"A Radioactive Cloud Wafts Over Europe, With Russia as Chief Suspect"

"LONDON — Scientists across Europe have been puzzling about a phenomenon that seemed laden with mystery and menace in somewhat uneven proportions — a concentration of radioactive pollution caused by a nuclide called ruthenium 106.

Official monitors in France and Germany concluded that, based on weather patterns, the contamination detected since late September had emanated from southern Russia or from Kazakhstan.

“The most plausible zone of release lies between the Volga and the Urals,” the French Institute for Radiation Protection and Nuclear Safety said on Nov. 9. Jean-Marc Peres, the institute’s director, told Reuters that the geographic area could indicate a spillage in Russia or in Kazakhstan."

Alan Cowell reports for the New York Times November 15, 2017.