BBC NEWS - An explosion on a submarine which killed two British sailors was caused by an emergency oxygen device, the US military has said.
The men died on board the Devonport-based nuclear submarine HMS Tireless during a joint British-US operation under the Arctic icecap.
A third sailor was airlifted to a US military hospital in Anchorage. He is expected to make a full recovery.
A Board of Inquiry has begun into the accident on Wednesday morning.
The Trafalgar-class submarine made an emergency surface after the explosion, breaking through the ice off the Alaskan coast.
Tireless is nuclear powered, but it does not carry nuclear-armed missiles
US authorities said air-purification equipment, known as a self-contained oxygen generation candle, was the source of the blast.
The air purification system, which is not the submarine's main oxygen supply, is in the forward escape compartment - a "quiet" area at the front of the vessel, where submariners go to relax when they are not on duty.
Oxygen candles are emergency devices that create oxygen through a chemical reaction. Some devices burn at high temperatures during the reaction.
HMS Tireless was launched in 1985. The piece of air-purification machinery thought to have failed was fitted as part of an update in 2001.
The submarine is the third of seven Trafalgar-class SSN submarines in the Royal Navy, and usually carries of crew of 130.
All Trafalgar-class submarines are armed with five tubes capable of firing Tomahawk missiles.
Thursday, March 22, 2007