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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

K-band TWT using new diamond rod technology

A 75-W CW helix TWT for satellite communications systems is being developed to operate at 20 GHz with an efficiency goal of 60 percent. A nonbrazed nonbonded diamond rod fabrication technique is used to develop the helix-type TWT. Techniques to enhance TWT efficiency are described, including the incorporation of a velocity tapered helix and a multistage graphite collector. Results from testing a breadboard TWT show a CW output power greater than 100 W and a 54.6 overall efficiency.

Aldana, S. L.↗
DOE OSTI2020

Gamma Spectrometry Examination of the AGR-3/4 Irradiation

The results from gamma spectrometry examination of the different components from the combined third and fourth U.S. Advanced Gas Reactor (AGR) TRISO-coated particle fuel irradiation tests (AGR-3/4) have been analyzed. This experiment was designed to provide information about in-pile fission product migration. In each of the 12 capsules, a single stack of four compacts with designed-to-fail (DTF) particles surrounded by inner and outer graphite and/or graphitic matrix rings and a graphite sink ring were irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL). Gamma spectrometry has been used to evaluate the gamma-emitting fission product inventory of compacts from the irradiation and evaluate the burnup of these compacts based on the activity of the radioactive cesium isotopes (i.e., Cs-134 and Cs-137) in the compacts. Burnup from gamma spectrometry compares well with predicted burnup from simulations. The inner and outer rings were also examined by gamma spectrometry to evaluate the total fission product inventory of the rings, and gamma emission computed tomography (GECT) was used to investigate the spatial distribution of gamma-emitting fission products within the rings. This report focuses on results obtained via the Precision Gamma Scanner (PGS) for the compacts and inner and outer rings. These non-destructive gamma measurements are currently being compared to recent destructive measurements of spatial fission product distributions in the rings and to predictions made via mathematical modeling. A separate report discusses the entire AGR-3/4 fission product mass balance for all irradiation capsule components including the inner and outer rings, graphite sink rings, capsule spacers, capsule foils, through tubes, and felts. This report is similar to the conference proceedings: Harp, J.M., Demkowicz, P.A., and Stempien, J.D., “Initial gamma spectrometry examination of the AGR-3/4 irradiation,” International Topical Meeting High Temperature Reactor Technology (HTR 2016), Las Vegas, NV, USA, November 2016, Paper HTR2016-18593, but it has been updated to reflect all the data that has been collected on AGR-3/4 using PGS. The Appendices contain extensive data from the collected gamma spectra.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Pseudo-Hot-Isostatic Pressing (P-HIP)

Researchers at Los Alamos National Laboratory developed a technology to produce high performance ceramic or metal with a combination of major key properties such as versatile-complicated shape, high density, uniform density distribution, and minimal amounts of starting material. The novel pseudo-hot-isostatic-pressing (P-HIP) uses graphite or boron nitride flakes as the stress transmission media to transmit stress instead of the conventional solid graphite punch. The graphite and boron nitride flakes are solid lubricants and can slide among one another to re-distribute the stress from high stress concentration area to the low stress concentration areas, resulting in a self-stress-relief action. This innovative P-HIP enables the manufacturing of complicated shapes with near-net-shape capability while minimizing the energy used and reducing waste. This is a revolutionary breakthrough to the ceramics and powder metallurgy industries.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Development of a Sulfur Tolerant CHG Process (CRADA 442) (Final Report)

