The Interfax news agency reported that the fire had broken out near the town of Nenoksa, about 25 km west of Severodvinsk. Russian news outlets have reported that a naval weapons test range is nearby.
The accident resulted in a “measurement of a short-term elevation in radiation,” the local government said in a statement, citing Severodvinsk’s director of civil defence, Valentin Magomedov.
The statement said that two radiation metres in the city had showed elevated levels shortly after 11.50am on Thursday. The readings declined within half an hour and returned to normal by 2pm, it said.
The state-run Tass news agency had earlier cited the Defence Ministry as offering a different assessment, saying that “there was no release of toxic materials into the atmosphere and the radiation level is normal.”
That account was consistent with readings from the Norwegian Radiation and Nuclear Safety Authority, which tracks radiation levels in the region. It said it had detected no indications of leakage as of Thursday evening.
Interfax later reported that shipping and sailing would be prohibited for a month in Dvina Bay, which is in an area of the White Sea close to the military range where the fire took place.
There were also discrepancies over details of the accident.
Tass, citing an unidentified emergency services official, reported that a fire had broken out onboard a vessel of Russia’s northern fleet northwest of Severodvinsk. An earlier report by Interfax had said the episode occurred at a weapons testing range.
No evacuation was planned for Severodvinsk, whose population is about 190,000 people, Tass reported, citing the region’s governor, Igor Orlov.