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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 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Forklift Safety Fundamentals, #20299, Test 20300

A powered industrial truck (PIT) is defined as a mobile, powerdriven vehicle used to carry, push, pull, lift, or stack material (not including vehicles intended primarily for earth moving). There are many types of and names for PITs, including forklifts, trucks, fork trucks, platform lift trucks, motorized hand trucks, and tractors. Although not every PIT is a forklift, because PITs are commonly called “forklifts,” this course manual generally uses the term “forklift,” although at times the terms “truck” and “PIT” are also used. In some areas of this course, you will see green boxes that refer to the Occupational Safety and Health Administration (OSHA) regulation for PITs, which is 29 Code of Federal Regulations (CFR) 1910.178, Powered Industrial Trucks. The letter in the parentheses refers to the specific section of the regulation.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2016

Report on fundamental modeling of irradiation-induced swelling and creep in FeCrAl alloys

In order to improve the accident tolerance of light water reactor (LWR) fuel, alternative cladding materials have been proposed to replace zirconium (Zr)-based alloys. Of these materials, there is a particular focus on iron-chromium-aluminum (FeCrAl) alloys due to much slower oxidation kinetics in high-temperature steam than Zr-alloys. This should decrease the energy release due to oxidation and allow the cladding to remain integral longer in the presence of high temperature steam, making accident mitigation more likely. As a continuation of the development for these alloys, the material response must be demonstrated to provide suitable radiation stability, in order to ensure that there will not be significant dimensional changes (e.g., swelling), as well as quantifying the radiation hardening and radiation creep behavior. In this report, we describe the use of cluster dynamics modeling to evaluate the defect physics and damage accumulation behavior of FeCrAl alloys subjected to neutron irradiation, with a particular focus on irradiation-induced swelling and defect fluxes to dislocations that are required to model irradiation creep behavior.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Overcoming the Fundamental Bottlenecks to a New World-Record Silicon Solar Cell (Final Technical Report)

The objective of the work performed within this contract is to reveal the materials and device physics that currently limit the experimental world record efficiency to 25% for single junction Si (2013), and to demonstrate 26.5% efficiency. The starting efficiency for this project was 23.9% in 2013. Four strategies are being combined throughout the project to achieve 26.5% cell efficiency: (1) passivated contacts via tunnel dielectrics, (2) emitter optimization and passivation through dopant profile engineering, (3) enhanced light trapping through development of photonic crystals and (4) base optimization.

14 SOLAR ENERGY↗
DOE OSTI2017

Final Report: Fundamental Research on the Fractionation of Carbon Isotopes during Photosynthesis, New Interpretations of Terrestrial Organic Carbon within Geologic Substrates

The goal for the current grant period (2013 – 2016) was to quantify the effect of changing atmospheric carbon dioxide concentration (pCO2) on published terrestrial carbon isotope excursion events. This work supported four scientists across multiple career stages, and resulted in 5 published papers.

58 GEOSCIENCES↗
DOE OSTI2017

Fundamental Processes in Plasmas

This Final Technical Report gives brief summaries of the plasma physics results developed under DOE grant DE-SC0002451; and provides reference to the published journal articles giving full scientific descriptions. General topics include 1) cyclotron modes; 2) damping and decay of Langmuir modes; 3) 2D vortex dynamics and diocotron modes; 4) separatrix-induced transport and damping; and 5) long-range collisional velocity slowing.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2017

Final Technical Report: Fundamental Research on the Fractionation of Carbon Isotopes during Photosynthesis, New Interpretations of Terrestrial Organic Carbon within Geologic Substrates

The goal for the current grant period (2013 – 2016) was to quantify the effect of changing atmospheric carbon dioxide concentration (pCO2) on published terrestrial carbon isotope excursion events. This work supported four scientists across multiple career stages, and resulted in 5 published papers.

