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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 1,459 records · Page 81
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Statistical uncertainty analysis applied to the DRAGONv4 code lattice calculations and based on JENDL-4 covariance data

In this paper, multi-group microscopic cross-section uncertainty is propagated through the DRAGON (Version 4) lattice code, in order to perform uncertainty analysis on k{infinity} and 2-group homogenized macroscopic cross-sections predictions. A statistical methodology is employed for such purposes, where cross-sections of certain isotopes of various elements belonging to the 172 groups DRAGLIB library format, are considered as normal random variables. This library is based on JENDL-4 data, because JENDL-4 contains the largest amount of isotopic covariance matrixes among the different major nuclear data libraries. The aim is to propagate multi-group nuclide uncertainty by running the DRAGONv4 code 500 times, and to assess the output uncertainty of a test case corresponding to a 17 x 17 PWR fuel assembly segment without poison. The chosen sampling strategy for the current study is Latin Hypercube Sampling (LHS). The quasi-random LHS allows a much better coverage of the input uncertainties than simple random sampling (SRS) because it densely stratifies across the range of each input probability distribution. Output uncertainty assessment is based on the tolerance limits concept, where the sample formed by the code calculations infers to cover 95% of the output population with at least a 95% of confidence. This analysis is the first attempt to propagate parameter uncertainties of modern multi-group libraries, which are used to feed advanced lattice codes that perform state of the art resonant self-shielding calculations such as DRAGONv4. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2011

Study of Heating and Fusion Power Production in ITER Discharges

ITER simulations, in which the temperatures, toroidal angular frequency and currents are evolved, are carried out using the PTRANSP code starting with initial profiles and boundary conditions obtained from TSC code studies. The dependence of heat deposition and current drive on ICRF frequency, number of poloidal modes, beam orientation, number of Monte Carlo particles and ECRH launch angles is studied in order to examine various possibilities and contingencies for ITER steady state and hybrid discharges. For the hybrid discharges, the fusion power production and fusion Q, computed using the Multi-Mode MMM v7.1 anomalous transport model, are compared with those predicted using the GLF23 model. The simulations of the hybrid scenario indicate that the fusion power production at 1000 sec will be approximately 500 MW corresponding to a fusion Q = 10.0. The discharge scenarios simulated aid in understanding the conditions for optimizing fusion power production and in examining measures of plasma performance.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

Using SWIFT Data

SWIFT has been shown to be a promising new diagnostic tool with many applications. SWIFT diagnostics coupled with PDV and other tools represent an exciting new source of data. SIAS is the name for the methodology we use to couple our SWIFT data to calculations for maximum utilization. SIAS, formerly Schlieren Inverse Analysis Software -- now SWIFT Inverse Analysis Software, uses SWIFT data and a hydro code calculation repeated in a genetic algorithm loop to reconstruct pressure history of shock transducer material interface.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Analysis of a nuclear data experiment: MANTRA-3

To improve the accuracy on the nuclear data, the uncertainties should be kept as low as possible. The major portion of these uncertainties comes from the input data and the assumptions made in the simulation models. For a high profile project like MANTRA, the pre and post irradiation analysis is very important. The current paper discusses the pre and post irradiation analysis of MANTRA-3 that could affect the end results using MCNP5 (a stochastic code) and ECCO-ERANOS (a deterministic code). This analysis was very helpful for understanding the possible uncertainties in MANTRA-3 and for calculating the final results. (authors)

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Fast Reactor Core Analysis Using AZNHEX Neutron Diffusion Code

The AZTLAN platform project emerged as an initiative to rank Mexico at a competitive level in software aspects for the analysis of nuclear reactors, in an effort to achieve autonomy in this area. The AZTLAN platform is conformed by a thermo-hydraulic code (AZTHECA), a neutron transport code (AZTRAN) and two neutron diffusion codes (AZKIND, AZNHEX). AZNHEX is a 3D diffusion code that solves numerically the time dependent neutron diffusion equations in hexagonal z-geometry using the RTN0 nodal finite element method. With this code, it is possible to simulate and analyze light water reactors, such as the Russian VVER, and variety of fast reactors. In this work, a sodium-cooled fast reactor core in steady state, with control rods fully withdrawn, is simulated. The comparison and validation of the values obtained with AZNHEX was done with the results obtained with MCNP6 Monte Carlo code.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2011

