Russian submarine Kursk (K-141)

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, full name Атомная подводная лодка «Курск», which, translated, means the nuclear-powered submarine "Kursk" [АПЛ "Курск"] in Russian, 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.

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.

Explosion

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, she prepared to fire dummy torpedoes at the Kirov-class battlecruiser Pyotr Velikiy. These practice torpedoes had no explosive warheads and were manufactured and tested at a much lower quality standard.

On 12 August 2000, at 11:28 local time (07:28 UTC), 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 5000 times, generating vast quantities of steam and oxygen. The pressure produced by the expanding HTP ruptured the kerosene fuel 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 kilometres (84 mi) off Severomorsk, at 69°40′N 37°35′E. 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.[8]:208

Rescue attempts

Though the Americans, British and Norwegian navies offered assistance, Russia refused all help.

All 118 sailors and officers aboard Kursk perished. The Russian Admiralty initially told the public that the majority of the crew died within minutes of the explosion, but on August 21 Norwegian and Russian divers found 24 bodies in the ninth compartment, the turbine room at the stern of the boat. Captain-lieutenant Dmitri Kolesnikov wrote a note listing the names of 23 sailors who were alive in the compartment after the ship sank.

A potassium superoxide cartridge of a chemical oxygen generator, used to absorb carbon dioxide and chemically release oxygen to enable survival, appears to have been the cause of the survivors' death. The investigation found a cartridge had come in contact with the sea water inside the ninth compartment, causing a chemical reaction and a flash fire. The investigation showed that some men temporarily survived this fire by plunging under water, as fire marks on the bulkheads indicated the water was at waist level at the time. But the fire consumed all remaining oxygen, killing the remaining survivors.

Russia's then President Vladimir Putin, though immediately informed of the tragedy, was told by the navy that they had the situation under control and rescue was imminent. He waited five days before he ended his holiday at a presidential resort in subtropical Sochi on the Black Sea. Only four months into his tenure as President, the public and media were extremely critical of Putin's decision to remain at a seaside resort, and his highly favourable ratings dropped dramatically. The President's response appeared callous and the government's actions looked incompetent.

A year later he said, "I probably should have returned to Moscow, but nothing would have changed. I had the same level of communication both in Sochi and in Moscow, but from a PR point of view I could have demonstrated some special eagerness to return."

Submarine recovery

A consortium formed by the Dutch companies Mammoet and Smit International was awarded a contract by Russia to raise the vessel, excluding the bow. They modified the barge Giant 4 which eventually raised Kursk and recovered the remains of the sailors.

When the salvage operation raised the boat in 2001, there were considerable fears that preparing to move the wreck could trigger explosions. But the salvage team first cut the bow off using a tungsten carbide-studded cable. This tool had the potential to cause sparks which would ignite remaining pockets of volatile gases, such as hydrogen. The successfully recovered portion of Kursk was towed to Severomorsk and placed in a floating dry dock where extensive forensic analysis was accomplished.

The remains of Kursk's reactor compartment were towed to Sayda Bay on Russia's northern Kola Peninsula – where more than 50 reactor compartments were afloat at pier points – after a shipyard had defuelled the boat in early 2003.

The rest of the boat was then dismantled for scrap.

In the end the bow was not recovered and was destroyed by explosives in 2002. Only small pieces of the bow were recovered (some torpedo and torpedo tube fragments).

Official inquiry results

Finally pushing aside the Navy's long-standing blame on a collision with a foreign vessel, a report issued by the government attributed the disaster to a torpedo explosion caused when high-test peroxide (HTP), a form of highly concentrated hydrogen peroxide, leaked from a faulty weld in the torpedo's casing. The report found that the initial explosion destroyed the torpedo room compartment and killed everyone in the first compartment. The blast entered the second and perhaps the third and fourth compartments through an air conditioning vent. All of the 36 men in the command post located in the second compartment were immediately incapacitated by the blast wave and possibly killed. The first explosion caused a fire that raised the temperature of the compartment to more than 2,700 °C (4,890 °F). The heat triggered the warheads of between five to seven additional torpedoes to detonate, creating an explosion equivalent to 2-3 tons of TNT] that was measured 4.2 on the Richter scale on seismographs across Europe and was detected as far away as Alaska.

Other explanation

Vice-Admiral Valery Ryazantsev differed with the government's official conclusion. He cited inadequate training, poor maintenance, and incomplete inspections that caused the crew to mishandle the weapon. During the examination of the wrecked sub, investigators recovered a partially burned copy of the safety instructions for loading HTP torpedoes, but the instructions were for a significantly different type of torpedo and failed to include essential steps for testing an air valve. The 7th Division, 1st Submarine Flotilla never inspected Kursk's crew's qualifications and readiness to fire HTP torpedoes.

The Kursk's crew had no prior experience with and hadn't been trained in handling or firing HTP powered torpedoes. Due to their inexperience and lack of training, compounded by incomplete inspections and oversight, and because the Kursk's crew followed faulty instructions when loading the practice torpedo, Ryazantsev believes they set off a chain of events that led to the explosion