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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Proposed Updates to Pu Evaluation for ENDF/B-VIII.0β 2 [Slides]

This presentation shows current status of in ENDF/B-VIII.0 and ENDF/B-VIII.0β 1 Pu evaluations. With a focus on the Pu thermal solutions (PST) and sanity check on fast metal assemblies (PMF). Pu ENDFβ 1 file in the low-energy region included updates in RRR (up to 2.5 keV), TNC and PFNS. Discussed are improvements over ENDF/B-VIII.0 in the C/E benchmarks (PST 81 cases) with preliminary ν p and cross section covariance generation for the resolved resonance energy range up to 2.25 keV. Highlighted are proposed updates for ENDFβ 2 with an extension of the RRR evaluation up to 5 keV, inclusion of Mosby’s data including proper resolution function (thanks to Marian J.), and a particular focus on η energy dependence from thermal up to 10 eV with the impact of the capture-to-fission ratio at 0.29 eV. This presentation concludes with an updated ν p and cross section covariance generation for the resolved resonance energy range up to 5 keV. And additional validation to test performance at about 2 eV and in the keV region.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2026

Thermal Performance of Neutron Sensor Qualification Device

The neutron sensor qualification device was developed to provide a temperature-controlled environment for neutron sensors and dosimetry, enabling irradiation in a neutron field at the Armed Forces Radiobiology Research Institute (AFRRI) TRIGA reactor facility. The device, constructed from low-activation and low neutron cross-section materials, features a modular tube furnace design with three independently controlled heating zones for controlling axial temperature distribution. Laboratory testing validated the device's thermal performance, including uniform temperature distribution with less than 6°C variation across the central region, a steady-state operational temperature of 350°C achieved in approximately 3 hours, and a cooling time constant of 3.5 hours. External surface temperatures remained safe for handling, with the surrounding aluminum structure remaining at ambient conditions. The results confirm the device’s suitability for neutron sensor qualification experiments, with potential for future operation at higher temperatures and further optimization of performance.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗
DOE OSTI2021

Ion Mobility Spectrometry Characterization of the Intermediate Hydrogen-Containing Gold Cluster Au7(PPh3)7H52+

We employ ion mobility spectrometry and density functional theory to determine the structure of Au7(PPh3)7H52+ (PPh3 = triphenylphosphine) which was recently identified by high mass resolution mass spectrometry. Experimental ion-neutral collision cross sections represent the momentum transfer between the ionic clusters and gas molecules averaged over the relative thermal velocities of the colliding pair, thereby providing structural insights. Theoretical calculations indicate the geometry of Au7(PPh3)7H52+ is similar to Au7(PPh3)7+, with three hydrogen atoms bridging two gold atoms and two hydrogen atoms forming single Au–H bonds. Collision induced dissociation products observed during IMS experiments reveal that smaller hydrogen containing clusters may be produced through fragmentation of Au7(PPh3)7H52+. Our findings indicate that hydrogen containing species like Au7(PPh3)7H52+ act as intermediates in the formation of larger phosphine ligated gold clusters. These results advance the understanding and ability to control the mechanisms of size selective cluster formation which is necessary for scalable synthesis of clusters with tailored properties. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. M.A.H. acknowledges support from the DOE Science Undergraduate Laboratory Internship (SULI) program. H.H. acknowledges support from the DOE Office of Workforce Development for Teachers and Scientist (WDTS) under the Visiting Faculty Program (VFP). The efforts of K.A.M. and B.H.C. were supported by the Defense Threat Reduction Agency (Grant No. HDTRA1-14-1-0023). The research was performed using EMSL, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for DOE under Contract DE-AC05-76RL01830.

Ligare, Marshall R.↗
DOE OSTI2023

Qualification and Commissioning of Helium Flow Loop Experiment for Blanket Design Measurements

Sufficient cooling of plasma-facing materials remains an outstanding challenge in the design of fusion reactor blankets in commercial power demonstration plants. Due to its chemical inertness and low neutron interaction cross section, pressurized helium is a candidate coolant fluid for such systems; however, helium has a small thermal mass compared to liquid coolants, potentially reducing heat removal performance. To address this need, a number of heat transfer enhancements have been proposed to improve the cooling efficiency of such components, thereby decreasing pumping power needs and improving overall plant efficiency. Toward this end, a helium flow loop experiment (HFLE) has been designed and commissioned to test advanced passive heat transfer enhancements in unit-cell test sections, providing necessary data for model validation and subsequent system design. The HFLE is designed to provide flow of pressurized (up to 4 MPa) helium at flow rates up to 80 g/s, enabling heat transfer and pressure drop measurements in test pieces at Reynolds numbers in excess of 180 000. To explore the effects of novel and complex heat transfer enhancements, test sections are produced via additive manufacturing, providing geometries not typically obtainable by conventional machining. Here in this work, we present results from HFLE commissioning and the initial thermal-hydraulic tests of an additively manufactured rifled-rib test section. Results are compared to smooth pipe correlations, and plans are described for future HFLE measurements. These preliminary experiments indicate the utility of the HFLE for heat transfer enhancement testing and simulation validation activities.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

