Kursk submarine disaster

The Kursk submarine disaster occurred during a major Russian naval exercise in the Barents Sea on Saturday, 12 August 2000. The (Russian: Project 949A "Antey") was preparing to load a dummy 65-76 "Kit" torpedo when a large explosion caused the ship to sink. Nearby ships registered the explosion but did not know what to make of it. A second, much larger, explosion took place two minutes and 15 seconds later, and was powerful enough to register on seismographs as far away as Alaska.

The Russian Navy did not recognize that the vessel had sunk for more than six hours and it took more than 16 hours for them to locate the sunken ship. Over four days they used four different diving bells and submersibles to try to attach to the escape hatch without success. The navy's response was criticized as slow and inept. The government initially misled the public and media about the timing of the accident, stating that communication had been established and that a rescue effort was under way, and refused help from other governments. The Russian Navy offered a variety of reasons for the sub's sinking, including blaming the accident on a collision with a NATO or U.S. vessel. On the fifth day, the Russians accepted British and Norwegian offers of assistance. Seven days after the submarine went down, Norwegian divers finally opened a hatch to the rescue tube in the ship's ninth compartment, hoping to locate survivors, but found it flooded.

An investigation after most of the wreck was raised along with analysis of pieces of debris found that a crack in the casing of the practice torpedo leaked high-test peroxide that caused the kerosene fuel to explode. The initial explosion destroyed the torpedo room, severely damaged the control room, incapacitated or killed the control room crew, and caused the submarine to sink. The fire resulting from this explosion in turn triggered the detonation of between five and seven torpedo warheads after the submarine had struck bottom. This second explosion was equivalent to between 2 to 3 t of TNT. It collapsed the first three compartments and all the decks, and destroyed compartments four and five, killing everyone forward of the nuclear reactor compartment.

It was later determined that 23 sailors in the sixth through ninth compartments survived the two explosions and took refuge in the ninth compartment. They survived more than six hours before an oxygen cartridge contacted the oily sea water, triggering an explosion and flash fire that consumed the remaining oxygen. All 118 sailors and officers—111 crew members, five officers from 7th SSGN Division Headquarters, and two design engineers—aboard the Kursk died. The following year, a Dutch team was contracted by the Russians to raise the hull. Employing newly developed lifting technologies, they recovered all but the bow of the vessel, including the remains of 115 sailors, which were buried in Russia.

Naval exercise
On the morning of 12 August 2000, Kursk was participating in the "Summer-X" exercise, the first large-scale naval exercise planned by the Russian Navy in more than a decade and since the end of the Soviet Union. It included 30 ships and three submarines.

The crew had recently won a citation for its excellent performance and been recognized as the best submarine crew in the Northern Fleet. Although it was an exercise, the Kursk loaded a full complement of combat weapons. It was one of the few ships authorized to carry a combat load at all times. This included 18 SS-N-16 "Stallion" anti-ship missiles that were designed to defeat the best Western naval air defenses.

The Kursk was supposedly unsinkable. The submarine had a double hull with a 3.5 m gap separating them, nine water-tight compartments, and was as long as two jumbo jets. It had a mythical standing and was reputed to be able to withstand a direct hit from a torpedo.

At 08:51 local time, the Kursk requested permission to conduct a torpedo training launch and received the response "Dobro" ("Good"). After considerable delay, the submarine was set to fire two dummy torpedoes at the Pyotr Velikiy, the Northern Fleet's flagship. At 11:29 local time, a practice 65-76 "Kit" torpedo, (Russian: tolstushka, or "fat girl", because of its size), without a warhead, was loaded into Kursk's number 4 torpedo tube on the starboard side. It was 35 ft long and weighed 5 t.

Initial torpedo explosion
At 11:29:34 (07:29:50 UTC), seismic detectors at the Norwegian seismic array (NORSAR) and in other locations around the world recorded an explosion at a magnitude of 1.5 on the Richter scale. The location was fixed at coordinates 69.63333°N, 37.31667°W, north-east of Murmansk. about 250 km from Norway, and 80 km from the Kola Peninsula. The resulting fire was later estimated to have burned at 2700 C.

Secondary explosion
At 11:31:48, two minutes and 15 seconds after the first, a much larger explosion took place within the submarine. The blast, located at 69.6°N, 37.56667°W, showed that the ship had moved about .40 km after the initial explosion. Seismic data from stations across Northern Europe show that the explosion occurred at the same depth as the sea bed. This was enough time for the ship to sink 108 m and remain on the sea floor for a short while.

