A cloud of radioactive pollution over Europe in recent weeks indicates that an accident happened in a nuclear facility in Russia or Kazakhstan in the last week of September, the French nuclear safety institute IRSN has said.



The IRSN on Thursday 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, it 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.

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“Russian authorities have said they are not aware of an accident on their territory,” IRSN director Jean-Marc Peres told Reuters. He added that the institute had not yet been in contact with Kazakh authorities.

A spokeswoman for the Russian emergencies ministry said she could not immediately comment. It was not immediately possible to reach authorities in Kazakhstan or the Kazakh embassy in Moscow.

Peres said that in recent weeks IRSN and several other nuclear safety institutes in Europe had measured high levels of ruthenium-106, a radioactive nuclide that is the product of splitting atoms in a reactor and does not occur naturally.

IRSN estimates a significant quantity of ruthenium-106 was released, 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 several kilometres around the accident site.

The ruthenium-106 was probably released in a nuclear fuel treatment site or centre for radioactive medicine, Peres said. Because of its short half-life of about a year, ruthenium-106 is used in nuclear medicine – for example in cancer therapy for eye tumours – but can also be released when nuclear fuel is reprocessed.

Jean-Christophe Gariel, director for health at the IRSN, said the responsibility for identifying the source of the nuclear cloud was now with the Russians or Kazakhs. If they failed to identify where the contamination had come from, the matter could be referred to the United Nations, he said.

“The matter is closed as far as France is concerned. It’s not a problem for France, what is not satisfactory is that ruthenium-106 has been detected across Europe and that poses a question,” Gariel told the Guardian.



Gariel confirmed the IRSN’s conclusion that the radioactive pollution had no detrimental consequences of human health or the environment in Europe, and said he had spoken directly to Russian colleagues.



“We have come up with a plausible zone of where it could have come from; we can’t do any more. Russia is a vast country and we’re not aware of all the installations on its territory. The ball is now in the other camp.”

He added: “I have spoken to my Russian counterparts; these are people we know and they have told me in all honesty they have had no reporting of an accident.”

The IRSN ruled out an accident in a nuclear reactor, as that would have led to contamination with other substances. It also ruled out the crash of a ruthenium-powered satellite as an investigation by the International Atomic Energy Agency has concluded that no ruthenium-containing satellite has fallen back on Earth during this period.

Measurement from European stations showed relatively high levels of ruthenium-106 in the atmosphere of the majority of European countries at the beginning of October, with a steady decrease from 6 October onwards. The radioactive element has not been detected in France since 13 October.

Duncan Cox, leader of Public Health England’s radiation emergency response group, said: “Radiation monitors at our sites in Oxfordshire and Glasgow have been checked since September when this substance was reported by other European radiation monitoring institutes, and we have not detected any unusual sources of radiation.”

Monitoring stations in Germany, Austria, Italy and Switzerland all detected very low levels of ruthenium-106 from late September. Seven German stations recorded levels from a few microbecquerels to five millibecquerels per cubic metre of air, posing no hazard to health.

The French institute also said that the probability of importation into France of foodstuffs, notably mushrooms, contaminated by ruthenium-106 near the site of the accident is extremely low.

Reuters contributed to this report