58 GEOSCIENCES↗
DOE OSTI2017

Final Report, Fundamental Mechanisms of Transient States in Materials Quantified by DTEM

At the project’s inception, there was growing evidence that the time domain for in situ observations of material evolution held great promise for allowing measurements to be made in never previously contemplated regimes. Also, central to the development of the project was the knowledge that phase transformations are of central importance to the development of materials microstructure and hence properties. We addressed this opportunity by developing a transmission electron microscope that could be operated in the pulsed mode (DTEM), with exposure times down to 20 ns and interframe times down to 20 ns in the nine-frame movie mode, designed with the intent of performing in situ experiments. This unprecedented capability allowed us to investigate structural phase transformations, intermetallic formation reactions, crystallization from the amorphous phase, rapid solidification of liquid metals, transformations in phase change materials, and catalyst nanoparticles. The ability of the electron microscope to create images with high spatial resolution allows for the accurate measurement of position. Common to all of the transformations mentioned above is the presence of a distinct interface between the old phase and the growing new phase. Measuring the position of the interface as a function of time, combined with the ability to count nucleation sites as a function of time, allowed for the exceptionally accurate measure of transformation kinetics. These measurements were used to guide and constrain the development of models and simulation methods for the classes of transformations studied.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Fundamental Aspects of Zeolite Waste Form Production by Hot Isostatic Pressing

The direct conversion of iodine-bearing sorbents into a stable waste form is a research topic of interest to the US Department of Energy. The removal of volatile radioactive 129I from the off-gas of a nuclear fuel reprocessing facility will be necessary in order to comply with the regulatory requirements that apply to facilities sited within the United States (Jubin et al., 2012a), and any iodine-containing media or solid sorbents generated by this process would contain 129 I and would be destined for eventual geological disposal. While recovery of iodine from some sorbents is possible, a method to directly convert iodineloaded sorbents to a durable waste form with little or no additional waste materials being formed and a potentially reduced volume would be beneficial. To this end, recent studies have investigated the conversion of iodine-loaded silver mordenite (I-AgZ) directly to a waste form by hot isostatic pressing (HIPing) (Bruffey and Jubin, 2015). Silver mordenite (AgZ), of the zeolite class of minerals, is under consideration for use in adsorbing iodine from nuclear reprocessing off-gas streams. Direct conversion of I-AgZ by HIPing may provide the following benefits: (1) a waste form of high density that is tolerant to high temperatures, (2) a waste form that is not significantly chemically hazardous, and (3) a robust conversion process that requires no pretreatment.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Fundamental study of key issues related to advanced sCO 2 Brayton cycle: Prototypic HX development and cavitation

Diffusion bonded heat exchangers are the leading candidates for the sCO 2 Brayton cycles in next generation nuclear power plants. Commercially available diffusion bonded heat exchangers utilize set of continuous semi-circular zigzag micro channels to increase the heat transfer area and enhance heat transfer through increased turbulence production. Such heat exchangers can lead to excessive pressure drop as well as flow maldistribution in the case of poorly designed flow distribution headers. The goal of the current project is to fabricate and test potential discontinuous fin patterns for diffusion bonded heat exchangers; which can achieve desired thermal performance at lower pressure drops. Prototypic discontinuous offset rectangular and Airfoil fin surface geometries were chemically etched on to 316 stainless steel plate and sealed against an un-etched flat pate using O-ring seal emulating diffusion bonded heat exchangers. Thermal-hydraulic performance of these prototypic discontinuous fin geometries was experimentally evaluated and compared to the existing data for the continuous zigzag channels. The data generated from this project will serve as the database for future testing and validation of numerical models.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2018

White Dwarf Photospheres in the Laboratory: A Testbed for Fundamental Atomic Processes

While the spectrum of pure hydrogen plasmas at low densities seems well understood, at higher densities this is not the case. In this domain the line broadening can be extreme and the lines overlap, making the determination of the continuum problematic. The surfaces of white dwarf stars (WDs) fall into this high-density category. Observationally, we find a systematic offset between the masses of WDs derived using the gravitational-redshift method and those using the spectral line-shape fitting method (Falcon et al. 2010, ApJ, 712,585). Given the straightforward nature of the gravitational-redshift method, this discrepancy points toward incompleteness in the modeling of the broadening of hydrogen lines. The resulting uncertainty in mass hinders the many uses of WDs in astronomy and physics: for example, as Galactic chronometers (Winget et al. 1987, ApJL, 315, 77), tracers of stellar evolution, and probes of dense Coulomb plasmas (Winget et al. 2009, ApJL, 693, 6). This has motivated recent attempts to improve the theoretical line profiles used in white dwarf atmosphere models by independent groups, including us. Laboratory benchmarks are essential for assessing the viability of these new theories (Falcon et al. 2013, HEDP, 9, 82). Therefore, our goal is to make laboratory benchmark measurements of atomic line shapes in H – eventually He and C and O as well--for comparison with the lines observed in the photospheres of white dwarf stars.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Fundamental Study of Disposition and Release of Methane in a Shale Gas Reservoir