The importance of phonon spectrum measurements for accurate prediction of thermal scattering laws [Slides]

Although approximate phonon spectra (e.g. Debye model) are sufficient to reproduce integral quantities (e.g. total INS cross section) in reasonable agreement with the measured data, more accurate phonon spectra are needed to achieve agreement with the differential data. SANS component is essential for reproducing the total scattering cross section; this is the case for nanodiamonds and other materials where SANS components are present (such as porous materials like nuclear graphite). A format proposal for SANS data in ENDF or GNDS is needed. Therefore, differential (e.g. phonon spectrum) and integral (e.g. total cross section) measurements are necessary in the process of creating an ENDF evaluation. We have successfully developed a method by which ENDF evaluations can be directly compared to the relevant experimentally measured quantities. INS experiments at SNS, ILL, ISIS, and, in the future, ESS, as well as total cross section measurements at the VESUVIO instrument at ISIS, are accessible through user programs.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

FEM Analysis of Hybrid LTS/HTS Cos-Theta Dipole Magnet

After the recent results on Bi-2212 superconductive magnets realized and tested in canted cosine-theta and solenoid designs, respectively, at Lawrence Berkeley National Laboratory (LBNL) and NHMFL, the first Bi-2212 stress-managed cosine-theta insert magnet is in the assembly phase at Fermilab. This insert will be part of the first hybrid cosine-theta magnet made of Nb3Sn outer layers within the US-MDP effort to reach 20 T bore field. This paper reports the analytical analysis of the cosine-theta Nb3Sn/Bi-2212 hybrid magnet. As an introduction, it shows the validation of the finalized HTS coils' design optimized using the ROXIE code. Subsequently, it reports the parameters, logic, and implementation method of the 2D electromagnetic and mechanical FEM analysis of the LTS/HTS hybrid magnet. Results from the ANSYS detailed model made with sub-modeling geometry are compared with the homogeneous model implemented in the past. Moreover, a Python code was implemented to simulate the current degradation due to stresses in the detail-modeled conductor areas. The current degradation is introduced in the simulation dynamics for both conductors as an iteration process during the energization load step only after applying pre-stress and thermal loads. The numerical and graphic results of the 2D cosine-theta LTS/HTS magnet cross-section will be described and analyzed.

D'Agliano, A.↗
DOE OSTI2025

Wafer-Free Crystalline Silicon Solar Cells (CRADA Final Report)

This CRADA project, based on the DOE Solar Energy Technologies Office (SETO) Solar Prize Voucher program, helped Leap Photovoltaics to develop methodologies to immobilize Si particles by permanently attaching them to an Al-coated substrate and thereby forming carrier-selective electrical contacts to the Si particles. The bigger goal was to help Leap Photovoltaics develop these immobilized and contacted particle arrays into relatively efficient, inexpensive, and industrially relevant solar cells. By using Si particles instead of wafers in a solar cell absorber layer, one can avoid costs associated with growing monocrystalline Si ingots, then diamond-sawing them into wafers, then processing wafers into cells – a mainstream practice in today's high-efficiency Si cell and module technology. Monocrystalline or polycrystalline Si particles can be obtained in various ways: for example, Si kerf from wafer sawing is monocrystalline; recycled Si cell wafers can be ball-milled into particles; particles can be grown using various gas-phase techniques (mostly from SiH4). These Si particles can be assembled onto a substrate and serve as an absorber layer for the solar cell, absorbing photons to generate photocarriers. The challenge with this technique is to collect photocarriers from individual Si particles, with separation of photogenerated electrons to the negative cell’s electrode and positive photogenerated holes to the positive electrode. Therefore, each particle must have two isolated, carrier-selective contacts: one for electrons and one for holes. Plus, particles need to be immobilized onto a solid substrate. The goal of this work was focused on the immobilization of Si particles and creating hole-selective contact to them at the same time, using industrially relevant Si photovoltaic (PV) cell technology: screen printing of Al back-surface field electrodes. This is used in the mainstream Propane Education and Research Council (PERC) technology for hole-collecting contacts at the back of the cell. The work performed at NREL consisted of screen printing of Al metal paste on substrates, spreading Si particles onto it, and thermally processing the structures to form hole-collecting contacts. The final structures were investigated by scanning electron microscopy (SEM) after focused ion beam (FIB) cross-sectioning and polishing. The work was done jointly by NREL staff and Leap Photovoltaics (Leap PV) employees stationed at NREL. The samples were then taken to Leap PV for further processing. Training the Leap PV employee on various NREL techniques (laser cutting, screen printing, thermal processing, characterization) was part of the scope.

