Sensitivity and uncertainty analysis for eigenvalue and few-group constants of reactor-physics calculations

The effects of nuclear-data uncertainties on the predictions of the reactor-physics calculations are quantified in this paper. Uncertainty analysis has been applied to the TMI-1 assembly at both Hot Zero Power (HZP) and Hot Full Power (HFP) conditions, propagating the nuclear-data uncertainties to the eigenvalue and few-group constants. The statistical sampling method has been applied to the uncertainty analysis for lattice calculations of TMI-1 assembly. The 172-group WIMSD-4 formatted microscopic cross-section library and corresponding cross-section covariance matrices based on the ENDF/B-VII.1 have been generated and applied for the uncertainty analysis. From the numerical results of the uncertainty analysis, it can be observed that the relative uncertainties of the eigenvalue and two-group constants at HFP are a little larger than these at HZP. The v_t and v_p covariance matrices of ²³⁵U impact the uncertainty results notably. Both at HZP and HFP, the relative uncertainty of the eigenvalue is about (4.7±0.09)‰ (applying v_p covariance of ²³⁵U) or (7.1±0.20)‰ (applying v_t covariance of ²³⁵U); the relative uncertainties of two-group constants vary from about (2.9±0.06)‰ (for Σ_t,2) to (11.9±0.34)‰ (for Σ_s,1,2).