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Title: Activation product interpretation of structural material for fast critical assemblies

Abstract

This work evaluates whether activation products in stainless steel components can be used to infer initial conditions (i.e. alloy composition, position within the fluence, etc.) and the associated uncertainties in a fast neutron irradiation. Activation measurements of stainless steel and elemental components were obtained through a Flattop critical assembly irradiation experiment. A forward model was developed, utilizing MCNP6.1 and FISPACT ii, to estimate activation product concentrations from several input parameters: alloy composition, source specifications, and foil positioning. While some of the calculated activation product concentrations agreed fairly well with measurements, some isotopics (i.e. 57Co) had large discrepancies. It became clear that uncertainties in both measurements and nuclear data drove this divergence for select isotopics, and the quantification of this impact was needed. By treating both experimental measurement and nuclear data uncertainty in a Bayesian framework, it was possible to infer unknowns from given activation ratios. The developed approach showed promise in constraining mass parameters, but degeneracy existed when considering position within the neutron flux. Higher threshold reactions could potentially break the degeneracy, such as 57Co, but uncertainty estimation needs to be better resolved for those isotopes.

Authors:
 [1];  [1];  [1];  [1];  [2];  [2];  [2]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
OSTI Identifier:
1463508
Alternate Identifier(s):
OSTI ID: 1548111
Report Number(s):
LA-UR-18-23116
Journal ID: ISSN 0306-4549; TRN: US1902310
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Accepted Manuscript
Journal Name:
Annals of Nuclear Energy (Oxford)
Additional Journal Information:
Journal Name: Annals of Nuclear Energy (Oxford); Journal Volume: 119; Journal Issue: C; Journal ID: ISSN 0306-4549
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Keith, Corey, Selby, Hugh, Lee, Amy, White, Morgan, Bandong, Bryan, Roberts, Kevin, and Church, Jennifer. Activation product interpretation of structural material for fast critical assemblies. United States: N. p., 2018. Web. doi:10.1016/j.anucene.2018.04.028.
Keith, Corey, Selby, Hugh, Lee, Amy, White, Morgan, Bandong, Bryan, Roberts, Kevin, & Church, Jennifer. Activation product interpretation of structural material for fast critical assemblies. United States. doi:10.1016/j.anucene.2018.04.028.
Keith, Corey, Selby, Hugh, Lee, Amy, White, Morgan, Bandong, Bryan, Roberts, Kevin, and Church, Jennifer. Sat . "Activation product interpretation of structural material for fast critical assemblies". United States. doi:10.1016/j.anucene.2018.04.028. https://www.osti.gov/servlets/purl/1463508.
@article{osti_1463508,
title = {Activation product interpretation of structural material for fast critical assemblies},
author = {Keith, Corey and Selby, Hugh and Lee, Amy and White, Morgan and Bandong, Bryan and Roberts, Kevin and Church, Jennifer},
abstractNote = {This work evaluates whether activation products in stainless steel components can be used to infer initial conditions (i.e. alloy composition, position within the fluence, etc.) and the associated uncertainties in a fast neutron irradiation. Activation measurements of stainless steel and elemental components were obtained through a Flattop critical assembly irradiation experiment. A forward model was developed, utilizing MCNP6.1 and FISPACT ii, to estimate activation product concentrations from several input parameters: alloy composition, source specifications, and foil positioning. While some of the calculated activation product concentrations agreed fairly well with measurements, some isotopics (i.e. 57Co) had large discrepancies. It became clear that uncertainties in both measurements and nuclear data drove this divergence for select isotopics, and the quantification of this impact was needed. By treating both experimental measurement and nuclear data uncertainty in a Bayesian framework, it was possible to infer unknowns from given activation ratios. The developed approach showed promise in constraining mass parameters, but degeneracy existed when considering position within the neutron flux. Higher threshold reactions could potentially break the degeneracy, such as 57Co, but uncertainty estimation needs to be better resolved for those isotopes.},
doi = {10.1016/j.anucene.2018.04.028},
journal = {Annals of Nuclear Energy (Oxford)},
number = C,
volume = 119,
place = {United States},
year = {2018},
month = {5}
}

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