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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 1,261 records · Page 70
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Spent Fuel NDA Project: Data Authentication Considerations

The overall spent fuel nondestructive assay project seeks to develop improved measurement capability for the verification of spent nuclear fuel, especially before its disposal or movement to hard-to-access storage. Various systems are being considered, employing neutron and/or gamma radiation detection with either passive or active methods; their use scenarios are not yet well defined. In a practical deployment, the measurement system would likely need to operate in unattended mode. The output results may also need to be shared between multiple recipients with various interests. The data authentication task considers what issues are important in being able to trust the measurement results. By defining and analyzing a generic (3z(Bbaseline(3y (Bsystem scenario, we have identified five key factors needing specific attention: application use-case details, equipment tamper indication, supporting (ancillary) instruments, systems implementation, and instrument state-of-health reporting.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Introduction to the Consortium for Monitoring, Technology, and Verification (MTV) [Slides]

Our mission is to develop new technologies that detect and deter nuclear proliferation activities while training the next generation of nuclear professionals. The three technical thrust areas are: 1. Fundamentals of nuclear and particle physics, 2. Signals and source terms for nuclear nonproliferation, and 3. Nuclear explosion. There are opportunities for collaborations with university faculty, possible student and post-doc work, and posting job ads. Further, MTV hosts various workshops, symposiums.

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

Progress Report for the Pathfinder Project: A Laser-Based / Fiber Optic IAEA Seal That Implements Spectral Interferometry

This is the first progress report for the Laser / Fiber-Optic Based IAEA Seal. This seal implements spectral interferometry, which is crucial for its resilience to tampering. Indeed, based on our understanding of telecommunications-based fiber optic technology, it is essentially impossible to tamper with the fiber without detection either immediately (with an active system) or subsequently (with a passive system).

36 MATERIALS SCIENCE↗
DOE OSTI2026

SILICON CARBIDE THERMOMETRY USING RAMAN SPECTROSCOPY ON IRRADIATED TRISO PARTICLES

Silicon carbide (SiC) passive thermometry has emerged as a promising post-irradiation examination (PIE) technique for estimating irradiation temperature near the end of irradiation. While dilatometry techniques have been traditionally used to analyze prismatic samples after irradiation, Raman spectroscopy has recently been shown to provide comparable results by analyzing Raman-active phonon modes. In this work, Raman spectroscopy has been applied to the SiC layer of cross-sectioned irradiation tristructural isotropic (TRISO) particles from the AGR-5/6/7 experiment to evaluate the feasibility of particle-scale passive thermometry. Two-dimensional Raman mapping was used to measure the position of the SiC longitudinal optical (LO) phonon, which was then converted to an apparent irradiation temperature using a previously established empirical correlation. Particles from AGR-5/6/7 Compacts 2-2-1 and 5-1-3 were selected as their calculated time-averaged, volume-averaged (TAVA) temperatures (828°C and 706°C, respectively) fall within the range of the sensitivity of the experimental approach. The use of SiC thermometry was anticipated to confirm or highlight potential deviations from calculated end-of-life TAVA temperature across compacts. Four particles from Compact 2-2-1 and two particles from Compact 5-1-3 were selected based on 110mAg inventory (either some measurable activity or below the minimum detection limit) which is commonly used as an indicator of in-pile temperature variation of particles within the same compact. Across every particle selected it was determined that the average LO peak position was located around 968 cm-1 to 969 cm-1. Using the previously determined empirical correlation, this corresponds to an irradiation temperature around 950°C to 966°C, which does not align with the reported TAVA temperature values. This discrepancy in apparent irradiation temperatures likely reflects a combination of uncertainties in the calculated particle temperatures and differences in irradiation history between the present specimens and those used to establish the empirical Raman calibration such as neutron flux (damage rate) and SiC microstructure (as fabricated and irradiated).

Vawdrey, Josh [ORNL]↗
DOE OSTI2012

Microbial Reduction of Chromate in the Presence of Nitrate by Three Nitrate Respiring Organisms

