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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 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Subscale maturation of advanced reactor technologies (SMART): A path forward for nuclear thermal propulsion fuel and reactor development

Nuclear Thermal Propulsion (NTP) systems are actively being developed for future crewed missions to Mars. NTP systems excel in missions where both high thrust and high specific impulse are required, but modern NTP systems currently do not have a Technology Readiness Level (TRL) high enough for use in crewed space exploration. TRLs are used to demonstrate the level of rigor with which a component/system has been tested/demonstrated for its intended use. While space systems technology in general must be qualified as a unit, nuclear technology must be first demonstrated to meet qualification level requirements both at the fuel (component) level and the reactor (subsystem) level. Here, in this paper, historic NTP development programs are surveyed to identify a testing and development strategy that can be effectively implemented to allow for NTP reactor development. Based on this strategy, required facilities to enable such activities are identified. Current domestic experimental capabilities to support NTP qualification are limited to separate effects testing of individual components. Separate effects testing is found extensively in historic NTP development efforts but is not sufficient for full fuel and reactor qualification. Combined effects testing allows for an accurate assessment of fuel performance but is not achievable for NTP conditions in existing facilities. Assessment of historic development programs suggests that an intermediate, subscale test facility is necessary to advance NTP TRLs. A solution to meet this need is proposed, namely the Subscale Maturation of Advanced Reactor Technologies (SMART) facility. SMART will mitigate risk to NTP development by enabling performance and reactor physics demonstrations of NTP subsystems. A SMART facility could be built by modifying existing nuclear test facilities, which may potentially enable schedule and cost savings. To pursue reactor qualification beyond the subscale, a new ground test facility will be necessary. This ground test facility should be developed concurrently with SMART to allow for the facility to be operational in time for expedited NTP engine demonstration.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Enhancement of risk informed validation framework for external hazard scenario

In recent years, the U.S. Nuclear Regulatory Commission (USNRC) and the International Atomic Energy Agency (IAEA) have developed methodologies to assess the vulnerabilities of nuclear plants against site specific extreme hazards. In many cases, advanced simulation tools are being considered to simulate multi-physics, multi-scale phenomena and to evaluate vulnerability of nuclear facilities. The credibility of advanced simulation tools is assessed based on a formal verification, validation, and uncertainty quantification procedure. One of the key limitations in validation is the lack of relevant experimental data at system-level. This limitation leads to a decrease in the confidence of system-level risk predictions. Therefore, a robust validation framework is needed to formalize the confidence in predictive capability of advanced simulation results. Additionally, this study enhances the existing risk informed validation methodology, originally proposed by Kwag et al. [1] and Bodda et al. [2], by developing additional attributes and a new set of validation indicies for a complete and wider applicability of the framework. In this manuscript, the methodology to identify the critical path that leads to the system-level failure is illustrated. The overall validation is checked for completeness and consistency by comparing the critical path for both the system-level simulation and experimental models. The applicability of the code for an intended application is represented in terms of various maturity levels and helps in the process of decision making.

42 ENGINEERING↗
DOE OSTI2023

Structural design challenges and implications for high temperature concentrating solar power receivers

High operating temperatures along with diurnal cycling and high operating stresses bring many material and engineering challenges for concentrated solar power (CSP) receivers. Current design rules in ASME Boiler and Pressure Vessel (B&PV) Code for high temperature structural components were not intended for CSP components. The paper reviews the design rules in several sections of ASME B&PV Code in terms of their applicability in designing high temperature CSP receivers. With some restrictions and modifications, the conditions assumed in the design rules in Section III, Division 5 of ASME B&PV Code are found to closely resemble the loading conditions of CSP receiver, including accounting for the interaction between creep and fatigue damage. Further, the paper applies the proposed design rules to an external tubular receiver design and discusses several lessons learned from the design study. The creep damage accumulation due to high thermal stresses resulting from circumferentially non-uniform flux distribution is found to control the design of CSP receivers. Several mitigation actions to improve the design life of receivers are also discussed.