Kinetic solutions for electrons in multi-cusp ion source

Some analytical kinetic solutions are obtained for the primary and plasma electrons in multi-cusp ion source. The characteristics based on these solutions are discussed, such as frictional coefficient, collision frequency, electron current, electron diffusion, electron density, and electrical conductivity. A code based on one of these solutions is developed to discuss the plasma electrons diffusion; the simulation results are qualitatively consistent with our current experiences.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Multi-bit quantum random number generation by measuring positions of arrival photons

We report upon the realization of a novel multi-bit optical quantum random number generator by continuously measuring the arrival positions of photon emitted from a LED using MCP-based WSA photon counting imaging detector. A spatial encoding method is proposed to extract multi-bits random number from the position coordinates of each detected photon. The randomness of bits sequence relies on the intrinsic randomness of the quantum physical processes of photonic emission and subsequent photoelectric conversion. A prototype has been built and the random bit generation rate could reach 8 Mbit/s, with random bit generation efficiency of 16 bits per detected photon. FPGA implementation of Huffman coding is proposed to reduce the bias of raw extracted random bits. The random numbers passed all tests for physical random number generator.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

R and DE Robotic Sensor Intern Team: Remote 3D Mapping Overview

The Department of Energy (DOE) nuclear complex includes many hazardous and challenging environments that must be inspected remotely and routinely for structural integrity evaluation and long-term planning purposes. The H-Canyon Air Exhaust (HCAEX) Tunnel biannual inspection is an example of such an environment. Presently inspections are performed by teleoperated robotic crawlers provide low resolution video feedback to the structural engineers. Advanced sensors such as Lidar and panospheric hi-res cameras have the potential to provide additional valuable data in future inspections. UT-Austin Lidar work in support of an H-Canyon deployment began with the DOE EM sponsored H-Canyon Integrated Research Project. The R and DE Robotic Sensor intern team includes two of the UT-Austin Masters students working on Lidar development to facilitate the pulling of university developed solutions to the field. The goal of this project is to develop a suite of sensors that could be used to gather advanced data in future HCAEX tunnel inspections. Of particular interest is the ability to map the tunnel walls at an accuracy that will allow for the comparison of two scans performed at different time periods to estimate the concrete erosion rate. Additionally, the development of the 3D point cloud in the GPS denied environment is the first step in being able to collect and overlay other 3D data such as radiation mapping. Project specific goals include: - Design and develop 3D mapping sensor suite. Merge Lidar point cloud with high res camera images Incorporate Inertial Measurement Unit (IMU) to assist with positioning. - Develop sensor software and user GUI Sensor data collection and integration software User GUI for reach back system. - Test solution on crawler in tunnel test bed Use crawler base similar to H-Canyon planned crawler Design and build test bed simulating tunnel conditions. To facilitate rapid sensor integration, software coding and user GUI development, the Robot Operating System (ROS) was employed as the development platform. ROS is a set of open source software libraries and tools that assist with the building of robot applications. ROS includes drivers for many sensors, state-of-the-art algorithms, and powerful developer tools. Sensors selected for the summer intern solution included assessment as to whether they possessed ROS drivers and associated sample code. Additionally, the ROS 3D Robot Visualizer (rviz) tool has been employed.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

HDTS 2017.0 Testing and verification document

This report is a continuation of the series of Hunter Dose Tracking System (HDTS) Quality Assurance documents including (Foley and Powell, 2010; Dixon, 2012). In this report we have created a suite of automated test cases and a system to analyze the results of those tests as well as documented the methodology to ensure the field system performs within specifications. The software test cases cover all of the functions and interactions of functions that are practical to test. With the developed framework, if software defects are discovered, it will be easy to create one or more test cases to reproduce the defect and ensure that code changes correct the defect. These tests con rm HDTS version 2017.0 performs according to its specifications and documentation and that its performance meets the needs of its users at the Savannah River Site.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

