-106,” explains Georg Steinhauser. “The measurements indicate the largest singular release of radioactivity from a civilian reprocessing plant.”
“We were able to show that the accident occurred in the reprocessing of spent fuel elements, at a very advanced stage, shortly before the end of the process chain,” says Steinhauser.
“Even though there is currently no official statement, we have a very good idea of what might have happened.”
“Based on airborne concentration spreading and chemical considerations, it is possible to assume that the release occurred in the Southern Urals region (Russian Federation),” the scientists reveal in their new paper.
In autumn of 2017, a cloud of ruthenium-106 was measured in many European countries, with maximum values of 176 millibecquerels per cubic meter of air.
It has been revealed that the values were up to 100 times higher than the total concentrations measured in Europe after the Fukushima incident.
The half-life of the radioactive isotope is 374 days.
This type of radiation releases is extremely unusual, and the fact that no radioactive substances other than ruthenium were measured is a clear indication that the source must have been a nuclear reprocessing plant.
The geographical extent of the ruthenium-106 cloud was extensive as it was measured in large parts of Central and Eastern Europe, Asia and the Arabian Peninsula. Ruthenium-106 was found even in the Caribbean.
The data was compiled by an informal international network of almost all European measuring stations.
In total, 176 measuring stations from 29 countries participated.
Although the release was unusual, the concentration of radioactive material did not reach levels that are harmful to human health anywhere in Europe. From the analysis of the data, a total release of approximately 250 to 400 terabecquerel of ruthenium-106 can be derived.
The Russian reprocessing plant Majak had already been the scene of the second largest nuclear discharge in history on September 1957, after Chernobyl and even larger than the nuclear disaster that happened in Fukushima.
At that time, a tank containing liquid wastes from plutonium production exploded, causing massive contamination of the area.
The conclusions are reported in PNAS.