A major challenge for the bioremediation of toxic metals is the co-occurrence of nitrate, as it can inhibit metal transformation. Geobacter metallireducens, Desulfovibrio desulfuricans, and Sulfurospirillum barnesii are three soil bacteria that can reduce chromate [Cr(VI)] and nitrate, and may be beneficial for developing bioremediation strategies. All three organisms respire through dissimilatory nitrate reduction to ammonia (DNRA), employing different nitrate reductases but similar nitrite reductase (Nrf). G. metallireducens reduces nitrate to nitrite via the membrane bound nitrate reductase (Nar), while S. barnesii and D. desulfuricans strain 27774 have slightly different forms of periplasmic nitrate reductase (Nap). We investigated the effect of DNRA growth in the presence of Cr(VI) in these three organisms and the ability of each to reduce Cr(VI) to Cr(III), and found that each organisms responded differently. Growth of G. metallireducens on nitrate was completely inhibited by Cr(VI). Cultures of D. desulfuricans on nitrate media was initially delayed (48 h) in the presence of Cr(VI), but ultimately reached comparable cell yields to the non-treated control. This prolonged lag phase accompanied the transformation of Cr(VI) to Cr(III). Viable G. metallireducens cells could reduce Cr(VI), whereas Cr(VI) reduction by D. desulfuricans during growth, was mediated by a filterable and heat stable extracellular metabolite. S. barnesii growth on nitrate was not affected by Cr(VI), and Cr(VI) was reduced to Cr(III). However, Cr(VI) reduction activity in S. barnesii, was detected in both the cell free spent medium and cells, indicating both extracellular and cell associated mechanisms. Taken together, these results have demonstrated that Cr(VI) affects DNRA in the three organisms differently, and that each have a unique mechanism for Cr(VI) reduction.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Identification of z ≳ 2 Herschel 500 μm sources using color deconfusion

We present a new method to search for candidate z ≳ 2 Herschel 500 μm sources in the Great Observatories Origins Deep Survey-North field using a S{sub 500 μm}/S{sub 24 μm} “color deconfusion” technique. Potential high-z sources are selected against low-redshift ones from their large 500 to 24 μm flux density ratios. By effectively reducing the contribution from low-redshift populations to the observed 500 μm emission, we are able to identify counterparts to high-z 500 μm sources whose 24 μm fluxes are relatively faint. The recovery of known z ≳ 4 starbursts confirms the efficiency of this approach in selecting high-z Herschel sources. The resulting sample consists of 34 dusty star-forming galaxies at z ≳ 2. The inferred infrared luminosities are in the range 1.5 × 10{sup 12}–1.8 × 10{sup 13} L{sub ⊙}, corresponding to dust-obscured star formation rates (SFRs) of ∼260–3100 M{sub ⊙} yr{sup −1} for a Salpeter initial mass function. Comparison with previous SCUBA 850 μm-selected galaxy samples shows that our method is more efficient at selecting high-z dusty galaxies, with a median redshift of z=3.07±0.83 and with 10 of the sources at z ≳ 4. We find that at a fixed luminosity, the dust temperature is ∼5 K cooler than that expected from the T{sub d}−L{sub IR} relation at z ≲ 1, though different temperature selection effects should be taken into account. The radio-detected subsample (excluding three strong active galactic nucleus) follows the far-infrared (far-IR)/radio correlation at lower redshifts, and no evolution with redshift is observed out to z∼5, suggesting that the far-IR emission is star formation dominated. The contribution of the high-z Herschel 500 μm sources to the cosmic SFR density is comparable to that of (sub)millimeter galaxy populations at z∼2.5 and at least 40% of the extinction-corrected UV samples at z∼4. Further investigation into the nature of these high-z dusty galaxies will be crucial for our understanding of the star formation histories and the buildup of stellar mass at the earliest cosmic epochs.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

The 2015–2016 Outburst of the Classical EXor V1118 Ori

After a quiescence period of about 10 years, the classical EXor source V1118 Ori has undergone an accretion outburst in 2015 September. The maximum brightness (ΔV≳4 mag) was reached in 2015 December and was maintained for several months. Since 2016 September, the source is in a declining phase. Photometry and low/high-resolution spectroscopy were obtained with MODS and LUCI2 at the Large Binocular Telescope, with the facilities at the Asiago 1.22 and 1.82 m telescopes, and with GIANO at the Telescopio Nazionale Galileo. The spectra are dominated by emission lines of H i and neutral metallic species. From line and continuum analysis we derive the mass accretion rate and its evolution during the outburst. Considering that extinction may vary between 1.5 and 2.9 mag, we obtain M-dot {sub acc} = 0.3–2.0 10{sup −8} M {sub ⊙} yr{sup −1} in quiescence and M-dot {sub acc} = 0.2–1.9 10{sup −6} M {sub ⊙} yr{sup −1} at the outburst peak. The Balmer decrement shape has been interpreted by means of line excitation models, finding that from quiescence to outburst peak, the electron density has increased from ∼2 10{sup 9} cm{sup −3} to ∼4 10{sup 11} cm{sup −3}. The profiles of the metallic lines are symmetric and narrower than 100 km s{sup −1}, while H i and He i lines show prominent wings extending up to ±500 km s{sup −1}. The metallic lines likely originate at the base of the accretion columns, where neutrals are efficiently shielded against the ionizing photons, while faster ionized gas is closer to the star. Outflowing activity is testified by the detection of a variable P Cyg-like profile of the Hα and He i 1.08 μm lines.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1973

