DOE Sets First 'Subcritical' Test for June

The Department of Energy (DOE) announced on April 4 that it would conduct the first in a series of "subcritical" experiments deep underground at the Nevada Test Site in June 1997, with the second experiment to follow this fall. The experiments, which will utilize high explosives and fissile materials (including plutonium) but not generate any nuclear yield, are part of DOE's ScienceBased Stockpile Stewardship program designed to ensure the safety and reliability of the U.S. nuclear arsenal under the recently signed Comprehensive Test Ban (CTB) Treaty. The treaty prohibits "any nuclear weapon test explosion or any other nuclear explosion." The experiments will, among other things, provide additional information on the behavior of weapons materials and components, allowing for improved computer simulations of nuclear explosions.

The first subcritical experiment was originally scheduled for June 1996, during the final stages of the CTB Treaty negotiations. DOE postponed it at the last minute, however, claiming that more time was needed to assess the environmental implications of such experiments. (See ACT, July 1996.)

The subcritical experiments remain controversial. Some critics have argued that the experiments will undermine the CTB Treaty because they will be perceived by some as an attempt by the United States to qualitatively improve its nuclear arsenal contrary to the spirit of the treaty. Other critics have argued that because they will be conducted underground at the Nevada Test Site, the experiments will complicate future verification efforts by establishing the precedent for continuing activities at former test sites. DOE has maintained, however, that the experiments are consistent with the CTB Treaty because they are not nuclear explosions and the treaty permits continued activities at former test sites.