Consistent Evaluation of the Prompt-fission Neutron Spectrum and Multiplicity for n+^235,238U and n+²³⁹Pu

Technical Report · Fri Sep 18 04:00:00 EDT 2020

DOI:https://doi.org/10.2172/1907356· OSTI ID:1907356

Lovell, A. E. ^[1]; Neudecker, D. ^[1]; Talou, P. ^[1]; Stetcu, I. ^[1]; Grosskopf, M. J. ^[1]; Kawano, T. ^[1]

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

This report was written to satisfy a FY20 NCSP milestone on ^235,238U and ²³⁹Pu. The milestone requires to “finalize a report assessing our methodology to evaluate prompt-fission neutron spectrum (PFNS) and multiplicity consistently”. More specifically, we study whether the code CGMF can reproduce ENDF/B-VIII.0 evaluated PFNS and average prompt-fission neutron multiplicities, $$\bar{v}$$, for ^235,238U and ²³⁹Pu using one joint parameter set per isotope. If CGMF is shown to be able to reasonably reproduce ENDF/B-VIII.0 within its model-parameter space, this code could be used for future consistent evaluations of PFNS and $$\bar{v}$$. To answer this question, we explore here the parameter space of CGMF and its impact on calculated values and whether they are close to evaluated and experimental data. We also list experimental data that would enter a future evaluation and statistics method that could be used to obtain evaluated data and covariances. We conclude that values of $$\bar{v}$$ calculated by CGMF are reasonably close to ENDF/B-VIII.0 data, while more work on modeling the PFNS is needed (parameter optimization and model improvements) to reliably use it for evaluations.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: AC52-06NA25396; 89233218CNA000001
• OSTI ID: 1907356
• Report Number(s): LA-UR-20-26932
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Average Prompt-fission Neutron Multiplicity
Prompt-fission Neutron Spectrum
CGMF
Nuclear Criticality Safety Program (NCSP)
Nuclear Data