The experiments use chemical high explosives to generate high pressures that are applied to nuclear weapons materials. High speed measurement instruments are used to obtain scientific data on the behavior of the materials. The configuration and quantities of explosives and nuclear materials have been designed so that no nuclear explosion will take place. Thus, the experiments are consistent with the Comprehensive Test Ban Treaty. They are called "subcritical" because there is no critical mass formed, i.e., no self-sustaining nuclear fission ch-- |