MOSCOW • Russia said yesterday that radioactive isotopes had been released in a recent accident at an Arctic missile test site that caused widespread alarm as the authorities kept details under wraps.
The Aug 8 blast killed five scientists and caused a spike in radiation levels, but Russia did not admit for several days that nuclear materials were involved.
The accident released swiftly decaying radioactive isotopes of strontium, barium and lanthanum, news agencies reported, citing tests by the Rosgidromet national weather and environmental monitoring agency.
Mr Alexander Uvarov, editor of the independent AtomInfo.ru news site, said the isotopes did not pose a threat to the population.
These isotopes are products of nuclear fission of uranium, he told RIA Novosti news agency.
Sensors in the nearby city of Severodvinsk detected radioactive elements with a half-life ranging from a few hours to up to 12.8 days, Rosgidromet said, adding that they broke down into radioactive inert gases. "These inert radioactive gases were the cause of a brief increase" in radiation levels, it said.
The monitor had said earlier that its sensors in Severodvinsk measured radiation levels that were up to 16 times higher than background levels after the explosion, returning to normal after 2½ hours.
Russia's Rosatom nuclear agency has said that its specialists killed in the accident were developing "new weapons" and providing support for a missile with an "isotope power source".
Norway's nuclear safety authority said it detected tiny amounts of radioactive iodine in a region bordering Russia after the blast but it could not determine if this was related to the accident.
The Russian authorities have confirmed that a doctor involved in treating those injured in the accident had a trace of radioactive isotope caesium-137 detected in his muscle tissue but denied that this was related to the incident.