TRANSPORT OF GASEOUS FISSION-PRODUCTS ADJACENT TO AN UNDERGROUND NUCLEAR TEST CAVITY

The 1989 Ingot underground nuclear test was drilled back in 1994 to in vestigate the behavior of radionuclides adjacent to the edge of a nucl ear explosion cavity. The Ingot event was fired above the static water level in bedded tuffs of the Nevada Test Site. Spectral gamma logging of the drill hole indicated a discrete zone of radioactivity at the d epth of the working (firing) point. Subsequent radiochemical analysis confirmed the presence of Cs-137 and Sr-90. The short lived gaseous pr ecursors of these species migrated through fractures created by the fo rce of the explosion. Geophysical logging, radiochemical analysis and solids characterization at Ingot emphasize the significance of gaseous transport to radionuclide migration near sites of underground nuclear explosions.