K-141 Kursk Submarine - Russia:

K-141 Kursk was an Oscar-II class nuclear-powered cruise missile submarine of the Russian Navy, lost with all hands when it sank in the Barents Sea on 12 August 2000. Kursk was a Project 949A Антей (Antey, Antaeus, also known by its NATO reporting name of Oscar II). It was named after the Russian city Kursk, around which the largest tank battle in military history, the Battle of Kursk, took place in 1943. One of the first vessels completed after the end of the Soviet Union, it was commissioned into the Russian Navy's Northern Fleet.

During her five years of service, Kursk completed only one mission, a six-month deployment to the Mediterranean during the summer of 1999 to monitor the United States Sixth Fleet responding to the Kosovo crisis. This was due to a lack of funds for fuel. As a result, many of her crew had spent little time at sea and were inexperienced.

K-141 Kursk Submarine

Kursk joined the "Summer-X" exercise, the first large-scale naval exercise planned by the Russian Navy in more than a decade, on 10 August 2000. It included 30 ships including the fleet's flagship Pyotr Velikiy ("Peter the Great"), four attack submarines, and a flotilla of smaller ships. The crew had recently won a citation for its excellent performance and been recognized as the best submarine crew in the Northern Fleet. While it was an exercise, Kursk loaded a full complement of combat weapons. It was one of the few ships authorized to carry a combat load at all times.

On the first day of the exercise, Kursk successfully launched a Granit missile armed with a dummy warhead. Two days later, on the morning of 12 August, Kursk prepared to fire dummy torpedoes at the Kirov-class battlecruiser Pyotr Velikiy (Peter The Great). These practice torpedoes had no explosive warheads and were manufactured and tested at a much lower quality standard.

K-141 Kursk Submarine

On 12 August 2000, at 11:28 local time, there was an explosion while preparing to fire. The Russian Navy's final report on the disaster concluded the explosion was due to the failure of one of Kursk's hydrogen peroxide-fueled Type 65 torpedoes. A subsequent investigation concluded that HTP, a form of highly concentrated hydrogen peroxide used as propellant for the torpedo, seeped through a faulty weld in the torpedo casing. When HTP comes in contact with a catalyst, it rapidly expands by a factor of 5000, generating vast quantities of steam and oxygen. The pressure produced by the expanding HTP ruptured the kerosene fuel tank in the torpedo and set off an explosion equal to 100–250 kilograms (220–550 lb) of TNT.

The submarine sank in relatively shallow water, bottoming at 108 metres (354 ft) about 135 km (84 mi) off Severomorsk. A second explosion 135 seconds after the initial event was equivalent to 3-7 tons of TNT. The explosions blew a large hole in the hull and collapsed the first three compartments of the sub, killing or incapacitating all but 23 of the 118 personnel on board. More details