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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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Benchmark Progress towards TREAT M8CAL Core Loading to Support Validation of TREAT Operations

Benchmark experiment data is necessary to validate modeling and simulation activities to support Transient Reactor Experiment Test (TREAT) Facility restart and operations. Key measurements of interest include criticality, control rod worth, excess reactivity, and shutdown margin for varying core loading sizes. Benchmark evaluations are being developed according the guidelines provided in the International Handbook of Evaluated Reactor Physics Benchmark Experiments (IRPhEP Handbook) that can also support advanced modeling and simulation activities, new experiment design for advanced reactors and accident tolerant fuel, and potential low-enriched uranium conversion of the TREAT reactor. This summary discusses development activities supporting a benchmark evaluation of the TREAT M8CAL core loading, which will be submitted for peer-review and publication in the IRPhEP Handbook with the identifier TREAT-FUND-RESR-002. Detailed models of TREAT were developed and evaluated to prepare benchmark models of the minimum critical mass configuration. Calculations were performed using MCNP6.1 with ENDF/B-VII.1 nuclear data libraries. Discussion of results.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1999

Dynamic Altitude Simulation System Performance Modeling

The "Dynamic Altitude Simulation Prediction Program," DASSPP, is a program to predict the transient response of an engine, test cell, ejector system under engine shutdown conditions. These transients are important to know so that corrective modifications can be adapted to prevent any damage to the engine or test cell. The "Dynamic Altitude System Simulation Prediction Program," DASSPP, is a major rewrite of the existing program "RL-1000" written in BASIC. The RL-1000 program was written to analyze the transients of the RL-10 system only. The new program is written to run in Excell 97 and utilizes the Visual BASIC language in Excell. The program has many added features not included in the original "Rl-1000" program. The program utilizes the ejector models developed during the summer of 1997. The new program is very user friendly and utilizes a dialog box for data input.

LaFrance, Leo J.↗
DOE OSTI2024

Transient behavior of oxide fuels with controlled microstructure and Cr2O3 additive

Abstract Microstructure and Cr 2 O 3 doping profoundly impact the thermal-mechanical properties and fracture of oxides fuels. It is a challenge to study the transient behavior of nuclear fuels under loss-of-coolant-event (LOCA). In this study, the crack behavior of UO 2 pellets with controlled grain structure and Cr 2 O 3 doping was tested with rapid power ramping (300−900 °C per min) mimicking a prototypical LOCA heating profile. Dense micron-sized UO 2 pellets display well-maintained integrity without cracking with the ramping up to 1500 °C at a heating rate of 8 °C per second. Fracture occurs in both pure and Cr 2 O 3 -doped dense nano-sized UO 2 pellets. The Cr 2 O 3 doped oxide fuel pellet with a larger grain size (~ 22.2 μm) displays the best performance under LOCA testing due to its highest thermal conductivity under high temperature. FEA calculations suggest a temperature gradient across the fuel pellet during transient testing, resulting in residual stress and cracking, which can be correlated with their thermal-mechanical properties.

Zhao, Dong (ORCID:0000000191377257)↗
NASA NTRS1989

Automated Heat-Flux-Calibration Facility

Computer control speeds operation of equipment and processing of measurements. New heat-flux-calibration facility developed at Lewis Research Center. Used for fast-transient heat-transfer testing, durability testing, and calibration of heat-flux gauges. Calibrations performed at constant or transient heat fluxes ranging from 1 to 6 MW/m2 and at temperatures ranging from 80 K to melting temperatures of most materials. Facility developed because there is need to build and calibrate very-small heat-flux gauges for Space Shuttle main engine (SSME).Includes lamp head attached to side of service module, an argon-gas-recirculation module, reflector, heat exchanger, and high-speed positioning system. This type of automated heat-flux calibration facility installed in industrial plants for onsite calibration of heat-flux gauges measuring fluxes of heat in advanced gas-turbine and rocket engines.

Liebert, Curt H.↗
DOE OSTI2017

Temperature-Dependent Characterization, Modeling, and Switching Speed-Limitation Analysis of Third-Generation 10-kV SiC MOSFET

The temperature-dependent characteristics of the third-generation 10-kV/20-A SiC MOSFET including the static characteristics and switching performance are carried out in this paper. The steady-state characteristics, including saturation current, output characteristics, antiparallel diode, and parasitic capacitance, are tested. Here, a double pulse test platform is constructed including a circuit breaker and gate drive with >10-kV insulation and also a hotplate under the device under test for temperature-dependent characterization during switching transients. The switching performance is tested under various load currents and gate resistances at a 7-kV dc-link voltage from 25 to 125 C and compared with previous 10-kV MOSFETs. A simple behavioral model with its parameter extraction method is proposed to predict the temperature-dependent characteristics of the 10-kV SiC MOSFET. The switching speed limitations, including the reverse recovery of SiC MOSFET's body diode, overvoltage caused by stray inductance, crosstalk, heat sink, and electromagnetic interference to the control are discussed based on simulations and experimental results.

