About a month ago, we noted reports from the French nuclear watchdog ISRN that a spike in airborne radioactivity had been detected in the air in Western and Central Europe: "Ruthenium-106 has been detected by several European networks involved in the monitoring of atmospheric radioactive contamination, at levels of a few milliBecquerels per cubic meter of air."
According to IRSN calculations, the very low levels of atmospheric contamination of ruthenium 106 observed by European monitoring networks had no environmental or health consequences but several agencies across Europe were actively seeking answers on the origin of the contamination.
Fast forward to today, and the IRSN now believes they can narrow down the source of the "nuclear accident" to a nuclear facility in Russia or Kazakhstan sometime in the last week of September. Per the Telegraph:
A cloud of radioactive pollution over Europe in recent weeks indicates that an accident has happened in a nuclear facility in Russia or Kazakhstan in the last week of September, French nuclear safety institute IRSN said on Thursday.
The IRSN ruled out an accident in a nuclear reactor, saying it was likely to be in a nuclear fuel treatment site or centre for radioactive medicine. There has been no impact on human health or the environment in Europe, the IRSN said.
IRSN, the technical arm of French nuclear regulator ASN, said in a statement it could not pinpoint the location of the release of radioactive material but that based on weather patterns, the most plausible zone lay south of the Ural mountains, between the Urals and the Volga river.
This could indicate Russia or possibly Kazakhstan, an IRSN official said.
And while the source of the contamination is yet to come forward, IRSN notes that if an accident of similar magnitude happened in France "it would have required the evacuation or sheltering of people in a radius of a few kilometers around the accident site."
IRSN estimates that the quantity of ruthenium 106 released was major, between 100 and 300 teraBecquerels, and that if an accident of this magnitude had happened in France it would have required the evacuation or sheltering of people in a radius of a few kilometers around the accident site.
The ruthenium 106 was probably released in a nuclear fuel treatment site or center for radioactive medicine, Peres said. Because of its short half-life of about a year, ruthenium 106 is used in nuclear medicine.
The IRSN ruled out an accident in a nuclear reactor, as that would have led to contamination with other radionuclides too. It also ruled out the crash of a ruthenium-powered satellite as an IAEA investigation has concluded that no ruthenium-containing satellite has fallen back on earth during this period.
Measurement from European stations showed high levels of ruthenium 106 in the atmosphere of the majority of European countries, at the beginning of October, with a steady decrease from Oct. 6 onwards.
Despite the concern for residents in close proximity to the "accident," IRSN has again confirmed that the concentrations of ruthenium 106 in the air that have been recorded in Europe were of no consequence for human health and the environment.