Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Extreme indices”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

MARVEL Reactor Fuel Performance Report (Rev.2)

The Microreactor Applications Research Validation and EvaLuation (MARVEL) project is producing a high temperature liquid metal-cooled nuclear test bed at Idaho National Laboratory (INL) to ultimately improve the integration of microreactors to end-user applications. This ambitious effort seeks to design, authorize, construct, test, and operate the reactor within five years. In order to construct and operate the MARVEL reactor in a timely manner, the system will utilize materials and component designs which have already been used, qualified, or licensed from previous reactors. The MARVEL reactor will be located at the INL Transient Reactor Test (TREAT) facility in the north high-bay equipment pit and will use the existing 304 stainless steel-clad U-ZrH1.6 pin-type fuel system developed by General Atomics and purchased from TRIGA International. This fuel has been previously qualified under the United States Department of Energy’s (US DOE) Reduced Enrichment for Research and Test Reactors (RERTR) Program. Even though the regulator of the MARVEL reactor is the US DOE, the standards and overall approach recommended by the Nuclear Regulatory Commission is well-defined and utilized here. Following NUREG-1537 regulatory guidance, this report documents the authorization case for the MARVEL fuel system’s application to MARVEL and establishes stable and predictable fuel performance during the most thermophysically unfavorable conditions achievable in the MARVEL reactor. To that end, this report provides a comprehensive survey of the known thermophysical properties, performance, and quantitative relationships associated with the MARVEL reactor fuel element and uses this information to determine its mechanical integrity and risk of reaching unacceptable conditions during the most extreme accident scenarios predicted for the reactor using the most conservative assumptions available. The information contained herein is compiled from a combination of historical reports and peer reviewed scientific publication manuscripts. Known mechanisms under which the fuel is susceptible to failure are highlighted and compared to conditions that could exist in the MARVEL reactor during an unanticipated transient or accident scenario. The two scenarios considered for analysis in this report are (1) an unprotected loss of flow accident and (2) a hypothetical unprotected loss of coolant accident during the loss of flow accident. Preliminary 2D steady-state analyses herein indicate that both fuel-cladding chemical interactions and fuel-cladding mechanical interactions are negligible throughout the fuel’s operational cycle under both normal and high temperature accident scenario conditions. Although higher fidelity 3D time-dependent modeling and simulations are planned, the following may be concluded presently. The MARVEL fuel element maintains its geometric stability and structural integrity during the most extreme accident scenarios predicted for the MARVEL reactor. The hoop stress during the unprotected loss of flow accident reaches about -1.27 MPa; this negative stress indicates that it is compressive rather than tensile. The compressive stress is a result of the NaK pressure on the outside of the fuel element, caused by the restricted thermal expansion of the NaK coolant, exceeding the internal pressures generated inside of the fuel element. The hoop stress generated in the cladding during the unprotected loss of coolant accident reaches a maximum of about approximately 10 MPa, which is nearly an order of magnitude less than the predicted yield strength of the cladding under high-temperature accident scenario conditions. Calculations were compared with results from high performance computational simulations using BISON and are in very close agreement. A conservative MARVEL fuel meat peak temperature limit of 900 °C is recommended presently, which is about 180 °C higher than the peak fuel temperature predicted to occur during the most extreme accident. Based on the known properties and behavior of the MARVEL fuel element, the fuel successfully meets its design and safety requirements under normal and most extreme accident conditions with a large safety margin.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2026

