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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Improved Pyrotechnic Shock Scaling Method Based on Shock Response Spectrum and Statistical Energy Analysis

It has been more than forty years since the pyrotechnic shock scaling method was introduced. The scaling method estimates the attenuation of the Shock Response Spectrum (SRS) based on the distance from the source, structural configurations, types of structural joints and interfaces, and intervening structure [1]. The method has been successfully used in the spacecraft community countless times and still is frequently used to develop pyrotechnic shock requirements at various levels of assembly of a spacecraft. However, since the method was derived empirically from a limited set of shock test data [2], the aerospace community has been looking for an alternative approach. In this paper, a computational scaling method based on Statistical Energy Analysis (SEA) is re-visited. SEA is traditionally used as a method for investigating the diffusion of acoustic and vibratory energies of a system at steady-state [3]. Previously, an approach using the SRS as an acceleration constraint condition to the SEA model was introduced to estimate the attenuation from a shock source [4,5]. In the current investigation, additional examples are provided to further validate the approach. In addition, responses in the time domain are produced by the Local Modal Phase Reconstruction (LMPR) approach which was recently introduced to the community [6].

Fernandez, Juan P.↗
DOE OSTI2017

Material impacts and heat flux characterization of an electrothermal plasma source with an applied magnetic field

To produce a realistic tokamak-like plasma environment in linear plasma device, a transient source is needed to deliver heat and particle fluxes similar to those seen in an edge localized mode (ELM). ELMs in future large tokamaks will deliver heat fluxes of ~1 GW/m 2 to the divertor plasma facing components at a few Hz. An electrothermal plasma source can deliver heat fluxes of this magnitude. These sources operate in an ablative arc regime which is driven by a DC capacitive discharge. An electrothermal source was configured in this paper with two pulse lengths and tested under a solenoidal magnetic field to determine the resulting impact on liner ablation, plasma parameters, and delivered heat flux. The arc travels through and ablates a boron nitride liner and strikes a tungsten plate. Finally, the tungsten target plate is analyzed for surface damage using a scanning electron microscope.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Aeroacoustic Computations of a Generic Low Boom Concept in Landing Configuration: Part 3 - Aerodynamic Validation and Noise Source Identification

Wind tunnel test data were used to validate the predicted aerodynamic behavior of a 15%-scale version of a generic, low-boom aircraft. The test was conducted in the NASA Langley 14- by 22-Foot Subsonic Tunnel to determine the low-speed aerodynamic characteristics of the model. Measured steady surface pressures and global forces were used to validate predicted aerodynamic results obtained from high-fidelity simulations of the model as installed in the tunnel. Very good agreement between predicted and measured aerodynamic trends was demonstrated, providing the impetus to proceed with companion airframe noise simulations that were conducted in a free-air setting. Computed near-field flow variables acquired on a permeable data surface were used to generate synthetic pressure records for two 800-element phased microphone arrays positioned overhead and to the side of the model. The array data were beamformed to generate noise source localization maps for the clean model and several landing configurations. Primary and secondary airframe sources were identified and their relative strengths were determined. Far-field integrated noise spectra for the full aircraft, as well as individual components, were obtained from the source maps via integration of tailored regions. The analysis showed that noise produced by the landing gear was the dominant contributor to the far-field acoustic signature of the model, followed by flap noise. The effects of permeable data surface end caps, spatial resolution, array orientation, angle of attack, component interaction, velocity scaling, and numerical precision on synthetic far-field spectra were also evaluated.

low boom↗
NASA NTRS2013

Characterization of the Reverberation Chamber at the NASA Langley Structural Acoustics Loads and Transmission (SALT) Facility

