MOSCOW -- A Russian nuclear submarine caught fire and was spewing smoke into the air at a port city in Russia's Far East early Monday, but fire crews extinguished the blaze, and the authorities said no radiation leaked.
Two nuclear reactors were on board, but they had been shut down before the fire started.
Crews had also removed the arsenal of torpedoes and missiles, so there was no risk of an explosion, Russian military officials said, according to the Interfax news agency.
The submarine, called the Tomsk, was docked at a shipyard near Vladivostok for repairs.
The crew evacuated after smoke started to fill the boat, the RIA news agency reported. And photographs showed smoke billowing from vents along the submarine's sides.
Concerns about radiation leaks into the Pacific Ocean are high after the Fukushima nuclear power plant disaster in Japan two years ago. And for the Russians, any submarine accident rekindles memories of the sinking of the Kursk in the Barents Sea in 2000, when some crew members were trapped alive for days but did not survive.
The Russians said the Kursk went down after one of its torpedoes exploded, but the blast did not rupture the hardened reactor segments of the submarine to release radiation.
Vows to improve safety followed, but lean post-Soviet military budgets continued to strain the Russian Navy. Under a modernization plan, Russia intends to spend 5 trillion rubles, or $166 billion, repairing and replacing naval vessels over the next eight years.
Sparks from welding during work to repair and upgrade the Tomsk most likely caused the fire on Monday, RIA reported, quoting Aleksei Kravchenko, a spokesman for the United Shipbuilding Corporation, the state-owned company doing the work.
The submarine has two hulls. An inner hull is thick enough that the interior of the submarine can be maintained at the pressure of the surface, even when deep underwater. The reactors are inside this pressurized hull.
A space for ballast tanks and other equipment separates this rigid cylinder of metal from the thin outer hull.
The fire broke out between the two hulls, Mr. Kravchenko said, separated from the two nuclear reactors by the thick inner hull. It burned paint and insulation. Firefighters extinguished it with foam, reports said.
The Tomsk is an attack submarine and, as such, would not carry strategic nuclear warheads even if all the weaponry had not been removed from the boat for the repairs. It was never threatened by the fire, the Russian authorities asserted.
An American nuclear submarine, the Montpelier, collided with a ship in 2012, and a British nuclear submarine, the Astute, beached on a sandbar in 2010. Fires broke out on Russian nuclear submarines in 2011 and in 2008 without causing a radiation leak.
This article originally appeared in The New York Times.