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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 1,351 records · Page 75
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Unstructured mesh-based multi-physics reactor transient simulation with iMC code

In this study, we present a time-dependent Monte Carlo simulation result about a complex fuel-loaded light water reactor system with thermal-hydraulic feedback using the KAIST iMC code. The intra-pin temperature distribution is calculated based on Monte Carlo-tallied detailed power distribution and the finite element heat transfer method. The temperature effect of fuel, absorber, and coolant are adequately reflected into the dynamic response by the on-the-fly Doppler broadened cross-section correction. For the time-dependent Monte Carlo transport simulation, the predictor-corrector quasi-static Monte Carlo method is used for this study. We tested the coupled analysis framework with a 17-by-17 fuel assembly loaded with the centrally-shielded burnable absorber (CSBA) fuel element. The temperature feedback effect on the material cross-section and the moderator density incurred negative reactivity in response to the external positive reactivity insertion, showing the inherent stability of the reactor system. The pin-wise power and temperature change during the system transient are presented and discussed. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2015

Oxide driven strength evolution of silicon surfaces

Previous experiments have shown a link between oxidation and strength changes in single crystal silicon nanostructures but provided no clues as to the mechanisms leading to this relationship. Using atomic force microscope-based fracture strength experiments, molecular dynamics modeling, and measurement of oxide development with angle resolved x-ray spectroscopy we study the evolution of strength of silicon (111) surfaces as they oxidize and with fully developed oxide layers. We find that strength drops with partial oxidation but recovers when a fully developed oxide is formed and that surfaces intentionally oxidized from the start maintain their high initial strengths. MD simulations show that strength decreases with the height of atomic layer steps on the surface. These results are corroborated by a completely separate line of testing using micro-scale, polysilicon devices, and the slack chain method in which strength recovers over a long period of exposure to the atmosphere. Combining our results with insights from prior experiments we conclude that previously described strength decrease is a result of oxidation induced roughening of an initially flat silicon (1 1 1) surface and that this effect is transient, a result consistent with the observation that surfaces flatten upon full oxidation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Water-cooled Reactor Cavity Cooling System Flow Analysis

A research team at University of Wisconsin - Madison designed and constructed a 1/4 scaled experimental facility to study natural circulation cooling in a water based reactor cavity cooling system (WRCCS) for decay heat removal in an advanced high temperature reactor. The facility is capable of natural circulation operation scaled for simulated decay heat removal (up to 45 kW input power, which is equivalent to 1.70 MW at full scale) and pressurized up to 2 bar pressure. The WRCCS facility has been used to study natural circulation flow behavior from transients due to evaporation of the water inventory from decay heat removal. The natural circulation flow is observed to be oscillatory with the mean flow increasing as the pressure head in the system drops due to evaporation of the water inventory during two-phase operation. A first principles model was developed to understand the behavioral limits and trends. Through the use of void fraction measurements and the model, we find that the mass flow rate in the system increases due to small increases in the time-averaged void fraction over the course of a four-hour boil-off experiment. This increase in void fraction causes an increase in the buoyancy head and mass flow. The model also determines the operational limits on the mass flow rate under two-phase operation that can be verified with extended tests in the WRCCS facility. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2026

Fuel-Cladding Eutectic Study of Legacy Fast Flux Test Facility (FFTF) MFF HT9/U-10Zr Metallic Fuel

