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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Summary of ALSEP Test Loop Solvent Irradiation Testing

Separating the minor actinide elements (americium and curium) from the fission product lanthanides is an important step in closing the nuclear fuel cycle. Isolating the minor actinides will allow transmuting them to short lived or stable isotopes in fast reactors, thereby reducing the long-term hazard associated with these elements. The Actinide Lanthanide Separation Process (ALSEP) is being developed by the DOE-NE Material Recovery and Waste Form Development Campaign to accomplish this separation with a single process. To develop a fundamental understanding of the solvent degradation mechanisms for the ALSEP Process, testing was performed in the INL Radiolysis/Hydrolysis Test Loop for the extraction section of the ALSEP flowsheet. This work culminated in the completion of the level two milestone (M2FT-16IN030102021) "Complete ALSEP test loop solvent irradiation test.” This report summarizes the testing performed and the impact of radiation on the ALSEP Process performance as a function of dose.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS2003

Response Modeling of Lightweight Charring Ablators and Thermal Radiation Testing Results

Under NASA's In-Space Propulsion/Aerocapture Program, ARA conducted arc-jet and thermal-radiation ablation test series in 2003 for advanced development, characterization, and response modeling of SRAM-20, SRAM-17, SRAM-14, and PhenCarb-20 ablators. Testing was focused on the future Titan Explorer mission. Convective heating rates (CW) were as high as 153 W/sq cm in the IHF and radiation rates were 100 W/sq cm in the Solar Tower Facility. The ablators showed good performance in the radiation environment without spallation, which was initially a concern, but they also showed higher in-depth temperatures when compared to analytical predictions based on arc-jet thermal-ablation response models. More testing in 2003 is planned in both of these facility to generate a sufficient data base for Titan TPS engineering.

Congdon, William M.↗
NASA NTRS1985

Hover and forward flight acoustics and performance of a small-scale helicopter rotor system

A 2.1-m diam., 1/6-scale model helicopter main rotor was tested in hover in the test section of the NASA Ames 40- by 80- Foot Wind Tunnel. Subsequently, it was tested in forward flight in the Ames 7- by 10-Foot Wind Tunnel. The primary objective of the tests was to obtain performance and noise data on a small-scale rotor at various thrust coefficients, tip Mach numbers, and, in the later case, various advance ratios, for comparisons with similar existing data on full-scale helicopter rotors. This comparison yielded a preliminary evaluation of the scaling of helicopter rotor performance and acoustic radiation in hover and in forward flight. Correlation between model-scale and full-scale performance and acoustics was quite good in hover. In forward flight, however, there were significant differences in both performance and acoustic characteristics. A secondary objective was to contribute to a data base that will permit the estimation of facility effects on acoustic testing.

Kitaplioglu, C.↗
DOE OSTI2019

Antarctic Cloud Macrophysical, Thermodynamic Phase, and Atmospheric Inversion Coupling Properties at McMurdo Station—Part II: Radiative Impact During Different Synoptic Regimes

Different cloud types are generated over Antarctica as a result of various synoptic conditions. The cloud characteristics affect their impact on the surface energy budget. In this study, the dominating synoptic regimes over Antarctica (centered on the Ross Ice Shelf) are classified using self-organizing map (SOM) analysis, applied over long-term ERA-Interim 700 hPa geopotential height data. The corresponding cloud properties over McMurdo Station (measured as part of the AWARE campaign) are described and discussed with respect to the synoptic settings and sea-ice extent conditions. Cloud radiative forcing calculations are performed as well, and a particular focus is given to the net longwave “radiatively cloudy/opaque” (RO) regime. These results are compared with measurements performed at the West Antarctic Ice Sheet (WAIS) Divide to examine their variability and applicability to other Antarctic locations. It is found that the McMurdo cloud properties are strongly affected by the regional mesoscale cyclonic activity, which counterweights the larger-scale synoptic regime influence, while the WAIS clouds are more susceptible to the varying synoptic settings. In addition, it is suggested that the positive trend in the (frequent) cyclonic activity near the Antarctic coastal regions makes ice-clouds an increasing prominent contributor for the RO cases, especially during freeze-up and maximum sea-ice conditions.

antarctic clouds↗
NASA NTRS1976

Improved space radiation shielding methods

The computing software that was used to perform the charged particle radiation transport analysis and shielding design for the Mariner Jupiter/Saturn 1977 spacecraft is described. Electron fluences, energy spectra and dose rates obtained with this software are presented and compared with independent computer calculations.

Davis, H. S.↗
NASA NTRS1974

Performance of a Brayton power system with a space type radiator

Test results of an experimental investigation to measure Brayton engine performance while operating at the sink temperatures of a typical low earth orbit are presented. The results indicate that the radiator area was slightly oversized. The steady state and transient responses of the power system to the sink temperatures in orbit were measured. During the orbital operation, the engine did not reach the steady state operation of either sun or shade conditions. The alternator power variation during orbit was + or - 4 percent from its mean value of 9.3 kilowatts.

