PARIS, France - A report by Frances nuclear safety institute has revealed that the cloud of radiation that swept through Europe in recent weeks originated at a nuclear facility in either Russia or Kazakhstan.
The report stated that at least for Europeans living outside of the immediate area, the levels of radiation were never dangerous, but the exact cause of the incident is still unknown.
On Thursday, the Institute for Radiological Protection and Nuclear Safety (IRSN) ruled out an accident at a nuclear reactor, saying the release of radioactive Ruthenium-106 likely originated from a nuclear fuel treatment site or a center for radioactive medicine.
Ruthenium-106, a radioactive nuclide is a byproduct of splitting atoms in a nuclear reactor, and does not occur naturally.
The French institute stated that the accidental release of radiation happened during the last week of September.
The IRSN and several other European nuclear safety institutes have been tracking the radioactive cloud over the past few weeks.
Experts specified that most European countries were affected, with radiation levels measuring between 100 and 300 teraBecquerels.
They noted that one becquerel is the activity of a quantity of radioactive material in which one nucleus decays per second.
In comparison, they said that the 1986 Chernobyl nuclear disaster produced a total of about 5.2 million teraBecquerels, and the 2011 Fukushima disaster churned out an estimated 900,000 teraBecquerels.
The IRSN said in its report, The concentration levels of Ruthenium-106 in the air that have been recorded in Europe and especially in France are of no consequence for human health and for the environment.
IRSN also noted that if the incident happened in France, authorities would have had to evacuate or shelter people from a radius of the order of a few kilometres around the location of the release.
It said that based on weather patterns, the radiation originated south of the Ural mountains between the Urals and the Volga river which let to the conclusion that it likely happened in either Russia or Kazakhstan.
In a statement, IRSN director Jean-Marc Peres said that Russian authorities have said they are not aware of an accident on their territory.
Commenting on the cause, Peres said he suspects an accident at a nuclear fuel treatment site or at a center for radioactive medicine.
Further, the IRSN ruled out an accident at a nuclear reactor, saying it would have resulted in contamination with other detectable airborne substances.
Experts also ruled out the crash of a ruthenium-powered satellite, as no satellite fell to Earth during this time.
According to the IRSN, agricultural products in the regions around the point of radioactive release would likely have been affected by the incident, but that French citizens have nothing to worry about.
It said in its report, The possibility of exceeding maximum permitted levels near the accident site led IRSN to study the scenario of importing foodstuffs from this area. From this analysis, IRSN considers, on the one hand, that the probability of a scenario that would see the importation into France of foodstuffs (especially mushrooms) contaminated by Ruthenium-106 near the source of the release is extremely low and, on the other hand, the potential health risk associated with this scenario is also very low. It does not therefore appear necessary to introduce systematic controls on the contamination of imported foods.
The IRSN said that it was now up to Russian and Khazak authorities to figure it out.
Jean-Christophe Gariel, director for health at the IRSN said, We have come up with a plausible zone of where it could have come from; we cant do any more. Russia is a vast country and were not aware of all the installations on its territory. The ball is now in the other camp.