Evaluations of Energy Spectra of Neutrons Emitted Promptly in Neutron-induced Fission of 235 U and 239 Pu

Neudecker, Denise; Talou, Patrick; Kawano, Toshihiko; Kahler, Albert C.; White, Morgan C.; Taddeucci, Terry N.; Haight, Robert C.; Kiedrowski, Brian; O'Donnell, John M.; Gomez, Jaime A.; Kelly, Keegan J.; Devlin, Matthew; Rising, Michael E.

doi:10.1016/j.nds.2018.02.006

Title: Evaluations of Energy Spectra of Neutrons Emitted Promptly in Neutron-induced Fission of 235 U and 239 Pu

Full Record
Other Related Research

Abstract

The energy spectra of neutrons emitted promptly in the neutron-induced fission reactions of ²³⁵U and ²³⁹Pu were re-evaluated for ENDF/B-VIII.0. The evaluations presented here are based on a careful modeling of all relevant physics processes, an extensive analysis of experimental data and a detailed quantification of pertinent uncertainties. Energy spectra of neutrons emitted in up to fourth chance fission are considered and both compound and pre-equilibrium processes are included. Also, important nuclear model parameters, such as the average total kinetic energy of the fission fragments and the multiple chance fission probabilities, and their uncertainties are estimated based on experimental knowledge, model information and evaluated data. In addition to experimental information already available for ENDF/B-VII.1, these new evaluations make use of recently published experimental data either of high precision or spanning a broad incident energy range, information on legacy measurements explaining discrepancies and recently measured data of the average total kinetic energy as a function of incident neutron energy. The resulting evaluated data and covariances agree well with the experimental database used for the evaluation. However, the evaluated spectra are softer than the ²³⁵U and ²³⁹Pu ENDF/B-VII.1, JENDL-4.0 and JEFF-3.2 evaluations for incident neutron energies E_inc ≤ 1.5 MeV and E_incmore »« less

Authors:

^[1]; Talou, Patrick ^[1];

^[1]; Kahler, Albert C. ^[1];

^[1]; Taddeucci, Terry N. ^[1]; Haight, Robert C. ^[1]; Kiedrowski, Brian ^[2]; O'Donnell, John M. ^[1];

^[1]; Kelly, Keegan J. ^[1];

^[1];

^[1]

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Univ. of Michigan, Ann Arbor, MI (United States)

Publication Date:: Thu Feb 01 00:00:00 EST 2018

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

Sponsoring Org.:: USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:: 1427374

Report Number(s):: LA-UR-17-25589
Journal ID: ISSN 0090-3752; TRN: US1802585

Grant/Contract Number:: AC52-06NA25396

Resource Type:: Accepted Manuscript

Journal Name:: Nuclear Data Sheets

Additional Journal Information:: Journal Volume: 148; Journal Issue: C; Journal ID: ISSN 0090-3752

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats


                    Neudecker, Denise, Talou, Patrick, Kawano, Toshihiko, Kahler, Albert C., White, Morgan C., Taddeucci, Terry N., Haight, Robert C., Kiedrowski, Brian, O'Donnell, John M., Gomez, Jaime A., Kelly, Keegan J., Devlin, Matthew, and Rising, Michael E. Evaluations of Energy Spectra of Neutrons Emitted Promptly in Neutron-induced Fission of 235 U and 239 Pu.  United States: N. p., 2018. 
Web.  doi:10.1016/j.nds.2018.02.006.

