Title: Evaluating the Importance of Barometric Pumping for Subsurface Gas Transport Near an Underground Nuclear Test Site

Abstract

Core Ideas Gas transport modeling can estimate ground surface breakthrough after an underground nuclear explosion. Comparison tracer‐injection experimental and model results reveals parameter sensitivity. Barometric pumping may explain gas breakthrough following an underground nuclear explosion. Amplitude and period of barometric pressure signal are key in controlling breakthrough. An underground nuclear explosion (UNE) generates and distributes radioactive gases that can be transported to the ground surface though preexisting and explosion‐induced fractures over timescales of hours to months. If detected, the presence of short‐lived radionuclides in gas is evidence of a recent UNE. Numerical modeling can provide estimates of surface arrival times that can help inform gas monitoring strategies at suspected foreign test sites. Efforts are underway at historic US UNE sites to better understand subsurface gas‐transport processes following a UNE by geologic characterization of the near‐field damage structures, field‐scale tracer experiments, and subsurface air pressure monitoring. The development of numerical models using historical and experimental datasets from former UNE sites can improve predictions by testing conceptual models, highlighting key processes, and constraining parameter ranges. The models developed in this study represent the U20az site at the Nevada National Security Site where the Barnwell device was expended in December 1989. A two‐phasemore » (water and air), dual‐permeability flow and transport model of the U20az site was built to investigate gas transport processes under recent experimental conditions and following the Barnwell nuclear event. Results indicate that the model can explain both the lack of arrival of radioactive gas tracers in a 2013 field experiment as well as the observed arrival of radioactive gases following the 1989 Barnwell event using barometric pressure records from the respective periods, even when additional advective processes associated with the Barnwell detonation are ignored. The results demonstrate that the character of the barometric records may be a key factor in explaining the differences in transport behavior.« less

Authors:

Bourret, S. M. ^[1]; Kwicklis, E. M. ^[1]; Miller, T. A. ^[1]; Stauffer, P. H. ^[1]

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+ Show Author Affiliations

1. Computational Earth Sciences, Earth and Environmental Sciences Division Los Alamos National Lab. Los Alamos NM 87545

Publication Date:

Thu Mar 14 00:00:00 EDT 2019

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation

OSTI Identifier:

1598699

Alternate Identifier(s):

OSTI ID: 1511228; OSTI ID: 1598702

Report Number(s):

LA-UR-18-20804
Journal ID: ISSN 1539-1663

Grant/Contract Number:  

DE‐AC52–06NA24596; 89233218CNA000001

Resource Type:

Published Article

Journal Name:

Vadose Zone Journal

Additional Journal Information:

Journal Name: Vadose Zone Journal Journal Volume: 18 Journal Issue: 1; Journal ID: ISSN 1539-1663

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES