Nuclear data effect on BWR stability parameter uncertainty at stable core conditions

Abstract

The objective of this study is to quantify the influence of nuclear data uncertainties on both steady-state and dynamic core parameters in BWRs, with a specific focus on the uncertainty quantification of stability parameters such as the decay ratio and resonance frequency at stable core conditions. This investigation is carried out within the framework of the OECD/NEA benchmark on the Oskarshamn-2 stability event that occurred in February 1999. The nuclear data uncertainties are propagated, using the in-house SHARK-X platform, through the 2-D lattice calculations using CASMO5 and followed by downstream static and dynamic calculations using and SIMULATE3 and SIMULATE-3 K, respectively. For steady-state, the uncertainty is estimated in terms of k-eff, radial and axial power peaking factors, void fraction, and average fuel temperature, while for the transient, the estimated uncertainties are obtained, for the first time, for the decay ratio and resonance frequency. The results indicate that nuclear data uncertainties have a non-negligible impact on most of the analyzed parameters. More specifically, the uncertainty in k-eff, radial and axial power peaking factors, nodal void fraction peak, and nodal fuel temperature peak for steady-state could reach about 0.5 %, 0.4 %, 2.8 %, 0.1 %, and 1.5 %, respectively, For transient, the uncertainty due to nuclear data for the two stability parameters could reach about 9 % and 2 % for the decay ratio and resonance frequency, respectively.