A Scary Accident at Sea

By MICHAEL D. LEMONICK

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.

The sub's twin reactors, on the other hand, are filled with highly radioactive material, but the Navy believes their design minimizes the danger of environmental release. First of all, the nuclear fuel inside the reactors is bound to fuel plates, which are made of corrosion-resistant material that Carter says deteriorates "very, very slowly, even in seawater, at a rate of a fraction of a millimeter per thousand years."

More important, even though Soviet nuclear subs are believed to have less shielding around their reactor cores than their U.S. counterparts (making them lighter and faster), that shielding is substantial. The radioactive material, Carter says, is contained in a "massive and heavy stainless-steel, corrosion-proof reactor vessel," which under normal operation is pressurized and filled with water. Unlike air-filled compartments in a sinking ship, it will not crush under the pressures of the deep.

"You essentially not only have the fuel bound into these plates," says Carter, "but they're in a little vault of their own inside this huge reactor vessel, which would take forever to corrode through. It's possible it could crack or rupture, but even if it did . . . this material is still tightly bound into the fuel plates, so . . . nothing would happen."

Carter's confidence is based on more than speculation. The U.S. has lost two nuclear submarines, the Thresher in 1963 and the Scorpion in 1968. Since then the Navy has periodically taken ocean-bottom, marine-life and water samples in the areas where the craft went down. Says Carter: "We've never had any detectable increase over the normal background radiation in that part of the world. We expect this to be the same."

Though both the U.S. and the Soviet Union have submersibles that can operate at an 18,000-ft. depth, Burpee believes no effort will be made to recover the remains of the sub. The U.S. could learn little from the design of the vessel, and the Soviets had ample time to remove or destroy any sensitive documents and equipment. Says Burpee about recovering it: "That's a Soviet responsibility." Anyway, says Carter, "it would be quite a feat. I don't think you could do it." --By Michael D. Lemonick. Reported by Dick Thompson/Washington

With reporting by Dick Thompson/Washington