This report presents the first systematic investigation of fuel-cladding eutectic interaction (FCEI) in irradiated HT9/U-10Zr metallic fuel from the Fast Flux Test Facility (FFTF) Materials Fuels Form (MFF) program, using differential scanning calorimetry (DSC) coupled with scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Two irradiated fuel cross-sections, MNT07H (9.5 at% burnup, x/L = 0.78) and MNT08H (7.0 at% burnup, x/L = 0.93), were subjected to three successive isothermal annealing rounds (R1–R3) at 820°C for 20 minutes each, yielding a cumulative transient duration of one hour. This study directly addresses a recognized gap in the existing FCEI database, which previously lacked irradiated HT9/U-10Zr data at burnup levels above 8 at%. Two principal findings emerge from the study. First, for both samples, FCEI remained spatially confined within the pre-existing fuel-cladding chemical interaction (FCCI) zone boundaries after R3, with no measurable eutectic penetration into unaffected cladding beyond the original FCCI layer. This self-limiting behavior is consistent with historical Fuel Behavior Test Apparatus (FBTA) results and is attributed to the near-eutectic phase composition of the FCCI zone, which rapidly absorb the available eutectic-forming constituents and then stall penetration once the FCCI zone is consumed. A comparison with unirradiated surrogate data further supports this mechanism: whereas a U–34 at.% Fe sample would be expected to show ~176 µm of iron penetration under comparable conditions, the irradiated samples exhibited only ~20 µm, a discrepancy attributed to irradiation-induced interfacial porosity and pre-existing FCCI composition gradients. Second, for MNT08H, FCEI was observed exclusively on the half of the cladding circumference where pre-existing steady-state FCCI was present, with no detectable FCEI on the opposite half. Three hypotheses are proposed to explain this asymmetry: the inhibiting role of a zirconium-rich rind at the fuel-cladding interface; the chemical sequestration of iron by redistributed zirconium within the fuel matrix; and the persistence of fuel-cladding gaps on the FCEI-free half that preclude direct contact. All three hypotheses require further experimental investigation. The results extend the empirical FCEI database into higher-burnup territory and demonstrate the viability of DSC-based testing as a substitute for the no-longer-available FBTA apparatus. Future work will include additional cross-section testing, compilation of the full FCEI dataset, model evaluation, and DSC testing of ternary fuel compositions to broaden the experimental basis for safety assessment of sodium-cooled fast reactor systems.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

NRC Multiphysics Analysis Capability Deployment FY2020: Part 3

This report details progress and activities of Idaho National Laboratory (INL) on the Nuclear Regulatory Commission (NRC) project “Development and Modeling Sup- port for Advanced Non-Light Water Reactors.” The tasks completed for this report are: Task2c: Explicit modeling of pebble transient temperature response. In this simulation, the 400 MWth Pebble-Bed Modular Reactor (PBMR) design, PBMR- 400, experiences a 20-second power ramp from 100% to 150% power. This is followed by a similar reduction in the power back to 100%. Several multiscale pebble coupling approaches are tested with one pebble per mesh element in the active core region. The results show good conservation behavior and the stability of the coupling.; Extended scope part 1: An assessment of the computational efficiency of the Discontinuous Finite Element Method (DFEM) heat transfer solver shows good scalability. The DFEM solver is a factor of 4 more expensive in solution time than the Finite Element Method (FEM) solver for heat transfer problems due to the increased number of degrees of freedom. Nonetheless, the DFEM approach provides the user with the flexibility to model gap heat transfer problems.; Extended scope part 2: The GapHeatTransferInterfaceMaterial was improved to give the user increased flexibility with the modeling of heat transfer through gaps with the DFEM solver. A number of gap parameters can now be coupled both through functions and variables.; Extended scope part 3: Demonstration of how the gap width between hexagonal fuel cells can be calculated during a heat-up transient and used in the GapHeatTransferInterface model. A full-domain DFEM model with gap expansion is coupled to a SubApp that models the thermal expansion of the base plate. The results show the expected physical behavior, although have not been fully bench-marked at this point in time.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

SATS Enhanced Capabilities and Demonstration of Improved Ramp Rates for In-Cell Testing