The second explosion was equivalent to 2-3 tons of TNT, or about 5-7 combat-ready torpedo warheads. A single Type 65 torpedo carries a large 450 kg warhead that is powerful enough to sink an aircraft carrier. Acoustic data from Pyotr Velikiy indicated an explosion of about 7 torpedo warheads in rapid succession. The second blast, 250 times larger than the first,, was measured 4.2 on the Richter scale on seismographs across Europe and was detected as far away as Alaska.

Rescue response


Other ships in the exercise detected an explosion, but the captain of another submarine, the Karelia, assumed that the explosion was part of the exercise. The crew aboard the battlecruiser Petr Velikiy detected a hydro-acoustic signal characteristic of an underwater explosion and felt their hull shudder. They reported the phenomena, but their report was ignored. At 13:30, the scheduled time period for Kursk to complete the practice torpedo firing expired without any contact from the sub. Fleet Commander Popov was accustomed to the constant failure of communications equipment, and so was not initially alarmed. Personnel on the Petr Velikiy interpreted the acoustic signal as an emergency ascent, but a helicopter sent to look for the Kursk didn't find it on the surface, and this was reported to Popov. The Northern Fleet duty officer notified the head of the fleet's search and rescue forces, Captain Alexander Teslenko. His primary rescue ship was the 20 year old Mikhail Rudnitsky, a former lumber carrier converted to support submersible rescue operations. She was not equipped with stabilizers capable of keeping in position during stormy weather and could only lower her rescue vessels in calm weather. Toslenko notified the Rudnitsky's captain to be ready to depart on one hour's notice.



Early in the evening, more than six hours after the explosion, Kursk failed to complete a scheduled communication check at 18:00. The Northern Fleet command became concerned and tried to contact Kursk. After repeated failures, at 18:30 they began a search and rescue operation, dispatching aircraft to locate the submarine, which failed to locate the ship on the surface. An Ilyshin 38 aircraft was dispatched to search for the Kursk but returned at 20:00 without spotting anything. At 22:30, the Northern Fleet declared an emergency, and the exercise was stopped. Between fifteen and twenty-two vessels of the Northern Fleet, including about 3000 sailors, began searching for the submarine. The Mikhail Rudnitsky, carrying  AS-32 and AS-34  (Project 1855) rescue vessels, was dispatched at 00:30.

Foreign assistance refused
On the afternoon of the explosion, even before the Kremlin had been informed of the submarine's sinking, U.S. National Security Adviser Sandy Berger and Defense Secretary William Cohen were told that the Kursk had sunk. Once officially informed, the British government, along with France, Germany, Great Britain, Israel, Italy, and Norway offered help, and the The United States offered the use of one of its two deep submergence rescue vehicles, but the Russian government absolutely refused all foreign assistance. Minister of Defence Igor Sergeyev told the American Embassy that the rescue was well underway. The Russian Navy told reporters that a rescue was imminent.

Russian rescue efforts falter
At 04:50, personnel aboard the Petr Velikiy found two anomalies on the seabed. At 09:00 the Rudnitsky arrived at the location. While setting anchor, it recorded what it interpreted as an acoustic SOS signal from the submarine, but the head of search and rescue aboard the Rudnitsky concluded this was produced by the anchor chain striking the anchor hole. At 11:30 on Sunday, August 13, the crew of the Rudnitsky began preparing to lower the AS-34, which entered the water at 17:30. At 18:30, the AS-34 reported colliding with an object, and through a porthole saw a propeller and stern stabilizer. The AS-34 was damaged and surfaced, so the crew of the Rudnitsky began preparing the AS-32 for operations.

At 22:40, the AS-32 entered the water and began searching for the submarine but was unable to locate it. Crew aboard the Rudnitsky tried to contact the Kursk and briefly thought they heard an acoustic SOS signal, but this was determined to be of biological origin. They reported the sounds to the Petr Velikiy.

The AS-34 was repaired and was launched at 05:00 on Monday, 14 August. At 06:50, the AS-34 located the Kursk and attempted to attach to the aft escape trunk over the Kursk's ninth compartment, but its batteries were depleted and they were forced to surface to recharge the batteries. Winds increased, blowing 10-12 m/sec to 15-27 m/sec (22MPH-38MPH), and the waves rose to 3-4 points (4-8 feet), forcing the Russians to suspend rescue operations.

At 20:00 Tuesday, AS-34 was launched again but was damaged when it struck a boom as it was being lowered into the sea. It was brought back aboard, repaired, and relaunched at 21:10. On Tuesday, August 15, three days after the sinking, the crane ship PK-7500 arrived with the more manoeuvrable Project 18270 Bester-type DSRV (AC-36). But the weather prevented the PK-7500 from launching the DSRV, and the rescue team decided to launch the submersible near the coast and tow it to the rescue site with a salvage tug.

