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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,315 records · Page 73
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Center-Ignited Spherical-Mass Explosion (CISME); FY 2018 Report

It is not known whether pristine (i.e. mechanically and thermally undamaged) PBX 9501 can transition from a deflagration to a detonation in realistic scenarios, with relevant charge masses and inertial and mechanical confinement. In order to place bounds on the behavior, a series of experiments was conducted in which a spherical PBX 9501 charge is center-ignited using a fiber-delivered infrared laser pulse. Charge diameter was varied from 1.5 in ch to 10 inch. Experiments were conducted in a “bare” (unconfined) configuration, and a confined configuration with 4 mm-thick stainless-steel hemispherical shells bolted together. In all eight experiments, the reaction exhibited a relatively benign pressure burst; no transition to detonation (DDT) was observed. Most of the explosive was unconsumed and recovered post-test. Confined tests demonstrated slightly greater violence than unconfined tests, as anticipated.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2018

Unsupervised Machine Learning for Evaluation of Aging in Explosive Pressed Pellets

This project is an evaluation of the changes in the dimensional geometry of pressed explosive powder pellets when stored for prolonged periods under unmonitored storage conditions. Through the application of Structural Health Monitoring (SHM) techniques, questions to be answered by this investigation are what, if any, effect has the long-term storage of the pellets had on their physical attributes and, if changes have occurred, are the resulting differences of significant magnitude to affect the performance of the pellets. This resulting report includes a summary of the relevant background information, explanation of the SHM approach used to analyze the available data, presentation and discussion of the results, concluding remarks, and an accompanying appendix containing the MATLAB program developed for the project.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Explosion Source Models and the Scattering Origin of Regional Phases from SPE Phase 1 Coda Spectral Ratios

The Source Physics Experiment(SPE)explosions provide comprehensive ground truth information,and nearby recordings that are rarely available in typical monitoring scenarios. Here, we look for relationships with local and regional distance data to understand source and propagation effects in an effort to improve monitoring at a distance. We examine source spectral ratios, which can be measured to high precision by taking advantage of many SPE and independently operated stations, as well as the redundancy available from coda waves. Classical source models (Mueller and Murphy, 1971, MM71; Denny and Johnson, 1991, DJ91)predict the source ratios poorly; however, a hybrid model(MM71 with DJ91 cavity radii)performs better, and by varying cavity and elastic radii we obtain models that fit to within measurement precision. Based on this, the best prediction model for the SPE suite is the hybrid model with cavity radius decreased by 95%, and elastic radius decreased by 75%. This works best for mid-range scaled depths of burial (SPE-1, 2, 3, and 5). We do not guarantee transportability to other geologies,depth and scaled depth ranges. Finally, we observe a distinct spectral modulation at 6-9Hzthat is not predicted by classical models, and is most likely the result of interference of short period surface waves(Rg)with those produced by spallation of near surface layers.The same modulationis observed for compressional (P) and shear(S) waves at distance, indicating the origin of these waves as scattered Rg.The scattering process must be accounted for quantitatively when using distant signals to monitor treaty compliance over broad regions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Geologic Framework Model for the Underground Nuclear Explosions Signatures Experiment P Tunnel Testbed, Aqueduct Mesa, Nevada National Security Site