Copy to clipboard


                    Neudecker, Denise, Talou, Patrick, Kawano, Toshihiko, Kahler, Albert C., White, Morgan C., Taddeucci, Terry N., Haight, Robert C., Kiedrowski, Brian, O'Donnell, John M., Gomez, Jaime A., Kelly, Keegan J., Devlin, Matthew, & Rising, Michael E. Evaluations of Energy Spectra of Neutrons Emitted Promptly in Neutron-induced Fission of 235 U and 239 Pu.  United States.  https://doi.org/10.1016/j.nds.2018.02.006

Copy to clipboard


                    Neudecker, Denise, Talou, Patrick, Kawano, Toshihiko, Kahler, Albert C., White, Morgan C., Taddeucci, Terry N., Haight, Robert C., Kiedrowski, Brian, O'Donnell, John M., Gomez, Jaime A., Kelly, Keegan J., Devlin, Matthew, and Rising, Michael E. Thu .  
"Evaluations of Energy Spectra of Neutrons Emitted Promptly in Neutron-induced Fission of 235 U and 239 Pu".  United States.  https://doi.org/10.1016/j.nds.2018.02.006.  https://www.osti.gov/servlets/purl/1427374.

Copy to clipboard


                    
@article{osti_1427374,

  title        = {Evaluations of Energy Spectra of Neutrons Emitted Promptly in Neutron-induced Fission of 235 U and 239 Pu},

  author       = {Neudecker, Denise and Talou, Patrick and Kawano, Toshihiko and Kahler, Albert C. and White, Morgan C. and Taddeucci, Terry N. and Haight, Robert C. and Kiedrowski, Brian and O'Donnell, John M. and Gomez, Jaime A. and Kelly, Keegan J. and Devlin, Matthew and Rising, Michael E.},

  abstractNote = {The energy spectra of neutrons emitted promptly in the neutron-induced fission reactions of 235U and 239Pu were re-evaluated for ENDF/B-VIII.0. The evaluations presented here are based on a careful modeling of all relevant physics processes, an extensive analysis of experimental data and a detailed quantification of pertinent uncertainties. Energy spectra of neutrons emitted in up to fourth chance fission are considered and both compound and pre-equilibrium processes are included. Also, important nuclear model parameters, such as the average total kinetic energy of the fission fragments and the multiple chance fission probabilities, and their uncertainties are estimated based on experimental knowledge, model information and evaluated data. In addition to experimental information already available for ENDF/B-VII.1, these new evaluations make use of recently published experimental data either of high precision or spanning a broad incident energy range, information on legacy measurements explaining discrepancies and recently measured data of the average total kinetic energy as a function of incident neutron energy. The resulting evaluated data and covariances agree well with the experimental database used for the evaluation. However, the evaluated spectra are softer than the 235U and 239Pu ENDF/B-VII.1, JENDL-4.0 and JEFF-3.2 evaluations for incident neutron energies Einc ≤ 1.5 MeV and Einc ≤ 5 MeV, respectively. For Einc > 5 MeV, the evaluated spectra show structures due to the improved modeling which are not present in ENDF/B-VII.1 and JEFF-3.2 but can be observed in JENDL-4.0 evaluations. Part of these new evaluations were adopted for ENDF/B-VIII.0, while the ENDF/B-VII.1 239Pu PFNS was retained for Einc ≤ 5 MeV awaiting more conclusive experimental evidence.},

  doi          = {10.1016/j.nds.2018.02.006},

  journal      = {Nuclear Data Sheets},

  number       = C,

  volume       = 148,

  place        = {United States},

  year         = {Thu Feb 01 00:00:00 EST 2018},

  month        = {Thu Feb 01 00:00:00 EST 2018}

}

Copy to clipboard

Journal Article:

Free Publicly Available Full Text

Accepted Manuscript (DOE)

Publisher's Version of Record

https://doi.org/10.1016/j.nds.2018.02.006

Other availability

Search WorldCat to find libraries that may hold this journal

Citation Metrics:

Cited by: 16 works

Citation information provided by
Web of Science

Save / Share:

Export Metadata

Save to My Library

Similar Records in DOE PAGES and OSTI.GOV collections:

Measurement of the U 235 ( n , f ) prompt fission neutron spectrum from 10 keV to 10 MeV induced by neutrons of energy from 1 MeV to 20 MeV