On Wednesday, 16 August, at 00:20, AS-34 attempted to attach to the ninth compartment escape hatch twice but was unsuccessful. It surfaced and as it was being lifted onto the deck its propulsion system was seriously damaged. The crew of the Rudnitsky elected to cannibalize the AS-32 to repair the AS-34. Rescue operations were suspended while the repairs were made.

On Thursday at 12:00, Popov reported to the General Staff of the Navy that there had not been an explosion aboard the Kursk, the sub was intact on the seafloor, and that an "external influence" may have caused a leak between the first and second compartment.

The salvage tug Nikolay Chiker (SB 131) arrived early in the rescue operation. It used its deep water camera equipment to obtain the first images of the wrecked submarine. Video camera pictures showed severe damage from the sub's bow to its conning tower. They also revealed that the Kursk was listing at a 60 degree angle and down 5-7 degrees by the bow. The bow had ploughed about 22 m deep into the clay seabed, at a depth of 108 m. The periscope was raised, indicating that the accident occurred at a depth of less than 20 m. The bow and the sailbridge were damaged, the conning tower windows were smashed, and two missile tube lids had been torn off.

The rescue ship Altay attempted to attach a Kolokol diving bell to the sub but was unsuccessful. Russian Navy Headquarters in Moscow told media that rescuers had heard tapping from within the ship's hull, spelling "SOS... water", although the possibility of hearing tapping through the double hull was later discounted, and other reports said the sounds had been misinterpreted or even made up. The Russian Navy had previously operated two s, each of which carried a pair of small rescue submarines that could reach a depth of 693 m, but in a cost-cutting effort the vessels had been decommissioned in 1995.

Rescue divers did not attempt to tap on the hull to signal potential survivors acoustically.

Bad weather, 3.7 m waves, strong undersea currents and limited visibility impaired the rescue crews' ability to conduct operations on Tuesday and Wednesday. On Tuesday they lowered a diving bell twice but were unable to connect to the sub. They then tried and failed to manoeuvre a ROV onto the rescue hatch. On Wednesday, the PK-7500 repeatedly lowered the DSRV 110 m to the submarine but it was unable to latch onto an escape hatch. One of the rescue capsules was damaged by the storm.

On Thursday the Russian Priz DSRV made another attempt to reach the aft area of the submarine but was unable to create the vacuum seal necessary to attach to the escape trunk. Western media criticised the Russian's 32 hour response time, however the standard for deploying a recovery vessel in 2000 was 72 hours. On Friday, the rescue crews reported that the ship was listing at 20 degrees instead of the earlier reported 60 degrees.

Fragments of both the outer and inner hulls were found nearby, including a piece of Kursk's nose weighing 5 MT, indicating a large explosion in the forward torpedo room.

Britain and Norwegian help
The private Russian NTV television network and Russian newspapers criticized the navy's refusal to accept international assistance. Five days after the accident on 17 August 2000, President Putin accepted the British and Norwegian governments' offer of assistance. On 19 August at 20:00, the Norwegian ship Normand Pioneer arrived with the British rescue submarine LR5 on board, seven days after the disaster. Six teams of Russian, British, and Norwegian divers arrived on on Friday, 20 August. The Russian 328th Expeditionary rescue squad, part of the Navy's office of Search and Rescue, also provided divers.

On Friday 20 August, the Norwegians lowered a remotely operated vehicle (ROV) to the submarine. They found that the first 18 m of the ship had been destroyed by the explosions. The entire bow of the ship was a mass of twisted metal and debris.

Russian Navy officials imposed specific constraints that restricted the Norwegians divers to work on the stern of the ship, specifically the escape hatch over compartment nine and an air control valve connected to the rescue trunk. The Norwegian deep-sea divers protested against the restrictions which they felt impeded their rescue operations.

When the divers attempted to open the air control valve, it wouldn't move. Russian experts on one of the most technologically advanced submarines in the Russian fleet told the divers that they must open the valve counter-clockwise or they would break it. The divers finally went against the expert's advice and tried turning it clock-wise, which worked.

The divers tried to use the arms of the ROV to open the hatch but were unsuccessful until the morning of Monday, 21 August, when they found the rescue trunk full of water. That morning, they used a custom tool to open the lower hatch of the rescue trunk, releasing a large volume of air from the ninth compartment. Divers lowered a video camera on a rod into the compartment and found several bodies.

The salvage companies agreed that the Norwegian divers would cut the holes in the hull but only Russian divers would enter the submarine. The Norwegian divers cut a hole in the hull of the eighth compartment to gain access, and the Russian divers entered the wreck and opened a bulkhead hatch to compartment nine.

