Evaluation and application of delayed neutron precursor data

Technical Report · Sat Apr 01 04:00:00 EST 1989

DOI:https://doi.org/10.2172/6187550· OSTI ID:6187550

Brady, M. C. ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Up to 1300 nuclides are yielded in fission. Of these, 271 have been identified as precursors for delayed neutron emission. An extensive reference library of delayed neutron data has been compiled which contains fission yields and branchings, delay neutron emission probabilities and spectra for each of these 271 precursor nuclides. The emphasis of the present work has been in improving the spectral data. Experimental spectra from laboratories in the United States, Germany, and Sweden have been incorporated in this evaluation. The experimental spectra have been augmented with model calculations such that the spectra included in the final library extend over the full theoretical energy range for delayed neutron emission. Models were also used to predict spectra for nuclides with no measured data. The data compiled in the precursor library have been used to calculate the aggregate behavior of delayed neutrons for the 43 fissioning systems having evaluated fission yields. Delayed neutron activities predicted using the explicit precursor data have also been approximated by three, six, nine and twelve time-groups using least squares techniques. The fitted six group data, being the more conventional representation, were also used to predict a consistent set of six-group spectra. Comparisons with the University of Lowell's recently published measurements of /sup 235/U delay interval spectra were also made. Beta-effective calculations for a simple Godiva system were performed and were compared to the experimental value.

• Research Organization: Los Alamos National Lab., NM (USA)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6187550
• Report Number(s): LA-11534-T; ON: DE89009586
• Country of Publication: United States
• Language: English

Related Subjects

651000* -- Nuclear Physics
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
DATA
DELAYED NEUTRON PRECURSORS
EVALUATION
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
FISSION
HEAVY NUCLEI
INFORMATION
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MINUTES LIVING RADIOISOTOPES
NUCLEAR DATA COLLECTIONS
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
RADIOISOTOPES
URANIUM 235
URANIUM ISOTOPES
USES
YEARS LIVING RADIOISOTOPES