14 SOLAR ENERGY↗
DOE OSTI2020

Getting a THUMP from a WIMP

Producing an acceptable thermal relic abundance of dark matter with masses >> 10 2 TeV is a challenge. We propose a novel mechanism where GeV-scale states establish a tiny thermal relic abundance for dark matter, which is later promoted to ultra massive status by a very light scalar. We refer to this dark matter as a THermal Ultra Massive Particle (THUMP). Direct detection of THUMPs can be naturally expected due to large scattering cross sections mediated by low mass states that couple THUMPs to the Standard Model. Our model generically leads to signals for the associated GeV-scale states at accelerator experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Dancoff-based Wigner-Seitz approximation for the subgroup resonance self-shielding in the VERA neutronic simulator MPACT

The MPACT neutronics module of the Virtual Environment for Reactor Analysis (VERA) has used the subgroup method for resonance self-shielding calculation, for which two-dimensional (2D) fixed-source transport calculations are performed using the method of characteristics for resonance energy groups. When considering thermal feedbacks, the subgroup calculation must be performed at each outer iteration. Therefore, the computing time for cross section processing is a significant burden for computational efficiency. The Dancoff-based Wigner-Seitz approximation (DWA) capability has been implemented into MPACT in conjunction with the subgroup method, which has been used in SCALE/XSProc since SCALE version 6.0 and has recently been called an equivalent Dancoff-factor cell (EDC) method. The issue of relatively large reactivity bias in DWA for the gadolinia rods was resolved by introducing multiple Dancoff factors. Benchmark results for the VERA pressurized and boiling water reactor benchmark suites show that the DWA capability would significantly enhance computational efficiency with comparable accuracy. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2020

Neutronics Enhanced Meshing Operations (NEMO) Users Manual V.1.0

The is a Python framework developed at Idaho National Laboratory that uses the Cubit Python to build Cubit models and export them in EXODUS II format. These EXODUS mesh files can be used by any -based application, but NEMO is specialized for coupled neutronics calculations. Therefore, the primary purpose of NEMO is to prepare mesh files for reactor geometries and generate a homogenization overlay file for the Serpent Monte Carlo code. This homogenization overlay file ensures the consistency of the mesh with the generation of homogenized cross sections and reference fluxes for the Superhomogenization method. NEMO also supports the preparation of mesh files for thermal and thermo-mechanical models, particularly the discontinuous finite element gap heat transfer model in Griffin. This manual introduces the user to the basic capabilities in NEMO for prismatic geometries.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

TEX-Hf Assemblies: Highly Enriched Uranium Plates with Hafnium Using Polyethylene Moderator and Polyethylene Reflector

This report documents the integral experiment evaluation and publication for IER-532 (TEX-Hf), Thermal/Epithermal eXperiments (TEX) with highly enriched uranium (HEU) fuel and hafnium (Hf), moderated and reflected by polyethylene. The design of TEX-Hf is a variation of IER-297 (TEX-HEU), with the inclusion of hafnium as a diluent material. The experiment and evaluation include seven configurations, all of which were acceptable as benchmark cases. These benchmark cases provide validation for hafnium in the thermal, intermediate, and fast neutron energy regimes by maximizing the sensitivity in k eff to the hafnium cross sections. The evaluation was reviewed and accepted by the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Technical Review Group on April 17, 2024, and was submitted to the ICSBEP in August 2024 following subgroup approval.

