Nuclear Submarine Accidents

From 1961 up to the present, there have been a number of accidents and incidents involving Soviet/Russian nuclear submarines. At least 507 people have died in accidents on submarines throughout this period.  The most serious accidents have been caused by fires that have resulted in the sinking of the submarine, or by severe damage to the nuclear reactor following overheating of the reactor core (loss of coolant accidents) and a number of smaller incidents in which radioactivity has been released. Most of the vessels affected by accidents have belonged to the Russian Northern Fleet. This chapter discusses only those accidents that have resulted in the loss of life and/or in releases of radioactivity.

There have also been a number of other incidents in which Northern Fleet submarines have been involved. These include collisions with other submarines, fires at naval bases and shipyards, submarines that have become entangled in trawler nets, accidents during test launches of submarine launched missiles, collisions with icebergs and so forth.

Sunken nuclear submarines

As a consequence of either accident or extensive damage, there are six nuclear submarines that now lie on the ocean floor: two American vessels (USS Thresher and USS Scorpion) and four Soviet (K-8, K-219, K-278 Komsomolets and K-27). The two American submarines and three of the Soviet nuclear submarines sank as a result of accident; the fourth Soviet vessel was scuttled in the Kara Sea upon the decision of responsible authorities when repair was deemed impossible and decommissioning too expensive. All four of the Soviet submarines belonged to the Northern Fleet.

Despite the differences in time and in location, the Soviet submarine accidents all followed a similar pattern:

1.      Fire while submerged on return from patrol.

2.      Surfacing of the submarine. Attempts made to salvage the submarine, both in submerged and surface position. By the time of surfacing, vessel had already lost power and possibility for outside contact.

3.      Penetration of outside water into the vessel.

4.      Command post loss of control over submarine's essential systems.

5.      Loss of buoyancy and stability of pitch.

6.      Capsize and sinking.

It was not always an accident involving the nuclear reactor that caused these submarines to sink. On all of the Soviet vessels that have sunk, the reactor's shut-down mechanism had been engaged. For extra security, the control rods were lowered manually to their lowest position, an operation entailing such great risk of radiation that it presented a real threat to life.

There have been a number of incidents involving naval nuclear reactors of the Northern Fleet that have had serious consequences. Among them are accidents that have resulted in the deaths or overexposure to radiation of the crew, as well as extensive damage to the submarine. The damage was expensive and difficult to repair; and in some instances, the damage to the vessel was so comprehensive that future use was impossible.

The three most serious accidents involving Soviet nuclear submarines are described below.

K-8

The first accident involving a Soviet nuclear submarine involved the Project 627 A - November class vessel K-8, which sank in the Bay of Biscaya on April 8, 1970 while returning from the exercise OKEAN. Two fires started simultaneously in both the third (central) and eighth compartments. The submarine surfaced, but the crew was unable to extinguish the fires. The reactor emergency systems kicked in, leaving the submarine with virtually no power. The auxiliary diesel generators could not be started either. The control room and all the neighbouring compartments were filled with fumes from the fire. Air was pumped into the aft most main ballast tanks in an attempt to keep the vessel afloat. By April 10, the air tanks had been emptied, and water began to flow into the seventh and eighth compartments. On the evening of April 10, part of the crew was evacuated to an escorting ship. On the morning of April 11 at 06:20, the submarine sank at a depth of 4680 metres following a loss of stability in pitch. Fifty two people died, including the captain of the vessel. Details of this accident were kept secret until 1991.

K-219

In October 1986, the strategic nuclear submarine K-219 (Project 667 A - Yankee class) sank in the Atlantic ocean north of Bermuda with ballistic missiles on board after an explosion in one of the missile tubes. The explosion caused a leak in the fourth compartment (missile compartment). Steam and smoke from the missile fuel began to stream out of the damaged missile tube. At the time of the explosion, only one of the vessel's two reactors was running. The submarine surfaced and the other reactor was started up. Despite the fact that water was beginning to come in, a fire broke out in the fourth compartment. A short in the electrical system tripped off one of the submarine's emergency systems. One life was lost in the struggle to lower the control rods. Though still in a surfaced position, the buoyancy of the submarine was steadily impaired when water filled the main ballast tank. When the second reactor broke down, the crew was transferred to a rescue vessel. The captain and nine crew members remained in the conning tower, but when the bow began to sink, they were obliged to abandon ship. On October 6, at 11:03, the submarine sank with a loss of four lives.

The reason for the explosion in the missile tube is unclear. There are two theories of how the accident happened: a defect in the missile tube itself or a fire that broke out following a collision with an American submarine.  The submarine had two nuclear reactors and carried 16 nuclear missiles.

K-278 (Komsomolets)

In April, 1989, the nuclear submarine K-278, Komsomolets, (Project 685 - Mike class) sank in the Norwegian Sea following a fire. Komsomolets was a unique titanium-hulled submarine that could dive to depths of 1000 metres. On the morning of April 7, 1989, the vessel was on the way back to her base at Zapadnaya Litsa, positioned at a depth of 160m approximately 180km south of Bear Island. At 11:03 the alarm sounded due to a fire in the seventh compartment. Eleven minutes after the fire had broken out, the vessel surfaced. However, the fire had caused short circuits in the electrical system which set off the reactor's emergency systems. The fire was so fierce that a leak was sprung in the compressed air system, and this led in turn to a spreading of the fire. Attempts by the crew to extinguish the flames were futile. The submarine lost power, and finally ran out of compressed air. By 17:00, the leak had worsened, and the submarine lost buoyancy and stability. The crew began to be evacuated into life rafts, but there were not enough rafts. The life rafts that were lowered were too far away for the crew to reach. At 17:08, the submarine sank at a depth of 1685 meters, with a loss of 41 lives and her commander. The ship Aleksandr Khlobystsov which came to the rescue after 81 minutes took aboard 25 survivors and 5 fatalities. The exact cause of the fire is unknown. One speculation is that the concentration of oxygen in the seventh compartment was too high, setting off short circuits in the electrical system.

 The nuclear submarine Komsomolets sank in the Norwegian Sea on April 7, 1989, south of Bear Island. The submarine sank with its reactor and two nuclear warheads on board, and lies at a depth of 1 685 metres.

It has also been asserted that shortly before the accident, the vessel had completed a test that indicated it was not seaworthy. Others claim that K-278's crew was not qualified to serve on the Komsomolets.