They found that dust and ashes inside compartment nine severely restricted visibility. Gradually working their way inside the compartment and down two levels, Warrant Officer Sergei Shmygin found the remains of Lieutenant-Captain Dmitry Kolesnikov and a note on his body. All of the casualties had clearly been badly burned. The divers cut additional holes in the hull over the third and fourth compartments. The Russian divers removed secret documents and eventually recovered a total of 12 bodies, two written messages, and the ship’s log, but then had to suspend work because of severe winter weather. The rescue teams conducted ongoing measurements of radiation levels inside and outside the submarine but none of the readings exceeded normal ranges.

On 21 August, the Chief of staff of the Russian Northern Fleet Mikhail Motsak announced to the public that the Kursk was flooded and the crew was dead. Additional plans were made to continue to remove the bodies, but the Russian Navy could not agree on a contract with a foreign company, and the families of those who died on the submarine protested that they did not want additional lives put at risk to bring up the dead.

Official government response
The Russian Navy initially downplayed the incident. Late on Saturday night, nine hours after the ship sank, Northern Fleet commander Admiral Popov ordered the first search for the submarine. Twelve hours after it sank, Popov informed the Kremlin, but Putin was not told until Sunday morning. On Sunday, after Popov already knew that the Kursk was missing and presumed sunk, he briefed reporters on the progress of the exercise. He said the exercise had been a resounding success and spoke highly of the entire operation.

The Russians first announced on Monday that the Kursk had experienced "minor technical difficulties" on Sunday. They stated that the submarine had "descended to the ocean floor", that they had established contact with the crew, were pumping air and power to the ship, and that "everyone on board is alive."

As the operation unfolded, senior officers in the Russian Navy offered varying explanations for the accident. At first they unequivocally blamed the sinking on a collision with a U.S. submarine, although they had no evidence to support this statement. Later on they offered other theories, including striking a World War II mine, malfunction of a torpedo, a missile strike by the Pyotr Velikiy, Chechen espionage, human error, and sabotage. This was the largest naval exercise that the Russian navy had conducted in more than a decade which increased the chances of a friendly fire incident.

Criticism of government response
While the government insisted that bad weather was making it impossible to rescue the sailors, President Putin was shown enjoying himself in casual dress on a summer holiday at a villa on the Black Sea. His seeming indifference outraged the families of the Kursk sailors and many other Russians.

Four days after the accident the government held a news briefing. During the briefing, Nadezhda Tylik, the mother of Kursk submariner Lt. Sergei Tylik, was present. She was extremely emotional and interrupted the news conference. She would not be quieted. While the cameras rolled, a woman behind her forcibly injected her with a sedative and officials removed her from the room. The government's response to her outburst and their overall handling of the disaster generated considerable public outcry.

The Russian media was extremely critical of the government's handling of the sinking. Images of angry family members demanding information or waiting anxiously at the dock for news of their family members were shown on media worldwide. Some relatives said they only learned of the disaster from the public media. They complained they didn't receive any information from the government on the status of the disaster or rescue efforts until Wednesday, five days after the sinking. Some could not even confirm whether their family members were among the crew on board the ship. The government refused to release a list of the missing sailors even to the families of those aboard until a Pravda reporter paid an officer ₽18,000 rubles for the list. Even then, the government tried to prohibit reporters from contacting family members.

The continued problems the rescuers had reaching survivors and ongoing conflicting information about the cause of the incident inflamed Russian public opinion. Media described the Russian government's response to the disaster as "technically inept" and their stories as "totally unreliable."

Putin meets with families


President Putin had been advised by the military from the start of the disaster that they had the situation under control and that he did not need to intervene. He was told that there was a strong possibility that a foreign vessel had caused the accident and that Russia should not accept help from them. Only four months into his tenure as President, the public was 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, the government's response looked incompetent, and a sailors' mothers was injected with a sedative against her will to keep her quiet.

On Tuesday, 22 August, 10 days after the sinking, Putin met at 20:00 in the Vidyayevo navy base officers club and cultural centre for almost three hours with about 400-600  angry and grief-filled family members of the Kursk's crew. The meeting was closed and access was tightly controlled. Two Russian journalists from Nezavisimaya Gazeta and Kommersant, who posed as family members, witnessed hysterical widows and mothers howling at Putin, demanding to know why they were receiving so much conflicting information and who was going to be punished for the deaths of their family members.

