Complex The Laboratory and the Department of Energy Nevada Operations Office successfully conducted the subcritical experiment Stagecoach Wednesday at the Nevada Test Site. Analysis of data from monitoring instruments confirmed that the experiment remained subcritical, that is, no nuclear chain reaction occurred. Preliminary analysis also indicated that the quantity of data returned from the experiment was consistent with expectations. The Stagecoach experiment was conducted at 10 a.m. The explosive products and plutonium debris resulting from the experiment were contained by design in a permanently sealed room in the underground complex.
Subcritical experiments are fully consistent with the Comprehensive Test Ban Treaty.
Subcritical experiments are designed to obtain needed scientific data and technical information on the effects of aging and behavior of nuclear weapon materials. The experiments support the Department of Energy's science-based Stockpile Stewardship Program to maintain the safety and reliability of the U.S. nuclear weapons stockpile without underground testing. The primary objective for Stagecoach was to obtain important physics information on plutonium samples of varying ages. Stagecoach involved chemical high explosives that generated high pressures that were applied to weapon materials, in particular, plutonium. Explosively driven flyer plate techniques developed by Los Alamos over the past 40 years were used to generate the high pressures applied to the nuclear materials.