The Pacific Northwest Laboratory (PNNL) has developed the Catalytic Hydrothermal Gasification (CHG) technology, which can convert low-value organics dispersed in aqueous streams, such as the aqueous phase byproduct from hydrothermal liquefaction (HTL) of wet wastes, to a mixture of methane, H 2 , and CO 2 . The current CHG catalyst, ruthenium (Ru) on a graphite substrate, was selected for its effectiveness as a reducing catalyst. However, the target waste aqueous feedstock, the HTL aqueous phase from wet wastes, such as sewage sludge, contains a fair amount of sulfur in both organic and inorganic forms. Like many other reduced metal catalysts, Ru is deactivated or poisoned by exposure to sulfur, among other contaminants. In general, a deactivated Ru catalyst cannot be reactivated or restored except by removing and returning it for remanufacturing. Therefore, there is an urgent need for a sulfur-resistant catalyst to enable CHG processing of the HTL aqueous waste stream. PNNL, with support from SoCalGas CRADA, has developed a sulfur resistant CHG catalyst and demonstrated a stable CHG process for converting HTL aqueous phases from wet wastes. Here, we report the major accomplishments of the project: • We have demonstrated that sulfided Ru based catalysts is stable during CHG of HTL aqueous waste stream, with a requirement of activity improvement. • We have developed a new catalyst, with 0.5-2 wt.% Ru loading, showing better activity compared to the baseline 6.7 wt.% RuSx/C catalyst. • With the new catalysts, the single-pass COD reduction is approximately 60% and two-pass COD reduction can reach approximately 85%. • The process is robust in terms of being effective across a wide range of organic species in the feedstock. • Techno-economic analysis was conducted to evaluate the economic impact of catalyst advancement and identify further improvement requirements. This type of catalyst shows great potential to be efficient and robust for CHG with low catalyst cost.

03 NATURAL GAS↗
DOE OSTI2022

U.S. High Temperature Materials Highlights

U.S. GIF VHTR work is continuing on graphite qualification, Alloy 617 regulatory issues beyond the Code space, Alloy 800H weldments, and ASME Codes and Standards R&D is still considering both pebble bed and prismatic and steam generator and heat exchanger U.S. DOE Advanced Reactor Demonstration Program (ARDP) Two U.S.-based teams were selected to demonstrate advanced nuclear reactors in the United States that can be operational by 2027 One of the teams is X-energy (Rockville, MD) which will demonstrate a modular gas-cooled reactor design (Xe-100) with four 80 MWe, TRISO fuel, pebble bed reactors A number of U.S.-based teams were selected to design and develop safe and affordable reactor technologies that can be licensed and deployed over the next 10 to 14 years (Risk Reduction) One of the teams is BWXT Advanced Technologies, LLC which will develop a commercially viable transportable microreactor with the design focused on using TRISO fuel particles and silicon carbide (SiC) matrix A number of U.S.-based teams were selected to assist the progression of advanced reactor designs in their earliest phases (Advanced Reactor Concepts-20) One of the teams is Massachusetts Institute of Technology which will mature the Modular Integrated Gas-Cooled High Temperature Reactor (MIGHTR) concept with a horizontal compact design from a pre-conceptual stage to a conceptual stage to support commercialization

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Proximity Spin–Orbit Torque on a Two-Dimensional Magnet within van der Waals Heterostructure: Current-Driven Antiferromagnet-to-Ferromagnet Reversible Nonequilibrium Phase Transition in Bilayer CrI 3

The recently discovered two-dimensional magnetic insulator CrI 3 is an intriguing case for basic research and spintronic applications since it is a ferromagnet in the bulk but an antiferromagnet in bilayer form, with its magnetic ordering amenable to external manipulations. Using the first-principles quantum transport approach, we predict that injecting unpolarized charge current parallel to the interface of the bilayer-CrI 3 /monolayer-TaSe 2 van der Waals (vdW) heterostructure will induce spin–orbit torque and thereby drive the dynamics of magnetization on the first monolayer of CrI 3 in direct contact with TaSe 2 . By combining the calculated complex angular dependence of spin–orbit torque with the Landau-Lifshitz-Gilbert equation for classical dynamics of magnetization, we demonstrate that current pulses can switch the direction of magnetization on the first monolayer to become parallel to that of the second monolayer, thereby converting CrI 3 from antiferromagnet to ferromagnet while not requiring any external magnetic field. We explain the mechanism of this reversible current-driven nonequilibrium phase transition by showing that first monolayer of CrI 3 carries current due to evanescent wave functions injected by metallic transition metal dichalcogenide TaSe 2 , while concurrently acquiring strong spin–orbit coupling via such a proximity effect, whereas the second monolayer of CrI 3 remains insulating. Furthermore, the transition can be detected by passing vertical read current through the vdW heterostructure, encapsulated by a bilayer of hexagonal boron nitride and sandwiched between graphite electrodes, where we find a tunneling magnetoresistance of ≃240%.