This report presents the development of the second-generation Severe Accident Test Station, referred to as SATS 2.0. SATS 2.0 represents a major advancement in addressing critical research needs for the United States nuclear industry, particularly in relation to fuel fragmentation, relocation, and dispersal (FFRD) concerns associated with the nuclear industry’s goal to extend fuel burnup beyond a peak rod average of 62 GWd/tU. The central objective of SATS 2.0 was the deployment a new furnace capable of achieving heating rates up to 100°C/s. This achievement addresses critical capability gaps, enabling assessment of prioritized research objectives established by the Electric Power Research Institute’s (EPRI) Collaborative Research on Advanced Fuel Technologies (CRAFT) working group. These research objectives are directly related to high-burnup loss-of-coolant accident (LOCA) conditions and the effects of prolonged exposure to elevated temperatures, both of which are crucial to enhancing nuclear safety and efficiency. The SATS 2.0 system builds upon prior experience with the original SATS system, which focused on evaluating accident-tolerant fuel (ATF) cladding concepts during accident conditions. However, the new system not only expands upon prior core capabilities by achieving higher heating rates with a better furnace but also plans to incorporate novel auxiliary systems to create a versatile platform for addressing current research needs. For example, a system was developed for the quantification and characterization of fission gas released during high-temperature transients. Additionally, in situ measurement capabilities were developed, such as digital image correlation which enabled the real-time capture of strain related to balloon and burst events and fiber-optic sensors that allowed for high-fidelity characterization of temperature gradients. Demonstration tests of the new 12-lamp furnace achieved heating rates up to 120°C/s. Notably, SATS 2.0 demonstrated its capacity to simulate LOCA burst tests at different pressures, yielding burst data that align with historical empirical models. Moreover, the system exhibited its capability to simulate complex conditions observed in anticipated operational occurrences, while effectively mitigating temperature overshoots. These accomplishments mark significant progress toward overcoming FFRD challenges and advancing the United States nuclear industry's safety basis and technical capabilities for extended burnup.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

An approach for the measurement of the bulk temperature of single crystal diamond using an X-ray free electron laser

We present a method to determine the bulk temperature of a single crystal diamond sample at an X-Ray free electron laser using inelastic X-ray scattering. The experiment was performed at the high energy density instrument at the European XFEL GmbH, Germany. The technique, based on inelastic X-ray scattering and the principle of detailed balance, was demonstrated to give accurate temperature measurements, within 8% for both room temperature diamond and heated diamond to 500 K. Here, the temperature was increased in a controlled way using a resistive heater to test theoretical predictions of the scaling of the signal with temperature. The method was tested by validating the energy of the phonon modes with previous measurements made at room temperature using inelastic X-ray scattering and neutron scattering techniques. This technique could be used to determine the bulk temperature in transient systems with a temporal resolution of 50 fs and for which accurate measurements of thermodynamic properties are vital to build accurate equation of state and transport models.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Structure/property relationships in copolymers comprising renewable isosorbide, glucarodilactone, and 2,5-bis(hydroxymethyl)furan subunits

Carbohydrates and their derivatives have great potential as building blocks for the development of renewable materials that are cost and performance competitive with conventional petroleum-based materials. To this end, the rigid carbohydrate-derived diols, glucarodilactone and isosorbide were functionalized with a castor oil derivative, 10-undecenoic acid, forming α,ω-dienes suitable for acyclic diene metathesis (ADMET) polymerization. Equimolar copolymerizations of these two monomers, glucarodilactone undecenoate (GDLU) and isosorbide undecenoate (GDLU), transform brittle homopolymers into elastic materials with shape memory capabilities. To understand the source of these properties, a series of copolymers consisting of a range of GDLU and IU compositions (100:0, 77:23, 76:24, 52:48, 48:52, 18:82, 0:100 mol percent GDLU to IU) was synthesized. The material and chemical properties were characterized by uniaxial tensile testing, small-amplitude oscillatory shear rheology, X-ray scattering and hydrolytic degradation testing. Small compositional changes in this family were shown to have a drastic impact on the observed mechanical performance and degradability of these materials. Rheological measurements of GDLU-containing copolymers found evidence for the presence of transient networking within these materials. We posit that the transient network within this material is responsible for the elasticity and shape memory abilities of the GDL-containing materials. In confirmation of these properties, a novel α,ω-diene 2,5-bis(hydroxymethylfuran) undecenoate (BHMFU) was developed and served as a direct replacement for either GDLU or IU in copolymerizations. The replacement of GDLU resulted in a total loss of the elasticity and shape memory of the copolymers, supporting the role of GDLU in the mechanical performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Degradation and corresponding failure mechanism for GaN-based LEDs

The degradation behaviors of high power GaN-based vertical blue LEDs on Si substrates were measured using in-situ accelerated life test. The results show that the dominant failure mechanism would be different during the operation. Besides that, the corresponding associated failure mechanisms were investigated systematically by using different analysis technologies, such as Scan Electron Microscopy, Reflectivity spectroscopy, Transient Thermal Analysis, Raman Spectra, etc. It is shown that initially, the failure modes were mainly originated from the semiconductor die and interconnect, while afterwards, the following serious deterioration of the radiant fluxes was attributed to the package. The interface material and quality, such as die attach and frame, play an important role in determining the thermal performance and reliability. In addition, the heating effect during the operation will also release the compressive strain in the chip. These findings will help to improve the reliability of GaN-based LEDs, especially for the LEDs with vertical structure.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2012

