Kursk explosion

On 12 August 2000, the Russian class 949a "Antey" submarine Kursk sank in the Barents Sea. An investigation showed that a leak of hydrogen peroxide in a torpedo led to explosion of its fuel, causing the submarine to hit the bottom which in turn triggered the detonation of further torpedo warheads about two minutes later. This second explosion was equivalent to between two to three tonnes of TNT, large enough to register on seismographs across Northern Europe.

Despite a rescue attempt by British and Norwegian teams, which was severely delayed due to the Russians refusing them access, all 118 sailors and officers aboard Kursk died. The next year, a Dutch team recovered the wreckage and all of the bodies, which were buried in Russia.

The explosion
On the morning of 12 August 2000, as part of a naval exercise, Kursk was to fire two dummy torpedoes at Kirov-class battlecruiser Pyotr Velikiy, the flagship of the Northern Fleet. At 11:29 local time (07:29:50 UTC), a 65-76 "Kit" torpedo was loaded into Kursk's number 4 torpedo tube. Because of a leaking weld in the torpedo's fuel system, high test peroxide, a form of highly concentrated hydrogen peroxide used as an oxidiser for the torpedo's engine, escaped into the torpedo casing where it catalytically decomposed on the metals and oxides present there, yielding steam and oxygen. The resulting overpressure ruptured the kerosene fuel tank, causing an explosion that registered as a weak seismic signature on detectors hundreds of kilometres away. A similar incident was responsible for the loss of HMS Sidon in 1955.

Recovered remains of the torpedo later allowed the first explosion to be pinpointed to the middle part of the torpedo. According to maintenance records the dummy torpedoes, manufactured in the 1990s, had never had their welds checked; such checks were considered unnecessary as the torpedoes did not carry warheads.

The explosive reaction of 1.5 tons of concentrated hydrogen peroxide and 500 kg of kerosene blew off the external torpedo tube cover and the internal tube door. (The torpedo tube cover was later found on the seabed and its position relative to the rest of the submarine served as evidence of this version of events.) The tube door, which should have been capable of withstanding such an explosion, was not properly closed; the electrical connectors between the torpedoes and the tube doors were unreliable and often required repeated reclosing of the door before a contact was established, so it is likely that at the moment of explosion the door was not fully closed. The blast entered the front compartment, probably killing all seven men there. The bulkhead should have arrested the blast wave, but it was penetrated by a light air conditioning channel which allowed passage of the blast wave, fire, and toxic smoke into the second and perhaps third and fourth compartments, injuring or disorienting the 36 men in the command post located in the second compartment and preventing the initiation of an emergency ballast tank blow to resurface the submarine.

An automatic emergency buoy, designed to release itself on detection of conditions such as fire or rapid pressure changes and intended to help rescuers locate the stricken vessel, did not deploy. The previous summer, in a Mediterranean mission, fears that the buoy might accidentally deploy and reveal a submarine's position to the U.S. fleet had led to it being disabled.

Two minutes and fifteen seconds after the initial eruption, a much larger explosion took place on the submarine. Seismic data from stations across Northern Europe show that the explosion occurred at the same depth as the sea bed, suggesting that the submarine's collision with the sea floor, combined with rising temperatures due to the initial explosion, had caused other torpedoes to explode. The second explosion was equivalent to 2-3 tons of TNT, or about 5-7 torpedo warheads, and measured 4.2 on the Richter scale. Acoustic data from Pyotr Velikiy indicated an explosion of about 7 torpedo warheads in rapid succession.

The second explosion ripped a 2 m2 hole in the hull of the craft, which was designed to withstand depths of 1000 m, and also ripped open the third and fourth compartments. Water poured into these compartments at 90000 l per second killing all those in the compartments, including five officers from 7th SSGN Division Headquarters. The fifth compartment contained the ship's two nuclear reactors, encased in 13 cm of steel and resiliently mounted to absorb shocks in excess of 50g. The bulkheads of the fifth compartment withstood the explosion, allowing the two reactors to shut down automatically and preventing nuclear meltdown or contamination.

Later forensic examination of two of the reactor control room casualties showed extensive skeletal injuries which indicated that they had sustained shocks of over 50g during the explosions. These shocks would have temporarily disoriented the operators and possibly other sailors further aft.

Twenty-three men working in the sixth through ninth compartments survived the two blasts. They gathered in the ninth compartment, which contained the secondary escape hatch (the primary hatch having been in the destroyed second compartment). Captain-lieutenant Dmitri Kolesnikov (one of three surviving officers of that rank) appears to have taken charge, writing down the names of those who were in the ninth compartment. The air pressure in the compartment following the secondary explosions was still normal surface pressure and so it would be possible, at least from a physiological point of view, to don survival suits and use the hatch to escape one man at a time, swimming up through 100 m of Arctic water to await help at the surface.

It is not known if the escape hatch was workable from the inside; opinions differ about how badly it was damaged. The men would likely have rejected risking the escape hatch even if it were operable, and may have preferred instead to take their chances waiting for a submarine rescue ship to clamp itself onto the hatch. As the nuclear reactors had automatically shut down, emergency power would soon have run out, plunging the crew into complete darkness and falling temperatures. Kolesnikov wrote two further messages, much less tidily.

