Work

Re-evaluating the prompt fission neutron spectrum of spontaneously fissioning

Year: 2025

Type: article

Abstract: The prompt fission neutron spectrum (PFNS) of spontaneously fissioning 252Cf is a Neutron Data Standards observable. Nearly all fission spectra of actinides were measured relative to it, using efficiencies derived from it, or analyzed with simulations validated by it. The current Standards evaluation was published by W. Mannhart in 1987. It could not be updated because the evaluation input, experimental mean values and covariances, were lost. First, we attempt to reproduce it. However, Mannhart’s evaluation can only be reproduced within its one-σ uncertainties as some of its aspects (e.g., experimental covariances, rejected data points) remain unknown. Therefore, a new evaluation is presented: We revisit all existing experimental 252Cf(sf) PFNS data, including those published after the release of the current Standards evaluation, and re-estimate associated covariances. The newly evaluated 252Cf(sf) PFNS differs distinctly from Mannhart’s below 300 keV and extends it to lower and higher outgoing neutron energies (500 eV–25 MeV). The new evaluated uncertainties are larger from 3–9 MeV and smaller otherwise. Spectrum averaged cross sections of importance to the International Reactor Dosimetry and Fusion File community calculated with the new spectrum are close to those calculated with Mannhart’s evaluation and agree with experimental values well within their uncertainties.

Source: Springer Link (Chiba Institute of Technology)

DOI: 10.1051/epjn/2025061/pdf

Authors: D. Neudecker, K.J. Kelly, A.D. Carlson, B. Pritychenko, D. Brown, M.J. Grosskopf, S.A. Van der Wiel, R.C. Haight, R. Capote, T.N. Massey, A. Trkov, N.A.W. Walton

Institutions: Los Alamos National Laboratory, National Institute of Standards and Technology, Brookhaven National Laboratory, International Atomic Energy Agency, Ohio University, Jožef Stefan Institute, University of Tennessee at Knoxville

Language: English

Topic: Nuclear reactor physics and engineering

Subfield: Aerospace Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: green

Funders: U.S. Department of Energy, Office of Science, National Nuclear Security Administration, Nuclear Physics, Brookhaven National Laboratory, Los Alamos National Laboratory

Awards: G1017065088, G1126863173, G1279347439, G132563423, G1527848044, G1572106353, G211823381, G498139845, G5292656900, G5955292761, G604949671, G6410514744, TO CONDUCT NONPROLIFERATION RESEARCH IN NUCLEAR SCIENCE AND ENGINEERING AND DEVELOP HUMAN CAPITAL FOR THE NATION'S NATIONAL AND NUCLEAR SECURITY MISSIONS IN SUPPORT OF DNN R&D., G969889393

OpenAlex ID: W7113896934

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