At first the accident appeared to have chilling overtones of Chernobyl. A Soviet Yankee I-class submarine on patrol in the Atlantic had been crippled by an explosion and fire that had killed three crew members, and had surfaced about 550 miles east of Bermuda. Of immediate concern: the sub was powered by twin nuclear reactors and carried up to 16 SS-N-6 ballistic missiles, each tipped with two nuclear warheads.
To the crew of a U.S. P-3C Orion antisubmarine plane circling overhead, substantial damage was clearly visible. The sub was venting smoke from a gaping hole behind its sail, or vertical superstructure, where a hatch covering one of the 16 missile-launching tubes had been located. Said Defense Department Spokesman Commander Robert Prucha after examining photos: "The hatch was peeled back like a sardine can." But when the nearby U.S. oceangoing tug Powhatan offered assistance, the sub declined, requesting that the tug "stand clear."
For three days, though apparently taking in water, the stricken sub managed to stay afloat, limping eastward under its own power before accepting a tow from one of several Soviet merchant ships that had arrived on the scene. Then, early last week, the towline was disconnected, and the remaining 120 crew members were evacuated under the glare of red and green safety flares. The 9,600-ton sub disappeared under the waves, sinking some 18,000 ft. to the bottom.
As it turned out, there were few parallels with last spring's disaster at Chernobyl. For one thing, Mikhail Gorbachev notified Ronald Reagan of the accident the day after it happened, winning praise from the President and the State Department for his candor. More important, Soviet officials announced that there was no danger of radioactive contamination of the environment--a claim quickly supported by U.S. experts, who took samplings of air and water around the site.
Although the Soviets did not reveal what caused the explosion, it was apparently the highly volatile liquid fuel of the SS-N-6's. The fuel is "some kind of propellant combined with liquid oxygen," says Lieut. General Richard Burpee, director for operations of the Joint Staff. "Those will ignite on contact with each other, so you have to keep them separate. Handling those two fuels in the same missile is not without its hazards." Because of the danger, liquid-fueled missiles are carried only on older Soviet subs like the Yankee I class, which went into service between 1967 and 1974; the ballistic missiles on U.S. and latest Soviet subs are powered by solid fuel, which is far more stable.
Experts were quick to allay any public concern that such an accident might set off the missile warheads. A nuclear device, unlike older conventional explosives, cannot be detonated simply by a physical shock. The fission and then fusion reactions that must occur to explode an H-bomb can take place only if the weapon is armed electronically, which cannot happen accidentally. The warheads in the damaged tube "were obviously blown apart in the force of the explosion," says Vice Admiral Powell Carter Jr., director of the Joint Staff. Whether their remnants burned up or sank to the bottom of the ocean, they pose no danger; undetonated warheads contain only a small amount of radioactive material.