14 SOLAR ENERGY↗
DOE OSTI2025

Stress-dependent χ phase transformation in a Ni-based superalloy

The ongoing push to elevate operating temperatures in aerospace gas turbine engines – driven by goals of enhanced fuel efficiency and reduced CO 2 emissions – mandates advancements in the creep resistance of Ni- and Co-based superalloys, which are integral for critical engine components. This study elucidates the role of stress assisted localized phase transformations in the creep properties of these alloys. By leveraging chemo-mechanical coupling, self-healing γ′ precipitates are designed to immobilize planar defects, thereby increasing creep resistance. Employing advanced characterization techniques such as high-resolution Scanning Transmission Electron Microscopy (HR-STEM), in conjunction with atomistic simulations and thermodynamic calculations, novel deformation pathways facilitated by χ local phase transformation (LPT) strengthening have been uncovered; notably, the formation of χ nano-laths through microtwinning and superlattice intrinsic stacking fault (SISF) shearing. This study highlights critical insights into the compositional boundaries necessary for optimizing LPT strengthening while avoiding deleterious bulk formation of η/χ phases. These advancements will guide the design of new alloys maximizing high-temperature creep strength for advanced aerospace applications.

Egan, Ashton J. [Friedrich-Alexander University Er↗
DOE OSTI2021

Scoping study of lower hybrid current drive for CFETR

The paper assesses the applicability of lower hybrid current drive (LHCD) for two potential operating scenarios for the China Fusion Engineering Test Reactor (CFETR): the “hybrid” scenario in which some of the plasma current is sustained by the Ohmic transformer, and the fully non-inductive “steady state” scenario. Here, the πScope workflow engine was used to set up a large number of ray tracing/Fokker-Planck simulations (> 10 4 ) with parametric scans in the antenna poloidal position and launched parallel refractive index (n || ) for both the hybrid and steady state scenarios. Modeling predicts efficient off-axis current drive (1.3 MA for 20 MW launched power) with a peak near ρ of 0.6-0.65 for waves launched from the high field side (HFS). Waves launched from the low field side (LFS) damp at larger radius (ρ > 0.73) with similar efficiency to HFS launch. Stability analysis of the CFETR scenarios favors current drive profiles peaked near the mid-radius, suggesting that HFS launch is preferable due to the current drive location. The effect of wave scattering from density blobs in the edge/scrape-off-layer region was assessed through rotation of the perpendicular wavenumber at the ray origin. Simulations show that this effect can be quite large both in efficiency and damping location, however by adjusting the launched n|| much of the unperturbed performance can be recovered.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Antitoxin control of optimal transcriptional repression in the atypical HigB–HigA toxin–antitoxin system from Proteus vulgaris

Abstract Bacterial toxin–antitoxin (TA) pairs transcriptionally autoregulate their expression via a repression/derepression mechanism in response to changing environmental conditions. The structural diversity of TA systems influences the mechanisms of transcriptional regulation. Here, we define the molecular mechanism for the plasmid-encoded HigB–HigA TA pair originally identified in a post-operative infection with antibiotic-resistant Proteus vulgaris. We determine DNA binding and promoter activity by the HigB–HigA complex supported by structural biology and molecular dynamics simulations of an elusive DNA operator–TA repressor complex. To define the optimal oligomeric TA repressor–DNA operator complex required for derepression, we engineered a dedicated trimeric HigB–HigA2 complex that represses transcription more than 26-fold as compared to the tetrameric HigB2–HigA2. These results expand the known diversity of how the HigB–HigA TA family is autoregulated.

Biochemistry & Molecular Biology↗
DOE OSTI2020

A Flexible and Secure Evaluation Platform for Overvoltage Protection in Power Electronics Systems

This paper summarizes the fault mechanisms specifically for the overvoltage protection schemes in power electronic converters and the resulted power electronics enabled systems. A flexible and secure evaluation platform for overvoltage protection, has also been presented based on this conceptual mechanism. The proposed platform aims at testing the protection performance of distinctive overvoltage protection schemes. It would be applied to verify the effectiveness, identify potential strengths and weaknesses, and obtain the most critical protection response time to provide sufficient engineering insights for the designer. The operation principle and detailed design guideline have been presented first. The comprehensive component stress has been analyzed. An intensive set of LTSpice simulations have been conducted to show the validity of the proposed assessment approach.

