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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 1,297 records · Page 72
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Measurements of inner-shell excited levels of Na-, Mg-, and Al-like europium on the LLNL EBIT

We report on a measurement of several n = 3 → n = 2 inner-shell transitions in sodiumlike, magnesiumlike, and aluminumlike europium, performed at the EBIT-I electron beam ion trap facility at the Lawrence Livermore National Laboratory using an x-ray calorimeter. Although the inner-shell x-ray lines of such M-shell ions are typically dominated by electric dipole allowed transitions, we have also identified a weak feature that appears to be the result of electric quadrupole decay in sodiumlike Eu 52+ . Here, we compare the measured transitions energies to the calculated values obtained using the flexible atomic code. We find agreement in most cases within 2 eV or better.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2024

Generation of meter-scale hydrogen plasmas and efficient, pump-depletion-limited wakefield excitation using 10 GeV electron bunches

High repetition rates and efficient energy transfer to the accelerating beam are important for a future linear collider based on the beam-driven plasma wakefield acceleration scheme (PWFA-LC). This paper reports the first results from the Plasma Wakefield Acceleration Collaboration (E300) that are beginning to address both of these issues using the recently commissioned FACET-II facility at SLAC national accelerator laboratory. Here we have generated meter-scale hydrogen plasmas using time-structured 10 GeV electron bunches from FACET-II, which hold the promise of dramatically increasing the repetition rate of PWFA by rapidly replenishing the gas between each shot compared to the hitherto used lithium plasmas that operate at 1–10 Hz. Furthermore, we have excited wakes in such plasmas that are suitable for high gradient particle acceleration with high drive-bunch to wake energy transfer efficiency- a first step in achieving a high overall energy transfer efficiency. We have done this by using time-structured electron drive bunches that typically have one or more ultra-high current (> 30 kA) femtosecond spike(s) superimposed on a longer (~0.4 ps) lower current (< 10 kA) bunch structure. The first spike effectively field-ionizes the gas and produces a meter-scale (30–160 cm) plasma, whereas the subsequent beam charge creates a wake. The length and amplitude of the wake depends on the longitudinal current profile of the bunch and plasma density. We find that the onset of pump depletion, when some of the drive beam electrons are nearly fully depleted of their energy, occurs for hydrogen pressure ≥ 1.5Torr. We also show that some electrons in the rear of the bunch can gain several GeV energies from the wake. These results are reproduced by particle-in-cell simulations using the QPAD code. At a pressure of ~2Torr, simulation results and experimental data show that the beam transfers about 60% of its energy to the wake.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Structure of odd- A Pt isotopes along the line of stability

The structure of the odd-A isotopes 193,195,197 Pt, which lie along the line of stability, has been studied up to high spin through multinucleon transfer reactions. Positive- and negative-parity sequences in Pt- 193,195 Pt have been considerably extended and multiple band crossings established. An isomer with T 1/2 = 5.0(5) ns and I π = 25/2 - is present in 195 Pt. Additionally, the isotopes 193,195 Pt are characterized by moderate oblate deformation, and angular momentum generation at high spin in the yrast, positive-parity sequences is attributed to the rotation alignment of i 13/2 neutrons and h 11/2 protons. Lastly, a detailed understanding of the observed features is presented using calculations based on tilted axis cranking covariant density functional theory as well as others with the ULTIMATE CRANKER code.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Experimentally constrained ( p , γ ) Y 89 and ( n , γ ) Y 89 reaction rates relevant to p -process nucleosynthesis

The nuclear level density and the g-ray strength function have been extracted for 89 Y, using the Oslo Method on 89 Y(p,p'γ) 89 Y coincidence data. The g-ray strength function displays a low-energy enhancement consistent with previous observations in this mass region ( 93-98 Mo). Shell-model calculations give support that the observed enhancement is due to strong, low-energy M1 transitions at high excitation energies. The data were further used as input for calculations of the 88 Sr(p,γ) 89 Y and 88 Y(n,γ) 89 Y cross sections with the TALYS reaction code. Lastly, comparison with cross-section data, where available, as well as with values from the BRUSLIB library, shows a satisfying agreement.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Quasicontinuum γ decay of Zr 91 , 92 : Benchmarking indirect ( n , γ ) cross section measurements for the s process

