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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 1,549 records · Page 86
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Radiochemistry and Trinity

Forty seconds after Trinity detonated, Noble Laureate Enrico Fermi calculated the bomb’s energy release. By measuring the lateral dispersion of small pieces of paper dropped before, during, and after the blast wave passed him, he calculated an explosive yield of ten kilotons. Although Fermi’s estimate was only half of the official yield, it provided immediate confirmation that nuclear fission could be fashioned into a weapon of war.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Los Alamos National Laboratory Floodplain Assessment for Fire Risk Mitigations at the Lower Slobbovia Testing Site in (TA-36)

The National Nuclear Security Administration (NNSA), a semi-autonomous agency within the U.S. Department of Energy (DOE), is proposing to take fire pre-suppression actions at Los Alamos National Laboratory (LANL) Technical Area (TA) 36. Constructing a fire break and a fuel break surrounding the Lower Slobbovia explosives testing site in addition to the current vegetation mowing practices would establish a safety perimeter to help prevent fires from spreading away from the firing point. NNSA has prepared this floodplain assessment in accordance with 10 Code of Federal Regulations (CFR) Part 1022 Compliance with Floodplain and Wetland Environmental Review Requirements (10 CFR 1022), which was promulgated to implement DOE requirements under Executive Order 11988 Floodplain Management (EO 1977). A floodplain is defined in 10 CFR 1022 as “the lowlands adjoining inland and coastal waters and relatively flat areas and flood prone areas of offshore islands,” and a base floodplain as “the 100-year floodplain, that is, a floodplain with a 1.0 percent chance of flooding in any given year (CFR 2003).” This floodplain assessment evaluates potential impacts to floodplain values and functions from implementation of the proposed action, identifies alternatives to the Proposed Action, and allows for meaningful public comment.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Evaluation of the PhaseNet Model Applied to the IMS Seismic Network

Producing a complete and accurate set of signal detections is essential for automatically building and characterizing seismic events of interest for nuclear explosion monitoring. Signal detection algorithms have been an area of research for decades, but still produce large quantities of false detections and misidentify real signals that must be detected to produce a complete global catalog of events of interest. Deep learning methods have shown promising capabilities in effectively characterizing seismic signals for complex tasks such as identifying phase arrival times. We use the PhaseNet model, a UNet-based Neural Network, trained on local distance data from northern California to predict seismic arrivals on data from the International Monitoring System (IMS) global network. We use an analyst-curated bulletin generated from this data set to compare the performance of PhaseNet to that of the Short-Term Average/Long-Term Average (STA/LTA) algorithm. We find that PhaseNet has the potential of outperforming traditional processing methods and recommend the training of a new model with the IMS data to achieve optimal performance.

58 GEOSCIENCES↗
DOE OSTI2021

Assessing the Accuracy of a Borehole-Controlled Velocity Model of Yucca Flat, Nevada, Using Large-N Seismic Data

The Source Physics Experiment (SPE) aims to improve nuclear test monitoring capabilities through a series of chemical explosions in Yucca Flat within the Nevada National Security Site (NNSS) (Snelson et al., 2013). With geologic data from over 950 boreholes, Yucca Flat has excellent borehole control on stratigraphy. These data were used to create a Geologic Framework Model (GFM) of the basin to aid in the study of seismic wave propagation through the Earth. However, the seismic velocities of the geologic units in the GFM are less well-defined. With the acquisition of five new active source Large-N datasets, we can now quantitatively assess the accuracy of the seismic model previously controlled by borehole data alone.

58 GEOSCIENCES↗
DOE OSTI2021

Large-Scale Trajectory Analysis via Feature Vectors

The explosion of both sensors and GPS-enabled devices has resulted in position/time data being the next big frontier for data analytics. However, many of the problems associated with large numbers of trajectories do not necessarily have an analog with many of the historic big-data applications such as text and image analysis. Modern trajectory analytics exploits much of the cutting-edge research in machine-learning, statistics, computational geometry and other disciplines. We will show that for doing trajectory analytics at scale, it is necessary to fundamentally change the way the information is represented through a feature-vector approach. We then demonstrate the ability to solve large trajectory analytics problems using this representation.

