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

Neudecker, Denise; Talou, Patrick; Kahler, Albert Comstock III; White, Morgan Curtis; Kawano, Toshihiko

doi:10.1051/epjconf/201714604012

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

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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:

^[1]; Talou, Patrick ^[1]; Kahler, Albert Comstock III ^[1];

^[1];

^[1]

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:: Wed Sep 13 00:00:00 EDT 2017

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:: 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

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                    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.

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                    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.  https://doi.org/10.1051/epjconf/201714604012

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                    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.  https://doi.org/10.1051/epjconf/201714604012.  https://www.osti.gov/servlets/purl/1396117.

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

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