Recent nuclear cavity pressure measurements

An underground nuclear test is typically conducted in an emplacement hole hundreds of metres deep that has been back-filled with sand gravel and concrete plugs. These plugs, which vary in thickness and strength, serve not only to prevent radioactive material from reaching the surface but also, ideally, to constrain it to a region near the explosion cavity. When we determine the appropriate depth of burial (DOB) for a device, we have to make it shallow enough to be economical but deep enough to reasonably ensure containment given the expected yield of the device and the particular geology of the hole. To do this, we have developed sophisticated computer models that consider each site's geologic structure and physical properties to predict explosion effects such as ground motion, confining stresses around the cavity, and cavity pressure. However, to be able to assess the performance and relative accuracy of these computational models, we must develop a data base of the measured values for each of these effects that can be compared with predictions. This report discusses pressure measurements and devices at the Cornucopia, Mission Ghost and Rhyolite Events.