The Russian state channel RTR was the only media granted access. They broadcast a heavily edited version of the meeting that only showed the president speaking, eliminating many emotional and contentious interactions between the President and family members. Their single TV camera fed its signal to a satellite truck on loan to RTR from the German TV Company RTL, and they recorded the entire event. RTL provided the Russian newspaper Kommersant with an unedited transcript. Putin told the families that Admiral of the Fleet Vladimir Kuroyedov had agreed to accept foreign assistance as soon as it was offered on Wednesday, 16 August, but he was shouted down as soon as he offered this explanation. The family members knew from media reports that foreign assistance had been offered on Monday. Up to this point, family members had received ₽1000 rubles (about USD$37 in 2000) in compensation, and Putin offered the families additional compensation equivalent to ten years' salary, about USD$7,000 in 2000.

In a speech to the Russian people a few days later, Putin furiously attacked the Russian media, accusing them of lies and discrediting the country. He said they were trying to profit from the tragedy.

Family compensation announced
On the same day as Putin's broadcast, Deputy Prime Minister Valentina Matviyenko announced that the families of the Kursk sailors would receive not only 10 years' salary, but free housing in the Russian city of their choice, free college education for their children, and free counselling. With the addition of other donations received from across the world, the families received about USD$35,000 in payments, a relative fortune.

Claim of collision with NATO submarine


The Russian government convened a commission, chaired by vice-premier Ilya Klebanov, on August 14. On August 29 or 30, it announced that the likely cause of the sinking was a "strong 'dynamic external impact' corresponding with 'first event'", probably a collision with a foreign submarine or a large surface ship, or striking a World War II mine.

Russian naval sources initially said that the Kursk collided with a NATO or American submarine shadowing the exercise. 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. When the exercise was cancelled due to the accident, they put in at European ports.

U.S. Secretary of Defence William S. Cohen responded to Russian accusations of a collision with a submarine at a press conference in Tokyo on 22 September 2000.

Official inquiry
Almost a year later, the government commission and Russia's Prosecutor-General, Vladimir Ustinov, announced that the hydrogen peroxide fuel in the dummy torpedo set off the initial explosion that sank the Kursk. Ustinov released a 133 volume secret report in August 2002, two years after the disaster. A summary that was made public revealed "breaches of discipline, shoddy, obsolete and poorly maintained equipment," and "negligence, incompetence and mismanagement." The report said the rescue operation was unjustifiably delayed.

Practice torpedo explodes
Finally pushing aside the Navy's long-standing blame on a collision with a foreign vessel, the report confirmed that the Kursk had been sunk by a torpedo explosion caused when high-test peroxide (HTP), a form of highly concentrated hydrogen peroxide, leaked from cracks in the torpedo's casing. It found that the initial explosion killed everyone in the forward compartments of the ship.

HTP is normally stable until it comes in contact with a catalyst. HTP then expands 5000 times and acts as an oxidiser, generating large volumes of steam and oxygen. The oxygen is combined with kerosene fuel in the torpedo engine to propel the missile at a very high velocity. Investigators concluded that the leaking HTP had catalytically decomposed when it came in contact with copper commonly found in the bronze and brass used to manufacture the Kursk's torpedo tubes. The resulting overpressure ruptured the torpedo's kerosene fuel tank and caused an explosion that was registered as a weak seismic event on detectors hundreds of kilometres away.

The fuel in the torpedoes carried by the Kursk was inexpensive and very powerful. Torpedoes using HTP had been in use since the 1950s, but other navies stopped using them because of the danger inherent in their design. The HMS Sidon sank in 1955 when an experimental torpedo containing HTP exploded as it was being loaded, killing 13 sailors. But the cash-strapped Russian Navy continued to use the design because the fuel is very inexpensive.

Analysis revealed that when the 1000 kg of concentrated high-test peroxide and 500 kg of kerosene exploded, the internal torpedo tube cover and the external tube door were blown off, opening the torpedo room to the sea. Salvage crews located a piece of the number four torpedo hatch on the seabed 50 m behind the main wreckage. Its position, distance and direction relative to the rest of the submarine indicated that it was deposited there as a result of the first explosion in that tube.

Maintenance records revealed that the 65-76 "Kit" practice torpedo carried by the Kursk came from a batch of 10 manufactured in 1990, six of which were rejected due to faulty welding. An investigation revealed that because the torpedoes were not intended to carry warheads, the welds had never been inspected. When salvage crews finally recovered the remains of the torpedo and the launch tube, analysis determined that both bore signs of distortion and heat damage that were consistent with an explosion near the middle of the torpedo, very close to an essential welded joint.