58 GEOSCIENCES↗
DOE OSTI2021

Estimating Beam-Target Heating

At Los Alamos National Laboratory, two high-current linear induction accelerators (LIAs) are used to produce bremsstrahlung source spots for flash radiography of high-explosive driven hydrodynamic experiments at the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility. Measurements of the electron-beam current density profile are valuable for understanding the beam dynamics in order to improve the quality of the radiography source spot. A technique commonly used at DARHT is to image the profile in Cerenkov or Optical Transition Radiation (OTR) light created by the beam striking a thin target inserted into the beam line. Target materials include aluminized dielectrics and titanium foils for OTR, and fused silica wafers for Cerenkov radiation. A practical complication with this technique is heating of the target by the electron beam. If the beam density is too great, the target can be destroyed. Moreover, even if the beam density is kept low enough to be nondestructive, the beam can heat the target to a high enough temperature to desorb gas from the surface. In that case, direct impact ionization of the gas by beam electrons can partially neutralize the beam, causing it to over-focus, thereby spoiling the data, if not destroying the target. The purpose of this note is to review some of the fundamental physics of electron beam heating in order to provide some elementary guidance for design of these imaging experiments to avoid overheating the target. Some specific examples for materials that we often use for imaging targets and beam-target experiments are provided.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Sandia National Laboratories Ecosystem for Open Science: Metadata Schema v0.2 Description.

The Ecosystem for Open Science (eOS) initiative was established in 2019. Its objective is improving openness and sharing of data and information across Defense Nuclear Nonproliferation (DNN) Research and Development (R&D) activities. To support this initiative, the eOS team at Sandia National Laboratories (SNL) developed metadata and data standards and proposed a machine-readable metadata schema. The nuclear explosion monitoring field was selected as a focus area due to its the wide range of pertinent phenomenologies.We developed the DCAT-eOS-AP metadata schema extending the Data Catalog Vocabulary version 2 (DCATv2) standard using an application profile (AP), to fit the needs of multi-disciplinary NA-22 projects. The DCAT-eOS-AP metadata schema describes data at different levels of granularity ranging from general descriptions to more domain-specific granular metadata. Its implementation and serialization is flexible with the ability to include new file or data types. Thus, it will scale with the ever-increasing data management needs of government research. Due to the multitude of phenomenologies represented in the DCAT-eOS-AP schema, we anticipate that it will be easily extensible to various projects across many DOE mission areas. This document describes data management challenges faced within the DNN R&D portfolio and provides insight on how metadata and data standards/guidelines combined with a comprehensive metadata schema can add value to programs throughout the Department of Energy (DOE). It reviews the importance of metadata standards, FAIR (Findability, Accessibility, Interoperability, and Reusability) data principles, and metadata schemas. Additionally, it summarizes input from subject matter experts (SME) at SNL and other National Laboratories that resulted in metadata and data standards/guidelines encompassing domains relevant to NA-22 projects. Finally, we discuss the DCAT-eOS-AP metadata development. Implementation recommendations and future development directions are included for those keen on adopting the DCAT-eOS-AP metadata schema.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2021

Simulations of SITI Cookoff Experiments Carried Out with Different Lots of PBX 9502

A pressure dependent cookoff model for PBX 9502 was developed by Hobbs’ et. al. PBX 9502 is composed of 95% by mass triaminotrinitrobenzene (TATB) and a 5% by mass chlorotrifluoroethylene/vinylidine fluoride binder. The objective in this study is to implement this cookoff model in Aria to simulate Sandia Instrumented Thermal Ignition (SITI) experiments that were carried out with different manufacturing lots of PBX 9502. The SITI design consists of solid cylinders (1" diameter × 1" height) of insensitive high explosive (IHE) confined by a cylindrical aluminum case. An electric heater is wrapped around the lateral surface of the case. This heater produces a temperature heating ramp on the outer surface of the case. Internal thermocouples measure the IHE temperature rise from the center to locations close to the IHE-aluminum interface. The energetic material is heated until thermal ignition occurs. Pressure is measured with a static pressure transducer installed on top of the confinement case. Two–dimensional axisymmetric heat conduction finite element models were implemented to simulate these experiments using four options of the PBX 9502 cookoff model. In addition, the predictive ability of this thermal decomposition model is evaluated using Latin Hypercube Sampling (LHS) techniques.

