On March 21st, the British attack submarine (SSN) HMS Tireless
lost two men when a SCOG (Self-Contained Oxygen Generator) exploded during a
training exercise. The SCOG apparently had some of its vents clogged or
blocked. That's a dangerous situation. A SCOG works by burning (at about 1,100
degrees Fahrenheit) sodium chlorate and iron powder, which releases oxygen. For
every pound of material burned, there's enough oxygen produced to keep a man
alive for three hours. These cylindrical devices are commonly called "oxygen
candles." They are only used in emergencies, or in combat situations where
maximum silence is required (to avoid enemy detection.) The normal oxygen
producing and distribution system contains
machinery that makes some noise. The SCOGs are much quieter. The most recent
"oxygen candles" are actually square, but are unwrapped, visually inspected and
inserted into the SCOG just like the older cylindrical ones.
HMS Tireless was participating in an exercise in the Arctic Ocean, off the
coast of Alaska, with American forces. After the explosion, a commercial
helicopter met the surfaced sub and transported a third sailor, who was injured
by the exploding SCOG, to a nearby airstrip. There, a U.S. Air National Guard
C-130 took the British sailor to a major hospital in Anchorage, Alaska. From
the time of the explosion, to the burned sailor arriving at the regional
hospital, took about six hours.
There was no serious damage done to the submarine. The exact cause of the
explosion won't be known for a while, but it was probably a defective SCOG
(clogged vents or other poor construction).