42 ENGINEERING↗
DOE OSTI2024

Large eddy simulation of particle dispersion analysis in a pressurized reactive fluid–particle system

Pressurized oxy-combustion (POC) is a promising candidate to reduce carbon emissions in power generation. Designing an effective burner plays a vital role in developing new combustion technologies. Because of high pressure, the volumetric fraction of particles in a pressurized oxy-combustor could be higher than that in the conventional combustor, consequently, the particle dynamics in the pressurized vessel need to be evaluated accordingly. Specifically, the present computational work analyzes the pattern of the particle dispersion by extracting the particle mass flow rate and the particle size distribution in the pressurized combustor. A large eddy simulation (LES) with the environment pressure 15-bar and 100 kWth thermal input of fuel particle has been performed. The particle mass flow rates sampled in several cross-section planes strongly fluctuate, indicating the impacts of the flame as well as the gas-phase flow on the particle movement. Animations of the particle-gas flow show that the flow recirculation plays a major role in producing the pulsing phenomenon of the particle mass flow rate.

Li, Lei↗
DOE OSTI2024

Lithium Plating Characteristics in High Areal Capacity Li-Ion Battery Electrodes

Li-ion battery degradation and safety events are often attributed to undesirable metallic lithium plating. Since their release, Li-ion battery electrodes have been made progressively thicker to provide a higher energy density. However, the propensity for plating in these thicker pairings is not well understood. Herein, we combine an experimental plating-prone condition with robust mesoscale modeling to examine electrode pairings with capacities ranging from 2.5 to 6 mAh/cm 2 and negative to positive (N/P) electrode areal capacity ratio from 0.9 to 1.8 without the need for extensive aging tests. Using both experimentation and a mesoscale model, we identify a shift from conventional high state-of-charge (SOC) type plating to high overpotential (OP) type plating as electrode thickness increases. Further, these two plating modes have distinct morphologies, identified by optical microscopy and electrochemical signatures. We demonstrate that under operating conditions where these plating modes converge, a high propensity of plating exists, revealing the importance of predicting and avoiding this overlap for a given electrode pairing. Further, we identify that thicker electrodes, beyond a capacity of 3 mAh/cm 2 or thickness >75 μm, are prone to high OP, limiting negative electrode (NE) utilization and preventing cross-sectional oversizing the NE from mitigating plating. Here, it simply contributes to added mass and volume. The experimental thermal gradient and mesoscale model either combined or independently provide techniques capable of probing performance and safety implications of mild changes to electrode design features.

25 ENERGY STORAGE↗
DOE OSTI2020

Nanometer-Scale Imaging of Inhomogeneous Active Charge Carriers in Arsenic-Doped CdTe Thin Films

We report nanometer-scale imaging of active carrier distribution of As-doped CdTe films by scanning capacitance microscopy (SCM). We developed SCM sample preparation for CdTe by ion-milling followed by thermal processing. The nanometer-resolution carrier delineation for CdTe was validated by imaging on a CdTe cross-section sample made by a molecular beam epitaxy layer stack with As-doping concentrations of 10^15 ~10^18 /cm 3 . We found that the carrier distribution in As-doped films was significantly nonuniform, with inhomogeneity ranging from sub-um to a few um and concentration variation of one order of magnitude (low 10^16 to low 10^17 /cm 3 ). This nonuniformity is distributed randomly, independent of grain structure and grain boundary (GB). We used Kelvin probe force microscopy (KPFM) and cathodoluminescence (CL) to further map the surface potential and radiative illumination on the same area as the SCM image. Higher potential and lower CL intensity were found on GBs but not on SCM contrast, illustrating positive GB charging and GB recombination but not GB-distinguished doping. The overall KPFM potential image is in rough agreement with the SCM carrier distribution, in terms of Fermi-level position relative to the bandgap edge - thus resulting in the band-edge potential fluctuation. Nonuniform carrier concentration, potential fluctuation, and defect recombination can all together cause the Voc deficit of the As-doped CdTe device.

14 SOLAR ENERGY↗
DOE OSTI2022

Simulation for the fault current limiting operation of REBCO CORC superconducting cables with different core materials

With high power density and low loss, CORC superconducting cables composed of RE- Ba 2 Cu 3 O 7–δ (REBCO) coated conductors are of great interest for power transmission applications. They can also effectively be designed to serve as fault current limiters, thanks to their sharp superconducting-to-normal transition. Coupled electromagnetic-thermal finite element (FE) simulations implemented in COMSOL Multiphysics were developed and validated against the published results for the fault current limiting performance of two CORC cables of REBCO coasted conductors wound on either copper or stainless steel cores. For improved accuracy, temperature dependencies of electrical and thermal properties of all component materials were considered in the simulations. The simulations were performed in the cross-sections of the cables for every individual layer of each REBCO tape to deliver comprehensive understanding of evolution of the current distribution and temperature rise in those layers. Furthermore, the studies can suggest approaches to optimize cable design for fault current limiting (FCL) applications by assessing the role of individual components. In the paper, possible computational errors, challenges and improvements are also discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

