Another nuclear-related test conducted at Nevada Test site

Wednesday, March 25, 1998 | 2:05 a.m.

The so-called subcritical experiment, designed to obtain physics information on plutonium samples of varying ages, was conducted without incident, the Energy Department said.

Before the experiment, 21 anti-nuclear protesters gathered at the gates to the sprawling test site, 65 miles northwest of Las Vegas. Two were cited on simple trespass charges, then released, the DOE reported.

A DOE statement said analysis of data from monitoring instruments confirmed that the experiment remained subcritical, that no self-sustaining nuclear chain reaction occurred.

Data obtained from the experiment was "consistent with expectations," the statement said.

Sponsored by Los Alamos National Laboratory, the experiment, dubbed Stagecoach, was conducted in a chamber 926 feet underground.

The explosives products and plutonium debris resulting from the experiment are, by design, contained in a permanently sealed room in the underground complex, the DOE reported.

Chemical high explosives were used to generate high pressures that were applied to weapon materials in the underground complex.

The DOE conducted two similar tests last year, the first nuclear-related tests at the Nevada Test Site since a 1992 moratorium went into effect.

The DOE contends the tests are essential to the nation's program to maintain the safety and reliability of the nuclear weapons stockpile in the absence of underground nuclear testing.

Anti-nuclear activists claim the tests are part of a nuclear testing program.

"Instead of seizing this historic opportunity to advance the cause of nuclear disarmament, U.S. weaponeers are out at the Nevada Test Site advancing the frontiers of nuclear weapons science," said Bruce Hall, nuclear disarmament coordinator for Peace Action, an anti-nuclear group.

Both the shape and small amount of plutonium - about the size of a 50-cent piece - are designed to prevent a self-sustaining nuclear reaction and not violate the Comprehensive Test Ban Treaty, according to the DOE.

Before the 1996 test moratorium, weapons would be taken out of the stockpile and tested underground or in the atmosphere to determine their reliability.