In 2011 the noise generating capabilities in the reverberation chamber of the Structural Acoustic Loads and Transmission (SALT) facility at NASA Langley Research Center were enhanced with two fiberglass reinforced polyester resin exponential horns, each coupled to Wyle Acoustic Source WAS-3000 airstream modulators. This report describes the characterization of the reverberation chamber in terms of the background noise, diffusivity, sound pressure levels, the reverberation times and the related overall acoustic absorption in the empty chamber and with the acoustic horn(s) installed. The frequency range of interest includes the 80 Hz to 8000 Hz one-third octave bands. Reverberation time and sound pressure level measurements were conducted and standard deviations from the mean were computed. It was concluded that a diffuse field could be produced above the Schroeder frequency in the 400 Hz one-third octave band and higher for all applications. This frequency could be lowered by installing panel diffusers or moving vanes to improve the acoustic modal overlap in the chamber. In the 80 Hz to 400 Hz one-third octave bands a successful measurement will be dependent on the type of measurement, the test configuration, the source and microphone locations and the desired accuracy. It is recommended that qualification measurements endorsed in the International Standards be conducted for each particular application.

Grosveld, Ferdinand W.↗
DOE OSTI2019

Delayed Gamma-ray Assay for Nuclear Materials Safeguards. Comprehensive Technology Readiness Assessment

Spectroscopic analysis of beta-delayed gamma-rays emitted from fission products following active interrogation was investigated as a non-destructive assay technique for detection and characterization of nuclear materials in shielded and complex configurations. This measurement technique is expected to be applicable to a variety of applications within the nuclear material safeguards, arms control, and emergency response areas, where active neutron interrogation is acceptable. Potential applications of the delayed gamma-ray assay in the nuclear material safeguards area include characterization of U and Pu isotopic content in spent and unirradiated nuclear fuel, enrichment measurements, verification of bulk material in containers, and the characterization of nuclear wastes. In the arms control area, this method can be used as a part of warhead dismantlement measurements to confirm separation of components, and may be applicable in warhead confirmation. In the context of emergency response, it can be used for detailed diagnostics of an unknown item. At present, the delayed gamma-ray assay technology reliably qualifies for the Technical Readiness Level 3 (TRL 3). The R&D work completed under this project has successfully demonstrated the empirical proof-of-concept for this active interrogation technology for a variety of measurement configurations, neutron sources, and nuclear material samples. A robust first-principles analytical signature modeling methodology was developed, experimentally validated, and can be easily extrapolated to a range of realistic measurement scenarios. Several response analysis methodologies have been implemented and deemed reliable for a variety of active interrogation applications in the areas of nuclear material safeguards, arms control, and emergency response. The initial readiness level before the start of this project was assessed at TRL 0, since only fragmentary records of the signature observations and speculative statements of the relevant non-destructive assay applications existed at that time. The delayed gamma-ray technology readiness can be easily advanced to TRL 4 in a short period, if a certain measurement application is specified and set for a demonstration in a laboratory environment. The critical hardware components of the delayed gamma-ray measurement technology (neutron generators, gamma-ray spectrometers) are readily available as COTS and can be configured for a specific deployment configuration. The primary risk of the delayed gamma-ray assay methodology is defined by the applicationspecific uncertainties. Evaluation of the system performance can be effectively completed once the expected measurement purpose, nuclear material characteristics, dimensions, and radiation exposure constraints are specified. A minor risk can be associated with the delayed gamma-ray response analysis techniques. Several approaches were proposed and demonstrated primarily using the modeled signatures. The observed performance may not be easily transferrable to the conditions of a real measurement setup, and some additional R&D may be required. Overall, the delayed gamma-ray assay technology can be recommended for follow-up demonstrations addressing relevant measurement applications in the areas of nuclear material safeguards, arms control, and emergency response.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Galaxy–galaxy lensing estimators and their covariance properties

Here, we study the covariance properties of real space correlation function estimators – primarily galaxy–shear correlations, or galaxy–galaxy lensing – using SDSS data for both shear catalogues and lenses (specifically the BOSS LOWZ sample). Using mock catalogues of lenses and sources, we disentangle the various contributions to the covariance matrix and compare them with a simple analytical model. We show that not subtracting the lensing measurement around random points from the measurement around the lens sample is equivalent to performing the measurement using the lens density field instead of the lens overdensity field. While the measurement using the lens density field is unbiased (in the absence of systematics), its error is significantly larger due to an additional term in the covariance. Therefore, this subtraction should be performed regardless of its beneficial effects on systematics. Comparing the error estimates from data and mocks for estimators that involve the overdensity, we find that the errors are dominated by the shape noise and lens clustering, which empirically estimated covariances (jackknife and standard deviation across mocks) that are consistent with theoretical estimates, and that both the connected parts of the four-point function and the supersample covariance can be neglected for the current levels of noise. While the trade-off between different terms in the covariance depends on the survey configuration (area, source number density), the diagnostics that we use in this work should be useful for future works to test their empirically determined covariances.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