TEX-Hf: Integral Experiment Execution of Thermal/Epithermal eXperiments using Highly Enriched Uranium with Polyethylene and Hafnium (IER-532 CED-3b Report)

This report documents the experimental configurations and measurements for IER-532, Thermal/Epithermal eXperiments (TEX) with highly enriched uranium (HEU) fuel and interstitial hafnium (Hf), moderated and reflected by polyethylene. TEX-Hf is a variation of and based on the TEX-HEU (IER-297) design, with the inclusion of hafnium. These configurations provide integral experiments for validation of hafnium in the thermal, intermediate, and fast neutron energy regimes by maximizing the sensitivity in k eff to the hafnium isotope cross sections. The experiment campaign was completed over seven weeks during the end of FY22 and beginning of FY23 at the National Critical Experiments Research Center at the Nevada National Security Site. The campaign produced seven experimental configurations, four reproducibility measurements, and many additional dimensional measurements that will be of use to the future benchmark evaluation of this experiment and other experiments using the same HEU fuel. Table 1 summarizes the TEX-Hf experimental configurations, including their physical parameters, calculated fission fractions, and estimated excess reactivities.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Friction Stir Welding – an Advanced Approach to Repair Nuclear Power Plant Components

Solid phase joining technique friction stir welding (FSW) has been shown to mitigate helium-related issues in fusion welding of irradiated steels. Here, we present detailed characterization results of the first friction stir weld of an irradiated 304L stainless steel (SS) coupon contained 5.2 atomic parts per million (appm) helium. Scanning electron microscopy (SEM) was used to characterize a cross section specimen removed from the friction stir weld. No macro helium induced crack was observed at the analyzed cross-section, and only 1 – 1.5 µm size pores were found in the stir zone (SZ) and the thermal-mechanical affected zone (TMAZ). Moreover, some minor helium aggregations (Maximum ~20 µm in length) appeared along grain boundaries inside the TMAZ. Thereafter, miniature tensile specimens were extracted from the SZ, TMAZ and heat affected zone (HAZ), and base metal (BM) and tested. All welded specimens showed high total elongations (> 60%) and strengths (> 75% BM strengths). Overall, the weld made by FSW showed much better results comparing with traditional fusion welding on irradiated SS.

Tang, Wei↗
DOE OSTI2020

Measured Thermal and Fast Neutrons Fluence Rates for ATF-1 Holders During ATR Cycle 166B

This report contains the thermal (2200 m/s) and fast (E>lMeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 166B which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains measurements of the fluence rates corresponding to the particular elevations relative to the 80-ft. core elevation. The data in this report consist of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, and (3) plots of both the thermal and fast neutron fluence rates. All "BR" holder monitor wires for this cycle are 56.375 inches long. This length allows measurements from 31.17 inches above core midplane to 19.81 inches below core midplane. The distance from the end of the wires to the first count position was 4.25 inches for all wires counted from this cycle. The monitors were located in an outward small I-holes,1-22 and 1-23. Thermal neutron fluence was determined based on the activation of the CoAl wires and resonance corrections determined in the irradiation of Cycle 152A when the RML measured cadmium-covered as well as bare neutron monitors in the Southwest, Southeast, and H positions at the Center lobe to determine the division in neutron energy between epithermal and thermal neutrons. For more information please refer to letter “Radiation Measurements Laboratory measurements of in core ATR physics testing during cycle 152A. The measured values documented in RML procedure, “ACMM-3600, Flux Monitoring,” will be used indefinitely until further measurements supersede the current values. Fast neutron fluence was determined using the activation of nickel wires. Typically, a fission spectrum averaged cross section (E>1 MeV) is used as determined in detailed measurements described in “ATR Neutron Spectral Characterization,” which gives an effective cross section of 97 mb for the small I-holes. However, those measurements were performed with unfueled experiments. The fast fluence values reported here use a perturbed 114 mb effective>1 MeV spectrum averaged cross section for the small I-holes based on MCNP simulations for a previous fueled experiment in the1-24 position. Refer to “LWR- ATR Irradiation Measured Thermal and Fast Neutron Fluence Rates ATR CYCLE 133A 04/19/04 thru 05/17/04” for more information.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