Assessment of the reactivity bias and bias uncertainty due to WWER-440 fuel depletion uncertainties

In this paper, bias and bias uncertainty in the neutron multiplication factor due to biases and bias uncertainties in the calculated nuclide concentrations in the spent nuclear fuel of WWER-440 type was assessed. To determine isotopic biases and bias uncertainties in the calculated nuclide concentrations, they were compared to the results of the measurements of isotopic compositions from destructive radiochemical assay of WWER-440 spent fuel carried out in the RIAR. In calculations Monte Carlo uncertainty sampling method was used.