Criticality characteristics of mixtures of plutonium, silicon dioxide, Nevada tuff, and water

The major objective of this study has been to examine the possibility of a nuclear explosion (and evaluate this event if it is possible) should 50 to 100 kg of plutonium be mixed with SiO{sub 2}, vitrified, placed within a heavy steel container, and buried in the material known as Nevada tuff. To accomplish this objective we have created a survey of the critical states or configurations of mixtures of plutonium, SiO{sub 2}, tuff, and water and examined these data to isolate those configurations that might be unstable or autocatalytic. The survey of critical data now exists and is published herein. We identify regions of criticality instability with the possibility of autocatalytic power behavior (the existence of such autocatalytic phenomena is not new). Autocatalytic power behavior is possible for a very limited range of wet systems, but this behavior is improbable. A quantitative and conservative evaluation of the fission power behavior of these autocatalytic mixtures shows that no explosion should be expected