Acoustic-emission signal-processing analog unit for locating flaws in large tanks

Technique monitors structural flaws in 105-in. diameter tanks. Tank surface is divided into many areas and each area is sectioned into 20 equilateral triangles that form icosahedron. Twelve transducers are equally positioned on tank surface at vertex of each triangle. Transducers monitor area for flaws by detecting any increase in acoustical activity.

Moskal, F. J.↗
NASA NTRS1976

Terrestrial kilometric radiation: 2: Emission from the magnetospheric cusp and dayside magnetosheath

Measurements of the location of sources of terrestrial kilometric radiation obtained with the lunar orbiting Radio Astronomy Explorer-2 satellite have revealed a class of emission associated with the cusp and dayside magnetosheath. At frequencies near 250 kHz this emission is observed at radial distances between 2 and 20 R sub E at magnetic latitudes of 75 deg to 80 deg and is most often detected during periods of auroral activity (AE or approximately = 250) and southward orientation of the interplanetary magnetic field vertical component. During very disturbed times, the emission at the lowest frequencies ( or approximately = 200 kHz) appears to come from the dayside magnetosheath at distances or approximately = 12 R sub E. Whenever the geomagnetic dipole is tilted significantly with respect to the ecliptic pole ( or approximately = 10 deg) the cusp emission is confined to the hemisphere containing the sub solar point. The measurements also suggest that the region of cusp emission is rather narrowly confined in longitude to within + or - a few hours of the noon meridian.

Alexander, J. K.↗
NASA NTRS1977

Terrestrial kilometric radiation. II - Emission from the magnetospheric cusp and dayside magnetosheath

Measurements of the location of sources of terrestrial kilometric radiation obtained with the lunar-orbiting Radio Astronomy Explorer 2 satellite have revealed a class of emission associated with the cusp and dayside magnetosheath. At frequencies near 250 kHz, this emission is observed at radial distances between 2 and 20 earth radii at magnetic latitudes of 75 to 80 deg and is most often detected during periods of auroral activity and southward orientation of the interplanetary magnetic-field vertical component. During very disturbed times, the emission at the lowest frequencies (below about 200 kHz) appears to come from the dayside magnetosheath at distances of at least 12 earth radii. Whenever the geomagnetic dipole is tilted significantly with respect to the ecliptic pole, the cusp emission is confined to the hemisphere containing the subsolar point. The measurements also suggest that the region of cusp emission is rather narrowly confined in longitude to within a few hours of the noon meridian.

Alexander, J. K.↗
NASA NTRS1978

Lonar crater glasses and high-magnesium australites - Trace element volatilization and meteoritic contamination

Radiochemical neutron activation analysis was used to detect six siderophile elements (Ni, Re, Os, Pd, Ir and Au) and three volatile elements (Zn, Se and Cd) in two basalts, a pumice and three impact glasses from Lonar crater, India, and in six high-magnesium australites. Significant depletions in Re and Se with respect to the parent basalts were found in the Lonar glasses. These depletions, apparently correlated with the degree of shock, are probably due to volatilization under the oxidizing conditions characteristic of earth. One of the australites is substantially enriched in siderophiles relative to the level of these elements in the other five tektites. The element patterns in the australites resemble those of the carbonaceous or cometary component of an Apollo 16 soil.

Morgan, J. W.↗
NASA NTRS1981

Quarantine and protocol

The purpose of the Orbiting Quarantine Facility is to provide maximum protection of the terrestrial biosphere by ensuring that the returned Martian samples are safe to bring to Earth. The protocol designed to detect the presence of biologically active agents in the Martian soil is described. The protocol determines one of two things about the sample: (1) that it is free from nonterrestrial life forms and can be sent to a terrestrial containment facility where extensive chemical, biochemical, geological, and physical investigations can be conducted; or (2) that it exhibits "biological effects" of the type that dictate second order testing. The quarantine protocol is designed to be conducted on a small portion of the returned sample, leaving the bulk of the sample undisturbed for study on Earth.

