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Enhancing GADRAS Source Term Inputs for Creation of Synthetic Spectra

Horne, Steven M.; Harding, Lee

The Gamma Detector Response and Analysis Software (GADRAS) team has enhanced the source term input for the creation of synthetic spectra. These enhancements include the following: allowing users to programmatically provide source information to GADRAS through memory, rather than through a string limited to 256 characters; allowing users to provide their own source decay database information; and updating the default GADRAS decay database to fix errors and include coincident gamma information.

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TYPE SAND Report YEAR 2018
DOIOSTI

Modeling underwater noise propagation from marine hydrokinetic power devices through a time-domain, velocity-pressure solution

Journal of the Acoustical Society of America

Hafla, E.; Johnson, E.; Johnson, C.N.; Preston, Leiph; Aldridge, D.; Roberts, Jesse D.

Marine hydrokinetic (MHK) devices generate electricity from the motion of tidal and ocean currents, as well as ocean waves, to provide an additional source of renewable energy available to the United States. These devices are a source of anthropogenic noise in the marine ecosystem and must meet regulatory guidelines that mandate a maximum amount of noise that may be generated. In the absence of measured levels from in situ deployments, a model for predicting the propagation of sound from an array of MHK sources in a real environment is essential. A set of coupled, linearized velocity-pressure equations in the time-domain are derived and presented in this paper, which are an alternative solution to the Helmholtz and wave equation methods traditionally employed. Discretizing these equations on a three-dimensional (3D), finite-difference grid ultimately permits a finite number of complex sources and spatially varying sound speeds, bathymetry, and bed composition. The solution to this system of equations has been parallelized in an acoustic-wave propagation package developed at Sandia National Labs, called Paracousti. This work presents the broadband sound pressure levels from a single source in two-dimensional (2D) ideal and Pekeris wave-guides and in a 3D domain with a sloping boundary. The paper concludes with demonstration of Paracousti for an array of MHK sources in a simple wave-guide.

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TYPE Journal Article YEAR 2018
DOIOSTIScopus

sCO2 Brayton Cycle: Roadmap to sCO2 Power Cycles NE Commercial Applications

Mendez, Carmen M.; Rochau, Gary E.

The mission of the Energy Conversion (EC) area of the Advanced Reactor Technology (ART) program is to commercialize the sCO2 Brayton cycle for Advance Reactors and for the Supercritical Transformational Electric Production (STEP) program. The near-term objective of the EC team efforts is to support the development of a commercially scalable Recompression Closed Brayton Cycle (RCBC) to be constructed for the first STEP demonstration system with the lowest risk possible. This document details the status of technology, policy and market considerations, documentation of gaps and needs, and outlines the steps necessary for the successful development and deployment of commercial sCO2 Brayton Power Systems along the path to nuclear reactor applications.

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TYPE SAND Report YEAR 2018
DOIOSTI

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
Results 29401–29600 of 99,299
Results 29401–29600 of 99,299