42 ENGINEERING↗
DOE OSTI2021

Mother's Day tribute: Remembering mom of baby 'Trinity'

For Elizabeth “Diz” Graves, the summer months of 1945 were a symbolic intersection of her personal and professional lives. As a physicist with the then-secret lab in Los Alamos, Elizabeth participated in the Trinity test - the successful detonation of the world’s first nuclear weapon, which took place in the remote New Mexico desert on July 16, 1945. Her role was to observe the explosion that advanced science into the Atomic Age, according to records in the National Security Research Center (NSRC). This is the Lab’s classified library, which also houses unclassified legacy materials. And, Elizabeth was seven months pregnant.

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

SURFplus model calibration for PBX 9012

PBX 9012 is a plastic bonded explosive composed of 90.2 wt % HMX (cyclo-tetramethylene-tetranitramine) and 9.8 % Viton A (vinylidene-hexafluoropropylene copolymer). It has nearly the same composition as LX-07 (90% HMX and 10% Viton A) but with a slightly lower density. Hence it has a higher porosity and is slightly more shock sensitive. Here we describe the SURFplus model calibration for PBX 9012 using data from five shock-to-detonation transition (SDT) gas gun experiments by Burns and Chiquete, detonation front shape data from rate stick experiments and cylinder test experiment reported in Anderson et al., Jackson et al. The SDT experiments provide Pop plot data points (run distance-to-detonation) which characterize shock initiation, Lagrangian velocity time histories from embedded magnetic velocity gauges which give information on the reaction behind the lead shock, and Hugoniot data points for the reactants EOS. The rate stick experiments provide data on the curvature effect which characterize propagating detonation waves. The cylinder test experiments provide data on the detonation release isentrope used to calibrate the products EOS. The HE model uses a Davis reactants EOS with parameters that Burns and Chiquete [2020] fit to Hugoniot data, and Davis products EOS with parameters that Anderson et al. [2020] fit to cylinder test data.

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

On Two-Phase Pressure and Temperature Equilibration with Mie-Grüneisen Equations of State

In the course of reactive flow modeling, the phases of high explosive (HE) reactants and products introduce additional degrees of freedom to the underlying hydrodynamic equations of compressible reactive fluid mechanics. Hydrodynamic simulations track the bulk (mixture) conservation properties of mass, momentum and energy. When multiple phases are introduced, one must decide on appropriate closure rules to determine the relative phase volumes and energy distribution between the phases. One typical closure is to assume that the phases are in pressure and temperature equilibrium. Here, the requisite equations of p-T equilibration are explored for Mie-Grüneisen Equations of State (EOS). Examples with Davis reactants and Davis products EOSs will be given. The Davis forms are used in both the WSD and AWSD reactive flow models.

42 ENGINEERING↗
DOE OSTI2021

First atomic weapons following WWII were detonated 75 years ago Operation Crossroads kicks off era of testing Los Alamos-created weapons [Slides]

It was time to test. After the Los Alamos-created atomic bombs helped end World War II, the no-longer-secret Lab transitioned into an era of weapons testing, starting 75 years ago with Operation Crossroads with the goal of studying nuclear weapons’ effects on warships. In August 1945, U.S. Senator Brien McMahon, who later authored the Atomic Energy Act of 1946, said: “In order to test the destructive powers of the atomic bomb against naval vessels, I would like to see these (Japanese naval) ships taken to sea and an atomic bomb dropped on them. The resulting explosion should prove to us just how effective the atomic bomb is when used against the giant naval ships.”