2D magnetic materials↗
DOE OSTI2020

Preliminary Evaluation of Loading DOE Standard Canisters in the INL CPP-603 Irradiated Fuel Storage Facility - 20543

This paper looks at the equipment and operations necessary to load United States Department of Energy (DOE)-owned Spent Nuclear Fuel (SNF) into DOE Standard Canisters in the CPP-603 Irradiated Fuel Storage Facility (IFSF) in the Idaho Nuclear Technology and Engineering Center (INTEC) area at Idaho National Laboratory (INL). Two types of fuels are looked at in this evaluation: Advanced Test Reactor (ATR) fuel (uranium-aluminide fuel with aluminum cladding) and Peach Bottom fuel (thorium-uranium carbide fuel in a graphite matrix). The fuel ready for loading would come from fuel storage canisters in the CPP-603 facility. The paper describes the facility, the fuel types, the DOE Standard Canisters, and existing equipment; lists the needed loading operations; reviews facility features and equipment to perform the operations; and then lists the decisions, analyses, designs, demonstrations, and modifications that will be needed to perform the loading of DOE-owned SNF into DOE Standard Canisters in the CPP-603 IFSF. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1991

High-efficiency 20 GHz traveling wave tube development for space communications

A 75 watt CW high efficiency helix TWT operating at 20 GHz was developed for satellite communication systems. The purpose was to extend the performance capabilities of helix TWTs by using recent technology developments. The TWT described is a unique design because high overall efficiency is obtained with a low perveance beam. In the past, low perveance designs resulted in low beam efficiencies. However, due to recent breakthoughs in diamond rod technology and in collector electrode materials, high efficiencies can now be achieved with low perveance beams. The advantage of a low perveance beam is a reduction in space charge within the beam which translates to more efficient collector operation. In addition, this design incorporates textured graphite electrodes which further enhance collector operation by suppressing backstreaming secondaries. The diamond supported helix circuit features low RF losses, high interaction impedance, good thermal handling capability and has been designed to compensate for the low perveance beam. One more discussed tube feature is the use of a velocity taper in the output helix that achieves low signal distortion while maintaining high efficiency.

Aldana, S. L.↗
NASA NTRS1995

Analysis of selected compression splice joint locations in a graphite-epoxy transport wing stub box

Three critical compression splice joint locations in a stitched graphite-epoxy transport wing stub box have been analyzed to determine their expected structural performance. The wing box is representative of a section of a commercial transport wing box and was designed and constructed by McDonnell Douglas Aerospace Company as part of the NASA Advanced Composites Technology (ACT) program. The results of the finite element analyses of the splice joints are presented. The analysis results indicate that failure will not occur in the splice joint regions for loads less than the Design Ultimate Load of the wing box.

Jegley, Dawn C.↗
NASA NTRS2019

Wear Trends of the HERMeS Thruster as a Function of Throttle Point

A series of short-duration (200 h) wear tests were conducted with two Hall Effect Rocket with Magnetic Shielding (HERMeS) technology demonstration units. Front pole covers, cathode keeper, and discharge channel wear were characterized as a function of discharge voltage, magnetic field strength, and chamber pressure. No discharge channel erosion was observed. Inner pole cover erosion was shown to be a weak function of discharge voltage with most erosion occurring at the lowest value, 300 V. The Technology Demonstration Unit (TDU) 3 keeper electrode eroded with each operating condition, with high magnetic field yielding the greatest erosion rate. The TDU-1 keeper electrode exhibited net deposition suggesting its configuration is more consistent with meeting overall HERMeS service life requirements. Ratios of molybdenum to graphite erosion rates suggests, with high uncertainty, that the sputtering ions are originating downstream of the thruster exit plane, striking the surface with small angles of incidence.