Three-dimensional geologic framework model of the P-Tunnel Complex and vicinity has been constructed for the Underground Nuclear Explosion Signature Experiment to address anisotropy of physical properties within the experiment medium. The P-Tunnel geologic framework model was constructed using EarthVision geologic modeling software by Dynamic Graphics, Inc. The model area covers 4.36 square kilometers and includes the entire P-Tunnel Complex. The model extends vertically from 2,004 meters above mean sea level, the highest land surface elevation in the model area, to 1,000 meters above mean sea level. The P-Tunnel Complex lies at an elevation of approximately 1,676 meters above mean sea level. The model incorporates data and information from more than 55 years of geological and geophysical studies in the P-Tunnel region, including surface and subsurface geology maps, tunnel construction drawings, a digital elevation model of the topography, and orthophoto imagery. The model consists of thirteen layers, with each layer defining a distinct stratigraphic interval with similar physical properties. Because no faults with significant offset are present within the model area, no faults are incorporated directly into the model. Small-offset faults and other prominent fractures mapped during tunnel construction, however, were digitized and gridded to produce fault and fracture planes that can be viewed within the model. The model has been exported as simple ASCII text files that define the model layers as either two-dimensional surfaces representing the tops of each model layer, or as three-dimensional volumes. The model was also exported as binary-STL files for three-dimensional printing.

58 GEOSCIENCES↗
DOE OSTI2019

BOM: The Next Generation of High Performance Explosives

The EPA has declared phase-out of Trinitrotoluene (TNT) a priority due to toxicity concerns. LANL and the Army Research Laboratory created a melt-castable next generation high performance explosive to replace TNT. They invented bis(1,2,4-oxadiazole)bis(methylene) dinitrate, or BOM, a higher-performing, safer replacement, which is 50% more energetic than TNT. BOM is less toxic to produce and use than TNT. Unlike competitors, BOM requires no performance-enhancing additives. BOM could replace TNT in a variety of civilian and military applications. BOM has been synthesized at the multi-kilogram scale.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2020

Optimization of Geometric Perturbations on a Rod Moving Through a High Explosive Target

After completing a study to ensure the simulation results were converged, several high resolution 3D Smoothed Particle Hydrodynamic (SPH) simulations of copper rods impacting a high explosive (LX14) target were performed. This was then formulated into an optimization problem: I wanted to find the optimum shape and location of a perturbation on the rod that would maximize its erosion after it left the target. The shape of the perturbation was modeled as a 2D Gaussian bump and parameterized by its location along the rod axis (z 0 ) and amplitude (A). The final mass of the coherent part of the rod as it leaves the target was used as a metric to represent the erosion of the rod, and the optimization was formulated to maximize this metric with respect to the aforementioned design variables. Due to the expensive nature of the high-fidelity 3D SPH simulations, a surrogate model needed to be chosen so that many function calls to the optimizer would be feasible. Thus, a strategic full factorial sampling plan was chosen to build a dataset, which consisted of 24 high-fidelity simulations. Two surrogate models, a third order polynomial regression model and a Gaussian Process Model, were analyzed using a 14%/86% test/train holdout technique. The root mean square and R2 score of the test set was used to determine the best model, and the third order polynomial regression model was chosen as the surrogate model. Finally, the Nelder-Mead Simplex and Basin-hopping optimization algorithms were implemented, and it was found that the two algorithms gave slightly different optimum values. Nelder-Mead gave an optimum point of [z* 0 ;A*] = [9:9;0:4] and Basin-Hopping gave an optimum value of x* = [z* 0 ;A*] = [9:2;0:1].

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2020

Report on the recovery of legacy 1997-1998 Depth-of-Burial / Tunnel-and-Hole-Closure explosion data from the Kazakhstan former Soviet nuclear test site, Semipalatinsk.

In 1996, negotiations between the National Nuclear Center of the Republic of Kazakhstan (NNC), the U.S. Defense Special Weapons Administration (DSWA) and the U.S. Department of Energy led to an agreement for a joint series of experiments at the former Soviet nuclear test site Semipalatinsk (STS). These experiments had a dual purpose: to close holes and tunnels originally created for the purpose of testing nuclear weapons, and to characterize explosive sources at a former nuclear test site. This report covers the recovery of legacy data from the experiments conduct in 1997 and 1998. Two teams collected data. Los Alamos National Laboratory (LANL), in collaboration with the NNC, collected the near-source (local) data out to approximately 20 km. Lamont-Doherty Earth Observatory (LDEO), with funding from Lawrence Livermore Laboratory (LLNL), also in collaboration with NNC, collected regional data, 200 – 1000 km distant, leveraging the KZ regional seismic network that LDEO had recently installed in collaboration with NNC. The two teams also worked together to some extent, regarding instrumentation and planning. This report primarily addresses the near-source data collected by the LANL/NNC team.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2020