WE-AB-BRB-11: Portable Fast Neutron and Photon Dose Meter

Purpose: To develop an instrument for measuring neutron and photon dose rates from mixed fields with a single device. Methods: Stilbene organic scintillators can be used to detect fast neutrons and photons. Stilbene was used to measure emission from mixed particle sources californium-252 (Cf-252) and plutonium-beryllium (PuBe). Many source detector configurations were used, along with varying amounts of shielding. Collected spectra were analyzed using pulse shape discrimination software, to separate neutron and photon interactions. With a measured light output to energy relationship the pulse height spectrum was converted to energy deposited in the detector. Energy deposited was converted to dose with a variety of standard dose factors, for comparison to current methods. For validation, all measurements and processing was repeated using an EJ-309 liquid scintillator detector. Dose rates were also measured in the same configuration with commercially available dose meters for further validation. Results: Measurements of dose rates will show agreement across all methods. Higher accuracy of pulse shape discrimination at lower energies with stilbene leads to more accurate measurement of neutron and photon deposited dose. In strong fields of mixed particles discrimination can be performed well at a very low energy threshold. This shows accurate dose measurements over a large range of incident particle energy. Conclusion: Stilbene shows promise as a material for dose rate measurements due to its strong ability for separating neutrons and photon pulses and agreement with current methods. A dual particle dose meter would simplify methods which are currently limited to the measurement of only one particle type. Future work will investigate the use of a silicon photomultiplier to reduce the size and required voltage of the assembly, for practical use as a handheld survey meter, room monitor, or phantom installation. Funding From the United States Department of Energy and the National Nuclear Security Administration.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Verification of dry storage cask loading using monoenergetic photon sources

Safeguarding the contents of spent nuclear fuel dry storage casks requires the verification of cask contents, especially if continuity of knowledge has been lost. The high attenuation of the cask’s thick shielding and stored fuel assemblies makes verification difficult using conventional photon radiography. Thomson-scattering quasi-monoenergetic photon sources offer narrow angular and energy spread for increased penetration. This paper demonstrates the advantages of such a source by examining effects of source properties on transmission through thick, highly attenuating objects. This information is then applied to calculations and simulations of transmission for a variety of photon sources and cask configurations. Here, the performance of the source is compared to traditional bremsstrahlung sources and other advanced methods, in the context of typical nuclear fuel dry storage casks. It is shown that the use of a Thomson scattering based quasi-monoenergetic photon source enables determination of fuel assembly occupancies faster and more accurately than other methods.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Optimizing Cornell’s future geothermal district heating performance through systems engineering and simulation

Cornell University’s intention to lower its carbon footprint has motivated this engineering evaluation of using low-temperature geothermal energy to supply heat to the campus district energy system. Optimal selection and operation of heat pumps can significantly improve system performance. To support this analysis, we model the quantitative relationships between heat pump configurations and source flow, supply and distribution temperatures, facility heating design options, output heat generation, and carbon abatement outcomes. A systems approach is used for analysis, troubleshooting, and improvement of the model. The result of this effort is a dynamic tool that appropriately responds to hourly thermal demand and communicates energy response for techno-economic analysis. Simulations indicate that a single well-pair in the local Basement Contact Zone reservoir can satisfy almost 68% of annual thermal demand at nearly 20 MWth average capacity while remaining financially competitive compared to conventional heating with levelized cost of heating (LCOH) as low as $4.55/MMBTU ($15.53/MWh th ). A direct-use scheme with heat pump augmentation provided more carbon abatement and 50 to 150% more annual heat supply than one without augmentation. Exploration of three and four well-pair scenarios prove the capability to achieve 50 MW th baseload heating capacity with competitive LCOH and significant carbon reductions.

