Calculation of Reactor Kinetics Parameters β_eff and Λ with Monte Carlo Differential Operator Sampling

Japan Atomic Energy Agency, Nuclear Science and Engineering Directorate, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan

Abstract

The methods to calculate the kinetics parameters of β_eff and Λ with the differential operator sampling have been reviewed. The comparison of the results obtained with the differential operator sampling and iterated fission probability approaches has been performed. It is shown that the differential operator sampling approach gives the same results as the iterated fission probability approach within the statistical uncertainty. In addition, the prediction accuracy of the evaluated nuclear data library JENDL-4.0 for the measured β_eff/Λ and β_eff values is also examined. It is shown that JENDL-4.0 gives a good prediction except for the uranium-233 systems. The present results imply the need for revisiting the uranium-233 nuclear data evaluation and performing the detailed sensitivity analysis.