The internal tube door was designed to be three times stronger than the external torpedo door, so that any explosion inside the tube would be directed out into the sea. Salvage crews eventually found the internal tube door embedded in a bulkhead 12 m from the tube. It was known that the electrical connectors between the torpedoes and the internal tube door were unreliable and often required the torpedo crews to open and re-close the door to clean the connection before an electrical contact could be established. The Kursk had not fired a torpedo for three years and the crew had to perform maintenance to prepare to fire the practice torpedo. This included cleaning the torpedo tube. This led investigators to conclude that it was likely that the internal door was not fully closed when the explosion occurred.

The final report found that the officers who had issued the order approving use of the HTP torpedoes did not have the authority to issue that order. The dummy torpedo was 10 years old and some of its parts had exceeded their service life. Several sources said that one of the practice torpedoes had been dropped during transport, possibly leading to a crack in the casing, but that the weapon was put aboard the submarine anyway. The crane that would normally have been used to load the missiles was, as usual, out of order, and another had to be brought in, delaying the loading process. This also made the possibility of removing a damaged torpedo more difficult.

Personnel that had loaded the practice torpedoes the day before the exercise noticed that the rubber seals were leaking fuel and notified junior officers of the issue, but they took no action because the exercise was so important to the Russian Navy. Even though the leaks on the dummy torpedoes were detected, the rubber seals weren't inspected before the exercise. The crew was also supposed to follow a very strict procedure while preparing the practice torpedo for firing. They had no experience with HTP-powered torpedoes.

After the accident, investigators recovered a partially burned copy of the safety instructions for HTP torpedoes, but the instructions were for a significantly different type of torpedo and failed to include essential steps for testing an air valve. These lapses should have been caught during inspections by the 7th Division, 1st Submarine Flotilla. Included in the technical documentation were instructions that the HTP torpedo should never be loaded into the torpedo tube more than three hours before it would be fired. The Kursk's crew had no prior experience with and hadn't been trained in handling or firing HTP powered torpedoes.

No ship collision
Geophysicists who analysed the seismic signals of the two explosions concluded that the two events were very similar. The seismic waveforms of the second event, known to be the from the explosion of several torpedo warheads, also generated a high frequency bubble signature characteristic of an underwater explosion of approximately 3-7 tons of tons of TNT. When they compared the second event with the first, they concluded that first event was also the explosion of a torpedo.

For more than two years after the disaster, senior Russian Navy officials repeatedly insisted the sub had collided with another vessel. But the experts concluded that the seismic signal was an explosion and not a collision with another vessel.

Blast damage
The first blast destroyed the torpedo room compartment and killed all seven men within. The bulkhead should have arrested the blast wave, but in keeping with Russian submarine practice, the watertight bulkhead door was left open to minimize the change in pressure and noise of the weapon's launch. The bulkhead was also penetrated by a circular 47 cm air conditioning duct. The open bulkhead door and A/C channel allowed the blast wave, fire, and toxic smoke to enter the second and perhaps the third and fourth compartments as well, whose watertight doors were also open. All of the 36 men in the command post located in the second compartment were probably immediately killed. One sailor's body was found embedded in the ceiling of the second compartment. No one in the command post was able to initiate an emergency ballast tank blow that might have resurfaced the submarine.

Rescue buoy fails
The Kursk was equipped with an emergency rescue buoy on top of compartment seven that was designed to automatically deploy when it detected a fire or rapid pressure change. It was intended to float to the surface and send a signal that would help rescuers locate the stricken vessel. Some reports said that the buoy had repeatedly malfunctioned and had been welded in place. In fact, the Kursk had been deployed to the Mediterranean during the summer of 1999 to monitor the U.S. Fleet responding to the Kosovo crisis. Russian navy officers feared that the buoy might accidentally deploy, revealing the submarine's position to the U.S. fleet. They ordered the buoy to be disabled.

Secondary explosion
The first explosion caused a fire that raised the temperature of the compartment to more than 2700 C. The heat caused the warheads of between five to seven additional torpedoes to explode. The second explosion tore a 2 m2 hole in the ship's hull. Although the Kursk was designed to withstand the external pressure of depths of up to 1000 m, the internal explosions ripped open the third and fourth compartments to the sea. When underwater, there were normally 78 crew assigned to the first four compartments and 49 to the rear five compartments. It's likely that personnel in the fourth and fifth compartments, if able, would have tried to move to the third compartment in an attempt to reach the submarine rescue capsule in the sail, which was capable of evacuating the entire crew. The second explosion collapsed the first three compartments and all of the decks together, killing anyone who remained alive in the compartments. Water poured in at 90000 l per second. The dead included five officers from 7th SSGN Division Headquarters and two design engineers on board to observe the performance of a new battery in the USET-80 torpedo, set to be launched second.