Source record↗
NASA NTRS1985

Effects of weightlessness on neurotransmitter receptors in selected brain areas

The central nervous system receptor dynamics of rats exposed to 7 days of microgravity are studied. The receptor affinity and receptor number at the hippocampus, lateral frontal cortex, prefrontal cortex, corpus striatum, cerebellum and pons-medulla, and the Na(+)/K(+)ATPase activity are examined. The data reveal that there is no significant change in the receptor affinity and receptor number for the lateral frontal cortex, prefrontal cortex, cerebellum and pons-medulla; however, there is an increase from 81 + or - 11 to 120 + or 5 fmole/mg protein in the receptor number for hippocampal binding, and a decrease in receptor number for the striatum from 172 + or - 14 to 143 + or - 10 fmoles/mg protein. A 9 percent decrease in Mg-dependent Na(+)/K(+)ATPase activity is observed. It is detected that the terminal mechanism may be affected by exposure to microgravity.

Miller, J. D.↗
NASA NTRS1991

Experience gained in operation of the VLF ATD lightning location system

The United Kingdom (UK) Meteorological Office's Very Low Frequency (VLF) Arrival Time Difference (ATD) System for long-range location of lightning flashes started automatic international issue of lightning-location products on 17 Jun. 1988. Data from before and after this formal start-date were carefully scrutinized to judge performance. Techniques for estimating location accuracy include internal consistency and comparisons against other systems. Other areas studied were range (up to several thousand km); detection efficiency, saturation effects in active situations, and communication difficulties (for this redundant system); and spurious fix rate. Care was taken to assess the potential of the system, in addition to identifying the operational difficulties of the present implementation.

Lee, Anthony C. L.↗
NASA NTRS1991

A search for evidence of cold dust around naked T Tauri stars

Results of millimeter/ submillimeter photometry of 16 naked T Tauri stars, 11 of which lie in the nearby Taurus-Auriga star-forming region, are presented. Evidence of cold circumstellar dust, which could exist around these objects in the form of remnant disks if NTTS evolved from classical T Tauri stars, is explored. The only star detected at the primary observing wavelength of 1100 microns was V836 Tau, which was also detected at 800 microns with an upper limit obtained at 450 microns. Its spectral energy distribution longward of 10 microns is consistent with that expected for a flat axisymmetric moderately active disk with a solar mass of 0.04. Upper limits on the disk masses of undetected stars in Taurus-Auriga are typically 0.02 solar mass, for an assumed temperature of not less than 6 K at the outer disk radius. It is argued that the high levels of magnetic activity found in NTTS may produce detectable gyrosynchroton emission at millimeter wavelengths.

Skinner, Stephen L.↗
NASA NTRS1992

Further analyses of human kidney cell populations separated on the Space Shuttle

Cultured human embryonic kidney cells were separated into electrophoretic subpopulations in laboratory experiments and in two separation experiments on the STS-8 (Challenger) Space Shuttle flight using the mid-deck Continuous Flow Electrophoretic Separator (CFES). Populations of cells from each fraction were cultured for the lifetime of the cells, and supernatant medium was withdrawn and replaced at 4-day intervals. Withdrawn medium was frozen at -120 C for subsequent analysis. Enzyme assays, antibodies and gel electrophoresis were used as analytical tools for the detection and quantization of plasminogen activators in these samples. These assays of frozen-culture supernatant fluids confirmed the electrophoretic separation of plasminogen-activator-producing cells from nonproducing cells, the isolation of cells capable of sustained production, and the separation of cells that produce different plasminogen activators from one other.

Stewart, Robin M.↗
NASA NTRS1992

The hard x ray luminosity function and evolution of AGN

A large number of active galactic nuclei and quasars detected by the HEAO A1 x-ray survey and recently identified using results from the HEAO A3 experiments are described and preliminary results are presented. The sample shows some incompleteness and is not completely identified, so these effects are taken out in the analysis by correcting the effective coverage of the survey. Preliminary analysis indicates that significant evolution can be detected in this data and that the evolution rate appears stronger than that inferred from a sample selected at lower energies.

Marshall, Herman L.↗
NASA NTRS1994

Hydrazine-Vapor Samplers

Active sampling unit capable of detecting hydrazine and monomethyl hydrazine vapors at levels as low as 10 ppb in air developed. Includes detachable badge holder and pump which draws air through badge holder at selectable rate of 1 or 2 L/min. Coated strip in each badge designed to align with air passage in badge holder. Two types of badge holders constructed: one has open-face design for general monitoring of air in open spaces, while other has closed-face design with viewing window and intended for sampling through small openings to detect leaks.

Young, Rebecca↗