SPISEA: A Python-based Simple Stellar Population Synthesis Code for Star Clusters

We present Stellar Population Interface for Stellar Evolution and Atmospheres (SPISEA), an open-source Python package that simulates simple stellar populations. The strength of SPISEA is its modular interface which offers the user control of 13 input properties including (but not limited to) the initial mass function, stellar multiplicity, extinction law, and the metallicity-dependent stellar evolution and atmosphere model grids used. The user also has control over the initial–final mass relation in order to produce compact stellar remnants (black holes, neutron stars, and white dwarfs). We demonstrate several outputs produced by the code, including color–magnitude diagrams, HR-diagrams, luminosity functions, and mass functions. SPISEA is object-oriented and extensible, and we welcome contributions from the community. The code and documentation are available on GitHub (https://github.com/astropy/SPISEA) and ReadtheDocs (https://spisea.readthedocs.io/en/latest/), respectively.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2010

Ab-Initio-Based Potential Energy Surfaces for Complex Molecules and Molecular Complexes

A published ab initio-based potential energy surface and newly constructed dipole moment surface of acetylene have been used to compute vibrational band intensities. The line intensity calculations employed the variational nuclear motion code WAVR4 for computation of wave functions and energy levels, and a newly developed code DIPOLE4 for computation of dipole transitions. Owing to the high computational cost of J>0 transitions using direct variational methods only J=0 and J=1 states and transitions have been computed variationally. The intensities of J>1 transitions were extrapolated from J=0 and J=1 using Honl-London coefficients. The resulting effective rotational constants B and transition intensities are compared with experimental data for the (3 nu(4)+nu(5)) combination band, the nu(3) and the nu(5) fundamental band. The prospects of using this procedure for extensive calculations of a hot line list, important for cool stars and extrasolar planets are discussed.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2010

Ro-vibrational spectra of C 2 H 2 based on variational nuclear motion calculations

A published ab initio-based potential energy surface and newly constructed dipole moment surface of acetylene have been used to compute vibrational band intensities. The line intensity calculations employed the variational nuclear motion code WAVR4 for computation of wave functions and energy levels, and a newly developed code DIPOLE4 for computation of dipole transitions. Owing to the high computational cost of J>0 transitions using direct variational methods only J=0 and J=1 states and transitions have been computed variationally. The intensities of J>1 transitions were extrapolated from J=0 and J=1 using Honl-London coefficients. The resulting effective rotational constants B and transition intensities are compared with experimental data for the (3 nu(4)+nu(5)) combination band, the nu(3) and the nu(5) fundamental band. The prospects of using this procedure for extensive calculations of a hot line list, important for cool stars and extrasolar planets are discussed.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2011

Magnetic-field generation and electron-collimation analysis for propagating fast electron beams in overdense plasmas

An analytical fluid model is proposed for artificially collimating fast electron beams produced in the interaction of ultraintense laser pulses with specially engineered low-density-core-high-density-cladding structure targets. Since this theory clearly predicts the characteristics of the spontaneously generated magnetic field and its dependence on the plasma parameters of the targets transporting fast electrons, it is of substantial relevance to the target design for fast ignition. The theory also reveals that the rapid changing of the flow velocity of the background electrons in a transverse direction (perpendicular to the flow velocity) caused by the density jump dominates the generation of a spontaneous interface magnetic field for these kinds of targets. It is found that the spontaneously generated magnetic field reaches as high as 100 MG, which is large enough to collimate fast electron transport in overdense plasmas. This theory is also supported by numerical simulations performed using a two-dimensional particle-in-cell code. It is found that the simulation results agree well with the theoretical analysis.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