10-kV silicon carbide (SiC) metal–oxide–semiconduc↗
NASA NTRS1994

Testing For EM Upsets In Aircraft Control Computers

Effects of transient electrical signals evaluated in laboratory tests. Method of evaluating nominally fault-tolerant, aircraft-type digital-computer-based control system devised. Provides for evaluation of susceptibility of system to upset and evaluation of integrity of control when system subjected to transient electrical signals like those induced by electromagnetic (EM) source, in this case lightning. Beyond aerospace applications, fault-tolerant control systems becoming more wide-spread in industry; such as in automobiles. Method supports practical, systematic tests for evaluation of designs of fault-tolerant control systems.

Belcastro, Celeste M.↗
NASA NTRS2023

Metrics for Anomalous Charging currents in Polymer Tantalum Capacitors

Anomalous charging currents (ACC) in polymer tantalum capacitors may appear as a temporary short circuit that can last for dozens of milliseconds, cause failures to the parts, or cause malfunctions to fast operating electronic systems. Currently, there is no standard technique or set of metrics to evaluate the level of ACC which compares results obtained by different users and manufacturers. In this work, ACC in different types of capacitors were characterized by analysis of current transients during the constant voltage ramp or power surge testing (PST) techniques. It is shown that although the shape of transients may vary at different test conditions, the transfer charge and energy remain practically the same. The level of ACC is characterized by the energy dissipated in the part during PST. Variations of the dissipated energy with moisture content, test temperature, and voltage are evaluated. Effects of different reflow soldering conditions and long-term (up to 3000 hours) storage at 125 °C are discussed.

polymer tantalum capacitor↗
DOE OSTI2017

MITR RELAP5 Model Validations at Steady States and Transients

The Massachusetts Institute of Technology Reactor (MITR-II) is a 6 MW university research reactor designed primarily for experiments using neuron beams and in-core irradiation facilities, and education. The objective of this study is to validate the MITR RELAP5 model, which includes the reactor core, primary coolant loop, secondary coolant loop and heat exchanger models. Two sets of operational data were collected for validation. Steady-state data for 1 MW, 3 MW, 5.5 MW was obtained in the first test. The continuous startup transient data and the cooling tower outlet coolant temperature reduction obtained during the second test. The five steady-state conditions and two transient conditions were calculated by the RELAP5. The reactor power and cooling tower outlet temperature were used as boundary conditions while the reactor core inlet temperature and outlet temperature were calculated. A comparison was made between the modeling results and the temperature measurements. The results show that the MITR RELAP5 modeling results are in good agreement with measurement data for both steady-state and transient conditions.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRSDate not supplied

Comparison of Oxygen Liquefaction Gaseous Oxygen Injection via Ullage and Dip Tube

The Cryogenic Fluid In-situ Liquefaction for Landers (CryoFILL) testing demonstrated constant and transient oxygen liquefaction in a scaled lander tank integrated with an industrial cryocooler. Early in the test series, two methods for injecting gaseous oxygen into the test tank were ran under similar constant liquefaction conditions for comparison. Gaseous oxygen was either injected directly from the lid into the ullage or bubbled up through the liquid using a dip tube that extends to the bottom of the test tank. The direct comparison of these gaseous oxygen injection methods for constant liquefaction indicated ullage injection provided a greater liquefaction rate than injection via a dip tube. Injection through the ullage was subsequently selected as the nominal injection method for the CryoFILL test series. The comparison of the two injection methods will be highlighted with a discussion of what may cause the variation in liquefaction rate.

Cryogenic Fluid Management↗
DOE OSTI2019

OSU High Temperature Test Facility Test Acceptance Report, PG-29 Low Power (<350kW) Double Ended Inlet-Outlet Crossover Duct Break, Hybrid Heater

Test Acceptance Report for Test PG-29 at the Oregon State University High Temperature Test Facility. The purpose of this test is to examine the progression of the Double Ended Inlet-Outlet Crossover Duct Break transient in an integral test facility scaled to General Atomics’ Modular High Temperature Gas Reactor (MHTGR) design.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2025

