Revealing the Soviet nuclear submarine K-278 on the ocean floor

The Soviet submarine K-278 had a diving depth much greater than that of its contemporary competitors, beyond the diving range of enemy torpedoes.

Soviet submarine graphic. Source: US Defense Intelligence Agency.

In the mid-1980s, the Soviet Union built a super submarine unlike any other. It was fast and capable of diving to incredible depths. The Komsomolets submarine was introduced in 1984, signaling a new direction for the Soviet Navy.

But five years later, the submarine Komsomolets and its nuclear weapons lay at the bottom of the ocean. Two-thirds of the crew on board were killed.

The history of the ship Komsomolets dates back to 1966.

Double shell

A team from the Rubin Design Bureau (headed by NA Klimov) and chief designer YN Kormilitsin was instructed to begin work on project 685 – a deep-diving submarine.

The research effort lasted eight years, possibly due to the lack of a suitable metal that could withstand the enormous pressure of water at great depths. In 1974, the double-hull design was completed. Titanium alloy was chosen for the inner hull.

Project 685, also known as Project K-278, was a prototype ship for testing deep-diving Soviet submarines.

The Sevmash shipyard began construction of the ship on April 22 (Lenin's birthday) in 1978. The ship was officially completed on May 30, 1983. Difficulties in cutting and bending titanium added to the already long construction time.

The K-278 is 109m long and 12m wide. The inner hull is approximately 7.3m wide. The displacement is 6,500 tons. The use of titanium instead of steel has significantly reduced the weight of the ship.

The K-278 submarine has a unique double hull. The inner hull is made of titanium, which gives the submarine the ability to dive deep. The interior of the submarine is divided into 7 compartments, of which 2 are reinforced to create a safe zone for the crew. There is an escape compartment so that the sailors can abandon the submarine in case of an accident when the submarine is submerged at a depth of up to 1,500m.

The submarine is powered by a 190-megawatt OK-650B-3 nuclear pressurized water reactor, which drives two steam turbines. This engine allows the submarine to reach a submerged speed of 30 knots and a surface speed of 14 knots.

The submarine has the MGK-500 “Skat” (NATO codename Shark Gill) sonar system – this type is currently used on the Yasen-class attack submarines. This sonar system provides information to the Omnibus-685 Combat Information Control system.

The K-278 submarine's armament consisted of six torpedo tubes with a standard diameter of 533mm, including 22 type 53 torpedoes and Shkval anti-submarine torpedoes.

K-278 joined the Red Banner Northern Fleet in January 1984 and began a series of deep diving tests.

Under the command of Captain Yuri Zelensky, the submarine set a record diving depth of 1019m – an amazing achievement considering that the equivalent American Los Angeles-class submarine only has a maximum diving depth of 450m.

The Soviet submarine had a special surfacing system, called Iridium, which used gas generators to blow air into the ballast tanks.

The Soviet Navy believed that the K-278 submarine was not at risk of attack when it dived to a depth of over 1,000m. At that depth, it was very difficult to detect the submarine, while enemy torpedoes, especially the American Mark 48, could only dive to a maximum depth of 800m.

Although it was originally a test submarine, it was eventually converted into a fully operational vessel in 1988. It was named Komsomolets, which means “member of the Communist Youth League.”

Fire incident

On April 7, 1989, while operating at a depth of 386m, the Komsomolets suffered an accident in the middle of the Norwegian Sea. The crew on board was the second crew of the submarine, newly trained to operate the vessel. Furthermore, due to its origins as a test vessel, it lacked a damage control unit.

A fire broke out in the seventh chamber near the stern. The fire damaged the air supply valve. Fire suppression efforts failed. The reactor was shut down and the buoyancy system was activated to bring the submarine to the surface.

The fire continued to spread. The crew continued to fight the fire for another six hours before the order to abandon ship was given.

The fire was so intense that the anti-echo rubber coating on the outer shell peeled off due to the heat.

Captain Evgeny Vanin and four other officers returned to the ship to find sailors who had not heard the order to abandon ship.

Vanin and his rescue team could not go any further – the ship was listing 80 degrees ahead. The group entered the lifeboat, which was initially indestructible but eventually broke free of the badly damaged ship. As the lifeboat neared the surface, the sudden change in pressure caused the top hatch to blow off, throwing two sailors out of the lifeboat. However, the lifeboat, as well as the captain and the rest of the rescue team, then sank beneath the waves.

Up to that point, only four people had died from the submarine accident. However, after the ship sank, many sailors died from the cold water temperature. An hour later, the fishing boats Alexi Khlobystov and Oma swam in and rescued 30 people. Some of those rescued later died. Of the 69 sailors originally on board the submarine when the disaster occurred, 42 died, including Captain Vanin.

The Komsomolets sank at a depth of 1,600m, along with its nuclear reactor and two Shkval torpedoes equipped with nuclear warheads.

Between 1989 and 1998, seven expeditions were made to stop the radioactive leak and weld the torpedo tubes. Russian sources claim that during these expeditions, evidence of unauthorized visits to the sunken submarine by foreigners was discovered.

According to VOV