Reflector macroscopic cross-section data uncertainties effect on the nodal code full-core calculation

Abstract

The nodal codes still represent the key computational part of the nuclear power plant operation analysis. The mathematical model in the codes is connected with physical interpretation via macroscopic cross-section libraries. These data are generated using lattice codes, where the exact geometry is simulated. The uncertainties of the microscopic cross-sections and other geometrical uncertainties are typically not transferred from the lattice codes into the macroscopic libraries. This analysis starts with existing macroscopic data for radial reactor core reflectors and anticipated uncertainties of these data and investigates sensitivity of the critical boron concentration as well as the power prediction in the core to variations of these data. The provided analysis showed strong stability of the results with the changing reflector cross-section characteristics. Even with the highest perturbations of the reflector data the critical boron concentration was not changed by more than 0.15 % and pin power was predicted with less than 1.65% difference. The effects were found to be largely localized.