Verification and Validation of High Explosive Reactive Burn Models Implemented in LANL's EAP and LAP Code Base

Reactive burn models represent a significant leap in high explosive (HE) modeling capability. The first generation of engineering models of HE detonation are called programmed burn models and they are largely based on the distance between a prescribed detonation point and each zone in a simulation. There have been many advancements to programmed burn models over the years and when the assumptions upon which they are based are met, a properly tuned programmed burn model can be highly accurate but if any of their assumptions is not met, as is the case for corner turning or weakly initiated HE burn, they will give the wrong answer. Reactive burn models represent an entirely new way of modeling HE burn. They use the local conditions of a zone – e.g. temperature, pressure or density – as calculated by a hydrocode to determine if and when the zone is going to detonate and if so, how rapidly. This difference opens up an entirely new set of capabilities for HE modeling. It makes it possible to accurately and predictively model phenomena like the effect of confinement and the formation of dead zones. Reactive burn models have seen sustained development effort at LANL for at least the last decade but several recent developments make it timely to transition reactive burn models from a research topic to a production tool. The main goal of this milestone is to facilitate and accelerate the adoption of reactive burn as a commonly available modeling option, with recommendations on the resolution that will be required and uncertainties associated with their modeling choices. To achieve this, we have performed verification, validation, and uncertainty quantification (UQ) assessments of AWSD and SURF/SURFplus in xRage and FLAG on a variety of different problems.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2020

Applying Compression-Based Metrics to Seismic Data in Support of Global Nuclear Explosion Monitoring

The analysis of seismic data for evidence of possible nuclear explosion testing is a critical global security mission that relies heavily on human expertise to identify and mark seismic signals embedded in background noise. To assist analysts in making these determinations, we adapted two compression distance metrics for use with seismic data. First, we demonstrated that the Normalized Compression Distance (NCD) metric can be adapted for use with waveform data and can identify the arrival times of seismic signals. Then we tested an approximation for the NCD called Sliding Information Distance (SLID), which can be computed much faster than NCD. We assessed the accuracy of the SLID output by comparing it to both the Akaike Information Criterion (AIC) and the judgments of expert seismic analysts. Our results indicate that SLID effectively identifies arrival times and provides analysts with useful information that can aid their analysis process.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2020

Aerial Crosspolarized NQR-NMR: Buried Explosive Detection From a Safe Distance

Nuclear quadrupole resonance is a non-destructive detection and inspection technique with potential as a non-destructive test (NDT) tool. Establishment of the capability opens the door to its use in furthering the mission of the labs. There are many possible uses of the capability: explosive detection and stress/strain detection in epoxies are two of the more obvious and are the main results of this work. Enhancement of the signal-to-noise ratio (SNR) and improvements in the acquisition time of the experiment were key focuses of this work. These were achieved by combing special spin-lock pulse sequences with cross-polarization (CP) schemes to improve the signals with shorter acquisition times. A novel rotating magnetic field device was created to facilitate CP in the field. Implementation of these schemes provided a significant reduction in SNR/time.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2021

Modeling Explosive Dispersal of Radiological Material: A Nonparametric Analysis

The National Atmospheric Release Advisory Center (NARAC) is a Department of Energy (DOE) asset that provides guidance on the potential effects of atmospherically released hazards based on dispersion simulation results. Numerical simulation results are compared to well-characterized experimental measurements whenever possible to validate and refine the model predictions. In 2012, such measurements were obtained by Defence Research and Development Canada (DRDC) and collaborating organizations for the case of explosively released 140 La – a radioactive isotope with a half-life of 1.6781 days.