Here, nuclear level densities (NLDs) and γ-ray strength functions (γSFs) have been extracted from particle-γ coincidences of the 92 Zr(p,p´γ) 92 Zr and 92 Zr (p,dγ) 91 Zr reactions using the Oslo method. The new 91,92 Zr γSF data, combined with photonuclear cross sections, cover the whole energy range from Eγ ≈ 1.5 MeV up to the giant dipole resonance at Eγ ≈ 17 MeV. The wide-range γSF data display structures at Eγ ≈ 9.5 MeV, compatible with a superposition of the spin-flip M1 resonance and a pygmy E1 resonance. Furthermore, the γSF shows a minimum at Eγ ≈ 2–3 MeV and an increase at lower γ-ray energies. The experimentally constrained NLDs and γSFs are shown to reproduce known (n,γ) and Maxwellian-averaged cross sections for 91,92 Zr using the TALYS reaction code, thus serving as a benchmark for this indirect method of estimating (n,γ) cross sections for Zr isotopes.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Draft Genome Sequence of Anoxybacillus ayderensis Strain MT-Cab ( Firmicutes )

ABSTRACT The draft genome of the Gram-positive spore-forming Anoxybacillus ayderensis strain MT-Cab ( Firmicutes ), isolated from an enrichment culture of Chloracidobacterium thermophilum , was sequenced and comprises 2,577,015 bp in 92 contigs. The draft genome is predicted to consist of 2,699 protein-coding genes, 73 tRNA-coding genes, and an estimated 8 rRNA operons.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Radiative corrections: from medium to high energy experiments

Abstract Radiative corrections are crucial for modern high-precision physics experiments, and are an area of active research in the experimental and theoretical community. Here we provide an overview of the state of the field of radiative corrections with a focus on several topics: lepton–proton scattering, QED corrections in deep-inelastic scattering, and in radiative light-hadron decays. Particular emphasis is placed on the two-photon exchange, believed to be responsible for the proton form-factor discrepancy, and associated Monte-Carlo codes. We encourage the community to continue developing theoretical techniques to treat radiative corrections, and perform experimental tests of these corrections.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Task 1: Evaluation of M&S tools for micro-reactor concepts

The Westinghouse Electric Company (WEC) and Los Alamos National Laboratory (LANL) have been awarded a DOE ARPA-E MEITNER award for development of its eVinci microreactor design. Fundamentally, the attractiveness of heat pipe micro-reactors comes from the idea that the core is inherently self-regulating, simplifying the reactor design and requiring significantly fewer safety related components. While the WEC Design Team is focused on the experimental and fabrication tasks to ensuring self-regulation, the MEITNER Resource Team is focused on utilizing available codes to computationally show the core is indeed self-regulating. This requires the combination of fundamentally different codes to simulate the feedback mechanism between heat generation, temperature, and density.

42 ENGINEERING↗
DOE OSTI2016

Interrupted binary mass transfer in star clusters

Binary mass transfer (MT) is at the forefront of some of the most exciting puzzles of modern astrophysics, including SNe Ia, gamma-ray bursts, and the formation of most observed exotic stellar populations. Typically, the evolution is assumed to proceed in isolation, even in dense stellar environments such as star clusters. In this paper, we test the validity of this assumption via the analysis of a large grid of binary evolution models simulated with the SeBa code. For every binary, we calculate analytically the mean time until another single or binary star comes within the mean separation of the mass-transferring binary, and compare this timescale to the mean time for stable MT to occur. We then derive the probability for each respective binary to experience a direct dynamical interruption. The resulting probability distribution can be integrated to give an estimate for the fraction of binaries undergoing MT that are expected to be disrupted as a function of the host cluster properties. We find that for lower-mass clusters (≲10{sup 4} M{sub ⊙}), on the order of a few to a few tens of percent of binaries undergoing MT are expected to be interrupted by an interloping single, or more often binary, star, over the course of the cluster lifetime, whereas in more massive globular clusters we expect ≪1% to be interrupted. Furthermore, using numerical scattering experiments performed with the FEWBODY code, we show that the probability of interruption increases if perturbative fly-bys are considered as well, by a factor ∼2.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Competitiveness Improvement Project Informational Workshop

This presentation was given at the Competitiveness Improvement Project (CIP) Informational Workshop on December 6, 2017. Topics covered during the workshop include an overview of the CIP, past projects, scoring criteria, technical support opportunities, certification body requirements, standards applicable to distributed wind generators, information on the National Electric Code, certification testing requirements, test site requirements, National Environmental Policy Act, design review, levelized cost of energy, procurement/contracting, project management/deliverables, and outreach materials.