Nussle, R. C.↗
DOE OSTI2016

Radiation induced detwinning in nanotwinned Cu

Superior radiation tolerance has been experimentally examined in nanotwinned metals. The stability of nanotwinned structure under radiation is the key factor for advancing the application of nanotwinned metals for nuclear reactors. We thus performed in situ radiation tests for nanotwinned Cu with various twin thicknesses inside a transmission electron microscope. We found that there is a critical twin thickness (10 nm), below which, radiation induced detwinning is primarily accomplished through migration of incoherent twin boundaries. Lastly, detwinning is faster for thinner twins in this range, while thicker twins are more stable.

36 MATERIALS SCIENCE↗
DOE OSTI2016

SU-G-TeP2-11: Initial Evaluation of a Novel Split-Filter Dual-Energy CT for Use in Radiation Oncology

Purpose: To perform an initial evaluation of a novel split-filter dual-energy CT (DECT) system with the goal of understanding the clinical utility and limitations of the system for radiation therapy. Methods: Several phantoms were imaged using the split-filter DECT technique on the Siemens Edge CT scanner using a range of clinically-relevant doses. The optimum-contrast reconstruction, the mixed reconstruction, and the monoenergetic reconstructions (ranging from 40 keV to 190 keV) were evaluated. Each image was analyzed for CT number accuracy, uniformity, noise, low-contrast visibility (LCV), spatial resolution and geometric distortion. For comparison purposes, all parameters were evaluated on 120 kVp single-energy CT (SECT) scans used for treatment planning, as well as, a sequential-scan DECT technique for corresponding doses. Results: For all DECT reconstructions no observable geometric distortion was found. Both the optimal-contrast and mixed images demonstrated slight improvements in LCV and noise when compared to the SECT, and slight reductions in CT number accuracy and spatial resolution. The CT numbers trended as expected for the monoenergetic reconstructions, with CT number accuracy within 50 HU for materials of density <2 g/cm3. Spatial resolution increased with energy, and for monoenergetic reconstructions >70 keV the spatial resolution exceeded that of the SECT. The noise in the monoenergetic reconstructions increased with decreasing energy. Thus, the image uniformity, signal-to-noise ratio and LCV were diminished at lower energies (70 keV). Applying iterative reconstruction techniques to the low-energy images reduced noise and improved LCV. The signal-to-noise ratio was stable for energies >100 keV. Conclusion: The initial commissioning of the novel split-filter DECT technology demonstrated favorable results for clinical implementation. The mixed reconstruction showed potential as a replacement for the treatment planning SECT. The image parameters for the monoenergetic reconstructions varied appropriately with energy. This work provides an initial understanding of the limitations and potential applications for monoenergetic imaging.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Cytogenetic follow-up studies on humans with internal and external exposure to ionizing radiation

Cells exposed to ionizing radiation have a wide spectrum of DNA lesions that include DNA single-strand breaks, DNA double-strand breaks (DSBs), oxidative base damage and DNA-protein crosslinks. Among them, DSB is the most critical lesion, which when mis-repaired leads to unstable and stable chromosome aberrations. Currently, chromosome aberration analysis is the preferred method for biological monitoring of radiation-exposed humans. Here, stable chromosome aberrations, such as inversions and balanced translocations, persist in the peripheral blood lymphocytes of radiation-exposed humans for several years and, therefore, are potentially useful tools to prognosticate the health risks of radiation exposure, particularly in the hematopoietic system. In this review, we summarize the cytogenetic follow-up studies performed by REAC/TS (Radiation Emergency Assistance Center/Training site, Oak Ridge, USA) on humans exposed to internal and external radiation. In the light of our observations as well as the data existing in the literature, this review attempts to highlight the importance of follow-up studies for predicting the extent of genomic instability and its impact on delayed health risks in radiation-exposed victims.

61 RADIATION PROTECTION AND DOSIMETRY↗
NASA NTRS1989

Infrared thermal imaging figures of merit

Commercially available types of infrared thermal imaging instruments, both viewers (qualitative) and imagers (quantitative) are discussed. The various scanning methods by which thermal images (thermograms) are generated will be reviewed. The performance parameters (figures of merit) that define the quality of performance of infrared radiation thermometers will be introduced. A discussion of how these parameters are extended and adapted to define the performance of thermal imaging instruments will be provided. Finally, the significance of each of the key performance parameters of thermal imaging instruments will be reviewed and procedures currently used for testing to verify performance will be outlined.