COMPARISON OF RADIO-FREQUENCY INTERFERENCE MITIGATION STRATEGIES FOR DISPERSED PULSE DETECTION

Impulsive radio-frequency signals from astronomical sources are dispersed by the frequency-dependent index of refraction of the interstellar media and so appear as chirped signals when they reach Earth. Searches for dispersed impulses have been limited by false detections due to radio-frequency interference (RFI) and, in some cases, artifacts of the instrumentation. Many authors have discussed techniques to excise or mitigate RFI in searches for fast transients, but comparisons between different approaches are lacking. This work develops RFI mitigation techniques for use in searches for dispersed pulses, employing data recorded in a 'Fly's Eye' mode of the Allen Telescope Array as a test case. We gauge the performance of several RFI mitigation techniques by adding dispersed signals to data containing RFI and comparing false alarm rates at the observed signal-to-noise ratios of the added signals. We find that Huber filtering is most effective at removing broadband interferers, while frequency centering is most effective at removing narrow frequency interferers. Neither of these methods is effective over a broad range of interferers. A method that combines Huber filtering and adaptive interference cancelation provides the lowest number of false positives over the interferers considered here. The methods developed here have application to other searches for dispersed pulses in incoherent spectra, especially those involving multiple beam systems.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Transient Photocurrent From High-Voltage Vertical GaN Diodes Irradiated With Electrons: Experiments and Simulations

Radiation-hard high-voltage vertical GaN p-n diodes are being developed for use in power electronics subjected to ionizing radiation. Here, we present a comparison of the measured and simulated photocurrent response of diodes exposed to ionizing irradiation with 70 keV and 20 MeV electrons at dose rates in the range of 1.4x10 7 - 5.0x10 8 rad(GaN)/s. The simulations correctly predict the trend in measured steady-state photocurrent and agree with experimental results within a factor of 2. Furthermore, simulations of the transient photocurrent response to dose rates with uniform and non-uniform ionization depth profiles uncover the physical processes involved that cannot be otherwise experimentally observed due to orders of magnitude larger RC time constant of the test circuit. The simulations were performed using an Exploratory Physics Development code developed at Sandia National Laboratories. The code offers the capability to include defect physics under more general conditions, not included in commercially available software packages, extending the applicability of the simulations to different types of radiation environments.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

An approach for the measurement of the bulk temperature of single crystal diamond using an X-ray Free Electron Laser

We present a method to determine the bulk temperature of a single crystal diamond sample at an X-Ray Free Electron Laser using inelastic X-ray scattering. The experiment was performed at the High Energy Density (HED) instrument at the European XFEL GmbH, Germany. The technique, based on inelastic X-ray scattering and the principle of detailed balance, was demonstrated to give accurate temperature measurements, within 8% for both room temperature diamond and heated diamond to 500 K. Here, the temperature was increased in a controlled way using a resistive heater to test theoretical predictions of the scaling of the signal with temperature. The method was tested by validating the energy of the phonon modes with previous measurements made at room temperature using inelastic X-ray scattering and neutron scattering techniques. This technique could be used to determine the bulk temperature in transient systems with a temporal resolution of 50 fs and for which accurate measurements of thermodynamic properties are vital to build accurate equation of state models.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Improving Subsurface Stress Characterization for Carbon Dioxide Storage Projects by Incorporating Machine Learning Techniques

