U.S. Scientists Proclaim Success in Tests to Detect A-Arms on Ships

American scientists proclaimed success Thursday in a pioneering experiment to detect the presence of a nuclear warhead aboard a Soviet warship in the Black Sea.

The success of the experiment, if confirmed by other scientists, could bolster Soviet President Mikhail S. Gorbachev’s argument that it is possible to verify the presence of nuclear weapons aboard ships and submarines.

“It was very successful,” said Tom Cochran, a U.S. physicist with the Natural Resource Defense Council, a Washington group that organized the experiment with the Soviet Academy of Sciences.

But it remains possible for either side to shield weapons against detection by the type of devices used Wednesday, Cochran said.

Soviet government and private U.S. scientists used a variety of radiation detection devices to measure the emission of neutrons and gamma rays from a nuclear warhead on an SS-N-12 subsonic cruise missile aboard the Soviet missile cruiser Slava.

Cochran and other U.S. scientists from Princeton and Stanford University took their measurements with portable detectors placed alongside the deck launcher, less than a yard from the warhead.

Simultaneously, Soviet scientists from the academy’s institutes of geochemistry and earth physics used radiation detection devices carried in a military helicopter and a troop transport, said Cochran.

“All the systems tested successfully,” Cochran said in a telephone interview.

“We detected the signature of the nuclear warhead in the launcher,” he said. “We used a portable germanium detector that we placed alongside the launcher and got a strong signal from the U-235 and the plutonium in the warhead.” Plutonium and U-235, a form of uranium, are two main elements used in nuclear weapons.

At the same time, Soviet scientists circling in a helicopter 65 yards above the Slava used a neutron detector that indicated the presence of plutonium on the ship.

Soviet scientists aboard a troop transport circling 70 yards from the cruiser used a sodium iodide gamma ray detector that registered radiation from the warhead.

“None of the tools by themselves is adequate to verify limits on nuclear weapons, so you have to put together a package to cover the shortcomings of various systems,” he said.