One-Group Cross Sections Generation for Monte Carlo Burnup Codes


One-Group Cross Sections Generation for Monte Carlo Burnup Codes

Kotlyar, D.; Shwageraus, E.; Fridman, E.

Allowing Monte Carlo (MC) codes to perform fuel cycle calculations requires coupling to a point depletion solver. In order to perform depletion calculations, one-group (1-g) cross sections must be provided in advance. This paper focuses on generating accurate 1-g cross section values that are necessary for evaluation of nuclide densities as a function of burnup. The proposed method is an alternative to the conventional direct reaction rate tally approach, which is more computationally expensive. The method presented here is based on the multi-group (MG) approach(1), in which pre-generated MG sets are collapsed with MC calculated flux. In our previous studies(2), we showed that generating accurate 1-g cross sections requires their tabulation against the background cross-section (σ0) to account for the self-shielding effect. However, in previous studies, the model that was used to calculate σ0 was simplified by fixing Bell and Dancoff factors. This work demonstrates that 1-g values calculated under the previous simplified model may not agree with the tallied values. Therefore, the original background cross section model was extended by implicitly accounting for the Dancoff and Bell factors. The method developed here reconstructs the correct value of σ0 by utilizing statistical data generated within the MC transport calculation by default. The proposed method was implemented in BGCore code system. The 1-g cross section values generated by BGCore were compared with those tallied directly from the MCNP code. Very good agreement (<0.05%) in the 1-g cross values was observed. The method does not carry any additional computational burden and it is universally applicable to the analysis of thermal as well as fast reactor systems.

  • Contribution to proceedings
    The 27th Conference of the Nuclear Societies in Israel, 11.-13.02.2014, Daniel Dead Sea Hotel, Israel
    Proceedings of the 27th Conference of the Nuclear Societies

Permalink: https://www.hzdr.de/publications/Publ-19697
Publ.-Id: 19697