Heat load measurements for the PIP-II pHB650 cryomodule

This study presents a brief overview of the 1st and 2nd phases and an in-depth analysis of the 3rd phase heat load testing performed on the pHB650 (prototype High Beta 650 MHz) cryomodule at PIP2IT (PIP-II Injector Test Facility), with a focus on both the results and the methodological advancements that have improved testing efficiency and accuracy. A key challenge identified in the testing campaign is the higher-than-expected heat loads observed in the first PIP-II (Proton Improvement Plan II) prototype cryomodules (pSSR1 and pHB650) tested at PIP2IT. Elevated heat loads are concerning given the fixed capacity of the PIP-II cryoplant that is currently being installed at Fermilab. However, understanding the sources of these elevated heat loads offers a critical opportunity to implement effective heat load mitigations on upcoming PIP-II cryomodules to stay within the available capacity of the PIP-II cryoplant. The study includes a summary of test results, descriptions of measurement procedures, and key observations on parameters directly and indirectly related to heat load measurements. Direct observations include measured heat loads and the effectiveness of JT heat exchanger under varying conditions, while indirect observation analyze factors such as the temperature distribution on the two-phase pipe and relief piping under varying conditions. Thermal acoustic oscillations (TAO) were identified during testing, which was mitigated by replacing the original G10 stem with a stainless steel stem equipped with wipers for the cryomodule cooldown valve. A major innovation during pHB650 Phase 3 testing was the development of an automated Python script to streamline data acquisition, analysis, and reporting of heat load results. This script automatically retrieved data from ACNET (Accelerator Control Network), performed heat load calculations, and generated detailed reports featuring plots and tables. This advancement significantly reduced manual labor and enhanced the thoroughness of data analysis compared to earlier campaigns. The heat load test reports were promptly uploaded to the electronic logbook shortly after each test, enabling rapid feedback and collaboration between the SRF and cryogenic teams. The heat load measurements included various components: HTTS (high-temperature thermal shield), LTTS (low-temperature thermal shield), 2K isothermal and non-isothermal heat loads. Results were recorded both within the cryomodule and between the bayonet can supply and return. Measurements were conducted under different operating conditions such as "standard", "linac", and "simulated dynamic". Additionally, HTTS and LTTS heat loads were calculated in real time, allowing for the tracking of thermal stability and identification of changes during testing, both in steady-state and transient conditions. The results of this testing campaign not only provide valuable insights into the performance of the pHB650 cryomodule but also highlight best practices and lessons learned that will inform future cryomodule testing at PIP2IT. These include adopting automated tools for data analysis, refining real-time measurement capabilities, and emphasizing detailed pre-test planning. The framework established in this campaign aims to set an improved standard for cryomodule testing and heat load reporting in future cryomodule test campaigns.

Porwisiak, D. [Fermilab; Wroclaw Tech. U.]↗
DOE OSTI2019

OSU High Temperature Test Facility Test Acceptance Report, PG-31 Low Power (<350kW) Pressure Vessel Bottom Break with Restored Forced Convection Cooling Test

Test Acceptance Report for Test PG-31 at the Oregon State University High Temperature Test Facility. The purpose of this test is to examine the progression of the Pressure Vessel Bottom Break with Restored Forced Convection Cooling transient in an integral test facility scaled to General Atomics’ Modular High Temperature Gas Reactor (MHTGR) design.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2024

DEVELOPMENT OF TRANSIENT FISSION GAS RELEASE CAPABILITIES TO STUDY HIGH BURNUP COMMERCIAL FUEL PERFORMANCE UNDER LOSS OF COOLANT ACCIDENT CONDITIONS

The contribution of transient fission gas release to the burst behaviour of high burnup fuel during a loss of coolant accident (LOCA) for commercial light water reactors is a complex phenomenon that is not fully understood. During the temperature ramp associated with a LOCA, there is significant, additional transient fission gas release in excess of steady state fission gas release from normal operation. The timing of this release and the various conditions that impact this release warrant further study. To better characterize this phenomenon, a system was developed to capture and characterize fission gas released from irradiated fuel during simulated LOCAs. This system is an upgrade to the existing Oak Ridge National Laboratory Severe Accident Test Station LOCA test apparatus and detects fission gas by gamma counting cryogenically cooled cold traps and by using an online gas mass spectrometer. The examined fuel can be pressurized or open to the furnace atmosphere. The design and operation of this new capability are discussed. Results from the first tests on high burnup fuel are presented. In the initial test, the LOCA relevant transient fission gas release was 5.3% for an unpressurized segment. Post-test microscopy on the tested samples is presented to demonstrate the likely radial source of transient fission gas release.