Zheng, Sheng↗
DOE OSTI2022

Developments and Challenges in the Design of the ITER DRGA

We report the ITER Diagnostic Residual Gas Analyzer (DRGA) will measure the distribution of gas species, i.e., deuterium (D), tritium (T), and impurities, in the divertor exhaust stream and in the plasma periphery, with time resolution relevant to fusion plasma–wall particle dynamics. The uniqueness of the DRGA, over previous implementations of plasma dynamics residual gas analysis, is an integrated approach, combining mass and low-temperature plasma-activated optical spectroscopy, in a differentially pumped analysis station. A further unique feature of the ITER divertor-specific DRGA is an ~8-m separation of the analysis station from the sampled pumping duct, while still maintaining a ~1-s response time for hydrogen isotopic concentrations. ITER DRGA final design activities are strongly benefiting from testing of prototypical DRGA components and methods on present fusion devices, most currently on JET and W7-X. DRGA systems are implemented on both these devices and include sensors (and pumping methods) that are directly relevant to the ITER DRGA design. The recent JET-DTE2 campaign has provided the first experience on operating the combined ITER DRGA sensors with D-T plasmas. While enhancing system design for ITER, this experience on operating devices has also revealed additional engineering challenges, which further guide the continuing final design project. Meanwhile, the recent determination that the ITER DRGA, with slight optimization, will resolve the helium isotopes well enough to support an ITER pre-DT, He-3-based heating scheme, has greatly increased ITER Research Program interest in the DRGA and its implementation well ahead of the DT phase.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Rapid Commissioning of Large Machine Tools Using Finite Element-Based Correction of Geometric Errors

Large computer numerical control (CNC) machine tools derive their stiffness from monolithic cast iron bases or weldments that are sometimes integral to machine motion systems like box ways or guideways. However, the sheer size of castings and even floor flatness deviations result in dimensional errors in these systems, which manifest as machine motion errors. Typical geometric alignment processes rely on an iterative approach, where measurements are taken to assess alignment (straightness, squareness, and parallelism), followed by adjustment of the machine supports (fixators or leveling pads), which can take weeks even for an experienced operator. Conversely, a novel method is proposed to shorten the correction time by eliminating the trial-and-error process in favor of a more deterministic approach guided by a finite element (FE) method. A feasibility study is conducted on a CNC polymer hybrid machine, with a steel weldment frame, supported by six leveling pads. An FE model of the frame is utilized to obtain recommended leveling pad adjustments, based on measurement of machine errors taken using a laser tracker. After a single adjustment cycle, measurements reveal that geometric errors of the machine tool are reduced from 2.22 mm of flatness deviation to 0.32 mm, achieving an 85.6% reduction. Furthermore, the entire process including measurement, adjustment, and assessment is completed in just 6 h by two operators who are not professional service engineers. In conclusion, this methodology demonstrates feasibility for scaling up, especially to large, high-precision CNC machine tools with bases mounted by fixators, offering the capability for bidirectional adjustment.

42 ENGINEERING↗
DOE OSTI2022

Transparent conducting oxides: from all-dielectric plasmonics to a new paradigm in integrated photonics

During the past few years, the optics and photonics communities have renewed their attention toward transparent conducting oxides (TCOs), which for over two decades have been broadly employed for the fabrication of transparent electrodes in photovoltaic and communication technologies. This reinvigorated research curiosity is twofold: on the one hand, TCOs, with their metal-like properties, low optical absorption, and fabrication flexibility, represent an appealing alternative to noble metals for designing ultra-compact plasmonic devices. On the other hand, this class of hybrid compounds has been proved to possess exceptionally high optical nonlinearities when operating on a frequency window centered around their crossover point, the wavelength point at which the real part of the dielectric permittivity switches sign. Because TCOs are wide-bandgap materials with the Fermi level located in the conduction band, they are hybrid in nature, thus presenting both interband and intraband nonlinearities. This is the cause of a very rich nonlinear physics that is yet to be fully understood and explored. In addition to this, TCOs are epsilon-near-zero (ENZ) materials within a broad near-infrared spectral range, including the entire telecom bandwidth. In this operational window a myriad of novel electromagnetic phenomena have been demonstrated experimentally such as supercoupling, wavefront freezing, and photon doping. Furthermore, TCOs stand out among all other ENZ systems due to one fundamental characteristic, which is hardly attainable even by using structured materials. In fact, around their ENZ wavelength and for a quite generous operational range, these materials can be engineered to have an extremely small real index. This peculiarity leads to a slow-light effect that is ultimately responsible for a significant enhancement of the material nonlinear properties and is the cornerstone of the emerging field of near-zero-index photonics. In this regard, the recent history of nonlinear optics in conductive oxides is growing extremely fast due to a great number of experiments reporting unprecedentedly remarkable effects, including unitary index change, bandwidth-large frequency shift, efficient ultra-low-power frequency conversion, and many others. This review is meant to guide the reader through the exciting journey of TCOs, starting as an industrial material for transparent electrodes, then becoming a new alternative for low-loss plasmonics, and recently opening up new frontiers in integrated nonlinear optics. The present review is mainly focused on experimental observations.

