The reactor core was destroyed, and eight officers and two enlisted men standing nearby were killed instantly. A the blast threw debris was thrown into the air, and a plume of fallout 650 meters wide by 3.5 kilometers long traveled downwind on the Dunay Peninsula. More debris and the isotope Cobalt-60 [3] was thrown overboard and onto the nearby docks.
In 1985, a Soviet submarine undergoing a delicate refueling procedure experienced a freak accident that killed ten naval personnel. The fuel involved was not diesel, but nuclear, and the resulting environmental disaster contaminated the area with dangerous, lasting radiation. The incident, which remained secret until after the demise of the USSR itself, was one of many nuclear accidents the Soviet Navy experienced during the Cold War.
The Soviet Union’s nuclear war planners had a difficult time targeting the United States. While the United States virtually encircled the enormous socialist country with nuclear missiles in countries such as Turkey and Japan, the Western Hemisphere offered no refuge for Soviet deployments in-kind.
One solution was the early development of nuclear cruise missile submarines. These submarines, known as the Echo I and Echo II classes, were equipped with six and eight P-5 “Pyatyorka” [4] nuclear land attack cruise missiles, respectively. Nicknamed “Shaddock” by NATO, the P-5 was a subsonic missile with a range of 310 miles and 200- or 350-kiloton nuclear warhead. The P-5 had a circular error probable of 1.86 miles, meaning half of the missiles aimed at a target would land within that distance, while the other half would land farther away.
The missiles were stored in large horizontal silos along the deck of the submarine. In order to launch a P-5 missile, the submarine would surface, deploy and activate a tracking radar, then feed guidance information to the missile while it flew at high altitude. The system was imperfect—the command link was vulnerable to jamming, and the submarine needed to remain on the surface, helpless against patrol aircraft and ships, until the missile reached the target. Eventually the P-5 missiles were withdrawn and the P-5 missile was replaced with the P-6, a similar weapon but one with its own radar seeker for attacking U.S. aircraft carriers.
The introduction of the P-6 gave the Echo II a new lease on life. By 1985, the submarine K-431 was already twenty years old but still technically useful. Like all Echo IIs, K-431 was powered by two pressurized water reactors that drove steam turbines to a total of sixty thousand shipboard horsepower. As old as it was, K-431’s nuclear fuel supply needed replenishing, and by early August the process had started at the Soviet Navy’s facilities at Chazhma Bay.