Harp, Jason↗
DOE OSTI2023

Short Communication: Observation of Initial Burst Release of Fission Gas from High-Burnup UO 2 Nuclear Fuel During Thermal Transient

A system was developed and tested to provide a deeper understanding of the fission gas release kinetics from nuclear fuel during thermal transients. Pressure, temperature, spectral data, and optical images were simultaneously collected during resistive sample heating, and all released gases were collected in liquid nitrogen-cooled charcoal traps. Standup testing was performed with a high-burnup nuclear fuel segment from rod section with an average local burnup of 77 GWd/tU. During heating, the segment released approximately 6 ± 2% of generated fission gas inventory after ramp heating to 460°C. Here, heating ceased when the sample ejected from the holder, as observed by constant imaging.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1951

Control Performance of General Electric Fuel and Torque Regulator Operating on T31-3 Turbine-Propeller Engine in Sea-Level Test Stand

A .General Electric fuel and torque regulator was tested in conjunction with a T31-3 turbine-propeller engine in the sea-level static test stand at the NACA Lewis laboratory. The engine and control were operated over the entire speed range: 11,000 rpm, nominal flight idle, to 13,000 rpm, full power. Steady-state and transient data were recorded and are presented with a description of the four control loops being used in the system. Results of this investigation indicated that single-lever control operation was satisfactory under conditions of test. Transient data presented showed that turbine-outlet temperature did overshoot maximum operating value on acceleration but that the time duration of overshoot did not exceed approximately 1 second. This temperature limiting resulted from a control on fuel flow as a function of engine speed. Speed and torque first reached their desired values 0.4 second from the time of change in power-setting lever position. Maximum speed overshoot was 3 percent.

Oppenheimer, Frank L.↗
DOE OSTI2017

An improved prediction of residual stresses and distortion in additive manufacturing

In laser assisted additive manufacturing (AM) an accurate estimation of residual stresses and distortion is necessary to achieve dimensional accuracy and prevent premature fatigue failure, delamination and buckling of components. Since many process variables affect AM, experimental measurements of residual stresses and distortion are time consuming and expensive. Numerical thermo-mechanical models can be used for their estimation, but the quality of calculations depends critically on the accurate transient temperature field which affects both the residual stresses and distortion. Here in this study, a well-tested, three-dimensional, transient heat transfer and fluid flow model is used to accurately calculate transient temperature field for the residual stress and distortion modeling. The calculated residual stress distributions are compared with independent experimental results. It is shown that the residual stresses can be significantly minimized by reducing the layer thickness during AM. Inconel 718 components are found to be more susceptible to delamination than Ti-6Al-4V parts because they encounter higher residual stresses compared to their yield strength.

36 MATERIALS SCIENCE↗
NASA NTRS1980

Response of surge protection devices to fast rising pulses

Two types of lightning protection modules incorporating leadless (pill type) Zener like devices were evaluated with regard to their ability to suppress EMP induced transients. Two series of tests were performed to evaluate the ability of these modules to react to fast rate of rise ( 1Kv/ns) transients, and the attenuation introduced and the ability to limit damped sinusoid pulses which may be induced due to an EMP resulting from a nuclear detonation.

Mindel, I. N.↗
NASA NTRS2015

Thermal Testing and Model Correlation of the Magnetospheric Multiscale (MMS) Observatories

International Conference on Envronmental Systems (ICES), Seattle WA NCTS 20964-15. The Magnetospheric Multiscale (MMS) mission is a Solar Terrestrial Probes mission comprising four identically instrumented spacecraft that will use Earths magnetosphere as a laboratory tostudy the microphysics of three fundamental plasma processes: magnetic reconnection, energetic particle acceleration, and turbulence. This paper presents the complete thermal balance (TB) test performed on the first of four observatories to go through thermal vacuum (TV) and the minibalance testing that was performed on the subsequent observatories to provide a comparison of all four. The TV and TB tests were conducted in a thermal vacuum chamber at the Naval Research Laboratory (NRL) in Washington, D.C. with the vacuum level higher than 1.3 x 10-4 Pa (10-6 torr)and the surrounding temperature achieving -180 C. Three TB test cases were performed that included hot operational science, cold operational science and a cold survival case. In addition to the three balance cases a two hour eclipse and a four hour eclipse simulation was performed during the TV test to provide additional transient data points that represent the orbit in eclipse (or Earth's shadow) The goal was to perform testing such that the flight orbital environments could be simulated as closely as possible. A thermal model correlation between the thermal analysis and the test results was completed. Over 400 1-Wire temperature sensors, 200 thermocouples and 125 flight thermistor temperature sensors recorded data during TV and TB testing. These temperatureversus time profiles and their agreements with the analytical results obtained using Thermal Desktop and SINDAFLUINT are discussed. The model correlation for the thermal mathematical model (TMM) is conducted based on the numerical analysis results and the test data. The philosophy of model correlation was to correlate the model to within 3 C of the test data using the standard deviation and mean deviation error calculation. Individual temperature error goal is to be within 5 C and the heater power goal is to be within 5 of test data. The results of the model correlation are discussed and the effect of some material and interface parameters on the temperature profiles are presented.

Thermal↗