Propagation of Nuclear Data Uncertainties for PWR Burnup Calculation

Abstract

As the nuclear data are from either the experiment measurements or the estimation models, uncertainties would arise from the insufficient measurements and/or modeling uncertainties. The uncertainties in nuclear data would have effects on the best-estimated prediction results of the reactor system. In this paper, our home-developed code UNICORN, which has the capability of uncertainties analysis for the neutron physics calculations, has been applied to quantify the response uncertainties of the PWR burnup calculation introduced by the uncertainties of multigroup microscopic cross-section libraries. The burnup benchmark proposed by UAM (“Uncertainty Analysis in Modeling”) is selected for the demonstration purpose. Relative uncertainties of k _∞ , two-group constants and isotope concentrations with the fuel burnup introduced by the nuclear data uncertainties are quantified. It is observed that the relative uncertainty of the eigenvalue is 0.5%; the relative uncertainties of the two-group constants vary between 0.3% (for the Σ _t,2) and 1.9% (for the vΣ _f,2); the relative uncertainties for the isotope concentrations can reach 30%. These relative uncertainties introduced by the nuclear data are significant for the neutron physics calculations and cannot be ignored.