PNNL

Abstract

A novel approach is proposed to detect underground nuclear explosions (UNEs) through the displacement of natural radon isotopes (222Rn and 220Rn). Following an explosion, it is hypothesized that the disturbance and pressurization of the sub-surface would facilitate the movement of radon from the depth of the UNE towards the surface resulting in increased soil gas activity. The resulting signal may be magnified by a factor of 2.0 – 4.9 by the decay of radon to its short-lived progeny. To validate this hypothesis, radon detection instrumentation was deployed at the Dry Alluvium Geology (DAG) underground non-nuclear explosion experiments at the Nevada National Security Site (NNSS) during 2018 to 2019. Natural fluctuations in the soil gas activity due to barometric pumping, and the lower yield of the chemical explosions (1 T – 50 T) made it difficult to confirm a displacement of radon from the explosions, and further study to validate the proposed hypothesis is recommended.