The overall objective of this project is to develop a framework for reliable characterization and prediction of the state of stress in the overburden and underburden (including the basement) in CO 2 storage reservoirs using machine learning and integrated geomechanics and geophysical methods. Specifically, we propose to develop workflow encompassing of technologies and/or methods to predict stress and pressure changes due to CO 2 injection in an active tertiary recovery site and their impacts on subtle fault activation, fractures and occurrence of microseismic events and compare responses to field observations. In this project, we anticipate using dataset from the Farnsworth field Unit (FWU) which is operated by Purdure Petroleum. A novel elastic-waveform VSP inversion technique will be used to estimate high-resolution spatial and temporal changes of elastic moduli in CO 2 storage reservoirs, which will be combined with velocity-stress relationship derived from laboratory tests to obtain subsurface pressure and stress. Clustered microseismic data will be jointly inverted for improved focal mechanisms. Least-squares reverse-time migration of microseismic waveform data will be performed to directly image fracture/fault zones. Additionally, a deep neural network machine learning technique with convolutional and recurrent layers will be used for learning the spectro-temporal structures in microseismic waveforms. The results of this geotechnical data analysis will be integrated to develop a high-resolution 3D mechanical earth model extending from the overburden sealing formations to the underburden including the basement. Mechanical properties will be derived through integration of mechanical logs, tests, available results from chemo-mechanical laboratory tests, and elastic inversion of seismic data using a combination of Bayesian and stochastic methods as well as machine learning technique. Failure features (faults/fractures) will be represented and/or modeled based on seismic and core data analysis. A transient hydrodynamic-geomechanical model will be developed through coupling with the calibrated FWU reservoir simulation model. The full physics coupled model will be used to train a reduced order proxy model using machine learning algorithm for estimating stress which will then be used with appropriate constitutive relationships and forward seismological models to simulate pressure changes and induced microseismicity. An advanced optimization framework will be developed to perform a history match to minimize error between field observations and simulated. The history matched proxy model will be verified against the full-physics equivalent. The field observations that will be used in the coupled model calibration process include pressure/stress inverted from VSP, moment magnitude from microseismic analysis, real time downhole pressure measurements, production and injection data. Parameter sensitivity and uncertainty analysis will be performed to characterize the impact of model parameter uncertainty on stress estimates. The proposed project will have significant impact on future field implementation of the proposed technology. Because the project field site is an ongoing CO 2 EOR development, the value of the new technology will be demonstrated in an operational context and evaluated as a viable risk mitigation strategy. Cost/benefit will be evaluated together with the various commercial incentives for CO 2 sequestration available to oil and gas operators. The extensive available dataset and ongoing data acquisition under the SWP Phase III work plan provides flexibility for investigation of multiple approaches and reduces technical risk.

58 GEOSCIENCES↗
DOE OSTI2026

A Multiphysics Evaluation of Annular Uranium-Zirconium Metallic Fuels [Poster]

This study examines the performance of U-10Zr annular metallic fuel rodlets which were experimentally evaluated as part of the Advanced Fuels Campaign (AFC). The AFC mission is to develop novel fuel technologies and facilitate the implementation of those technologies by industry partners. A key objective is to improve steady-state and transient performance over current fuel types. The experiments of interest in this study included annular metallic U-Zr fuel rodlets within HT-9 cladding which were placed in SS-316 capsules and inserted in the Advanced Test Reactor (ATR). Certain mechanical and thermal conditions cannot be directly evaluated through experiments and fuel performance modeling is used to shed light on this evolution over time. In this study, BISON Multiphysics simulations are leveraged to investigate the state of the fuel system throughout and after the experimental conditions.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

INL POSTER 2025- KRYSTAL FOSTER

The Advanced Test Reactor (ATR) employs the N-16 system to measure reactor power by detecting beta particles emitted from nitrogen-16 isotopes. During startup, the N-16 pumps cause rapid oscillations in the discharge piping due to pressure transients, which cease when the valve supplying N-16 flow to the reactor is opened. To address this, a soft-starter is proposed to gradually increase the motor voltage, reducing mechanical stress and preventing pressure surges. This solution enhances system stability, lowers maintenance costs, extends equipment lifespan, and is more cost-effective than Variable Frequency Drives (VFDs), making it ideal for the infrequently activated N-16 pumps.

