SYMPOSIA PAPER Published: 01 January 2001

Adjustment of the U Fission Spectrum


The latest nuclear data are used to examine the sensitivity of the least squares adjustment of the 235U fission spectrum to the measured reaction rates, dosimetry cross sections, and prior spectrum covariance matrix. All of these parameters were found to be very important in the spectrum adjustment. The most significant deficiency in the nuclear data is the absence of a good prior covariance matrix. Covariance matrices generated from analytic models of the fission spectra have been used in the past. This analysis reveals some unusual features in the covariance matrix produced with this approach. Specific needs are identified for improved nuclear data to better determine the 235U spectrum. An improved 235U covariance matrix and adjusted spectrum are recommended for use in radiation transport sensitivity analyses.

Author Information

Griffin, PJ
Sandia National Laboratories, Albuquerque, NM
Williams, JG
Nuclear Reactor Laboratory, University of Arizona, Tucson, AZ
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Developed by Committee: E10
Pages: 352–359
DOI: 10.1520/STP13616S
ISBN-EB: 978-0-8031-5450-6
ISBN-13: 978-0-8031-2884-2