MARVEL Reactor Fuel Performance Report

The Microreactor Applications Research Validation and EvaLuation (MARVEL) project is producing a high temperature liquid metal-cooled nuclear test bed at Idaho National Laboratory (INL) to ultimately improve the integration of microreactors to end-user applications. This ambitious effort seeks to design, authorize, construct, test, and operate the reactor within five years. In order to construct and operate the MARVEL reactor in a timely manner, the system will utilize materials and component designs which have already been used, qualified, or licensed from previous reactors. The MARVEL reactor will be located at the INL Transient Reactor Test (TREAT) facility in the north high-bay equipment pit and will use the existing 304 stainless steel-clad U-ZrH1.6 pin-type fuel system developed by General Atomics and purchased from TRIGA International. This fuel has been previously qualified under the United States Department of Energy’s (US DOE) Reduced Enrichment for Research and Test Reactors (RERTR) Program. Even though the regulator of the MARVEL reactor is the US DOE, the standards and overall approach recommended by the Nuclear Regulatory Commission is well-defined and utilized here. Following NUREG-1537 regulatory guidance, this report documents the authorization case for the MARVEL fuel system’s application to MARVEL and establishes stable and predictable fuel performance during the most thermophysically unfavorable conditions achievable in the MARVEL reactor. To that end, this report provides a comprehensive survey of the known thermophysical properties, performance, and quantitative relationships associated with the MARVEL reactor fuel element and uses this information to determine its mechanical integrity and risk of reaching unacceptable conditions during the most extreme accident scenarios predicted for the reactor using the most conservative assumptions available. The information contained herein is compiled from a combination of historical reports and peer reviewed scientific publication manuscripts. Known mechanisms under which the fuel is susceptible to failure are highlighted and compared to conditions that could exist in the MARVEL reactor during an unanticipated transient or accident scenario. The two scenarios considered for analysis in this report are (1) an unprotected loss of flow accident and (2) a hypothetical unprotected loss of coolant accident during the loss of flow accident. Preliminary 2D steady-state analyses herein indicate that both fuel-cladding chemical interactions and fuel-cladding mechanical interactions are negligible throughout the fuel’s operational cycle under both normal and high temperature accident scenario conditions. Although higher fidelity 3D time-dependent modeling and simulations are planned, the following may be concluded presently. The MARVEL fuel element maintains its geometric stability and structural integrity during the most extreme accident scenarios predicted for the MARVEL reactor. The hoop stress during the unprotected loss of flow accident reaches about -1.27 MPa; this negative stress indicates that it is compressive rather than tensile. The compressive stress is a result of the NaK pressure on the outside of the fuel element, caused by the restricted thermal expansion of the NaK coolant, exceeding the internal pressures generated inside of the fuel element. The hoop stress generated in the cladding during the unprotected loss of coolant accident reaches a maximum of about approximately 10 MPa, which is nearly an order of magnitude less than the predicted yield strength of the cladding under high-temperature accident scenario conditions. Calculations were compared with results from high performance computational simulations using BISON and are in very close agreement. A conservative MARVEL fuel meat peak temperature limit of 900 °C is recommended presently, which is about 180 °C higher than the peak fuel temperature predicted to occur during the most extreme accident. Based on the known properties and behavior of the MARVEL fuel element, the fuel successfully meets its design and safety requirements under normal and most extreme accident conditions with a large safety margin.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Implications of Abiotic Oxygen Buildup for Earth-like Complex Life

One of the chief paradoxes of molecular oxygen (O{sub 2}) is that it is an essential requirement for multicellular eukaryotes on Earth while simultaneously posing a threat to their survival via the formation of reactive oxygen species. In this paper, the constraints imposed by O{sub 2} on Earth-like complex life are invoked to explore whether worlds with abiotic O{sub 2} inventories can harbor such organisms. By taking the major O{sub 2} sources and sinks of Earth-like planets into account using a simple model, it is suggested that worlds that receive time-averaged X-ray and extreme ultraviolet fluxes that are ≳10 times higher than Earth might not be capable of hosting complex lifeforms because the photolysis of molecules such as water may lead to significant O{sub 2} buildup. Methods for testing this hypothesis by searching for anticorrelations between biosignatures and indicators of abiotic O{sub 2} atmospheres are described. In the event, however, that life successfully adapts to high-oxygen environments, these worlds could permit the evolution of large and complex organisms.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Observed changes in hydroclimate attributed to human forcing

