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Title: Underground Nuclear Explosion Signatures Experiment.


Abstract not provided.

Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the 68th Underground Nuclear Weapons Testing Orientation Program (UNWTOP) held August 22-26, 2016 in Las Vegas, NV.
Country of Publication:
United States

Citation Formats

Vigil, Steven R. Underground Nuclear Explosion Signatures Experiment.. United States: N. p., 2016. Web.
Vigil, Steven R. Underground Nuclear Explosion Signatures Experiment.. United States.
Vigil, Steven R. 2016. "Underground Nuclear Explosion Signatures Experiment.". United States. doi:.
title = {Underground Nuclear Explosion Signatures Experiment.},
author = {Vigil, Steven R.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 9

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  • Subsequent to the dynamic effects from a contained explosion in rock there remains a residual stress field around the cavity. This field is associated with the dynamic rebound of the cavity. Calculations show that the radial component of the residual stress field is compressive, exhibits a maximum near the cavity, and decays to the in situ stress value. The tangential component shows a greater compressive value than the radial component, decays to a value below the in situ stress, and subsequently rises up to the in situ value. This residual stress effect is believed to be responsible for containment ofmore » underground explosions, for calculations show residual cavity pressures to be greater than the sum of the tensile strength of the rock and the overburden stress. A chemical explosion was conducted in an ash fall tuff at a depth of 425 meters and near a tunnel complex. The latter allows subsequent mineback. The experiment involved a 116 kg TNT sphere and a 0.2 meter diameter hole extending radially in the tuff from the emplaced charge. In effect, this provided an opening through the explosively formed residual stress field. Based on this experiment, an inexpensive fracturing technique for tight geologic formations is suggested.« less
  • This paper describes new research being performed to improve understanding of seismic waves generated by underground nuclear explosions (UNE) by using full waveform simulation, high-performance computing and three-dimensional (3D) earth models. The goal of this effort is to develop an end-to-end modeling capability to cover the range of wave propagation required for nuclear explosion monitoring (NEM) from the buried nuclear device to the seismic sensor. The goal of this work is to improve understanding of the physical basis and prediction capabilities of seismic observables for NEM including source and path-propagation effects. We are pursuing research along three main thrusts. Firstly,more » we are modeling the non-linear hydrodynamic response of geologic materials to underground explosions in order to better understand how source emplacement conditions impact the seismic waves that emerge from the source region and are ultimately observed hundreds or thousands of kilometers away. Empirical evidence shows that the amplitudes and frequency content of seismic waves at all distances are strongly impacted by the physical properties of the source region (e.g. density, strength, porosity). To model the near-source shock-wave motions of an UNE, we use GEODYN, an Eulerian Godunov (finite volume) code incorporating thermodynamically consistent non-linear constitutive relations, including cavity formation, yielding, porous compaction, tensile failure, bulking and damage. In order to propagate motions to seismic distances we are developing a one-way coupling method to pass motions to WPP (a Cartesian anelastic finite difference code). Preliminary investigations of UNE's in canonical materials (granite, tuff and alluvium) confirm that emplacement conditions have a strong effect on seismic amplitudes and the generation of shear waves. Specifically, we find that motions from an explosion in high-strength, low-porosity granite have high compressional wave amplitudes and weak shear waves, while an explosion in low strength, high-porosity alluvium results in much weaker compressional waves and low-frequency compressional and shear waves of nearly equal amplitude. Further work will attempt to model available near-field seismic data from explosions conducted at NTS, where we have accurate characterization of the sub-surface from the wealth of geological and geophysical data from the former nuclear test program. Secondly, we are modeling seismic wave propagation with free-surface topography in WPP. We have model the October 9, 2006 and May 25, 2009 North Korean nuclear tests to investigate the impact of rugged topography on seismic waves. Preliminary results indicate that the topographic relief causes complexity in the direct P-waves that leads to azimuthally dependent behavior and the topographic gradient to the northeast, east and southeast of the presumed test locations generate stronger shear-waves, although each test gives a different pattern. Thirdly, we are modeling intermediate period motions (10-50 seconds) from earthquakes and explosions at regional distances. For these simulations we run SPECFEM3D{_}GLOBE (a spherical geometry spectral element code). We modeled broadband waveforms from well-characterized and well-observed events in the Middle East and central Asia, as well as the North Korean nuclear tests. For the recent North Korean test we found that the one-dimensional iasp91 model predicts the observed waveforms quite well in the band 20-50 seconds, while waveform fits for available 3D earth models are generally poor, with some exceptions. Interestingly 3D models can predict energy on the transverse component for an isotropic source presumably due to surface wave mode conversion and/or multipathing.« less
  • Results from a long-term (9 year) field study of the distribution of radionuclides around an underground nuclear explosion cavity at the Nevada Test Site are reviewed. The goals of this Radionuclide Migration project are to examine the rates of migration underground in various media and to determine the potential for movement, both on and off the Nevada Test Site, of radioactivity from such explosions, with particular interest in possible contamination of water supplies. Initial studies were undertaken near the site of the low-yield test Cambric, which was detonated 73 m beneath the water table in tuffaceous alluvium. Solid samples weremore » obtained from just below ground surface to 50 m below the detonation point, and water was sampled from five different regions in the vicinity of the explosion. Ten years after the test, most of the radioactivity was found to be retained in the fused debris in the cavity region and no activity above background was found 50 m below. Only tritium and {sup 90}Sr were presented in water in the cavity at levels greater than recommended concentration guides for water in uncontrolled areas. A satellite well is being used to remove water 91 m from the detonation point. During seven years (7 x 10{sup 6} m{sup 3}) of pumping, tritium, {sup 85}Kr, {sup 36}Cl, and {sup 129}I have been detected in the water. Approximately 40% of the total tritium from the cavity region has been removed by pumping at the satellite well, and the maximum in the tritium concentration is clearly defined. Use of sensitive analytical techniques has permitted measurement of the very low concentrations of {sup 36}Cl and {sup 129}I present in the water. The {sup 36}Cl peak precedes the tritiated water, possibly as a result of anion exclusion. Additional analyses are in progress to better define the shape of the {sup 129}I concentration curve.« less