42 ENGINEERING↗
DOE OSTI2021

Nimble Feedthrough Qualification - 125% High Explosive Overpressure Test Plan RevA

The primary purpose of this High Explosive (HE) Over-Pressure Test (OPT) is to qualify top cover diagnostic feedthroughs that will be used on LLNL Nimble Subcritical Experiment (SCE) Series designs per experimental design verification requirements specified in ASME Boiler and Pressure Vessel Code Case 2564, Impulsively-Loaded Pressure Vessels, Section VIII, Division 3; and to satisfy the over-test requirement of DOE-STD-1212. The diagnostic feedthroughs are part of the Vessel Confinement System (VCS), which is credited as a Safety Significant Design Feature per the U1a Facility Documented Safety Analysis (DSA). The OPT will be conducted at the LANL Area 1, R306 Firing Site (TA-15-R306) in a 3-foot diameter VCS depicted in Figure 1.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2021

Phosgene Neutralization Chemistry for the Explosive Destruction System (EDS)

This report summarizes activities at Sandia National Laboratories as part of the Explosive Destruction System (EDS) Phase 3 (P3) System design. An exploration of chemical neutralization strategies of phosgene was conducted for safe disposal of recovered mortars and M79 1000 lb. bombs filled with carbonyl dichloride "phosgene" or "CG agent" (molecular formula = COCl 2 ). The incumbent strategy utilized aqueous sodium hydroxide was found to be the worst-case scenario, producing enough CO 2 gas that would cause an unacceptable pressure and temperature spike. Several chemical neutralization strategies were evaluated based on criteria set by the operating envelope of the P3 design. In the end, it was determined that a pure solution of N-methyl ethanolamine (MeEA) or 90% monoethanolamine (MEA)(aqueous) provided the best balance reaction profile, cost, and safety.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Los Alamos National Laboratory Floodplain Assessment for the High Explosive Transfer Facility Blast Radius Fence Project at Technical Area 08

The National Nuclear Security Administration (NNSA), a semi-autonomous agency within the U.S. Department of Energy (DOE), is proposing to take action at Los Alamos National Laboratory (LANL) within the upper Pajarito Canyon 100-year (yr.) floodplain at Technical Area (TA) 08. This action consists of installation of a 3-strand smooth wire fence to create an operational boundary in a radius of 1250 feet (ft.) from the TA-08 High Explosive (HE) Transfer Facility (Figure 1). The proposed fence is intended to provide a barrier between the public and direct access to the HE Transfer Facility.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Seismic Spatial Gradients and Machine Learning-Based Classifiers for Explosion Monitoring (LDRD 218327)

This final report summarizes the work completed under the Laboratory Directed Research and Development (LDRD) project “Seismic Spatial Gradients as a Machine Learning-Based Classifier for Explosion Monitoring.” The overarching goal of the project was to explore the efficacy of using machine learning-based classification algorithms where the input data are the spatial gradient of the seismic wavefield collected at a single point on the Earth’s surface. The methods that I describe here are in direct contrast to conventional methods of seismic discrimination which typically rely on a spatially extended network of instruments and physics-based wavefield attributes such as, for example, the ratio between $\textit{P}$ and $\textit{S}$ waves. Rather, we use the spatial gradient of the seismic wavefield observed at a single point on the Earth’s surface and data processing approaches inspired by the machine learning community. We tested two algorithms, a neural network and a modified version of principal component analysis termed Spectrally Filtered Principal Component Analysis (SFPCA). To test these algorithms, we first conducted a series of numerical tests using synthetic data and then conducted a small-scale controlled field experiment. The tests using synthetic data showed that both algorithms had high success rates on gradiometric data, even when simulated noise was added to the signal. Furthermore, we found that using seismic spatial gradients increased the performance of our discrimination algorithms when compared to using just the traditional translational motion seismic data. The tests with field data also showed a high degree of discriminative success.

58 GEOSCIENCES↗