Observational and modeling studies indicate significant changes in the global hydroclimate in the twentieth and early twenty-first centuries due to anthropogenic climate change. In this review, we analyze the recent literature on the observed changes in hydroclimate attributable to anthropogenic forcing, the physical and biological mechanisms underlying those changes, and the advantages and limitations of current detection and attribution methods. Changes in the magnitude and spatial patterns of precipitation minus evaporation (P–E) are consistent with increased water vapor content driven by higher temperatures. While thermodynamics explains most of the observed changes, the contribution of dynamics is not yet well constrained, especially at regional and local scales, due to limitations in observations and climate models. Anthropogenic climate change has also increased the severity and likelihood of contemporaneous droughts in southwestern North America, southwestern South America, the Mediterranean, and the Caribbean. An increased frequency of extreme precipitation events and shifts in phenology has also been attributed to anthropogenic climate change. While considerable uncertainties persist on the role of plant physiology in modulating hydroclimate and vice versa, emerging evidence indicates that increased canopy water demand and longer growing seasons negate the water-saving effects from increased water-use efficiency.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2023

Observed Changes in Hydroclimate Attributed to Human Forcing

Observational and modeling studies indicate significant changes in the global hydroclimate in the twentieth and early twenty-first centuries due to anthropogenic climate change. In this review, we analyze the recent literature on the observed changes in hydroclimate attributable to anthropogenic forcing, the physical and biological mechanisms underlying those changes, and the advantages and limitations of current detection and attribution methods. Changes in the magnitude and spatial patterns of precipitation minus evaporation ( P–E ) are consistent with increased water vapor content driven by higher temperatures. While thermodynamics explains most of the observed changes, the contribution of dynamics is not yet well constrained, especially at regional and local scales, due to limitations in observations and climate models. Anthropogenic climate change has also increased the severity and likelihood of contemporaneous droughts in southwestern North America, southwestern South America, the Mediterranean, and the Caribbean. An increased frequency of extreme precipitation events and shifts in phenology has also been attributed to anthropogenic climate change. While considerable uncertainties persist on the role of plant physiology in modulating hydroclimate and vice versa, emerging evidence indicates that increased canopy water demand and longer growing seasons negate the water-saving effects from increased water-use efficiency.

Drought↗
DOE OSTI2022

Anodic Interfacial Evolution in Extremely Fast Charged Lithium-Ion Batteries

Interfacial reaction mechanisms at the anode/separator interface play a central role in the performance and safety of lithium-ion batteries during fast charging. We report a mechanistic study on the evolution and interactions of the aging mechanisms at the anode/separator interface in lithium cobalt oxide/graphite pouch cells charged with variable charging rates (1–6C) over 10 cycles. In situ electrochemical measurements, including voltage relaxation, Coulombic efficiency, and direct current internal resistance, indicated an incremental lithium loss until the C rates were ≤5C. A substantial capacity fade is observed in the first few cycles of fast charging, but the magnitude of capacity fade progressively diminishes with the number of cycles, indicating a suppression in the lithium deposition mechanism. Post-mortem film thickness, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) analyses were performed to elucidate the evolution of electrolyte decomposition, the solid–electrolyte interface (SEI), lithium plating, and film fracture mechanisms with C rate. XPS measurements confirmed an increasing lithium concentration in an SEI film with an increase in the C rate. SEM images showed a growth of dendritic lithium on the anode surface from 1C to 3C. Precrack formation leading to an interfacial film fracture was observed at higher C rates. Furthermore, a differential analysis of the discharge capacity indicated a possible two-phase delithiation from the anode and reduced cathodic lithiation due to lithium loss at high C rates.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Data‐Driven Insights into Rare Earth Mineralization: Machine Learning Applications Using Functional Material Synthesis Data