The fifth compartment that contained the ship's two nuclear reactors was built to withstand larger forces than other interior bulkheads. Like the exterior hull, these bulkheads were designed to withstand pressure up to 1000 m. The reactors were additionally encased in 13 cm of steel and resiliently mounted to absorb shocks in excess of 50g. The bulkheads of the fifth compartment withstood both explosions, allowing the two reactors to automatically shut down and preventing nuclear meltdown and widespread contamination of the sea.

Later forensic examination of two of the reactor control room casualties showed extensive skeletal injuries which indicated that they had sustained explosive force of over 50g during the explosions. These shocks would have temporarily disoriented or killed the operators and possibly other sailors further aft. Damage and flooding prevented use of the escape trunk in the first compartment or the detachable escape module located in the sail within the third compartment.

Survivors in aft compartment
There were 24 men assigned to compartments six through nine towards the rear of the ship. Of that number, 23 men survived the two blasts and gathered in the ninth compartment which contained an escape hatch. Captain-lieutenant Dmitri Kolesnikov, head of the turbine department, and one of three surviving officers of that rank, apparently took charge.

Kolesnikov wrote two notes, parts of which were released to the media, listing the names of those in the ninth compartment.

"In the ninth compartment, there are 23 people. We feel bad, weakened by carbon dioxide... Pressure is increasing in the compartment. If we head for the surface we won’t survive the compression. We won't last more than a day."

"All personnel from sections six, seven and eight have moved to section nine. There are 23 people here. We have made the decision because none of us can escape."

Lt. Rashid Aryapov also wrote a note, written on the page of a book and wrapped in plastic, was found in a pocket of his clothing when his body was recovered. The contents of the note were not released until June 2001. Aryapov wrote that the first explosion was caused by a practice torpedo.

Escape hatch unused
Analysis of the wreck could not determine whether the escape hatch was workable from the inside. Analysts theorize that the men may have rejected risking the escape hatch even if it were operable, and would have preferred to wait for a submarine rescue ship to attach itself to the hatch. When the nuclear reactors automatically shut down, emergency power would have been limited, and the crew would have been in complete darkness and experienced falling temperatures.

There was considerable debate over how long the sailors survived. Russian military officers initially gave conflicting accounts, that survivors could have lived up to a week within the sub, but those that died would have been killed very quickly. The Dutch recovery team reported that they thought the men in the least affected ninth compartment might have survived for two to three hours. Lieutenant Kolesnikov's last note has a time of 15:15, indicating that he lived almost four hours after the explosion. Other notes recovered later show that some sailors in the ninth compartment were alive at least 6 hours and 17 minutes after the ship sank.

Death of survivors
The official investigation into the disaster found that a number of potassium superoxide chemical cartridges, used to absorb carbon dioxide and chemically release oxygen to enable survival, were found in the ninth compartment. But the level of carbon-monoxide in the compartment exceeded what people can produce in a closed space. Divers had found ash and dust inside the compartment when they first opened that hatch, showing evidence of a fire. But this fire was separate from that caused by the exploding torpedo. This and other evidence found in the salvaged wreck suggested that while the crew survived for a period of time, they may have accidentally dropped one of the chemical superoxide cartridges into the seawater slowly filling the compartment. When the cartridge came in contact with the oily sea water, it triggered a chemical reaction and 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, who died of asphyxiation or carbon monoxide poisoning.

Salvage operation
The Russians contracted with the Dutch marine salvage companies Smit International and Mammoet to raise the Kursk from the sea floor. It became the largest salvage operation of its type ever accomplished. The salvage operation was very dangerous due to the risk of radiation from the reactor, along with the presence of unexploded torpedo warheads (about 225 kg TNT equivalent each), the 23 SS-N-19 "Shipwreck" cruise missiles aboard (about 760 kg each), plus each silo contained a missile ejection charge (about 7 kg TNT equivalent).

The salvage divers first detached the bow from the rest of the vessel because it may have contained unexploded torpedo warheads and because it could break off and destabilize the lifting. Salvage divers built two hydraulic anchors into the seabed and attached a high-strength abrasive saw that was pulled back and forth between the anchors. It took 10 days to detach the bow.

While they cut the bow free, the salvage crews raised a piece of a torpedo tube weighing about a ton, to try to learn if the explosion occurred inside or outside the tube; a high-pressure compressed air cylinder weighing about half a ton, to learn more about 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.

