(Science) For 2 weeks in September and October last year, traces of the humanmade isotope ruthenium-106 wafted across Europe, triggering detectors from Norway to Greece and Ukraine to Switzerland. The radioactive cloud was too thin to be dangerous, containing no more than a few grams of material, but its origin posed an outsize mystery.
Now, scientists at the French Institute of Radioprotection and Nuclear Security (IRSN) in Paris say the isotope may have been released from the Mayak nuclear facility near Ozyorsk in southern Russia. IRSN argues that the leak could have taken place when Mayak technicians botched the fabrication of a highly radioactive component for a physics experiment at the Gran Sasso National Laboratory in L'Aquila, Italy.
The Russian government and state nuclear operator Rosatom have vehemently denied that an accident took place, however. Meanwhile, an international committee set up by the Russian Academy of Sciences's Nuclear Safety Institute (IBRAE) in Moscow that met on 31 January is divided over the origins of the pollution.
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