Understanding rare‐earth element (REE) mineralization mechanisms is essential for developing efficient separation strategies. Although the geochemical pathways that generate REE deposits are qualitatively known, quantitative links between specific conditions and mineralization outcomes remain limited. Herein, the repurpose laboratory REE hydrothermal synthesis data—originally collected for functional‐materials fabrication—as a surrogate for studying mineralization with data‐driven methods. The compiled 1,200+ hydrothermal reaction records and trained three machine‐learning models—K‐nearest neighbors (KNN), random forest (RF), and extreme gradient boosting (XGB)—to predict product elements and phases from precursors, additives, reaction conditions, and engineered features. Validation shows XGB achieves the highest accuracy. Feature importance indicates thermodynamic properties of cations and anions dominate model decisions. Correlations reveal positive relationships among precursor concentration, reaction time, pH, and temperature, consistent with classical crystallization behavior. XGB‐based regressors are built to predict crystallization temperature and pH from precursor/product attributes. Performance is strongest when similar training examples exist, while accuracy declines for underrepresented reactions, notably REE carbonates and heavy‐REE systems. Overall, the study shows that functional‐materials datasets can illuminate REE mineralization and provide priors for exploration and processing. Expanding datasets with less‐studied chemistries and conditions will improve generality and support deposit discovery and more efficient REE recovery.

feature importance analysis↗
DOE OSTI2022

Examining the changes in the spatial manifestation and the rate of arrival of large tornado outbreaks

This study presents an assessment of the spatial and temporal characteristics of large tornado outbreak (LTOs) days, in which several counties were impacted by tornadoes rated F2(EF2) or greater on the Fujita (Enhanced Fujita) scale in one day. A statistical evaluation of changes in the LTO clusters for two periods, 1950–1980 and 1989–2019, has been performed. There is a geographical shift of the nucleus (central impact location) towards the southeast United States. This spatial shift is also accompanied by reduced spatial variance, suggesting LTOs have become less dispersed (or more localized) in the recent period. The overall inter-arrival rate of LTOs, and how it changed during successive 31-year climatological blocks between 1950–2019 was investigated using an exponential probability model. The arrival rate has changed from 124 days during 1950–1980 to 164 days during 1977–2007 and remained relatively constant during later periods, indicating that LTOs are becoming less frequent.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Coherent charge hopping suppresses photoexcited small polarons in ErFeO 3 by antiadiabatic formation mechanism

Polarons are prevalent in condensed matter systems with strong electron-phonon coupling. The adiabaticity of the polaron relates to its transport properties and spatial extent. To date, only adiabatic small polaron formation has been measured following photoexcitation. The lattice reorganization energy is large enough that the first electron–optical phonon scattering event creates a small polaron without requiring substantial carrier thermalization. We measure that frustrating the iron-centered octahedra in the rare-earth orthoferrite ErFeO 3 leads to antiadiabatic polaron formation. Coherent charge hopping between neighboring Fe 3+ –Fe 2+ sites is measured with transient extreme ultraviolet spectroscopy and lasts several picoseconds before the polaron forms. The resulting small polaron formation time is an order of magnitude longer than previous measurements and indicates a shallow potential well, even in the excited state. The results emphasize the importance of considering dynamic electron-electron correlations, not just electron-phonon–induced lattice changes, for small polarons for transport, catalysis, and photoexcited applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Prospects for silvicultural enhancement of fire resistance in mesic westside forests of the Pacific Northwest

Increasing wildfire activity in mesic, temperate Pacific Northwest forests west of the Cascade Range crest has stimulated interest in understanding whether alternative forest management practices could reduce risk of stand-replacing fire. To explore how management can enhance fire resistance in these forests and assess tradeoffs among resistance enhancement, carbon sequestration and storage, and economic returns, we conducted 40-year simulations of stand development with BioSum, a framework for conducting landscape analysis with the Forest Vegetation Simulator (FVS), utilizing a statistically representative and spatially balanced sample of Forest Inventory and Analysis (FIA) plots. Simulation outcomes under business-as-usual silviculture were contrasted with fire-aware silviculture, and treatment optimization logic was developed and applied to represent landscape-scale outcomes under business-as-usual and fire-focused management scenarios. Simulation results indicate that fire-aware prescriptions and fire-focused management can meaningfully enhance stand- and landscape-scale fire resistance of westside forests under less than extreme fire weather, but at the cost of lower economic returns and reduced net carbon storage and sequestration over the 40-year analysis window. Shifting from business-as-usual regeneration harvests with short rotations to fire-aware, episodic selection harvest improved fire resistance the most, especially in young privately-owned forests, and with only modest tradeoffs in carbon and economic outcomes. While fire-aware treatments generally reduced net present value from forest operations over business-as-usual, most treatments still generated positive net present value and could be implemented without subsidy. Fire-aware prescriptions that removed and utilized non-merchantable harvest residues instead of burning them, via either pile or broadcast burning, partially mitigated carbon emissions associated with fire-aware treatments, with about the same improvement in fire resistance. Given the currently limited institutional and financial capacity to implement fire resistance enhancing treatments at scale, the insights from this analysis may aid managers seeking to elevate fire resistance to prioritize where and how to manage.

