The French Institute for Radioprotection and Nuclear Safety (IRSN) has identified in Russia the most likely source of radioactive elements detected in the atmosphere of many European countries in early October and released a map of ruthenium-106 and the assessment of the geographical location of the source of the pollution.
In late September and early October 2017, very unusual radioactive elements, ruthenium-106, were detected by several surveillance networks in European countries, including stations in the south of France, according to a report in the newspaper Le Figaro.
Pollution at very low concentrations, on the verge of detection in Western Europe and, consequently, at a non-hazardous level, the origin of which, however, was a mystery. What could emit such radioactive elements into the atmosphere and where did this pollution come from?
"Ruthenium-106 is not found in the physical state, so it should have been released into the environment from human activity," said Jean-Marie Perez, deputy director general of the French Institute for Radioprotection and Nuclear Safety.
The major European radioactivity watchdogs in Europe, the IRSN in France and the BfS in Germany, suspected at the time that the pollution was coming from eastern Europe and more specifically from the southern Urals region of Russia.
This crisis raises many questions, but there is no risk to public health, since the doses were so small, at least in Western Europe, since it is unknown whether there were populations in Russia exposed to it.
The map released by IRSN was based on the meteorological conditions prevailing at the time and the movements of the air carried by the ruthenium to the areas which were then detected by the measuring stations.
Based on these measurements, the source of the leak was located between the Volga River and the Ural Mountains, around the city of Perm.
At the end of October, Russia's Rosatom counterattacked, explaining that the release of ruthenium-106 into the atmosphere could not be due to its own activities, as none of its nuclear power plants had reported any leaks.
But Western European experts, such as the French and the Germans, agree that the leak came from Russia. At the same time, the mystery remains as to the cause of this pollution. This could not be an accident at a nuclear reactor at the Beloyarsk nuclear power plant, which is probably located east of the Urals, because ruthenium-106 is the only element detected, without being accompanied by other radioactive elements released in the event of a nuclear accident. also in the air.
It may be due to an accidental evaporation of ruthenium-containing solution during nuclear fuel treatment or to radioactive sources of ruthenium (used in the radiation of certain volumes) that have been lost or burned in an incinerator by mistake.
The Russian authorities prefer the case of falling and dissolving in the atmosphere of a satellite equipped with a ruthenium generator. "We have been investigating this case, but we have no information that a satellite with such equipment fell to Earth in the last week of September, so we can not say anything," said Jean-Marc Perez.
For the zone from which the leak most likely originated, the amount of ruthenium-106 released is very significant and is estimated by simulation at 100 to 300 terabequerels (100-300 trillion bequerels), according to the French Institute. The quantity is so large that if it happened in France, population protection measures would have to be applied in a zone of tens of kilometers around the point of leakage.