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Title: Evaluation of the 235U prompt fission neutron spectrum including a detailed analysis of experimental data and improved model information

Abstract

We present an evaluation of the 235U prompt fission neutron spectrum (PFNS) induced by thermal to 20-MeV neutrons. Experimental data and associated covariances were analyzed in detail. The incident energy dependence of the PFNS was modeled with an extended Los Alamos model combined with the Hauser-Feshbach and the exciton models. These models describe prompt fission, pre-fission compound nucleus and pre-equilibrium neutron emissions. The evaluated PFNS agree well with the experimental data included in this evaluation, preliminary data of the LANL and LLNL Chi-Nu measurement and recent evaluations by Capote et al. and Rising et al. However, they are softer than the ENDF/B-VII.1 (VII.1) and JENDL-4.0 PFNS for incident neutron energies up to 2 MeV. Simulated effective multiplication factors k eff of the Godiva and Flattop-25 critical assemblies are further from the measured k eff if the current data are used within VII.1 compared to using only VII.1 data. However, if this work is used with ENDF/B-VIII.0β2 data, simulated values of k eff agree well with the measured ones.

Authors:
ORCiD logo [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1396117
Report Number(s):
LA-UR-16-27468
Journal ID: ISSN 2100-014X
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
EPJ Web of Conferences
Additional Journal Information:
Journal Volume: 146; Conference: ND2016 ; 2016-09-11 - 2016-09-11 ; Brugge, Belgium; Journal ID: ISSN 2100-014X
Publisher:
EDP Sciences
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Neudecker, Denise, Talou, Patrick, Kahler, Albert Comstock III, White, Morgan Curtis, and Kawano, Toshihiko. Evaluation of the 235U prompt fission neutron spectrum including a detailed analysis of experimental data and improved model information. United States: N. p., 2017. Web. doi:10.1051/epjconf/201714604012.
Neudecker, Denise, Talou, Patrick, Kahler, Albert Comstock III, White, Morgan Curtis, & Kawano, Toshihiko. Evaluation of the 235U prompt fission neutron spectrum including a detailed analysis of experimental data and improved model information. United States. doi:10.1051/epjconf/201714604012.
Neudecker, Denise, Talou, Patrick, Kahler, Albert Comstock III, White, Morgan Curtis, and Kawano, Toshihiko. Wed . "Evaluation of the 235U prompt fission neutron spectrum including a detailed analysis of experimental data and improved model information". United States. doi:10.1051/epjconf/201714604012. https://www.osti.gov/servlets/purl/1396117.
@article{osti_1396117,
title = {Evaluation of the 235U prompt fission neutron spectrum including a detailed analysis of experimental data and improved model information},
author = {Neudecker, Denise and Talou, Patrick and Kahler, Albert Comstock III and White, Morgan Curtis and Kawano, Toshihiko},
abstractNote = {We present an evaluation of the 235U prompt fission neutron spectrum (PFNS) induced by thermal to 20-MeV neutrons. Experimental data and associated covariances were analyzed in detail. The incident energy dependence of the PFNS was modeled with an extended Los Alamos model combined with the Hauser-Feshbach and the exciton models. These models describe prompt fission, pre-fission compound nucleus and pre-equilibrium neutron emissions. The evaluated PFNS agree well with the experimental data included in this evaluation, preliminary data of the LANL and LLNL Chi-Nu measurement and recent evaluations by Capote et al. and Rising et al. However, they are softer than the ENDF/B-VII.1 (VII.1) and JENDL-4.0 PFNS for incident neutron energies up to 2 MeV. Simulated effective multiplication factors keff of the Godiva and Flattop-25 critical assemblies are further from the measured keff if the current data are used within VII.1 compared to using only VII.1 data. However, if this work is used with ENDF/B-VIII.0β2 data, simulated values of keff agree well with the measured ones.},
doi = {10.1051/epjconf/201714604012},
journal = {EPJ Web of Conferences},
number = ,
volume = 146,
place = {United States},
year = {Wed Sep 13 00:00:00 EDT 2017},
month = {Wed Sep 13 00:00:00 EDT 2017}
}

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