Williams, George J., Jr.↗
NASA NTRS2022

A Novel High-Performance Mission-Enabling Multi-Purpose Radioisotope Heat Source

Recent studies indicate science mission concepts targeting access to the sub-surface oceans of icy moons require ice-penetrating cryobots powered by advanced Radioisotope Power Systems (RPS). These systems would deliver waste heat for ice-melting in the range of 10 kW. Minimizing the transit time through the kilometers-thick ice shells to just a few years requires these RPS to utilize heat sources having a higher thermal energy volumetric density than the existing flight-qualified General-Purpose Heat Source (GPHS). A Compact Heat Source (CPHS)has been conceptualized in which the graphite impact shells(GIS) of the existing GPHS are rearranged in a hexagonal aeroshell containing seven GIS per module, as opposed to the standard two per module; offering a thermal energy density of 0.57 W/cm3versus 0.29 W/cm3 offered by the GPHS simply from the repackaging of Technology Readiness Level (TRL)9 subassemblies. Preliminary thermal modeling of the CPHS integrated into a notional radioisotope thermoelectric generator(RTG) structure further suggests that centerline temperatures are well within allowable limits during nominal operation. Given the need for the CPHS for a subset of missions, it is worth exploring the applicability of the CPHS for more general RTG purposes. We discuss herein how the CPHS may be implemented with either heritage or in-development thermoelectric converter technologies into a Next-Generation RTG concept. Due to a higher energy density, the legacy heat rejection fin arrangement must be modified to permit a sufficiently low cold-side temperature. Preliminary finite element analysis suggests fin-root temperatures can be kept as low as 520 K while allowing the generator to fit within the usable dimensions of currently available United States Department of Energy shipping containers. Such temperatures would certainly be compatible with the use of high temperature thermoelectric converter technologies.. A prime candidate is the heritage silicon-germanium (SiGe) unicouple, whose design could be adapted by approximately halving the leg-length, but without changes in hot and cold junction interfaces, which are features critical to the proven performance and reliability of these devices. The estimated Beginning of Life power for a SiGe-based CPHS-RTG using 12 CPHS for a thermal inventory of 10.5 kW is greater than 600 W under deep space operating conditions. Using higher performance segmented couples currently in development that are based on skutterudite,La3−xTe4and 14-1-11 Zintl thermoelectric materials in lieu of the SiGe unicouples would increase the power level to more than1 kW. The high specific power (We/kg) attribute of CPHS-RTGs found in this study could potentially enable Radioisotope Electric Propulsion (REP) mission concepts. Past NASA REP mission concept studies identified specific power needs in excess of 6to 8 We/kg. Based on a GPHS-RTG-like system configuration, we show that at fin root temperatures between 530 K and 570K (deep space environment), specific powers exceeding 10 We/kg are achievable using high performance segmented thermoelectric converters. The compact sizing and power density of the CPHS-RTG would constitute a significant step upgrade in specific power when compared to heritage GPHS-RTG (approximately5.1 We/kg) and off-the-shelf Multi-Mission RTG (approximately 2.6 We/kg).

Nesmith, Bill J.↗
DOE OSTI2021

ASME Code Rules and ASTM Standards Integration for Ceramic Composite Core Materials and Components 1

Fiber-reinforced ceramic matrix composites have many desirable properties for high-temperature nuclear applications, including excellent thermal and mechanical properties and reasonable to outstanding radiation resistance. Over the last 20 years, the use of ceramic composite materials has already expanded in many commercial nonnuclear industries as fabrication and application technologies mature. The new ASME design and construction rules under Section III, Subsection HH, Subpart B lay out the requirements and criteria for materials, design, machining and installation, inspection, examination, testing, and the marking procedure for ceramic composite core components, which is similar to the established graphite code under Section III, Subsection HH, Subpart A. Moreover, the general requirements listed in Section III, Subsection HA, Subpart B are also expanded to include ceramic composite materials. The code rules rely heavily on the development and publication of standards for composite specification, classification, and testing of mechanical, thermal, and other properties. These test methods are developed in the American Society for Testing and Materials Committee C28 on Advanced Ceramics with a current focus on ceramic composite tubes. Details of the composites code, design methodology, and similarities to the graphite code, as well as guidance for the development of specifications for ceramic composites for nuclear application and recent standard developments, are discussed. The next step is to "close the gap" to support licensing aspects by validating the code with benchmarking data.