15 GEOTHERMAL ENERGY↗
DOE OSTI2026

Elastic-wave sensitivity-guided adaptive seismic survey design for cost-effective monitoring of geological carbon storage

Effective seismic monitoring is essential for verifying CO₂ containment, detecting potential leakage, and optimizing operational decisions in geologic carbon storage. Here, this study presents a time-adaptive, elastic-wave sensitivity-guided framework for designing cost-effective seismic monitoring layouts for tracking CO₂ plume migration. The method is based on elastic-wave sensitivity analysis, which quantifies how variations in subsurface properties impact seismic wavefields. Two complementary design strategies are developed: one based on selecting a fixed number of seismic sources (Method A), and the other based on selecting source–receiver pairs contributing to a fixed fraction of cumulative elastic-wave sensitivity energy (Method B). The optimization workflow to identify source–receiver configurations with the highest detection potential is demonstrated using a hypothetical GCS scenario at the Kimberlina site in California using simulations of elastic-wave sensitivity data at multiple post-injection timesteps. Results show that both strategies adapt to evolving plume geometries and wavefield sensitivities, with Method B offering broader spatial coverage and Method A ensuring simpler deployment. This framework enables site-specific, cost-effective, and risk-informed seismic survey designs, enhancing the ability to monitor CO₂ migration over time in evolving geological environments

58 GEOSCIENCES↗
DOE OSTI2021

Configuration and impurity quantification of AmLi sources using radiography and gamma spectroscopy

This paper presents the non-destructive assay of two AmLi sources used for detector characterization and active interrogation at PNNL, identified as MRC-101 and MRC-103. First, a detailed description of the internal configuration of 2724-BT encapsulated MRC sources is established. X-ray radiographs of the AmLi sources are reported for the first time to verify the dimensions and orientation of the encapsulation. Notably, a density variation was observed as a contrast change across the height of the source cavities. Contrary to commonly made assumptions in literature, it is indirectly observed that the AmLi source/target material only occupies a portion of the source cavity. The intensity of the prompt gamma-rays resulting from the inelastic scatter of alpha particles on 7Li was used to calculate the mass ratios of LiH:AmO2. The gamma-ray spectra revealed the presence of numerous impurities in both source and target material (243Am, 237Np, 154Eu, 23Na, and 9Be). Neutron-gamma production ratios were applied to the intensity of the Doppler-broadened peaks from alpha-induced reactions with 7Li, 9Be, and 23Na to calculate neutron rates for both sources. A neutron/alpha production yield (derived in this work) was then related to the atomic concentration of these isotopes to find the approximate masses within each source. Ultimately, the AmLi source density was estimated with prompt gamma analysis based on partial source volumes as 0.45±0.08 g/cm^3.

DTRA, AmLi, neutron↗
DOE OSTI2015

Alternative RF coupling configurations for H{sup −} ion sources

RF heated sources for negative hydrogen ions both for fusion and accelerators require very high RF powers in order to achieve the required H{sup −} current what poses high demands on the RF generators and the RF circuit. Therefore it is highly desirable to improve the RF efficiency of the sources. This could be achieved by applying different RF coupling concepts than the currently used inductive coupling via a helical antenna, namely Helicon coupling or coupling via a planar ICP antenna enhanced with ferrites. In order to investigate the feasibility of these concepts, two small laboratory experiments have been set up. The PlanICE experiment, where the enhanced inductive coupling is going to be investigated, is currently under assembly. At the CHARLIE experiment systematic measurements concerning Helicon coupling in hydrogen and deuterium are carried out. The investigations show that a prominent feature of Helicon discharges occurs: the so-called low-field peak. This is a local improvement of the coupling efficiency at a magnetic field strength of a few mT which results in an increased electron density and dissociation degree. The full Helicon mode has not been achieved yet due to the limited available RF power and magnetic field strength but it might be sufficient for the application of the coupling concept to ion sources to operate the discharge in the low-field-peak region.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2017

