Russian Submarine Kursk.

The Russian submarine Kursk, which sank on August 12^th 2000, was the pride of the Russian navy, and with its unique double hull was designed to be indestructible - able to withstand a direct hit and survive. Indestructible that is, until a catastrophic event led to it sinking in the Barents sea with the loss of the whole crew, 118 men.

With the cause of the loss officially unannounced by the then Soviets, it was originally blamed on an underwater collision between the Kursk and one of the American submarines shadowing the Russian Navy exercises. However, analysed data from one of the UK's premier seismic monitoring stations suggested another cause.

Multiple Explosions.

The comparative seismic record of the event, obtained by secret British listening station, AWE Blacknest, was carefully analysed and it was realised that the event bore the hallmarks not of a collision, but of a double explosion, one lesser, and then the catastrophic one that destroyed the ship.

Based on knowledge of the construction of the Kursk, scientists looked for possible sources of explosive material, sufficient to be registered, but not enough to destroy the submarine. The torpedoes in the bow section on board the Kursk had conventional warheads, but they are powered by motors using high test hydrogen peroxide (HTP) as a source of oxygen for underwater running - designs owing more than a passing nod to those designed by Hellmuth Walter sixty years ago.

HMS Sidon's HTP Accident.

On the morning of 16^th June 1955, British submarine HMS Sidon was loading a new design of torpedo, the "Fancy", with an HTP supported motor whilst moored in Portland Harbour. Quite unexpectedly an explosion and fire blew out the watertight bulkhead at the forward end of the submarine, killing 12 submariners. Within a few moments HMS Sidon sank at the quayside, also claiming the life of the Medical Officer of the depot ship alongside which she was moored, who had rushed onto the stricken submarine to help in the rescue of the on-board crew.

After the accident was investigated, it was found that an engineer readying the torpedo for the morning's test firing had run the motor inside the submarine, overspeeding the motor, over-pressurising the torpedo's internal pipework. This had caused a leak in the HTP lines, and peroxide had come into contact with copper fittings inside the casing, decomposing it into oxygen, gas and steam. With the massive increase in volume in the sealed torpedo casing, an explosion was the consequence - not of the warhead, but a catastrophic rupturing of the metal casing under pressure, sending large pieces of the torpedo through the submarine with enormous force.

It is thought that in the Kursk, similar circumstances prevailed. The mission profile for the Kursk that day was to fire a torpedo, and testing it would certainly have been among the orders. The seismic record is consistent with the detonation from a build-up of HTP, and if the rupture of a torpedo casing produced a spray of pure oxygen, superheated steam and fuel, then students of this subject can see there is potential for a serious fire. A fire sprayed around in the confines of the Kursk torpedo room might run quickly out of control, detonating the other torpedo warheads in a huge explosion, sinking the impregnible submarine in a moment.

It's an interesting thought that the work done in Germany sixty years ago still has a relevance today, - the dangers of HTP having been well established and well catalogued. There is no suggestion that there was a mishandling of HTP, and under normal use it is safe and robust. But Britain abandoned the Fancy torpedo, and with the exception of Russia, and Sweden, few countries have pursued its use for underwater motors; the Spearfish torpedo being one of the remaining modern HTP units.

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