Geringer, Josina↗
NASA NTRS1977

Solar silicon via improved and expanded metallurgical silicon technology

A completed preliminary survey of silica sources indicates that sufficient quantities of high-purity quartz are available in the U.S. and Canada to meet goals. Supply can easily meet demand for this little-sought commodity. Charcoal, as a reductant for silica, can be purified to a sufficient level by high-temperature fluorocarbon treatment and vacuum processing. High-temperature treatment causes partial graphitization which can lead to difficulty in smelting. Smelting of Arkansas quartz and purified charcoal produced kilogram quantities of silicon having impurity levels generally much lower than in MG-Si. Half of the goal was met of increasing the boron resistivity from 0.03 ohm-cm in metallurgical silicon to 0.3 ohm-cm in solar silicon. A cost analysis of the solidification process indicate $3.50-7.25/kg Si for the Czochralski-type process and $1.50-4.25/kg Si for the Bridgman-type technique.

Hunt, L. P.↗
DOE OSTI2023

Development of Hydrogen Permeation Barrier and Matrix Interaction Protection Coatings for TZM Enclosure of Hydride Moderators (Microreactor Program M3 Report)

It is important to develop a high-performance enclosure solution for hydride-based microreactor moderation components to effectively suppress hydride thermal decomposition and prevent hydrogen loss in harsh in-reactor environments. Currently, the DOE-NE Microreactor Program (MR program) is investigating the titanium-zirconium-molybdenum (TZM) canned yttrium hydride (YH 2-x ) solution, which provides acceptable hydrogen retainment performance up to ~700 °C. However, improvements in the enclosure are necessary for increasing long-term operation temperature beyond 700 °C and enhancing short-term survivability at even higher temperatures during power transients. One potential solution is the addition of a dedicated hydrogen permeation barrier, which can potentially improve the enclosure's performance. Furthermore, the hydride moderator components will be inserted into the microreactor matrix, which may consist of materials that are not chemically inert against TZM. Therefore, the TZM might need to be protected from the external environment through the application of another surface protection coating. To address these critical issues, two types of barrier coatings optimized for TZM-based moderator enclosure has been developed. A multilayer coating approach has been used to identify TZM-compatible barrier materials. Behavior of these coating designs against H 2 permeation and long-term high-temperature graphite matrix interactions has been examined in detail. Additionally, the developed coatings' behavior when exposed to both high-temperature thermal cycling and heavy-ion irradiation has also been investigated. Overall, the development of these barrier coatings is essential for achieving maturity for the metal hydride moderator technology. The results in this report will provide crucial insights into the behavior of the developed coatings and their potential for improving the long-term performance of TZM-based moderator enclosures.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

Fully Fluorinated Local High Concentration Electrolytes Enabling High Energy Density Si Anodes

To develop fluorinated localized high concentration electrolytes as a novel approach for constructing a functional SEI on Si based anodes. The technological approach combines the SEI modification strategies of fluorinated carbonate solvents and local high concentration electrolytes. The resulting synergy of anion and fluorinated solvent decomposition will form a mechanically robust, fluorinated SEI that enables extended cycling with high capacity retention. The electrolytes will enable demonstration of silicon-graphite anodes with high Si content, paired with NMC811 cathodes. Characterization will focus on galvanostatic cycling to evaluate electrochemical performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1981

In-service inspection methods for graphite-epoxy structures on commercial transport aircraft

In-service inspection methods for graphite-epoxy composite structures on commercial transport aircraft are determined. Graphite/epoxy structures, service incurred defects, current inspection practices and concerns of the airline and manufacturers, and other related information were determind by survey. Based on this information, applicable inspection nondestructive inspection methods are evaluated and inspection techniques determined. Technology is developed primarily in eddy current inspection.

Phelps, M. L.↗