Journal Article Kelly, Keegan John ; Gomez, Jaime A. ; Devlin, Matthew James ; ... - Physical Review. C

The characterization of fission-driven nuclear systems primarily relies on calculations of neutron-induced chain reactions, and these calculations require evaluated nuclear data as input. Calculation accuracy heavily depends on input nuclear data evaluation accuracy, and thus high precision on the experimental input to the nuclear data evaluation is essential for fundamental quantities like the energy spectrum of neutrons emitted from neutron-induced fission (i.e., the prompt fission neutron spectrum, PFNS). Despite decades of measurement efforts, prior to the measurements described in this work there were only three literature data sets for the ²³⁵U(n,f) PFNS at incident neutron energies above 1.0 MeV considered reliable for inclusion in nuclear data evaluations and no reliable data sets above 3.0 MeV incident neutron energy. In this work we report on new measurements of the ²³⁵U(n,f) PFNS spanning a grid of 1.0–20.0 MeV in incident neutron energy and 0.01–10.0 MeV in outgoing (PFNS) neutron energy. These measurements were carried out at the Weapons Neutron Research facility at the Los Alamos Neutron Science Center and used a multifoil parallel-plate avalanche counter target with both a Li-glass and a liquid scintillator detector array in separate experiments to span the quoted outgoing neutron energy ranges. The PFNS results are shown in terms of the energy spectra themselves as well as the average PFNS energymore »« less
https://doi.org/10.1103/physrevc.105.044615

Full Text Available
Chi-Nu measurements of the prompt fission neutron spectrum of {sup 235}U and {sup 239}Pu - 25581

Conference Kelly, K. J. ; Gomez, J. A. ; O'Donnell, J. M. ; ...

Knowledge of the prompt fission neutron spectrum is crucial for understanding the behavior of energetic nuclear systems. Although this energy spectrum has been measured for the major actinides {sup 235}U and {sup 239}Pu for decades, the majority of the available literature data lack the coverage of both incident and outgoing neutron energies and the precision required to accurately guide evaluations and fission models. The Chi-Nu experiment is designed to measure the prompt fission neutron spectrum for a wide range of incident and outgoing neutron energies with attention to uncertainty estimation and assessment of systematic errors in order to provide reliablemore »« less
Measurement of the ²³⁹Pu$(n, f$) prompt fission neutron spectrum from 10 keV to 10 MeV induced by neutrons of energy 1–20 MeV

Journal Article Kelly, Keegan John ; Devlin, Matthew James ; O'Donnell, John M. ; ... - Physical Review C

Although the prompt fission neutron spectrum (PFNS) is an essential component of neutron-driven systems that has been measured for decades, there are still multiple glaring unknowns regarding the PFNS of major actinides in the fission neutron incident energy range, specifically with regard to multichance fission and pre-equilibrium neutron emission processes. The only impactful experimental ²³⁹Pu PFNS measurements included in recent nuclear data evaluations were measured over a limited outgoing neutron energy range at thermal and 1.5-MeV average incident neutron energy, while other potentially impactful measurements have been shown to contain errors that resulted in either large uncertainty increases or inmore »« less
https://doi.org/10.1103/PhysRevC.102.034615

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

Journal Article Neudecker, Denise ; Talou, Patrick ; Kahler, Albert Comstock III ; ... - EPJ Web of Conferences

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 thanmore »« less
Cited by 2
https://doi.org/10.1051/epjconf/201714604012

Full Text Available
Producing ENDF/B-quality Evaluations of ²³⁹Pu(n,f) and ²³⁵U(n,f) Average Prompt Neutron Multiplicities using the CGMF Model

Technical Report Neudecker, Denise ; Lovell, Amy Elizabeth ; Talou, Patrick

This report documents evaluations of the neutron-induced ²³⁹Pu and ²³⁵U average prompt neutron multiplicities,more »« less
https://doi.org/10.2172/1897963

Full Text Available

Similar Records