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The Effects of Stochastic Velocity Variations on Estimating Time Dependent Seismic Moment Tensors: Applications to the Blue Mountain Well Perforation Data

Poppeliers, Christian; Preston, Leiph

Resolving the time dependent terms in the seismic moment tensor provides important information that can be used to interpret the source process of an explosion, including the separation of isotropic explosion terms from shear forces and potentially isolated force couples. In this report, we detail our method of inverting three component seismic data for the seismic moment tensor. We review possible seismic source models from the simplest isotropic explosion type source to those incorporating the six independent moment tensor terms. The inversion we describe is formulated in the frequency domain, and results in estimates of time dependent moment tensor components. The inversion relies on an accurate estimate of the Green's functions of the Earth. However, given the complexity of the Earth, we explore the effects of inaccuracies in the presumed Earth model used to estimate the Green's functions needed for the inversion. Specifically, we explore the effects of stochastic variations in the Earth models on the inversion results. These tests are synthetic throughout, and show that adding stochastic density/velocity heterogeneity in the presumed Earth model results in reduced amplitude seismic moment tensor estimates, as well as degrading the data misfit. We suggest two mitigation strategies. First, produce a suite of Green's functions using different realizations of the stochastic field within the Earth Model. Secondly, perform the in- version in the power spectral domain, eliminating all phase information. Finally, we analyze actual seismic data collected in winter 2017/2018. The seismic data was collected at in active geothermal well site outside of Winnimucca, NV, and was produced during well stimulation operations. In general, the inversion results were poor, with a high degree of data misfit. We hypothesize that the poor results are a function of a poorly constrained Earth model as well as noisy, high-frequency data being used in the inversion.

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TYPE SAND Report YEAR 2018
DOIOSTI

Standoff Over the LRSO: Assessing the long-range stand-off missile's impact on strategic stability

Heimer, Brandon W.

While there is consensus both in the executive branch and Congress on the need to recapitalize the U.S. nuclear weapons enterprise, the delivery system and W80-4 warhead proposed to comprise the LRSO have generated considerable debate. Much of the public debate has focused on its potential to affect the strategic nuclear balance and stability. This paper seeks to elucidate both Russian and Chinese perspectives on strategic stability and apply them to a systematic analysis of how the LRSO might either enhance or diminish strategic stability for the purpose of better informing the decision-making process rather than advocate a particular position on this issue.

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TYPE Other Report YEAR 2018
DOIOSTI

How to ADAPT

Jankovsky, Zachary K.; Haskin, Troy C.; Denman, Matthew R.

The ADAPT software allows for the examination of aleatory and epistemic uncertainties in complex system transients using the Dynamic Event Tree (DET) methodology. This manual outlines the principles of operation of ADAPT and provides directions for its use. Future plans for the code are briefly outlined.

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TYPE SAND Report YEAR 2018
DOIOSTI

Testing Minimum Detectable Activity of Whole-Body Counting System in the Presence of Interfering Factors

Reese, Robert; Fournier, Sean D.; Allen, Mark B.

The recently updated technical standard for the Department of Energy Laboratory Accreditation Program (DOELAP) may soon require accredited laboratories to empirically verify the estimated minimum detectable activity (MDA) for the nuclides of interest measured by in-vivo detection systems. The Radiation Protection Sample Diagnostics (RPSD) program is the SNL on-site DOELAP accredited laboratory that provides in-vivo measurements of ingested gamma-emitting nuclides (or to prove the lack of significant ingested gamma-emitting nuclides) for the internal dosimetry program administered by Radiation Protection Dosimetry Program (RPDP). Currently, the main nuclides of concern for RPDP include cesium-137 and cobalt-60 as specified in the Statement of Work between the two programs. Historically, MDAs for the RPSD whole-body counting system (WBC) were calculated annually as a-priori values by averaging the critical levels (LC) of any twelve subjects with undetected Co-60 and Cs-137 and assuming MDA is twice the decision level. The purpose of this technical basis document is to evaluate the method and process that validates the a-priori MDA of the RPSD WBC.

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TYPE Other Report YEAR 2018
DOIOSTI

Tonopah Test Range Optical Tracking TSPI Uncertainty Qualification Analysis

Bays, Nathan R.

Tonopah Test Range (TTR) is an outpost of Sandia National Laboratories (SNL) in the Nevada desert, which has been used for the testing of ballistics and non-nuclear components of both nuclear and conventional weapons since 1957. These tests typically involve the drop or flight of test objects, which impact on one of several dry lake beds at the facility.

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TYPE Other Report YEAR 2018
DOIOSTI

Acoustoelasticity Testing: Changing Boundary Conditions and Damping

Schultz, Ryan

A series of modal tests were performed on an acoustoelastic system to explore how changes to the air and structural components affect the acoustoelastic coupling. This work is a continuation of previous experimental and analytical efforts. Here, the test method and perturbations were much more controlled than in previous tests, resulting in more refined data. Outputs of interest here are the coupled system modes as well as the resulting frequency response for various perturbations of the coupled system. Perturbations explored in this work include mass loading the structure, changing the air damping, and changing the air boundary conditions. Results of these tests indicate that simply adding damping to the air component, using foam or other absorptive material, is not sufficient to fully decouple the system. Rather, it is preferred to employ a change to the air boundary conditions, in the form of volume inclusions or scatterers, to prevent formation of the acoustic coupled mode.

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TYPE SAND Report YEAR 2018
DOIOSTI

Standoff Over the LRSO: Assessing the long-range stand-off missile's impact on strategic stability

Heimer, Brandon W.

While there is consensus both in the executive branch and Congress on the need to recapitalize the U.S. nuclear weapons enterprise, the delivery system and W80-4 warhead proposed to comprise the long-range stand-off (LRSO) missile have generated considerable debate. Much of the public debate has focused on its potential to affect the strategic nuclear balance and stability. This paper seeks to elucidate both Russian and Chinese perspectives on strategic stability and apply them to a systematic analysis of how the LRSO might either enhance or diminish strategic stability for the purpose of better informing the decision-making process rather than advocate a particular position on this issue.

More Details
TYPE Other Report YEAR 2018
DOIOSTI
Results 31201–31400 of 101,000
Results 31201–31400 of 101,000
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