Uncertainty Evaluation of Burnup Properties of Large Fast Reactors Using Data Adjustment Method

摘要

The burnup uncertainties of a fast-breeder reactor have been evaluated based on the cross section adjustment technique.A group cross section set, obtained using JENDL-2, was adjusted using experimental data of fast critical assemblies ZPPR and FCA. The adjusted cross section was applied to the neutronics characteristic calculation of a 1, 000 MWe-class fast reactor, and the changes in neutronics characteristics and their uncertainties due to the cross section adjustment were evaluated. The burnup reactivity loss was found to increase by 23% when the adjusted cross section library was used. This value corresponds to a reactivity decrease of about 0.7%Δk at the end of the equilibrium cycle for a typical 1, 000 MWe LMFBR of 1 yr operation cycle.The uncertainty in burnup reactivity due to the cross section error was found to decrease from 21% to 12% if the cross section ajustment method was employed. This brings the benefit of a reduction in control rod worth requirement by about 0.3%Δk.