Dual-gate operation and carrier transport in SiGe p–n junction nanowires

Here, we investigate carrier transport in silicon–germanium nanowires with an axial p–n junction doping profile by fabricating these wires into transistors that feature separate top gates over each doping segment. By independently biasing each gate, carrier concentrations in the n- and p-side of the wire can be modulated. For these devices, which were fabricated with nickel source–drain electrical contacts, holes are the dominant charge carrier, with more favorable hole injection occurring on the p-side contact. Channel current exhibits greater sensitivity to the n-side gate, and in the reverse biased source–drain configuration, current is limited by the nickel/n-side Schottky contact.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Determining g A / g V with High-Resolution Spectral Measurements Using a LiInSe 2 Bolometer

Neutrinoless double beta decay (0νββ) processes sample a wide range of intermediate forbidden nuclear transitions, which may be impacted by quenching of the axial vector coupling constant (g A /g V ), the uncertainty of which plays a pivotal role in determining the sensitivity reach of 0νββ experiments. Here we present measurements performed on a high-resolution LiInSe 2 bolometer in a “source = detector” configuration to measure the spectral shape of the fourfold forbidden β decay of 115 In . The value of g A /g V is determined by comparing the spectral shape of theoretical predictions to the experimental β spectrum taking into account various simulated background components as well as a variety of detector effects. We find evidence of quenching of g A /g V at >5 σ with a model-dependent quenching factor of 0.655 ± 0.002 as compared to the free-nucleon value for the interacting shell model. We also measured the 115 In half-life to be [5.18 ± 0.06(stat) $^{+0.005}_{- 0.015}$(sys)] x 10 14 yr within the interacting shell model framework. This Letter demonstrates the power of the bolometeric technique to perform precision nuclear physics single-β decay measurements, which along with improved nuclear modeling can help reduce the uncertainties in the calculation of several decay nuclear matrix elements including those used in 0νββ sensitivity calculations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Arcus v. 1.0

Arcus is a library developed and used within an internally developed network configuration tool. Arcus is being open sourced not the configuration tool.

Englehardt, Robert↗
DOE OSTI2023

Ratpac-Two v1.0.0

Geant-4 based detector simulations in c++ which combines simulation and analysis into a single framework to precisely model detector components and analyze experimental data. Ratpac allows the user to easily build new detector geometries and configurations through both the source library and through configurable text files at runtime.

Askins, Morgan↗
DOE OSTI2015

Lead Slowing Down Spectrometry Analysis of Data from Measurements on Nuclear Fuel

Improved non-destructive assay of isotopic masses in used nuclear fuel would be valuable for nuclear safeguards operations associated with the transport, storage and reprocessing of used nuclear fuel. Our collaboration is examining the feasibility of using lead slowing down spectrometry techniques to assay the isotopic fissile masses in used nuclear fuel assemblies. We present the application of our analysis algorithms on measurements conducted with a lead spectrometer. The measurements involved a single fresh fuel pin and discrete 239Pu and 235U samples. We are able to describe the isotopic fissile masses with root mean square errors over seven different configurations to 6.35% for 239Pu and 2.7% for 235U over seven different configurations. Funding Source(s):

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Optimizing Hydronic System Performance in Residential Applications

Even though new homes constructed with hydronic heat comprise only 3% of the market (US Census Bureau 2009), of the 115 million existing homes in the United States, almost 14 million of those homes (11%) are heated with steam or hot water systems according to 2009 US Census data. Therefore, improvements in hydronic system performance could result in significant energy savings in the US. When operating properly, the combination of a gas-fired condensing boiler with baseboard convectors and an indirect water heater is a viable option for high-efficiency residential space heating in cold climates. Based on previous research efforts, however, it is apparent that these types of systems are typically not designed and installed to achieve maximum efficiency. Furthermore, guidance on proper design and commissioning for heating contractors and energy consultants is hard to find and is not comprehensive. Through modeling and monitoring, CARB sought to determine the optimal combination(s) of components - pumps, high efficiency heat sources, plumbing configurations and controls - that result in the highest overall efficiency for a hydronic system when baseboard convectors are used as the heat emitter. The impact of variable-speed pumps on energy use and system performance was also investigated along with the effects of various control strategies and the introduction of thermal mass.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