Methodology for Generating Covariance Data of Thermal Neutron Scattering Cross Sections

Chris W. Chapman, Goran Arbanas, Alexander I. Kolesnikov, Luiz Leal, Yaron Danon, Carl Wendorff, Kemal Ramić, Li Liu, Farzad Rahnema

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

This paper details and implements a framework for evaluating thermal neutron scattering cross sections that provide (Formula presented.) data and covariance data for hydrogen in light water. This methodology involves perturbing model parameters of molecular dynamics potentials and fitting the simulation results to experimental data. The framework is general and can be applied to any material or simulation method. The fit is made using the Unified Monte Carlo method to experimentally measure double-differential scattering cross sections of light water at the Spallation Neutron Source at Oak Ridge National Laboratory. Mean values and covariance data were generated for model parameters, phonon density of states, double-differential cross sections, and total scattering cross sections. These posterior parameter values were very similar to their prior values with a maximum relative error of 0.54%. This falls within in the Unified Monte Carlo–calculated uncertainties on the order of 2.7%. Additionally, posterior double-differential cross sections agree favorably with ENDF/B-VIII.0 cross sections. The new thermal scattering law was tested by comparing it against benchmarks from the International Criticality Safety Benchmark Evaluation Project Handbook, which showed a slight improvement over the ENDF/B-VIII.0 library. Additionally, the covariance matrix of the phonon density of states was validated to confirm that the spread of keff from the density of states used to generate the covariance matrix was similar to the spread of keff from the density of states of the sampled covariance matrix.

Original languageEnglish
Pages (from-to)13-32
Number of pages20
JournalNuclear Science and Engineering
Volume195
Issue number1
DOIs
StatePublished - 2021

Funding

This work was supported by the DOE Nuclear Criticality Safety Program, which is funded and managed by the National Nuclear Security Administration for DOE. Additionally, this research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Nuclear Data and Nuclear Theory Program, Office of Nuclear Physics, and Office of Science of DOE under contract number DE-AC02-05CH11231. This research used resources at the SNS, a DOE Office of Science User Facility operated by ORNL. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. Department of Energy (DOE). The U.S. government retains and the publisher, by accepting the paper for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This work was supported by the DOE Nuclear Criticality Safety Program, which is funded and managed by the National Nuclear Security Administration for DOE. Additionally, this research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Nuclear Data and Nuclear Theory Program, Office of Nuclear Physics, and Office of Science of DOE under contract number DE-AC02-05CH11231. This research used resources at the SNS, a DOE Office of Science User Facility operated by ORNL. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. Department of Energy (DOE). The U.S. government retains and the publisher, by accepting the paper for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

FundersFunder number
DOE Public Access Plan
U.S. Government
U.S. Department of Energy
Office of Science
National Nuclear Security Administration
Nuclear PhysicsDE-AC02-05CH11231
Oak Ridge National Laboratory

    Keywords

    • Thermal neutron scattering
    • Unified Monte Carlo
    • uncertainty quantification

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