The recent boom in shale gas production through hydrofracturing has reshaped the energy production landscape in the United States. Wellbore production rates vary greatly among the wells within a single field and decline rapidly with time, thus bring up a serious concern with the sustainability of shale gas production. Shale gas production starts with creating a fracture network by injecting a pressurized fluid in a wellbore. The induced fractures are then held open by proppant particles. During production, gas releases from the mudstone matrix, migrates to nearby fractures, and ultimately reaches a production wellbore. Given the relatively high permeability of the induced fractures, gas release and migration in low-permeability shale matrix is likely to be a limiting step for long-term wellbore production. Therefore, a clear understanding of the underlying mechanisms of methane disposition and release in shale matrix is crucial for the development of new technologies to maximize gas production and recovery. Shale is a natural nanocomposite material with distinct characteristics of nanometer-scale pore sizes, extremely low permeability, high clay contents, significant amounts of organic carbon, and large spatial heterogeneities. Our work has shown that nanopore confinement plays an important role in methane disposition and release in shale matrix. Using molecular simulations, we show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~ 30 - 47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. The long-term production decline appears controlled by the second stage of gas release. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3 - 35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. We have successfully established experimental capabilities for measuring gas sorption and desorption on shale and model materials under a wide range of physical and chemical conditions. Both low and high pressure measurements show significant sorption of CH 4 and CO 2 onto clays, implying that methane adsorbed on clay minerals could contribute a significant portion of gas-in-place in an unconventional reservoir. We have also studied the potential impact of the interaction of shale with hydrofracking fluid on gas sorption. We have found that the CH 4 -CO 2 sorption capacity for the reacted sample is systematically lower (by a factor of ~2) than that for the unreacted (raw) sample. This difference in sorption capacity may result from a mineralogical or surface chemistry change of the shale sample induced by fluid-rock interaction. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs.

04 OIL SHALES AND TAR SANDS↗
DOE OSTI2018

Fundamental Studies of Irradiation-Induced Modifications in Microstructural Evolution and Mechanical Properties of Advanced Alloys

This final technical report summarizes the research performed during October 2014 and December 2017, with a focus on investigating the radiation-induced microstructural and mechanical property modifications in optimized advanced alloys for sodium-cooled fast reactor (SFR) structural applications. To accomplish these objectives, the radiation responses of several different advanced alloys, including austenitic steel Alloy 709 (A709) and 316H, and ferritic/ martensitic Fe–9Cr steels T91 and G92, were investigated using a combination of microstructure characterizations and nanoindentation measurements. Different types of irradiation, including ex situ bulk ion irradiation and in situ transmission electron microscopy (TEM) ion irradiation, were employed in this study. Radiation-induced dislocations, precipitates, and voids were characterized by TEM. Scanning transmission electron microscopy with energy dispersive X-ray spectroscopy (STEM-EDS) and/or atom probe tomography (APT) were used to study radiation-induced segregation and precipitation. Nanoindentation was used for hardness measurements to study irradiation hardening. Austenitic A709 and 316H was bulk-irradiated by 3.5 MeV Fe ++ ions to up to 150 peak dpa at 400, 500, and 600°. Compared to neutron-irradiated stainless steel (SS) 316, the Frank loop density of ion-irradiated A709 shows similar dose dependence at 400°, but very different temperature dependence. Due to the noticeable difference in the initial microstructure of A709 and 316H, no systematic comparison on the Frank loops in A709 vs 316H was made. It would be helpful that future ion irradiation study on 316 stainless steel could be conducted to directly compare the temperature dependence of Frank loop density in ion-irradiated 316 SS with that in neutron-irradiated 316 SS. In addition, future neutron irradiation on A709 at 400–600° at relative high dose (≥10 dpa) can be carried out to compare with ion-irradiated A709. The radiation-induced segregation (RIS) of Ni and Si was observed in both A709 and 316H in all irradiated conditions and was found at various sinks: line dislocations, dislocation loops, void surfaces, carbide-matrix interfaces, etc. Radiation also induced the formation of Ni,Si-rich precipitates. As suggested in a previous study on neutron-irradiated 316 stainless steel, one possible consequence of the significant RIS of Si is that the enrichment at defect sinks depletes the silicon in the matrix, which can lead to enhanced void nucleation rate. The enrichment of Ni and Si is accompanied by the depletion of Cr at defect sinks, which could also affect the corrosion resistance. Radiation-induced change in the orientation relationship of pre-existing MX precipitates was observed at 600°. It is believed that this change is associated with the network dislocations formed under irradiation. The underlying mechanism is still not well understood. This change could be a positive indication that the MX precipitates can survive high density network dislocations. It would be helpful if neutron irradiation at similar dose conditions could be carried out to verify that this effect is not unique for ion irradiation. Intragranular Cr-rich carbides with a core-shell structure, i.e. Cr-rich carbide core and Ni,Si-rich shell was found at 500° and 600° in the highest dose (150 peak dpa) specimens. Coarse voids (30 nm in diameter) were only commonly found at 500° in the 50 and 150 peak dpa specimens in regions less than 750 nm in depth. The highest swelling for A709 irradiated to 50 and 150 peak dpa at 500° is about 0.44% and 0.37%, respectively. Due to the choice of 100 degree temperature intervals, this study did not attempt to precisely identify peak void swelling conditions, merely the range of irradiation temperatures where this could be a concern. It is known high-dose ion irradiation can significantly suppress void nucleation. Future neutron irradiation in the 500–600° range (without considering the temperature shift) is needed to determine the onset of accelerated void swelling (possibly at lower dose).

