Predicting multiphase flow and tracer transport for an underground chemical explosive test

TL;DR

This paper uses simulations and field data to better understand how gases move after an underground explosion, improving monitoring and safety planning.

Contribution

The study uniquely integrates field data with modeling to predict gas migration after underground explosions.

Findings

Predictions of tracer arrival matched observations within one order-of-magnitude using a simplified 2D-radial model.

Transient blast forcing rapidly mobilizes gases from the cavity into surrounding rock.

Abstract

Detecting radionuclide gas seepage from clandestine underground nuclear tests is central to nonproliferation explosion monitoring research. Yet, early-time (<6 day) gas transport driven by the explosive pressure wave remains poorly constrained due to scarcity of field data. We simulate multi-phase gas transport in the vadose zone using pre-shot data from a recent chemical explosion in P-Tunnel at the Nevada National Security Site, USA. Despite using a simplified 2D-radial model, predictions of tracer arrival matched observations within one order-of-magnitude. Our results show how transient blast forcing rapidly mobilizes gases from the cavity into surrounding rock – critical for optimizing sensor placement and test planning. This unique integration of field data and modeling represents a significant improvement in our ability to predict gas migration from underground explosions. More broadly, it offers insights into the coupled dynamics of pressure waves and contaminant transport in the vadose zone, with implications for monitoring and hazard assessment.

The online version contains supplementary material available at 10.1038/s41598-026-35868-w.

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