Impact of the 235U Covariance Data in Benchmark Calculations
Abstract
The error estimation for calculated quantities relies on nuclear data uncertainty information available in the basic nuclear data libraries such as the U.S. Evaluated Nuclear Data File (ENDF/B). The uncertainty files (covariance matrices) in the ENDF/B library are generally obtained from analysis of experimental data. In the resonance region, the computer code SAMMY is used for analyses of experimental data and generation of resonance parameters. In addition to resonance parameters evaluation, SAMMY also generates resonance parameter covariance matrices (RPCM). SAMMY uses the generalized leastsquares formalism (Bayes method) together with the resonance formalism (Rmatrix theory) for analysis of experimental data. Two approaches are available for creation of resonanceparameter covariance data. (1) During the dataevaluation process, SAMMY generates both a set of resonance parameters that fit the experimental data and the associated resonanceparameter covariance matrix. (2) For existing resonanceparameter evaluations for which no resonanceparameter covariance data are available, SAMMY can retroactively create a resonanceparameter covariance matrix. The retroactive method was used to generate covariance data for 235U. The resulting 235U covariance matrix was then used as input to the PUFFIV code, which processed the covariance data into multigroup form, and to the TSUNAMI code, which calculated the uncertainty in the multiplication factormore »
 Authors:
 ORNL
 Publication Date:
 Research Org.:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Sponsoring Org.:
 USDOE National Nuclear Security Administration (NNSA)
 OSTI Identifier:
 962609
 DOE Contract Number:
 DEAC0500OR22725
 Resource Type:
 Conference
 Resource Relation:
 Conference: International Conference on the Physics of Reactors  Nuclear Power: A Sustainable Resource Cassino, Interlaken, Switzerland, 20080914, 20080919
 Country of Publication:
 United States
 Language:
 English
 Subject:
 29 ENERGY PLANNING, POLICY AND ECONOMY; BENCHMARKS; COMPUTER CODES; CROSS SECTIONS; EVALUATION; MATRICES; MULTIPLICATION FACTORS; NUCLEAR DATA COLLECTIONS; NUCLEAR POWER; PHYSICS; R MATRIX; RESONANCE; covariance; SAMMY; ENDF/B; nuclear data; TSUNAMI
Citation Formats
Leal, Luiz C, Mueller, Don, Arbanas, Goran, Wiarda, Dorothea, and Derrien, Herve. Impact of the 235U Covariance Data in Benchmark Calculations. United States: N. p., 2008.
Web.
Leal, Luiz C, Mueller, Don, Arbanas, Goran, Wiarda, Dorothea, & Derrien, Herve. Impact of the 235U Covariance Data in Benchmark Calculations. United States.
Leal, Luiz C, Mueller, Don, Arbanas, Goran, Wiarda, Dorothea, and Derrien, Herve. 2008.
"Impact of the 235U Covariance Data in Benchmark Calculations". United States.
doi:.
@article{osti_962609,
title = {Impact of the 235U Covariance Data in Benchmark Calculations},
author = {Leal, Luiz C and Mueller, Don and Arbanas, Goran and Wiarda, Dorothea and Derrien, Herve},
abstractNote = {The error estimation for calculated quantities relies on nuclear data uncertainty information available in the basic nuclear data libraries such as the U.S. Evaluated Nuclear Data File (ENDF/B). The uncertainty files (covariance matrices) in the ENDF/B library are generally obtained from analysis of experimental data. In the resonance region, the computer code SAMMY is used for analyses of experimental data and generation of resonance parameters. In addition to resonance parameters evaluation, SAMMY also generates resonance parameter covariance matrices (RPCM). SAMMY uses the generalized leastsquares formalism (Bayes method) together with the resonance formalism (Rmatrix theory) for analysis of experimental data. Two approaches are available for creation of resonanceparameter covariance data. (1) During the dataevaluation process, SAMMY generates both a set of resonance parameters that fit the experimental data and the associated resonanceparameter covariance matrix. (2) For existing resonanceparameter evaluations for which no resonanceparameter covariance data are available, SAMMY can retroactively create a resonanceparameter covariance matrix. The retroactive method was used to generate covariance data for 235U. The resulting 235U covariance matrix was then used as input to the PUFFIV code, which processed the covariance data into multigroup form, and to the TSUNAMI code, which calculated the uncertainty in the multiplication factor due to uncertainty in the experimental cross sections. The objective of this work is to demonstrate the use of the 235U covariance data in calculations of critical benchmark systems.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2008,
month = 1
}

Impact of ENDF/BVI (Evaluated Nuclear Data File) on thermal reactor benchmark calculations
The ENDF/BVI (Evaluated Nuclear Data File) data evaluations reflect several major changes relative to version V data that will be of interest in thermal reactor analysis. Some of the important changes in the {sup 235}U, {sup 239}Pu, and {sup 238}U data are summarized. It can be seen that significant modifications have been made in the {sup 235}U and {sup 239}Pu thermal data. Also, completely new resonance evaluations based on the ReichMoore formalism have been performed for {sup 235}U, {sup 239}Pu, and {sup 238}U, and the number of resolved resonances included in the evaluations has increased dramatically. To assess the meritmore » 
Dynamic pulse buckling of cylindrical shells under axial impact: A benchmark study of 2D and 3D finite element calculations
A series of tests investigating dynamic pulse buckling of a cylindrical shell under axial impact is compared to several 2D and 3D finite element simulations of the event. The purpose of the work is to investigate the performance of various analysis codes and element types on a problem which is applicable to radioactive material transport packages, and ultimately to develop a benchmark problem to qualify finite element analysis codes for the transport package design industry. During the pulse buckling tests, a buckle formed at each end of the cylinder, and one of the two buckles became unstable and collapsed. Numericalmore » 
A benchmark study of 2D and 3D finite element calculations simulating dynamic pulse buckling tests of cylindrical shells under axial impact
A series of tests investigating dynamic pulse buckling of a cylindrical shell under axial impact is compared to several finite element simulations of the event. The purpose of the study is to compare the performance of the various analysis codes and element types with respect to a problem which is applicable to radioactive material transport packages, and ultimately to develop a benchmark problem to qualify finite element analysis codes for the transport package design industry. 
Production of Multigroup data covariance in the resonance range by MonteCarlo calculations
The generation of Multigroup cross sections together with relevant uncertainties is fundamental to assess the quality of neutronic simulations. Key information that are needed to propagate the microscopic experimental uncertainties up to macroscopic reactor calculations are (1) the experimental covariance matrices, (2) the correlations between the parameters of the model and (3) the multigroup covariance matrices. This work proposes to apply a MonteCarlo approach to provide explicit data covariances between the resonance parameters. (authors)