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

摘要

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.l 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, and v_p covariance matrices of ~(235)U impact the uncertainty results notably. Both at HZP and HFP, the relative uncertainty of the eigenvalue is about (4.7±0.09)%o (applying v_p covariance of ~(235)U) or (7.1±0.20) %o (applying v, covariance of ~(235)U); the relative uncertainties of two-group constants vary from about (2.9±0.06)%o (for ∑_(t,2)) to (11,9 ± 0.34)%o (for ∑_(s,1,2)).