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

Particle Curtain Experiments at Sandia

Efforts at Sandia National Laboratories have focused on fundamental experiments to understand the dispersal of dense particle distributions in high-speed compressible flow. The experiments are conducted in shock tube facilities where the flow conditions and the initial conditions of the particle distributions are well controlled and well characterized. An additional advantage of the shock tube is that it is more readily able to accommodate advanced measurement diagnostics in comparison to explosive field tests.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Lawrence Livermore National Laboratory Ultrafast Closure Valve Use Cases

The purpose of this report is to document several use cases of the Ultra-Fast Closure Valve System (UCVS) at the Joint Actinide Shock Physics Experimental Research (JASPER) facility. The goal is to clearly identify the use cases so that an explosive hazard classification may be assigned.

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

Shock and Reaction in Granular Bed of HMX-Aluminum Powders

Ignition and material response properties of aluminumized HMX heterogeneous explosive mixtures were explored in a series of planar impact experiments performed over multiple years. This work expands on previous work studying material response to impact in single-component HMX granular materials. The addition of nanometric aluminum is shown to affect the ignition sensitivity and growth to reaction from impact. The gas gun test results are presented here varying parameters of particle size, shock strength, and aluminum mass fraction.

36 MATERIALS SCIENCE↗
DOE OSTI2020

High-Level Considerations for Access and Access Controls by Design

Nuclear power plants must be, by design and construction, robust structures and difficult to penetrate. Limiting access with difficult-to-penetrate physical barriers is going to be key for staffing reduction. Ideally, for security, the reactors would be sited underground, beneath a massive solid block, too thick to be penetrated by tools or explosives with all communications and power transfer lines also underground and fortified. Having the minimal possible number of access points and methods to completely block access from these points if a threat is detected will greatly help us justify staffing reduction.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2021

Laser Wavelength Shift from Splitters and Switches

The Detonation Science and Technology Group (Q-6) operates several photon Doppler velocimetry (PDV) systems as a diagnostic tool for measuring velocities in the 1–10 km/s range during high explosive (HE) detonation experiments. Q-6 uses “heterodyne” PDV systems that are produced by Traverse Solutions and Instrumentation, LLC (TS&I). These heterodyne systems combine wavelength (WL) tunable source and “reference” lasers with a WL offset of 10–100 pm from each other. Properly setting the source and reference WLs for an experiment can be critical for collecting the desired experimental data. The tunable lasers report WL readings in their control software, but these readings are based on a lookup table from a temperature reading and are not able to be calibrated. Therefore, recent test fire programs that require PDV as a diagnostic have also implemented requirements for monitoring the WL of the tunable lasers using a precision WL meter. To monitor the WL of several PDV lasers without disconnecting any patch fibers form the experimental setup, Q-6 developed a system splitters with a coupling ratio (%) of 99:1 and an optical switch with the switch output going to a single WL meter. A brief experiment was developed to determine if the splitters and/or switch introduced any WL bias into the readings. The purpose of this report is to document the system, the experiment, and its results.

42 ENGINEERING↗
DOE OSTI2021

Re-calibration of PBX9501 SURF model

PBX 9501 is a plastic bonded explosive composed of 95 wt % HMX and a binder; see [Gibbs and Popolato, 1980, pp. 109–119]. SURF is a reactive burn model for shock initiation and propagation of detonation waves. It has previously been calibrated for PBX 9501. Here the SURF model is recalibrated for PBX 9501; specifically, lot 730-010 at ρ = 1.837 g/cc 3 . The new calibration uses the Davis reactants and products EOS calibrated for the AWSD model [Aslam et al., 2020]. The burn rate in the shock initiation regime is fit to the Pop plot from 5 embedded gauge shock-to-detonation transition (SDT) experiments from [Gustavsen et al., 1999, see fig 12 and table 5]. In the propagation regime, the burn rate is fit to curvature effect data (detonation speed as function of front curvature); see [Aslam, 2007]. Also the burn parameters are adjusted to fit the gap-stick experiment [Hill et al., 2018]. Simulating the detonation wave speed in this experiment requires a model that is accurate for initiation with complex shock loading; in particular, a pressure decreasing gradient behind a curved lead shock. This is more difficult than calibrating to the standard SDT experiments which are 1-D and driven by a sustained shock. Simulations of the gap-stick experiment for PBX 9501 with the SURF model will be discussed in a subsequent report.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