42 - ENGINEERING↗
DOE OSTI2018

Effect of Base Metal Misorientation on Single-Crystal Superalloy Transient Liquid-Phase Bonded Joints

In this paper, experiments and theoretical analysis were conducted to elucidate the internal relation between base metal misorientation and the characteristics of DD5 single-crystal superalloy TLP joints. The alloy was bonded at 1513 K for 10 h in vacuum environment. High-temperature creep rupture tests were carried out to determine the joint’s quality. Results revealed that base metal misorientation exerted a remarkable influence on DD5 alloy TLP joints. The joints of base metals with [001] orientation were used in this research. When the misorientation was smaller than 9°-10°, the single crystallization of joints can be realized and joints can achieve excellent mechanical properties. When the misorientation was more than 10°, there would be second-phase particles distributed in grain boundaries, thus resulting in poor mechanical property of joint; moreover, the characteristics of joint did not change with base metal misorientation in this case.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Applications of Transient Grating Spectroscopy to Radiation Materials Science

Radiation damage is an inherently multi-scale phenomenon, with much of the key material evolution occurring at the mesoscale. Current techniques for the direct interrogation of material property changes due to irradiation either function with very small volumes, such as in-situ TEM, cannot cover the full range of defect populations produced, such as in positron annihilation spectroscopy, or requires destruction of the test material, such as in standard or micromechanical testing. In addition, the ultimate quantities of interest to radiation materials scientists are the changes in key material properties with irradiation. These include stiffness, ductility, and thermal conductivity for structural materials, and optical properties such as index of refraction or changes in transmittance spectra for optically active materials. The latter of these are often correlated directly to stress- or thermally-induced changes, themselves a function of the specific defect populations responsible for their change. The rapid study of such a mesoscale phenomenon requires an inherently mesoscale technique, where multiple quantities of interest can be accurately measured in very short times. Determining the sensitivity of any technique with known certainly is of critical importance to qualifying a new technique to measure in-situ material property changes during irradiation. In this paper, we present the new applicability of an existing technique, known as transient grating (TG) spectroscopy, to rapidly and accurately study key problems in radiation materials science. Results quantifying the absolute sensitivity of the technique are presented, alongside molecular dynamics (MD) simulations of the TG spectroscopy process to gauge direct agreement between theory, simulation, and experiment. An example problem of interest is demonstrated as an illustration of what is possible, showing elastic and thermal changes in irradiated silicon carbide (SiC) films. Finally, future work to quantify the effects of experimentally-simulated radiation defects is proposed, in support of building a database to use TG spectroscopy to deconvolve irradiated material property changes in-situ in terms of the defect populations responsible for their evolution. The application of the TG spectroscopy technique to in-situ radiation materials science has the potential to answer long-standing questions in the field, relating to ion beam rastering, the onset of void swelling, and direct measurement of radiation-created point defect concentrations. Before it can do so, the technique must carefully be analyzed and tuned to increase its sensitivity, the certainty of its results, and the ability to predict radiation-induced changes by simulations must be developed. Making such measurements in-situ with the aid of predictive MD simulations has the potential to elucidate mechanisms of radiation damage accumulation, as well as more rapidly qualify radiation-resistant alloys for service in nuclear systems. Work is underway to build this database of experimentally-simulated radiation-produced defects, which will be combined and compared with actual irradiated materials for eventual in-situ deconvolution of the TG signal into the defect populations responsible for irradiation-induced microstructural change. (authors)

36 MATERIALS SCIENCE↗
DOE OSTI2023

AI-Based Faster-Than-Real-Time Stability Assessment of Large Power Systems with Applications on WECC System

Achieving clean energy goals will require significant advances in regard to addressing the computational needs for next-generation renewable-dominated power grids. One critical obstacle that lies in the way of transitioning today’s power grid to a renewable-dominated power grid is the lack of a faster-than-real-time stability assessment technology for operating a fast-changing power grid. This paper proposes an artificial intelligence (AI) -based method that predicts the system’s stability margin information (e.g., the frequency nadir in the frequency stability assessment and the critical clearing time (CCT) value in the transient stability assessment) directly from the system operating conditions without performing the conventional time-consuming time-domain simulations over detailed dynamic models. Since the AI method shifts the majority of the computational burden to offline training, the online evaluation is extremely fast. This paper has tested the AI-based stability assessment method using multiple dispatch cases that are converted and tuned from actual dispatch cases of the Western Electricity Coordinating Council (WECC) system model with more than 20,000 buses. The results show that the AI-based method could accurately predict the stability margin of such a large power system in less than 0.2 milliseconds using the offline-trained AI agent. Therefore, the proposed method has great potential to achieve faster-than-real-time stability assessment for practical large power systems while preserving sufficient accuracy.

24 POWER TRANSMISSION AND DISTRIBUTION↗