The IRSN said the concentrations of ruthenium 106 in the air recorded in Europe were of no consequence for human health and the environment.
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.
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, 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.