To raise the rest of the ship's hull, the salvage divers completed an extremely complex operation that employed newly developed lifting technologies. They attached a series of 26 cables to the submarine using expansion bolts inserted in holes in the hull. The operation required planners to compensate for the effects of wave motion due to rough seas which could sever the cables suspending the sub beneath the barge. They designed a hydraulic jack that was mounted on a pneumatic heave compensator for each of the 26 cables. The hull was suspended beneath the specially modified barge Giant 4. On 8 October 2001, four months after the disaster, they raised the remainder of the ship. Once the sub was raised to satisfactory level, it was carried back under the barge to the Russian Navy's Roslyakovo Shipyard in Murmansk. Once there, it was transferred to a dry dock where the weaponry and the remaining bodies of the crew were removed.

The Russians said it was too risky to raise the remainder of the bow—possibly containing undetonated torpedoes—from the seabed floor. Some analysts theorized the Russians may also have wanted to prevent foreign countries from accessing the debris which had been classified as state secrets. They decided to destroy the remains where they lay and blew up the remnants of the bow in September 2002.

Aftermath
The sinking of the ship, the pride of their submarine fleet, was a devastating blow to the Russian military. The Kursk's participation in the exercise had been intended to demonstrate Russia's place as an important player on the international stage, but it's inept handling of the crisis instead exposed its weak political decision-making ability and the decline of the country's military. Finally recognizing the hazard of the HTP-fueled torpedoes, the Russian Navy ordered all of them to be removed from service.

Accusations of cover-up
The Communist newspaper Komsomolskaya Pravda reported in June 2001 that senior officers in the Russian Navy had engaged in an elaborate deception to cover the actual cause of the disaster. This included a message from the ship's Captain Lyachin, who asked headquarters immediately prior to the explosion, "We have a malfunctioning torpedo. Request permission to fire it."

The Russian Navy was later criticized as misrepresenting facts and misleading the public. Their response was compared to the Soviet style of cover up and stonewalling like that during the Chernobyl disaster. Minister of Defence Sergeyev said in interviews on March 21, 2000, that he had never refused any foreign help.

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

Putin's action
Putin removed a general from his position as Defence Minister, a move that shocked the Russian military. That position had always been filled by a professional member of the military. He transferred the Northern Fleet commander, Vyacheslav Popov, to a lateral job in the Ministry of Atomic Energy. Putin also dismissed Popov's chief of staff, Admiral Mikhail Motsak, and the fleet's submarine commander, Vice Admiral Oleg Burtsev. Prosecutor General Vladimir Ustinov told Putin that the entire exercise had been "poorly organized" and that the probe had revealed "serious violations by both Northern Fleet chiefs and the Kursk crew." Putin also demoted Deputy Prime Minister Ilya Klebanov, who had been in charge of the rescue operation and follow-up inquiry, to Minister of Industry, Science and Technology. The government dismissed another eight officers for their poor performance during the initial rescue efforts.

Remains removed
While Russia was roundly criticised for its slow response, experts generally agreed afterward that there was little hope in rescuing the sailors trapped in the ninth compartment. The Russian rescue teams were poorly equipped and badly organized, while foreign teams and equipment were simply too far away.

The remains of 115 dead crew members were removed from the wreck and buried in Russia. Three of the crew members could not be identified and recovered. President Putin signed a decree and awarded the Order of Courage to the entire crew, and the title Hero of the Russian Federation to the submarine's captain, Gennady Lyachin.

International cooperation
As a result of the disaster, Russian began participating in NATO search and rescue exercises during 2011. It was the first time a Russian submarine had taken part in a NATO led exercise. The Russian Navy also increased the number of deep-sea divers trained each year from 18-20 to 40-45.

Memorials
The torn sail of a submarine was used as a memorial at the submarine's home port, the Vidyayevo naval base. It lists the names of the crew members. Outside the city of Severokvinsk where the sub was built, a large granite slab was erected on the sand dunes. It was engraved, "This sorrowful stone is set in memory of the crew of the nuclear submarine Kursk, who tragically died on 12 August 2000, while on military duty." The port city of Severodvinsk erected a small memorial. Other memorials were built in Moscow, St. Petersburg, Sevastopol, Severomorsk and Kursk. The city of Kursk erected a memorial to the submarine named after the city.



On 17 March 2009, a reporter from the newspaper Murmanskiy Vestnik found the deck cabin from the sail of the Kursk in a dump. It had been left there after several years of negotiations had failed to raise money for a memorial. The discovery sparked an outcry among citizens of Murmansk and they demanded it be turned into a memorial to the men who died. After considerable difficulty, the memorial was finally completed and dedicated on Russian Navy’s Day, on Sunday, 26 July 2009. The inscription reads “To the submariners who died in peacetime”. The memorial contains a “Path of Glory” lined with 118 birches, one for each sailor who died aboard the submarine. Twelve of the sailors are buried at the memorial.