An explosion aboard a Royal Navy nuclear-powered submarine at 0420 GMT yesterday which left two sailors dead and a third injured was caused by an oxygen "candle", US and British military sources have conformed.
HMS Tireless is a Trafalgar-class nuclear attack submarine, which was on exercise under the polar ice cap with the USS Alexandria, a Los Angeles-class nuclear attack submarine. An explosion onboard Tireless forced the submarine to surface through the ice where one crew member was air lifted to the US military hospital in Anchorage.
The explosion was caused by an "oxygen candle", which is an emergency chemical oxygen generator. Oxygen candles are not dissimilar to a flare or other incendiary device in construction, the difference being that an oxygen candle produces, naturally enough, oxygen when it burns rather than consuming it.
The candles are located fore and aft on a submarine, in the emergency escape compartments where submariners go in the event of a critical accident onboard a sub. The oxygen candles allow submariners to extend their supply of breathable air until they can be rescued, if escape is not possible.
The Ministry of Defence was quick to point out that at no time was the nuclear reactor aboard the submarine in any danger, though the forward compartment is close to many weapons systems such as torpedoes. There is no "good" place to have an explosion onboard a submarine or other warship, and this is comparatively a minor accident in that the explosion was minor and contained.
The difference between a minor incident and a major incident onboard a submarine is often measured in very callous terms, and this will no doubt impact morale within the UK-submarine fleet, which has suffered technical and operational setbacks since 2001.