Scientists plan 2004 nuclear experiment at Nevada Test Site

LAS VEGAS (AP) -- Scientists at the Nevada Test Site are planning for a 2004 subcritical nuclear experiment, which will be conducted in a manner similar to full-scale nuclear weapons tests on hold since 1992.

The nuclear material will be detonated in a hole in the east-central part of the Nevada Test Site, about 85 miles northwest of Las Vegas, according to a statement issued Friday by the National Nuclear Security Administration.

Previous subcritical experiments were conducted in a cavern complex, 960 feet below ground at the vast federal test site.

"Initial site preparation for this experiment is under way," the statement said. "This activity, and the means for emplacement of the experimental hardware into the vertical hole, will appear visually similar to those employed in underground nuclear tests conducted prior to the 1992 moratorium."

Darwin Morgan, spokesman for the National Nuclear Security Administration in North Las Vegas, said the experiment, dubbed Unicorn, helps maintain mandated test readiness capabilities.

Bush administration officials said last year that they would like the test site to be ready to resume full-scale tests, if needed, in 18 months, or about half the time expected during the Clinton administration.

Subcritical experiments involve small amounts of nuclear materials and are designed to stop short of triggering nuclear reactions. They allow scientists to study how materials, such as plutonium, blow apart when detonated with high explosives.

The subcritical program was launched in 1997 as a way to maintain the skills of U.S. nuclear weapons scientists and allow them to check how the stockpile ages in the absence of full-scale nuclear weapons tests.

Unicorn will be the nation's 20th such experiment since the program began. The most recent subcritical experiment, Rocco, was conducted Sept. 26, 2002.