1996-12-01 04:00:00 PDT NEVADA; UNITED STATES -- Despite a newly concluded international test ban treaty, scientists at the nation's nuclear weapons labs are considering whether to conduct underground bomb tests that would stop just short of chain-reaction explosions.

The experiments could create an international furor because some Third World leaders and anti-nuclear activists have warned that such tests would violate the spirit of the treaty.

The proposed U.S. tests would involve small amounts of fissionable material, detonated just short of a "real" nuclear blast. Weapons scientists want the tests so they can ensure that the "primary" trigger of thermonuclear bombs will still work as the U.S. arsenal ages.


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Called "subcritical tests" because the bombs don't achieve the critical mass needed for full-scale nuclear explosions, the experiments would be conducted 961 feet beneath the Nevada desert, within a rabbit warren of rooms and tunnels packed with high-speed cameras and scientific instruments. The facility is called LYNER, an acronym for Low-Yield Nuclear Explosions Research.

The tests, set up by scientists from the Lawrence Livermore and Los Alamos national laboratories, would use chemical explosives to rapidly compress small amounts of the fissionable materials plutonium and uranium.

The rapid compression would trigger the same physical events that occur in the first microseconds of a nuclear blast, but before the atom-splitting snowballs into a

"chain reaction."

The blast would equal tens or hundreds of pounds of TNT.

Ignoring spirit of the treaty?

Anti-nuclear activists charge that subcritical tests would violate the spirit of the test ban treaty, signed Sept. 24 by leaders of more than 60 other countries at the United Nations.

Two prominent treaty holdouts were India and Pakistan, whose negotiators accused the five known nuclear powers - the United States, Russia, France, Britain and China, all of which signed the treaty - of hypocrisy for not abolishing their nuclear arsenals.

"I'm very concerned about (subcritical testing). . . . It violates the intent of the (treaty), which was to shut off all (nuclear bomb) testing by all countries in all environments for all time," said Douglas Roche, the former chair of the U.N. disarmament committee who served as Canada's ambassador for disarmament from 1984 to 1989.

"It illustrates the United States' reluctance, if not outright opposition, to following the (ruling of the) International Court of Justice, which called for the conclusion of negotiations to eliminate nuclear weapons," Roche said.

At the end of 1995, treaty negotiators from countries such as India, Pakistan and Malaysia were publicly critical of initial U.S. plans to conduct tests at the Nevada Test Site.

"Negotiations on the test ban treaty were at a delicate stage, and some ambassadors reacted very badly" to news of plans for the tests, said Rebecca Johnson, director of the Disarmament Intelligence Review, which is based in London and Geneva and monitors diplomatic arms-control initiatives. At that time, the tests were scheduled for June 1996.

The June tests were delayed - officially for technical reasons.

Now that the treaty is signed, the U.S. Department of Energy is again considering subcritical tests. Johnson expects a similar foreign reaction: "A number of states will feel the U.S. might not be violating the "letter' of the treaty, but that it is cheating against the spirit."

"If the United States pours more money into laboratory testing, subcritical testing and these high-technology substitutes for nuclear testing," Johnson said, "then you will never get India to sign - and in a few years the whole thing might collapse."

Reasons to test

But the Energy Department sees nothing wrong with subcritical tests.

"We don't believe there is ambiguity (about the legality of) those tests . . . (and) we think there's strong reason to do them," said Vic Reis, the DOE's assistant secretary for defense programs.

Reis maintains that subcritical blasts are legal because they don't generate self-sustaining nuclear reactions, like those in a nuclear bomb. He says the tests are needed to ensure the continued "safety and reliability" of U.S. weapons now that the nation can no longer legally test bombs the old-fashioned way: by blowing them up.

Still, Energy Department officials say they haven't decided whether to conduct the tests. But a plan is in place and ready to go, if and when approval is given.

In recent years, knowing that nuclear tests would soon come to an end, the weapons labs have developed hundreds of millions of dollars worth of "surrogate" ways to ensure that the arsenal remains "safe and reliable" into the indefinite future.

For example, a giant laser is being built at Livermore that will simulate the extreme heat and presure of a thermonuclear blast.

The first proposed subcritical test, code-named Rebound, would compress fissionable material with a "flying plate." An explosive charge would launch the metal plate toward the plutonium or uranium at thousands of feet per second.

Data from the test would be used to update computer simulations of nuclear bombs. The tests would be part of DOE's $4 billion-a-year "stockpile stewardship program."

Subcritical tests were a key issue during an October meeting between Reis and Lee Halterman, an aide to U.S. Rep. Ron Dellums, D-Berkeley, the ranking minority member on the House National Security Committee.

Dellums "remains convinced there is not currently a need for subcriticals and that proceeding with them could undermine important U.S. nonproliferation goals," Halterman told The Examiner.

"If we're serious about getting the (treaty) ratified (by the Senate) and luring the Indians and Pakistanis and others into it, we shouldn't be doing (the tests)," Halterman said.

The Energy Department faces congressional pressure to maintain a strong arsenal.

For example, on Oct. 30 Rep. Floyd Spence, R-S.C., who chairs the House National Security Committee, blasted Clinton "for not taking the necessary steps to ensure the safety and reliability of the nuclear stockpile and long-term viability of the U.S. nuclear deterrent."

However, "these subcritical tests are a terrible nuclear proliferation risk," counters Bay Area anti-nuclear activist Marylia Kelley, who toured above-ground facilities of the Nevada complex in June.

She and other critics say that countries would have trouble distinguishing between subcritical nuclear tests and illegal underground tests of small nuclear weapons.

Other plans in the works

Subcritical tests aren't the only high-tech toys on DOE's agenda, new documents reveal.

The agency also hopes to test powerful chemical explosives in Nevada to find a way to "disarm improvised (enemy or terrorist) nuclear devices," according to DOE documents released last week. The 8-inch-tall stack of paper is dubbed "Final Environmental Impact Statement for the Nevada Test Site and Off-Site Locations in the State of Nevada."

Scientists plan to trigger chemical explosions to find ways to disable enemy nuclear weapons, the documents show. No details are given.

Such explosions might disable the enemy bombs even if they're underground, presumably via seismic shock.

The same documents show that DOE is considering chemical explosive tests that may include two hydrogen isotopes, deuterium and tritium. These isotopes are commonly used in thermonuclear or "hydrogen" bombs, in which atomic nuclei are fused to unleash fusion energy. The tests would be conducted in a facility named BEEF - the Big Explosives Experimental Facility.

BEEF blasts would equal up to 70,000 pounds of TNT.

"Approximately 100 research and diagnostic experiments would be conducted annually," the environmental report says.

Why would BEEF scientists use deuterium and tritium in conjunction with such awesome chemical blasts? Officials won't say, and the documents don't tell.

The facility might be used to study the physics of

"boosting," a process in which deuterium and tritium gases are injected into the nuclear bomb to increase its explosive force.

"Pure fusion' bomb

But Kelley fears that BEEF scientists might use deuterium and tritium to find routes to an old dream: a "pure fusion" bomb.

A modern fusion or H-bomb is really two bombs. The key component is an old-fashioned "fission" bomb - the

"primary" - that contains plutonium or uranium. These elements' atomic nuclei are split or "fissioned" to release immense heat and pressure that, in turn, fry the bomb's "secondary," which contains the isotopes deuterium and tritium. Result: The isotopes merge or

"fuse," generating a far more powerful fusion blast.&lt;