Science & Technology - Other Topics↗
DOE OSTI2020

Top Loading Helium Cryostat Integrated with High-Pressure Cell with Fast Remote Pressure Control (Final Report for SBIR Phase 1)

A large number of physical phenomena, such as superconductivity and quantum critical phenomena, often appear only at very low temperatures below 5 K. There is an immense interest to investigate these phenomena at high pressure as a means of tuning interatomic distances, and thus the interaction parameters controlling these phenomena, in a continuous and controlled fashion. The current P-T condition for neutron scattering experiments are limited to either relatively low pressures of about 2 GPa at temperatures below 5 K, or to relatively high temperatures at pressures or tens of GPa. The purpose of this research is to develop neutron sample environment instrumentation for reaching 10-20 GPa at 1-2K with rapid and reliable online pressure and temperature control (i.e. without having to interrupt the experiment). The ultimate goal of the project is to design an integrated fast-cooling low-temperature sample environment cryogenic system compatible with state of the art neutron diamond anvil cells suitable for single-crystal neutron scattering experiments for temperatures down to 2K and pressures of several tens of GPa. The integrated system will consist of top-loading Helium flow cryostat with in-situ sample alignment mechanisms, large-volume diamond anvil cells (DAC) made from novel superalloy Pascalloy and optimized for fast cooling and heating, and a compact remote pressure control mechanism for the DAC based on a novel concept of inflatable bellows integrated with a lever-arm based force amplifier. In Phase I, we have designed, manufactured, and tested prototypes of the novel compact force-amplified pneumatic pressure control mechanism for Neutron Diamond Anvil Cell (nDAC), which allows to use pneumatic bellows system for smooth remote pressure control in the nDAC inside a top-loading cryostat with bore size of 70 mm or larger. This allows significant minimum temperature decrease in remotely controlled nDAC from 5-10 K down to 2 K. We also studied mechanical properties of a novel non-magnetic superalloy Pascalloy with different heat-treatment conditions and preliminary results indicate that up to date this is probably the strongest and most suitable material for making more compact and lightweight cryogenic nDACs for neuron scattering experiments at extreme conditions, allowing much faster cooling and heating. Potential applications: The new developments will allow to create a wide range of compact Diamond Anvil Cells for neutron diffraction which can reach several tens of GPA pressure at 2-4 K while preserving accurate remote pressure control capabilities. The new concepts can be used for developing sample environment instrumentation outside the neutron scattering field. The new development have very strong potential for expanding experimental capabilities in materials sciences and have high commercialization potential. The proposed new cryogenic high-pressure system or any of its individual components will be in high demand not only in neutron scattering facilities, but also at synchrotron beamlines and other high-pressure research facilities around the world.

36 MATERIALS SCIENCE↗
NASA NTRS1968

Study of Plasma Radiation Shielding

The Plasma Radiation Shield is an active device using free electrons, electric and magnetic fields for the purpose of shielding astronauts from energetic solar flare-produced protons. The concept of Plasma Radiation Shielding is reviewed in the light of current studies. The available evidence indicates that the concept is physically sound, but important practical questions remain in at least two areas: these have to do with establishment and control of the extremely high voltages required, and with integration of the concept into a realistic space vehicle design.

