Showing papers by "Luiz C Leal published in 2014"
Los Alamos National Laboratory1, Nuclear Energy Agency2, Brookhaven National Laboratory3, International Atomic Energy Agency4, National Institute of Standards and Technology5, Rensselaer Polytechnic Institute6, Oak Ridge National Laboratory7, Karlsruhe Institute of Technology8, Japan Atomic Energy Agency9, Ohio University10, Jožef Stefan Institute11, Nuclear Research and Consultancy Group12, Lawrence Livermore National Laboratory13, Argonne National Laboratory14, Idaho National Laboratory15, Institute for Reference Materials and Measurements16, Chalk River Laboratories17, Joint Institute for Nuclear Research18, Culham Centre for Fusion Energy19
TL;DR: The paper summarizes a program of nuclear science and computational work needed to create the new CIELO nuclear data evaluations and identifies discrepancies between various evaluations of the highest priority isotopes.
103 citations
11 Apr 2014-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a solution for mathematically impossible correlation matrices with negative eigenvalues and too low correlation coefficients between inherently positive parameters with large relative uncertainties is proposed. But the problem of efficient sampling of a large number of correlated parameters with extremely large uncertainties remains unsolved, and convergence of the random sampling for lognormal distribution with extremely high relative standard deviations is slow.
Abstract: Covariance data in the existing evaluated nuclear data libraries often include large relative uncertainties and mathematical inconsistencies, which arise especially in combination with random sampling. The 232 Th evaluation from the ENDF/B-VII.1 library has been taken as an example. Possible solutions for mathematically impossible correlation matrices with negative eigenvalues and too low correlation coefficients between inherently positive parameters with large relative uncertainties are proposed. Convergence of the random sampling for lognormal distribution with extremely high relative standard deviations is slow by nature. Using weighted sampling, single parameters or a limited number of correlated parameters with large uncertainties can be sampled. Efficient sampling of a large number of correlated parameters with extremely large relative uncertainties remains unsolved.
6 citations
01 Jan 2014
TL;DR: Recent progress in the Scale Monte Carlo module KENO to create problem dependent, Doppler broadened, cross sections, and results compare favorably with these expected results are discussed.
Abstract: For many Monte Carlo codes cross sections are generally only created at a set of predetermined temperatures. This causes an increase in error as one moves further and further away from these temperatures in the Monte Carlo model. This paper discusses recent progress in the Scale Monte Carlo module KENO to create problem dependent, Doppler broadened, cross sections. Currently only broadening the 1D cross sections and probability tables is addressed. The approach uses a finite difference method to calculate the temperature dependent cross-sections for the 1D data, and a simple linear-logarithmic interpolation in the square root of temperature for the probability tables. Work is also ongoing to address broadening theS (alpha , beta) tables. With the current approach the temperature dependent cross sections are Doppler broadened before transport starts, and, for all but a few isotopes, the impact on cross section loading is negligible. Results can be compared with those obtained by using multigroup libraries, as KENO currently does interpolation on the multigroup cross sections to determine temperature dependent cross-sections. Current results compare favorably with these expected results.
6 citations
TL;DR: In this article, the authors evaluated general purpose nuclear data files for the n+63Cu and n+65Cu reactions with upper neutron incident energy 200 MeV, and special attention was devoted to the accuracy and consistency of the evaluated data.
4 citations
TL;DR: In this article, the authors present the results of the 239 Pu resolved resonance evaluation effort and investigate the impacts of the prompt neutron multiplicity ( ν ¯ ) and the prompt neutrons fission spectrum (PFNS) have been investigated.
3 citations
TL;DR: In this paper, a new resolved resonance region evaluation of 63Cu and 65Cu was done in the energy region from 10-5 eV to 99.5 keV using the Reich-Moore approximation.
3 citations
Nuclear Energy Agency1, Los Alamos National Laboratory2, Rensselaer Polytechnic Institute3, Oak Ridge National Laboratory4, Karlsruhe Institute of Technology5, International Atomic Energy Agency6, Japan Atomic Energy Agency7, Brookhaven National Laboratory8, Tokyo Institute of Technology9, Nuclear Research and Consultancy Group10, Argonne National Laboratory11, Lawrence Livermore National Laboratory12, National Nuclear Laboratory13, Idaho National Laboratory14
TL;DR: OECD Nuclear Energy Agency's working party assesses nuclear data improvement needs and addresses these needs by initiating joint activities in the framework of dedicated WPEC subgroups, which include two subgroups on improved fission product yield evaluation methodologies and on modern nuclear database structures.
3 citations
TL;DR: In this article, the authors used the Reich-Moore approximation to fit with the R-matrix code SAMMY, the high-resolution measurements performed in 2010 and 2012 at the Geel linear accelerator facility.
2 citations
TL;DR: In this paper, the authors used prompt-gamma spectroscopy and time-of-flight techniques to measure (n,xnγ) cross-sections of interest.
2 citations
01 Oct 2014
2 citations
TL;DR: In this article, the authors focus on the issues related to the fluctuations in the cross sections above the resolved resonance range and define smooth cross sections in the unresolved resonance range based on the resolution-broadened total cross section measurements, where relevant.