Fission Product Yields from Fission Spectrum n+{sup 239}Pu for ENDF/B-VII.1

Journal Article · Wed Dec 15 00:00:00 EST 2010 · Nuclear Data Sheets

DOI:https://doi.org/10.1016/j.nds.2010.11.003· OSTI ID:21499798

Kawano, T; Barr, D W; Mac Innes, M R; Kahler, A C; Graves, T; Selby, H; Burns, C J; Inkret, W C; Keksis, A L; Lestone, J P; Sierk, A J; Talou, P ^[1]

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1. Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

We describe a new cumulated fission product yield (FPY) evaluation for fission spectrum neutrons on plutonium that updates the ENDF/B-VI evaluation by England and Rider, for the forthcoming ENDF/B-VII.1 database release. We focus on FPs that are needed for high accuracy burnup assessments; that is, for inferring the number of fissions in a neutron environment. Los Alamos conducted an experiment in the 1970s in the Bigten fast critical assembly to determine fission product yields as part of the Interlaboratory Reaction Rate (ILRR) collaboration, and this has defined the Laboratory's fission standard to this day. Our evaluation includes use of the LANL-ILRR measurements (not previously available to evaluators) as well as other Laboratory FPY measurements published in the literature, especially the high-accuracy mass spectrometry data from Maeck and others. Because the measurement database for some of the FPs is small - especially for {sup 99}Mo - we use a meta-analysis that incorporates insights from other accurately-measured benchmark FP data, using R-value ratio measurements. The meta-analysis supports the FP measurements from the LANL-ILRR experiment. Differences between our new evaluations and ENDF/B-VI are small for some FPs (less than 1-2%-relative for {sup 95}Zr, {sup 140}Ba, {sup 144}Ce), but are larger for {sup 99}Mo (4%-relative) and {sup 147}Nd (5%-relative, at 1.5 MeV) respectively. We present evidence for an incident neutron energy dependence to the {sup 147}Nd fission product yield that accounts for observed differences in the FPY at a few-hundred keV average energy in fast reactors versus measurements made at higher average neutron energies in Los Alamos' fast critical assemblies. Accounting for such FPY neutron energy dependencies is important if one wants to reach a goal of determining the number of fissions to accuracies of 1-2%. An evaluation of the energy-dependence of fission product yields is given for all A values based on systematical trends in the measured data, with a focus on the energy dependence over the fast neutron energy range from 0.2-2 MeV. Based on these trends, we present an evaluation of the FPY data at 0.5 and 2.0 MeV average incident neutron energies. This new set of ENDF/B-VII data will enable users to linearly interpolate between the pooled FPY data at {approx}0.5 MeV and our new data at 2 MeV to obtain FPYs at other energies.

• OSTI ID: 21499798
• Journal Information: Nuclear Data Sheets, Vol. 111, Issue 12; Other Information: DOI: 10.1016/j.nds.2010.11.003; PII: S0090-3752(10)00102-X; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0090-3752
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARIUM 140
CERIUM 144
ENERGY DEPENDENCE
EVALUATION
FAST NEUTRONS
FISSION
FISSION PRODUCTS
FISSION SPECTRA
KEV RANGE 100-1000
LANL
MASS SPECTROSCOPY
MEV RANGE 01-10
MOLYBDENUM 99
NEODYMIUM 147
NEUTRON REACTIONS
NUCLEAR DATA COLLECTIONS
PLUTONIUM 239
REACTION KINETICS
ZIRCONIUM 95
ACTINIDE NUCLEI
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
BARIUM ISOTOPES
BARYON REACTIONS
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CERIUM ISOTOPES
DAYS LIVING RADIOISOTOPES
ELEMENTARY PARTICLES
ENERGY RANGE
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FERMIONS
HADRON REACTIONS
HADRONS
HEAVY NUCLEI
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOTOPES
KEV RANGE
KINETICS
MATERIALS
MEV RANGE
MOLYBDENUM ISOTOPES
NATIONAL ORGANIZATIONS
NEODYMIUM ISOTOPES
NEUTRONS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEONS
PLUTONIUM ISOTOPES
RADIOACTIVE MATERIALS
RADIOISOTOPES
RARE EARTH NUCLEI
SPECTRA
SPECTROSCOPY
SPONTANEOUS FISSION RADIOISOTOPES
US DOE
US ORGANIZATIONS
YEARS LIVING RADIOISOTOPES
ZIRCONIUM ISOTOPES