The northern department of Russia’s federal service for hydrometeorology and environmental monitoring, Roshydromet, together with its research association Typhoon, on Monday revealed some of the radionuclide composition found after analyzing gases from the cloud sweeping over Severodvinsk in the hours after the fatal accident on Aug. 8. According to information posted by Roshydromet, the researchers found a mixture of isotopes of barium, strontium and lanthanum and daughter nuclides. All are short-lived fission products. Norwegian nuclear safety expert Nils Bøhmer says the information removes any doubts about the explosion's nuclear nature. "The presence of decay products like barium and strontium is coming from a nuclear chain reaction. It is proof that it was a nuclear reactor that exploded," Bøhmer says.

news Russia Finds Radioactive Isotopes in Test Samples After Accident in Severodvinsk Read more

He explains that such a mixture of short-lived isotopes would not have been found if it was simply an "isotope source" in a propellant engine that exploded like Russian authorities first said. Nils Bøhmer is today the head of R&D with Norwegian Nuclear Decommissioning, a governmental agency established to study options for safe handling of the spent fuel from the country’s closed-down research reactors. Several public statements from Russian officials in the days after the accident, which happened on a barge offshore from Nenoksa test site, claimed the failed test involved an "isotope source of a liquid-fueled propulsion unit." That triggered speculations it could have been a radioisotope thermoelectric generator (RTG). Such isotope sources are previously known to come from lighthouses in the remote Arctic regions and space satellites. "Had it been an RTG none of these isotopes would have been detected," Bøhmer says.