42 ENGINEERING↗
DOE OSTI2020

Site Environmental Report for Sandia National Laboratories California (2019)

Sandia National Laboratories, California (SNL/CA) is a Department of Energy (DOE) facility. The management and operations of the facility are under a contract with the DOE's National Nuclear Security Administration (NNSA). On May 1, 2017, the name of the management and operating contractor changed from Sandia Corporation to National Technology & Engineering Solutions of Sandia, LLC (NTESS). The DOE, NNSA, Sandia Field Office administers the contract and oversees contractor operations at the site. DOE and its management and operating contractor for Sandia are committed to safeguarding environmental protection, compliance, and sustainability and to ensuring the validity and accuracy of the monitoring data presented in this Annual Site Environmental Report. This Site Environmental Report for 2019 was prepared in accordance with DOE Order 231.1B, Environment, S afro and Health &potting (DOE 2012). The report provides a summary of environmental monitoring information and compliance activities that occurred at SNL/CA during calendar year 2019, unless noted otherwise. General site and environmental program information is also included.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Probabilistic Risk Assessment of a Light Water Reactor Coupled with a High Temperature Electrolysis Hydrogen Production Plant

Two generic probabilistic risk assessments (PRA) for the addition of a heat extraction system (HES) addition to a light water reactor (LWR) are performed, one for a pressurized water reactor (PWR) and one for a boiling water reactor (BWR). The results investigate the applicability of the potential licensing approaches which do not require a full U.S. Nuclear Regulatory Commission (NRC) licensing review. The PRAs are generic, and some assumptions are made. Many conservative assumptions from a the preliminary PWR PRA report were eliminated using design data for both the HES and the high temperature electrolysis facility (HTEF). The results of the PRA indicate that the 10 CFR 50.59 licensing approach is justified due to the minimal increase in initiating event frequencies for all DBAs, none exceeding 5.6%. The PRA results for CDF and LERF support the use of RG 1.174 as further risk information that supports a change without a full LAR. Further insights provided through hazard analysis and sensitivity studies confirm with high confidence that the safety case for licensing an HES addition and a HTEF sited at 1.0 km from the NPP is strong and that the placement of a HTEF at 0.5 km is a viable case. Site specific information can alter these conclusions.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2021

Site Environmental Report for 2020, Sandia National Laboratories, California

Sandia National Laboratories, California (SNL/CA) is a Department of Energy (DOE) facility. The management and operations of the facility are under a contract with the DOE's National Nuclear Security Administration (NNSA). On May 1, 2017, the name of the management and operating contractor changed from Sandia Corporation to National Technology & Engineering Solutions of Sandia, LLC (NTESS). The DOE, NNSA, Sandia Field Office administers the contract and oversees contractor operations at the site. DOE and its management and operating contractor for Sandia are committed to safeguarding environmental protection, compliance, and sustainability and to ensuring the validity and accuracy of the monitoring data presented in this Annual Site Environmental Report. This Site Environmental Report for 2020 was prepared in accordance with DOE Order 231.1B, Environment, Safety and Health Reporting (DOE 2012). The report provides a summary of environmental monitoring information and compliance activities that occurred at SNL/CA during calendar year 2020, unless noted otherwise. General site and environmental program information is also included.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

High Temperature Thermal Barrier Coating Evaluation of Yttrium Aluminum Garnet for Gas Turbine Applications

The Solution Precursor Spray Process (SPPS) process has been shown to overcome the durability and property challenges of applying yttrium aluminum garnet (YAG) coating for high temperature thermal barrier coating (TBC) applications (1200°C+) but only limited testing has been performed in representative application environments. In this study, YAG coatings were developed to optimize microstructure and tailor properties for combustion components in an industrial gas turbine. Thermal conductivity, erosion resistance and furnace cycling durability were used to validate YAG properties against the standard yttria-stabilized zirconia coating (YSZ). Graded and multi-layered microstructures were applied to enhance performance while maintaining durability. Further YAG process development was required to replicate coating properties and optimize deposition on more complex fuel injector nozzle and combustion liner components. Rig testing of both components was performed and compared against the baseline YSZ coating validating the high temperature capability and lower thermal conductivity of the SPPS YAG coating. The components in both tests were cycled for a minimum of ten cycles with the fuel injector test targeting a higher operating temperature while the combustor liner operated at standard conditions. A development engine test is planned to further validate performance in a gas turbine engine of this promising material.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Net-zero Microgrid Program Report: Microrred de la Montaña Feasibility Study (Executive Summary Extended)

