1970, April 8. A November class submarine, the K-8, sank in the Bay of Biscaya while returning from a naval exercise. Two fires started simultaneously, in the central and rear compartments. The submarine surfaced, but the crew was unable to extinguish the fires. The reactor emergency system kicked in, leaving the submarine with virtually no power. Two days later, on April 10, the air tanks keeping the submarine afloat had been emptied, and water began to flow into the rear compartments. On the morning of April 11 at 06:20, the submarine sank at a depth of 4,680 metres following a loss of stability in pitch. 52 crew members died, including the captain. The Soviet navy kept details of this accident secret until 1991. There are two reactors onboard the K-8.
1986, October 6. A Yankee class submarine, the K-219, sank in the Atlantic Ocean north of Bermuda. The submarine sank after an explosion in one of the missile tubes. The explosion caused a leak in the fourth compartment (where the missiles are). At the time of the explosion, only one of the submarine’s two reactors was running. One sailor died while trying to lower the control rods in one of the reactors. Three others died in the smoke and fire. The entire submarine sank at 11:03 with its two reactors and the 16 missiles with nuclear warheads.
1989, April 7. The K-278, the Komsomolets, sank in the Norwegian Sea following a fire. The Komsomolets was a unique titanium-hulled submarine that could dive to depths of 1,000 meters. On the morning of April 7, the submarine was on its way back to base in Zapadnaya Litsa at the Kola Peninsula. At 11:03 a fire started in the electrical equipment in the seventh compartment. The fire caused short circuits in the electrical systems that set off the single reactor’s emergency system. 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 evacuate into life rafts, but there were not enough rafts. 41 sailors died in the cold arctic water. The submarine sank to a depth of 1,685 meters with its reactor and two nuclear warheads on torpedoes.