LWR codes capability to address SFR BDBA scenarios: Modeling of the ABCOVE tests

The sound background built-up in LWR source term analysis in case of a severe accident, make it worth to check the capability of LWR safety analysis codes to model accident SFR scenarios, at least in some areas. This paper gives a snapshot of such predictability in the area of aerosol behavior in containment. To do so, the AB-5 test of the ABCOVE program has been modeled with 3 LWR codes: ASTEC, ECART and MELCOR. Through the search of a best estimate scenario and its comparison to data, it is concluded that even in the specific case of in-containment aerosol behavior, some enhancements would be needed in the LWR codes and/or their application, particularly with respect to consideration of particle shape. Nonetheless, much of the modeling presently embodied in LWR codes might be applicable to SFR scenarios. These conclusions should be seen as preliminary as long as comparisons are not extended to more experimental scenarios. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2016

Solution of the C5G7 Benchmark using the MOCUM Transport Code with ANSYS Unstructured Mesh

The objective of this research is to use finite element analysis (FEA) software to perform the unstructured meshing for reactor geometries and port the mesh information to MOCUM code. This workflow takes the advantage of the mature meshing module of the mainstream FEA; reduces the development effort for nuclear codes; and increases the nuclear code accuracy by using high quality meshes. In this work, ANSYS is used to build the reactor model and perform the unstructured meshing. The mesh information is then imported to the MOCUM code, a method of characteristic (MOC) transport program supporting unstructured meshes, using a developed MATLAB script. This procedure is verified by modeling the C5G7 benchmark problem. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2012

Practical considerations in realizing a magnetic centrifugal mass filter

The magnetic centrifugal mass filter concept represents a variation on the plasma centrifuge, with applications that are particularly promising for high-throughput separation of ions with large mass differences. A number of considerations, however, constrain the parameter space in which this device operates best. The rotation speed, magnetic field intensity, and ion temperature are constrained by the ion confinement requirements. Collisions must also be large enough to eject ions, but small enough not to eject them too quickly. The existence of favorable regimes meeting these constraints is demonstrated by a single-particle orbit code. As an example of interest, it is shown that separation factors of about 2.3 are achievable in a single pass when separating Aluminum from Strontium ions.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

The multi-scattering model for calculations of positron spatial distribution in the multilayer stacks, useful for conventional positron measurements

The spatial distribution of positrons emitted from radioactive isotopes into stacks or layered samples is a subject of the presented report. It was found that Monte Carlo (MC) simulations using GEANT4 code are not able to describe correctly the experimental data of the positron fractions in stacks. The mathematical model was proposed for calculations of the implantation profile or positron fractions in separated layers or foils being components of a stack. The model takes into account only two processes, i.e., the positron absorption and backscattering at interfaces. The mathematical formulas were applied in the computer program called LYS-1 (layers profile analysis). The theoretical predictions of the model were in the good agreement with the results of the MC simulations for the semi infinite sample. The experimental verifications of the model were performed on the symmetrical and non-symmetrical stacks of different foils. The good agreement between the experimental and calculated fractions of positrons in components of a stack was achieved. Also the experimental implantation profile obtained using the depth scanning of positron implantation technique is very well described by the theoretical profile obtained within the proposed model. The LYS-1 program allows us also to calculate the fraction of positrons which annihilate in the source, which can be useful in the positron spectroscopy.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Massively Parallel Simulation of Large Molecular Systems with Long-Range Interactions Final Report CRADA No. TC-0297-92-B

The purpose of this CRADA project is to develop and implement a large-scale molecular dynamics model for floppy molecules with long-ranged interaction on massively parallel supercomputers and accelerate the use of parallel supercomputers within the biomolecular and polymer industries. Within three years of the project, the partners will: create a new molecular dynamics computer simulation code (LAMMPS) from existing codes at SAndia National Laboratory-Albuquerque (SNL-A) and Lawrence Livermore National Laboratory (LLNL) and new algorithms and code developed during the CRADA project; design the resulting code to optimally use the emerging generation of massively parallel supercomputers; and apply the code to the solution of biomolecular problem suggested by Bristol-Myers Squibb (BMS) and polymer problems suggested by DuPont.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