17 WIND ENERGY↗
DOE OSTI2016

Common Cause Failure Mitigation Experience on Digital I and C System in NPP

CCF is failures of redundant or separate structures, systems, or components due to a shared root cause. The CCF includes those are resulted from severe environments, design errors, calibration and maintenance errors, and consequential failures. In addition, digital I and C systems can be vulnerable to CCF caused by software errors or software developed logic, which could defeat the redundancy achieved by the hardware architecture. Therefore, diversity and defense in-depth (D3) has become an important issue to overcome the CCF of the safety I and C system. The U.S. NRC has established regulatory guidance addressing a method for assessing D3 provided by the safety I and C system architecture at a NPP. This method enables determination of whether vulnerabilities to CCF have been adequately addressed. The guidance is included in BTP 7-19 and Chapter 7 of NUREG-0800. The regulatory guidance provides a methodology for designing diversity. APR1400 establishes the mitigating strategies that consider the characteristics of digital I and C system that contribute to the potential for CCF. The diversity strategies consist of a combination of diversity attributes and associated criteria to address potential CCF vulnerabilities in digital safety I and C system. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2016

Simulation of fission gas diffusion in UO{sub 2} by vacancy clusters

The low solubility of fission gas in nuclear fuel leads to inter- and intra-granular bubbles. These bubbles affect performance of the fuel rod and increase the fuel temperature through the increase of porosity in the fuel pellets and decreased thermal conductivity across the pellet-clad gap as gas is released into the plenum. The nucleation, growth, and inter-connectivity of the fission gas bubbles ultimately depend on the diffusivity of gas atoms through the fuel matrix. Using mechanisms and data previously established from density functional theory (DFT) and empirical potential calculations, diffusion and reaction models have been derived for xenon atoms, uranium atoms, and vacancies in the substitutional and interstitial locations. Although similar to previous models, the diffusion and reaction rates have been re-derived in a more robust manner. Previous studies have under-predicted the experimentally observed diffusivity of xenon atoms in UO{sub 2}, however it has been previously shown that by including xenon atoms bound to two vacancies, the calculated diffusivity approaches the measured data. The derived model for species diffusion and inter-species reactions has been implemented in the MARMOT phase-field code in a modular structure so as to capture the enhanced diffusion of xenon due to bound gas + vacancy-cluster movement. The MARMOT code allows for the diffusion, reaction, and source rates to be solved simultaneously, resulting in steady state or transient concentrations of each species, and ultimately the diffusion behavior of xenon atoms. By including the diffusion of clusters of different combinations of xenon and vacancies, the calculated diffusivity more closely captures the measured diffusivity of xenon when using preliminary parameters. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

A NOVEL TOOL FOR IMPROVING THE DATA COLLECTION PROCESS DURING CONTROL ROOM MODERNIZATION HUMAN-SYSTEM INTERFACE TESTING AND EVALUATION ACTIVITIES

The U.S. Department of Energy (DOE) Light Water Reactor Sustainability (LWRS) Program is developing a scientific basis to extend the existing U.S. nuclear power plant (NPP) operating life beyond the current 60-year licensing period and to ensure NPP long-term reliability, productivity, safety, and security. Under the Advanced Instrumentation, Information, and Control (II&C) Systems Technologies pathway, the LWRS Program conducts targeted research and development to address long-term aging and obsolescence of existing instrumentation and control technologies, as well as to implement and test new digital II&C technology that enables broad innovation and business improvement in the NPP operating model. To this end, the role of human factors engineering (HFE) is important as part of ensuring that the control room modernization (CRM) activities account for the operator’s cognitive and physiological characteristics. Part of the HFE process for CRM entails conducting tests and evaluations (T&Es) that will inform the design of new human-system interface (HSI) technologies. Qualitative data that captures operator feedback and important human-system interactions are an important part of T&E. However, the analyzing this qualitative data in order to provide actionable design recommendations can be time-consuming and error prone. This paper presents an early version of a tool that can be used to analyze this qualitative data to (1) sift through freeform text for improved design issue identification, (2) maintain consistency in theme coding conventions, and (3) readily provide actionable design guidance that can be traceable to state-of-the-art HFE guidelines such as NUREG-0700. A description of this tool is discussed next.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2023

Simulation toolkit for digital material characterization of large image-based microstructures

In this paper, an efficient image-based simulation toolkit for material characterization is presented, which is scalable to work from personal computers to workstations. The effective thermal conductivity, elasticity, and permeability are evaluated employing a computational homogenization framework based on the Finite Element Method (FEM). Two complementary open-source packages are presented: one developed in Python, which can convert digital images into voxel meshes (pyTomoviewer); the other developed in Julia, that can run numerical simulations to compute effective material properties (chpack). Also, a CUDA C version of chpack is provided (chfem_gpu). They were designed to deal with large multi-phase models, so strategies were devised to minimize their memory footprint, while avoiding a high toll on execution time. The voxel-based approach significantly simplifies the FEM meshes and allows efficient matrix-free implementations. In that sense, to handle large linear systems of equations, the element-by-element (EBE) technique is adopted, in conjunction with a low-memory implementation of the Preconditioned Conjugate Gradient (PCG) method. Finally, the code was thoroughly tested on an artificial geometry made of a square array of cylinders, for which analytical solutions exist, as well as on a real micro-tomographic reconstruction of FiberForm TM , a carbon preform commonly used in thermal protection systems.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microbial community and metagenome dynamics during biodegradation of dispersed oil reveals potential key-players in cold Norwegian seawater

