Calculational examination of the Baneberry event

On December 18, 1970, Baneberry, a 10-kt nuclear device, was detonated at a depth of 278 m in hole U8d at the Nevada Test Site. A shock-induced fissure near ground zero opened and vented radioactive gases and debris into the atmosphere. This report presents the calculational results describing the sequence of dynamic phenomena that produced the vent. The calculations predict the long positive velocity pulse and the surface motion that were observed experimentally. The surface fissure through which the material vented is the same radial distance from ground zero as the maximum horizontal displacement is calculated to be. The calculations predict a final cavity radius that is very close to the measured Baneberry cavity radius. Finally, the calculations indicate that an open fracture path runs from the cavity to the Baneberry Fault, up the fault to the spall region, and then vertically to the surface. This was the vent path predicted by calculations and is consistent with the vent path found from the radioactivity in postshot drill holes. Because of our extensions in computational capabilities, we believe this report advances the state of the art for numerical simulation of the containment problems associated with underground nuclear tests