This feasibility study provides the technical and economic rationale for the Microrred de la Montaña as a viable solution for supplying reliable and resilient electricity to an underserved region in Puerto Rico – a region that is the first to be disconnected from the grid and the last to be restored, enduring months long outages. It begins the process of the development of the microgrid through conceptual design, engineering, detailed electrical design, implementation, and operation. The Microrred de la Montaña is organized under the governance of the Cooperativa Hidroeléctrica de la Montaña (Cooperativa) which has legal status as a cooperative and power provider under the laws of Puerto Rico. The members are the municipalities of Adjuntas, Jayuya, Lares and Utuado with a combined population of 90,000. These municipalities are in central Puerto Rico – a mountainous region that is extremely vulnerable to weather events and excessive, long-duration power outages and are among the poorest and most disadvantaged regions in Puerto Rico. Funding from external sources is necessary to acquire the resources for a resilient power delivery system. Regulatory support is necessary to establish operational relationships with the incumbent power providers. The Microrred de la Montaña is envisioned as a resilient microgrid that manages distributed energy resources – local solar, storage, and hydroelectricity over an upgraded distribution network within the boundaries of four municipalities. This feasibility study provides the results of an extensive techno-economic analysis to form a sound basis for decision-making by community leaders, their constituents, funding and investment agencies, and regulators to realize the benefits that are achievable by fully implementing the design and planning recommended for the Microrred de la Montaña.

13 HYDRO ENERGY↗
DOE OSTI2022

Probabilistic Risk Assessment of a Light-Water Reactor Coupled with a High-Temperature Electrolysis Hydrogen Production Plant

This report details an expansion of the original two generic probabilistic risk assessments (PRAs) for the addition of a heat extraction system (HES) to a light-water reactor, one for a pressurized-water reactor and one for a boiling-water reactor. The new material in this revision includes a new HES design, direct electrical coupling of the nuclear power plant to the High-Temperature Electrolysis Facility (HTEF), and a smaller 100-MWt HTEF analysis. The results investigate the applicability of the potential licensing approaches, which do not require a full United States Nuclear Regulatory Commission licensing review. The PRAs are generic and include some assumptions. We eliminated many conservative assumptions from the preliminary pressurized-water reactor PRA report using design data for both the HES and HTEF. The PRA results indicate that the 10 CFR 50.59 licensing approach is justified due to the minimal increase in initiating event frequencies for all design basis accidents, with none exceeding 5.6%. The PRA results for core damage frequency and large early release frequency support the use of RG 1.174 as further risk information that supports a change without a full licensing amendment review. Further insights provided through hazard analyses and sensitivity studies confirm with high confidence that the safety case for licensing an HES addition and an HTEF sited 1.0 km from the nuclear power plant is strong and that the placement of a HTEF at 0.5 km is also a viable case. Site-specific information can alter these conclusions.

08 HYDROGEN↗
DOE OSTI2023

Limitations in Advanced Measurement Systems: An Overview for Power Systems

Measurements have been an essential part of managing the electric power system from the beginning. Surprisingly, today’s measurements are not always particularly trustworthy. Countless factors can influence measurement in real-world conditions. In this report, we look at the measurement system as a comprehensive information acquisition system with complicated interdependencies setting the limiting factors and affecting system performance. The first chapter provides an overview of the whole system and introduces the key elements of the limitations checklist. The second part of the document is a component checklist for measurement system limitations that concisely describes effects, common remedies, and underlying factors.

42 ENGINEERING↗
DOE OSTI2024

Pilot-Scale Algal Oil Production

The main objective of the project is complete: development of a preliminary planning and design for a pilot-scale algal oil cultivation and processing facility, FEL-3 design with -5% / +15% cost estimate accuracy, and conversion of the algal oil to biofuel in an off-site existing bio-oil refinery. The design basis includes 10 tons per day of dried algae cultivated with CO 2 supplied by direct air capture, electricity supplied solar power, well water supply, zero liquid discharge, off-site extraction, and off-site conversion of oil to biofuel. The design and permitting package is an important milestone in the path to commercialization of algal biofuels and bioproducts as it provides the preliminary design, permitting path, long-term land lease, planning documents, and team needed for success in future engineering, construction, start-up and operations of a pilot-scale farm at a site in Paso Robles, CA. Outcomes of the business assessment include (i) identification of a product spectrum for economical algal biofuels using co-products with markets that are commensurate with production of 6-7 billion gallons per year of sustainable aviation fuel (SAF), renewable diesel, and renewable gasoline, (ii) a path toward near-term contribution of algae oil to SAF, and (iii) an approach for long-term operation of a pilot-scale farm.

09 BIOMASS FUELS↗