There has been much debate over how long the sailors survived. Russian sources say that they would have died very quickly. The Dutch recovery team report a widely believed two- to three-hour survival time in the least affected sternmost compartment. In normal operation, water leaks into a stationary Oscar-II craft around the propeller shafts, and at 100 m depth it would have been impossible to prevent. Others point out that many superoxide chemical cartridges, used to absorb carbon dioxide and provide oxygen in an emergency, were found to have been used when the craft was recovered, suggesting survival for several days. The cartridges seem to have been the final cause of death: a cartridge appears to have come in contact with oily sea water, causing a chemical reaction and flash fire. The official investigation into the disaster showed that some men survived this fire by plunging under water (fire marks on bulkheads indicate the water was at waist level at the time) but the fire would have used up any remaining oxygen in the air, causing death by asphyxiation.

Rescue attempts


Initially the other ships in the exercise, all of which had detected an explosion, did not report it. Each only knew about its own part in the exercise, and assumed that the explosion was that of a depth charge, and part of the exercise. It was not until the evening that commanders stated that they became concerned that they had heard nothing from Kursk. Later in the evening, and after repeated attempts to contact Kursk had failed, a search and rescue operation was launched. The rescue ship Rudnitsky carrying two submersible rescue vessels, AS-32 and the Priz (AS-34) reached the disaster area at around 8:40 AM the following morning.

There has been much debate over how long the sailors might have survived. Some point out that many potassium superoxide chemical cartridges, used to absorb carbon dioxide and chemically release oxygen to enable survival, were found used when the craft was recovered, suggesting some of the crew survived for a significant time. Lieutenant Kolesnikov's last note has a time of 15:15, indicating that he and the others in the aft compartment lived at least four hours after the explosion. However 32 hours after the first explosion no attempt was made acoustically (i.e. hull tapping) to signal the Russian Submarine Rescue Vehicle (SRV) Priz when it attempted to mate with the aft escape trunk. Western media criticised the 32 hour response as being very slow however the international published SRDRS response time in 2000 was 72 hours. The submarine was found in an upright position, with its nose ploughed about 2 metres deep into the clay seabed, at a depth of 108 metres. The periscope was raised, indicating that the accident occurred at shallow depth. The bow and the sailbridge showed signs of damage, the conning tower windows were smashed and two missile tube lids were torn off. Fragments of both the outer and inner hulls were found nearby, including a fragment of Kursk's nose weighing 5 metric tons, indicating a large explosion in the forward torpedo room.

Priz reached Kursk's ninth compartment the day after the accident, but failed to dock with it. Bad weather prevented further attempts on Tuesday and Wednesday. A further attempt on Thursday again made contact but failed to create a vacuum seal required to dock.

The United States offered the use of one of its two Deep Submergence Rescue Vehicles, as did the British government, but all offers were refused by the Russian government. Four days after the accident on 16 August 2000, the Russian government accepted the British and Norwegian governments' assistance and a rescue ship was dispatched from Norway on 17 August and reached the site on 19 August. British and Norwegian deep-sea divers reached the ninth compartment escape hatch on 20 August. They were able to determine that the compartment was flooded, and all hope of finding survivors was lost.

Russian government response
The first fax sent from the Russian Navy to the various Press offices said the submarine had "minor technical difficulties". The government played down the incident and then claimed bad weather was making it impossible to rescue the people on board.

On 18 August 2000 Nadezhda Tylik, mother of Kursk submariner Lt. Sergei Tylik, produced an intense emotional outburst in the middle of an in-progress news briefing about Kursk's fate. After attempts to quiet her failed, a nurse injected her with a sedative by force from the back, and she was removed from the room, incapacitated. The event, caught on film, caused further criticism of the government's response to both the disaster, and how the government handled public criticism of said response.

According to Raising Kursk broadcast by the Science Channel:

Collision theory


At first, Russian naval sources expressed suspicion that Kursk collided with an American submarine. As is common, the exercise was monitored by two American Los Angeles-class submarines– USS Memphis (SSN-691) and USS Toledo (SSN-769)–and the Royal Navy Swiftsure class submarine HMS Splendid; after the disaster the exercise was cancelled and they put in at European ports.

The Guardian wrote in a 2002 review of two books on this topic, Kursk, Russia's Lost Pride and A Time to Die: The Kursk Disaster:

William S. Cohen (Secretary of Defence of the United States), at a press-conference in Tokyo on September 22, 2000, declared

Salvage
Most of the submarine's hull, except the bow, was raised from the ocean floor by the Dutch marine salvage companies Smit International and Mammoet in late 2001 and towed back to the Russian Navy's Roslyakovo Shipyard. The front section was cut off because of concerns it could break off and destabilize the lifting. It was cut off using a chain of drums covered with an abrasive, pulled back and forth between two hydraulic anchors dug into the seabed; the cutting took 10 days. The remnants of the bow were destroyed by explosives in September 2002, raising further concerns among the adherents of the conspiracy theory.

The bodies of the dead crew were removed from the wreck and buried in Russia – three of them were unidentifiable because they were so badly burned. Russian President Vladimir Putin signed a decree awarding the Order of Courage to all of the crew and the title Hero of the Russian Federation to the submarine's captain, Gennady Lyachin.

The first five fragments to be raised were a piece of a torpedo tube weighing about a ton (to ascertain if the explosion occurred inside or outside), a high-pressure compressed air cylinder weighing about half a ton (also to ascertain the nature of the explosion), part of the cylindrical section of the hard frame and part of the left forward spherical partition to determine the intensity and temperature of the fire in the forward compartment, and a fragment of the SONAR system dome.

The presence of explosives in the unexploded torpedoes (about 225 kg TNT equivalent each) and especially in the 23 SS-N-19 "Shipwreck" cruise missiles aboard (about 760 kg each, plus about 7 kg TNT equivalent of the silo ejection charge), together with the risk of radiation release from the reactors, presented a unique set of challenges to the salvage teams.