36 MATERIALS SCIENCE↗
DOE OSTI2017

Fundamental Studies of Tritium Solubility and Diffusivity in LiAlO 2 and Lithium Zirconates Pellets Used in TPBAR

Using atomistic level calculations, in this study, we propose to investigate the solubility and diffusivity properties of hydrogen isotopes in the blanket candidate materials (e.g. Li 2 O, LiAlO 2 , Li 2 ZrO 3 , Li 6 Zr 2 O 7 , Li 8 ZrO 6 , Li 4 SiO 4 , etc.) for TPBARs to enable tritium production in PWRs and to improve the performances of these components. With the knowledge of $3\atop{1}$T transport, the potential impact of the candidate performance mechanisms of the pellet materials can be evaluated computationally. Using results from our previously performed research on the electronic and thermodynamic properties of these ceramic materials, we will study the $3\atop{1}$T diffusivity and solubility in the abovementioned lithium ceramic materials. Lithium zirconates are stable at very high temperatures and have high densities and ion conductivities. These materials can also be used as pellets which may result in a better overall performance in TPBAR. Lithium zirconates contain lithium-rich phases, such as Li 6 Zr 2 O 7 , Li 8 ZrO 6 , which may result in a high 6 Li density to minimize the 6 Li enrichment. The focus of current research is to identify the mechanisms associated with atomic $3\atop{1}$T formation, diffusion, transport, deposition, and the kinetics at high temperature. For these purposes, we will employ first-principles density functional theory (DFT) and molecular dynamics (MD) simulations to perform our investigations.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2018

Quantum Nanofabrication: Mechanisms and Fundamental Limits

Quantum-size-controlled photoelectrochemical (QSC-PEC) etching, which uses quantum confinement effects to control size, can potentially enable the fabrication of epitaxial quantum nanostructures with unprecedented accuracy and precision across a wide range of materials systems. However, many open questions remain about this new technique, including its limitations and broader applicability. In this project, using an integrated experimental and theoretical modeling approach, we pursue a greater understanding of the time-dependent QSC-PEC etch process and to uncover the underlying mechanisms that determine its ultimate accuracy and precision. We also seek to broaden our understanding of the scope of its ultimate applicability in emerging nanostructures and nanodevices.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Fundamental Understanding of Creep-Fatigue Interactions in 9Cr-1MoV Steel Welds. Final Report