Source record↗
NASA NTRS1973

Experimental investigation of orthotropic panel flutter at arbitrary yaw angles, and comparison with theory

Flutter characteristics for yaw angles between 15 deg and 90 deg were determined experimentally for two types of corrugation-stiffened panels: those with weak twisting stiffness and those with strong twisting stiffness. By mounting the panels on a remotely controlled turntable, good definition of the flutter boundaries was obtained by rotating the panels into and out of flutter. Flutter tests were conducted at M = 2 and M = 1.6. Before testing, vibration tests and analyses were also performed. The experimental flutter data is compared with flutter theory for orthotropic panels utilizing quasi-steady aerodynamics. Five different corrugated panels were tested consisting of one single skin panel having a length-to-width ratio of 5 on clamped supports and four different square double skin panels on discrete flexible supports. The investigation indicated that flutter speed for corrugated panels is highly dependent on yaw angle. Reasonable flutter correlation between analysis and test was obtained for moderate yaw angles, but extreme sensitivity to structural parameters made the correlation at large yaw angles uncertain.

Shyprykevich, P.↗
NASA NTRS1978

Definition and effect of chemical properties of surfaces in friction, wear, and lubrication

Much of the data relative to the properties of surfaces that have been used in the past in analyzing, interpreting and predicting adhesion, friction and wear behavior for solid surfaces is now suspect. With the advent of analytical surface tools, careful and complete characterization of surfaces indicate that very frequently the outermost layers of solid surfaces are markedly different in chemistry than had been previously thought. These layers, as will be shown, are extremely important in adhesion, friction and wear behavior. Some of the properties to be discussed in the paper relative to their role in adhesion, friction, wear and lubrication will include: (1) adsorption, both physical and chemical; (2) orientation of the solid as well as the lubricant; (3) surface energy; (4) surface segregation; (5) surface versus bulk metallurgical effects; (6) electronic nature of the surface; and (7) bonding mechanisms.

Buckley, D. H.↗
NASA NTRS1979

Maximum likelihood estimation for life distributions with competing failure modes

The general model for the competing failure modes assuming that location parameters for each mode are expressible as linear functions of the stress variables and the failure modes act independently is presented. The general form of the likelihood function and the likelihood equations are derived for the extreme value distributions, and solving these equations using nonlinear least squares techniques provides an estimate of the asymptotic covariance matrix of the estimators. Monte-Carlo results indicate that, under appropriate conditions, the location parameters are nearly unbiased, the scale parameter is slightly biased, and the asymptotic covariances are rapidly approached.

Sidik, S. M.↗
NASA NTRS1979

A possible origin for the grooves of Phobos

A hypothesis that the age and distribution of grooves on the surface of Phobos may be explained by a hybrid origin due to varying tidal stresses induced after a large impact altered the satellite's rotation rate is presented. The theory that these grooves are surface manifestations of internal fractures induced by the decay of Phobos orbit is ruled out because this mechanism would require the grooves to be extremely young features, but their implied age is greater than 10 to the 9th power yr. The location and relationship of grooves to the largest crater, Stickney, indicate that they are related to the Stickney impact, but were formed shortly after that event with orientations determined by the shape of Phobos. If the impact destroyed the condition of synchronous rotation, the changing orientation of Phobos in the gravitational field of Mars would subject its interior to stresses, producing the systems of grooves.

Weidenschilling, S. J.↗
NASA NTRS1983

Current concepts of space flight induced changes in hormonal control of fluid and electrolyte metabolism

A systematic analysis of body fluid and renal dynamics during simulated space flight (head-down bedrest) was undertaken to increase understanding of the physiologic effects of acute cephalad fluid shifts. The earliest effects were increases in central venous pressure and decreases in plasma aldosterone, epinephrine and norepinephrine and glomerular filtration rate, 2 h after the beginning of bedrest. Decreases in plasma angiotensin I at 6 h may have resulted from the increased effective pressure and decreased sympathetic activity seen earlier in bedrest. The early decrease in aldosterone and ADH is thought to contribute to an increase, by 6 h, in urinary excretion of salt and water. Fluid and electrolyte losses occur during space flight, and analysis of body fluids from Space Shuttle crewmembers has indicated that conservation of these substances is begun almost immediately upon cessation of weightlessness. Operational medicine measures to counteract dehydration and electrolyte loss resulted in a less extreme physiologic response to the flight.

Leach, C. S.↗