Oil biodegradation as a weathering process has been extensively investigated over the years, especially after the Deepwater Horizon blowout. In this study, we performed microcosm experiments at 5 °C with chemically dispersed oil in non-amended seawater. We link biodegradation processes with microbial community and metagenome dynamics and explain the succession based on substrate specialization. Reconstructed genomes and 16S rRNA gene analysis revealed that Bermanella and Zhongshania were the main contributors to initial n-alkane breakdown, while subsequent abundances of Colwellia and microorganisms closely related to Porticoccaceae were involved in secondary n-alkane breakdown and beta-oxidation. Cycloclasticus, Porticoccaceae and Spongiiabcteraceae were associated with degradation of mono- and poly-cyclic aromatics. Successional pattern of genes coding for hydrocarbon degrading enzymes at metagenome level, and reconstructed genomic content, revealed a high differentiation of bacteria involved in hydrocarbon biodegradation. Finally, a cooperation among oil degrading microorganisms is thus needed for the complete substrate transformation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Fuel performance evaluation of annular metallic fuels for an advanced fast reactor concept

The annular metallic fuel design has been considered as a promising solution to relieve the fuel-cladding mechanical interaction (FCMI) caused by significant swelling of metallic fuels at high burnup. In this paper, the fuel performance of annular metallic fuel with HT9 cladding in a novel advanced fast reactor design optimized for high-burnup performance was evaluated. The BISON code was utilized to perform fuel performance simulations using a modified fuel swelling correlation for conservative evaluation. Three representative fuel pins, which feature highest peak burnup (26.8 % FIMA, fission per initial metal atom), highest fuel temperature (645 degrees C), and highest fast neutron flux (2.68 x 10 15 n/cm 2 ∙s), were investigated. A series of key fuel performance parameters, such as peak fuel temperature, reduction of fuel central void, and cumulative damage fraction (CDF) of the cladding, were predicted for both upper and lower plenum configurations. It is evident that annular fuel design with a lower smeared density is capable of accommodating the significant swelling of metallic fuel at high burnup. Finally, the adoption of a lower plenum configuration effectively lowers the gas pressure inside the rod and reduces the creep damage accumulation in the HT9 cladding.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Multiplexed infrared photodetection using resonant radio-frequency circuits

We demonstrate a room-temperature semiconductor-based photodetector where readout is achieved using a resonant radio-frequency (RF) circuit consisting of a microstrip split-ring resonator coupled to a microstrip busline, fabricated on a semiconductor substrate. The RF resonant circuits are characterized at RF frequencies as function of resonator geometry, as well as for their response to incident IR radiation. The detectors are modeled analytically and using commercial simulation software, with good agreement to our experimental results. Though the detector sensitivity is weak, the detector architecture offers the potential for multiplexing arrays of detectors on a single read-out line, in addition to high speed response for either direct coupling of optical signals to RF circuitry, or alternatively, carrier dynamics characterization of semiconductor, or other, material systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Alfvén eigenmode stability and critical gradient energetic particle transport using the Trapped-Gyro-Landau-Fluid model

The Trapped-Gyro-Landau-Fluid (TGLF) transport model is a physically realistic and comprehensive theory based on a local quasilinear transport model fitted to linear and nonlinear GYRO gyrokinetic simulations [Staebler et al., Phys. Plasmas 14, 55909 (2007)]. This work presents the first use of the TGLF model to treat low-n Alfvén eigenmode (AE) stability and energetic particle (EP) transport. TGLF accurately recovers the local GYRO toroidicity-induced AE (TAE) and energetic particle mode (EPM) linear growth and frequency rates for a fusion alpha case. With a very high grid resolution, TGLF can quickly find the critical EP pressure gradient profile for stiff EP transport based on an AE linear threshold given the background thermal plasma profiles in DIII-D. The TGLF critical gradient profile using the recipe γ AE =0, that is the linear AE growth rate without additional driving rates from the background plasma gradients, matches the more expensive linear GYRO results with a single worst toroidal mode number n. TGLF can easily find the minimum critical gradient profile with testing multiple ns. From a database of runs using a newly developed TGLFEP code, a rough but insightful parametric “power law” scaling for critical EP beta is demonstrated. An important toroidal stabilization condition on the EP pressure gradient p EP /L$EP\atop{p}$ drive is isolated: R/L$EP\atop{p}$ > C R ~ 3, where L$EP\atop{p}$ is the EP pressure gradient length and R is the tokamak major radius. This paper also demonstrates that relaxation of the fixed slowing down EP profile shape approximation often used to find the critical EP density profile has little effect on the resulting EP transport. The single EP species critical gradient model is generalized to handle two EP species.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