Updates to R-matrix Evaluations of Fissile Actinides: 233,235U, 239Pu [Slides]
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
This presentation begins by discussing the importance and significance of cross section fluctuations. It also discusses the motivation and overarching goals which are to establish the highest fidelity nuclear evaluated data. In conclusion, a procedure to accurately model the measured cross section fluctuations for inclusion into evaluated nuclear data files was developed and tested on 239Pu total cross sections. The procedure consisted of defining population of levels as well as related amplitudes extrapolated from the systematics of the resonance parameters in the resolved resonance region. By using realistic population of extrapolated levels, the fit of measured total cross section produced a continuous S-matrix function S(E) in Reich-Moore approximation. The S-matrix function averaged over a suitable energy interval was used to obtain averaged cross sections consistent with the measured data. Transmittable formatted files (ENDF, GNDS) with LSSF=1 will consist of File 3 which are smoothed cross sections and File 2 which are average resonance parameters fitted to the energy bins defined in File 3. The capability to store probability tables is a way to show the fluctuating cross sections.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1909798
- Country of Publication:
- United States
- Language:
- English
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