Kaplan, Herbert↗
DOE OSTI2021

Directed Flow and the Chiral Magnetic Effect in Ultrarelativistic Collisions at the LHC with CMS at the LHC (Final Technical Report)

This Technical Report focuses on two aspects of this project. First, the results from the calibration of the Spectator Reaction Plane Detector (SRPD) addition to the Zero Degree Calorimeter (ZDC) in the CMS experiment are presented, followed by the pre-liminary results from radiation studies of quartz being performed using the electron linac here at the University of Maryland. The data taken in the November 2018 run are being analyzed with the ultimate goal of producing a reaction plane measurement using spectator neutrons detected in the ZDC. Funds provided by this grant partially supported the graduate student who is performing these calibrations. They were also used to support radiation tests of quartz rod material being performed at the University of Maryland Radiation Facilities Electron Linear Accelerator.

43 PARTICLE ACCELERATORS↗
NASA NTRS2013

Radiation Engineering Analysis of Shielding Materials to Assess Their Ability to Protect Astronauts in Deep Space From Energetic Particle Radiation

An analysis is performed on four typical materials (aluminum, liquid hydrogen, polyethylene, and water) to assess their impact on the length of time an astronaut can stay in deep space and not exceed a design basis radiation exposure of 150 mSv. A large number of heavy lift launches of pure shielding mass are needed to enable long duration, deep space missions to keep astronauts at or below the exposure value with shielding provided by the vehicle. Therefore, vehicle mass using the assumptions in the paper cannot be the sole shielding mechanism for long duration, deep space missions. As an example, to enable the Mars Design Reference Mission 5.0 with a 400 day transit to and from Mars, not including the 500 day stay on the surface, a minimum of 24 heavy lift launches of polyethylene at 89,375 lbm (40.54 tonnes) each are needed for the 1977 galactic cosmic ray environment. With the assumptions used in this paper, a single heavy lift launch of water or polyethylene can protect astronauts for a 130 day mission before exceeding the exposure value. Liquid hydrogen can only protect the astronauts for 160 days. Even a single launch of pure shielding material cannot protect an astronaut in deep space for more than 180 days using the assumptions adopted in the analysis. It is shown that liquid hydrogen is not the best shielding material for the same mass as polyethylene for missions that last longer than 225 days.

Singleterry, R. C.↗
NASA NTRS1992

Rapid time variations and radiative instabilities of astrophysical masers

The time-varying intensities are obtained for astrophysical masers that are radiatively unstable. Numerical integrations of the time-dependent, nonlinear equations of radiative transfer are performed with the usual approximation of a linear maser. At long times after changes in the physical conditions, the intensity of maser radiation reaches an asymptotic behavior and oscillates permanently in these idealized calculations with a period that is related to the length of the maser divided by the speed of light. The intensity varies by more than a factor of 10. These intensities depend upon the same four parameters as we originally found to determine the regime for radiative instabilities based on a stability analysis of the steady state. A detailed comparison is made between the predictions of the stability analysis and the time variations of the intensities. Calculations are performed for interacting pairs as well as isolated, individual masers.

Scappaticci, Gerardo A.↗
NASA NTRS1991

Gallium Arsenide solar cell radiation damage experiment

Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

Maurer, R. H.↗
DOE OSTI2016

Cosmic Dawn (CoDa): the first radiation-hydrodynamics simulation of reionization and galaxy formation in the Local Universe

Cosmic reionization by starlight from early galaxies affected their evolution, thereby impacting reionization itself. Star formation suppression, for example, may explain the observed underabundance of Local Group dwarfs relative to N-body predictions for cold dark matter. Reionization modelling requires simulating volumes large enough [~ (100 Mpc) 3 ] to sample reionization ‘patchiness’, while resolving millions of galaxy sources above ~10 8 M ⊙ combining gravitational and gas dynamics with radiative transfer. Modelling the Local Group requires initial cosmological density fluctuations pre-selected to form the well-known structures of the Local Universe today. Cosmic Dawn (‘CoDa’) is the first such fully coupled, radiation-hydrodynamics simulation of reionization of the Local Universe. Our new hybrid CPU-GPU code, RAMSES-CUDATON, performs hundreds of radiative transfer and ionization rate-solver timesteps on the GPUs for each hydro-gravity timestep on the CPUs. CoDa simulated (91Mpc) 3 with 4096 3 particles and cells, to redshift 4.23, on ORNL supercomputer Titan, utilizing 8192 cores and 8192 GPUs. Global reionization ended slightly later than observed. However, a simple temporal rescaling which brings the evolution of ionized fraction into agreement with observations also reconciles ionizing flux density, cosmic star formation history, CMB electron scattering optical depth and galaxy UV luminosity function with their observed values. Photoionization heating suppressed the star formation of haloes below ~2 × 109 M ⊙ , decreasing the abundance of faint galaxies around M AB1600 = [-10, -12]. For most of reionization, star formation was dominated by haloes between 10 10 –10 11 M ⊙ , so low-mass halo suppression was not reflected by a distinct feature in the global star formation history. Intergalactic filaments display sheathed structures, with hot envelopes surrounding cooler cores, but do not self-shield, unlike regions denser than 100 $\langle$ρ$\rangle$.

Astronomy & Astrophysics↗