Ferritic-martensitic steels constitute a vital class of materials for current and future generation of nuclear reactors as well as ultra supercritical coal fired power plants due to their superior creep resistant properties. One particular ferritic-martensitic steel, 9Cr-1MoV (Grade 91) is one of five materials approved for high temperature use in nuclear service by the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC). Grade 91 is also a candidate material for proposed fission and fusion reactors such as the sodium cooled fast reactor (SFR). In service, Grade 91 components can be subjected to elevated temperatures and cyclic stresses, leading to the accumulation of creep-fatigue (CF) damage. While the monotonic creep properties of Grade 91 steels have been studied extensively, there is less knowledge concerning the mechanisms governing CF damage of this steel in the creep-dominated failure region. Moreover, the creep failure is especially pronounced in welded Grade 91 components, which are commonly joined using conventional arc welding techniques such as flux-cored arc welding (FCAW). In a Grade 91 weld, the creep failure typically occurs in the outer region of the heat affected zone (HAZ), specifically in the intercritical or fine-grained heat-affected zone (ICHAZ or FGHAZ), a phenomenon known as type IV failure. Currently, there exists a limited knowledge of CF damage mechanisms in Grade 91 welds. Improving the mechanistic understanding of the CF damage and failure of Grade 91 steel and its welds with inhomogeneous microstructure is crucial for the safety and design of key structural components in advanced, high-temperature reactors. The overall objectives of the project were to advance the state of knowledge and understanding of CF damage in both Grade 91 base metal and its welds, especially under loading conditions where creep is the dominant damage mechanism. Uncovering the mechanisms governing the creep-fatigue deformation and damage in Grade 91 base metal in creep-dominated region as well as type IV failure in Grade 91 welds contributes to a new knowledge that may lead to more accurate life prediction models than those currently in use. Moreover, the superior CF properties obtained by low heat input welding has a high potential to develop practical solutions to the premature failure of Grade 91 weld.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Fundamental Electrochemical Properties of Liquid Metals in LiCl-KCl for Separation of Alkali/Alkaline-Earths (Cs, Sr, and Ba)

In electrorefiner, uranium is recovered from used nuclear fuel using an electrorefining process in which a metallic used nuclear fuel anode is oxidized into molten LiCl-KCl-UCl 3 electrolyte and pure U is preferentially reduced onto an inert cathode. While electrorefiner systems facilitate the recycling of substantial amounts of uranium from used nuclear fuel, they also contribute to the production of nuclear waste due to the build-up of fission products such as 90 Sr and 137 Cs in the molten salt electrolyte as they are electrochemically more active than U. The accumulation of alkali/alkaline-earth elements (Ba, Sr, Cs) in the electrolyte presents a problem as Sr and Cs isotopes have high heat densities and produce large amounts of highly ionizing radiation; these hazards combined with difficulty in removing the highly stable alkali/alkaline-earth elements from the electrolyte necessitates frequent replacement and disposal of the electrolyte, which then increases the overall volume of nuclear waste. This research project focuses on evaluating the viability of using liquid metal electrodes for electrochemical separation of alkali/alkaline-earths from molten salts utilizing the strong atomic interactions between candidate liquid metals and alkali/alkaline-earths. The strength of chemical interactions was quantified by determining the thermodynamic properties (e.g., activity) in liquid metals of Bi, Sb, and Pb. Thermodynamic properties, including activities, partial molar entropies, and partial molar enthalpies, were determined using electromotive force measurements for the Sr-Bi, Sr-Sb, Sr-Pb, Ba-Bi, and Ba-Sb binary systems in order to elucidate the strength of interactions between the alkaline-earth elements and each liquid metal, and to develop a comprehensive understanding of their behavior. Activities as low as a Sr = 10 -13 at x Sr = 0.04 at T = 888 K were measured as well as liquid state solubility as high as 40 mol% at 988 K in Sr-liquid metal systems; activities as low as aBa = 10 -15 at xBa = 0.05 at T = 888 K with liquid state solubility as high as 30 mol% at 988 K in Ba-liquid metal systems. Experimental data was used as input data towards computational efforts involving first-principles calculations as well as the CALPHAD (CALculation of PHAse Diagram) technique in the case of the Sr-Sb and Ba-Bi systems to develop improved phase diagrams and provide further basis for the use of computational models in elucidating strongly interacting binary systems. Attempts to remove Sr and Ba from molten salt electrolyte using an electrochemical cell with liquid metal cathodes were successful, with post-mortem elemental analysis of the electrodes confirming significant quantities of Sr (6.5 mol%) and Ba (12.8 mol%) deposited into Bi. Furthermore, deposition results correlated well with the deposition behavior predicted from the aforementioned electromotive force measurements, inviting the possibility of using liquid metal electrodes for selectively removing alkali/alkaline-earth elements from molten LiCl-KCl electrolyte to recycle the process salt in electrorefiner.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Project Title: Fundamental Studies of Surface-Functionalized Mesoporous Carbons for Thermodynamic Stabilization and Reversibility of Metal Hydrides

The objective of this project is to understand the hydride/active-framework interactions that will allow designed functionalities to make use of unstable complex hydrides (those with ΔH° too small or even negative) for hydrogen storage. The desired interactions of the metal hydride (MH) nanoparticles (NPs) with the functional porous carbon (FPC) hosts will be achieved by controlling the electron donating properties of nanoporous carbons through known and controllable doping of the templates with heteroatom nitrogen.

08 HYDROGEN↗