Evaluation of Decay Ratio of BWRs using Singular Value Decomposition Method

概要

論文の詳細を見る
A new method for evaluating the decay ratio of boiling water reactors (BWR) using the singular value decomposition (SVD) method was proposed. In the SVD method, time-series data are decomposed into uncorrelated signal components and the auto-correlation functions (ACF) of these decomposed components are calculated. The ACF having a form of damping oscillation is related to the complex conjugate dominant poles of the frequency transfer function of BWR dynamics. The decay ratio and the natural frequency can be determined by applying a least square fitting to the ACF. The proposed method was applied to LPRM and APRM signals measured during stability experiments performed in Ringhals-1 at BOC-14. It was found that LPRM signals that were measured under 9 operating conditions were consistently decomposed into three type components whose ACFs had the forms of slow attenuation, fast attenuation and damping oscillation. Under the respective operating conditions, LPRM signals measured at various positions were decomposed into the ACFs with almost the same values of the decay ratio and the natural frequency. In virtue of this high decomposition performance, the decay ratios can be estimated with small standard deviations compared with conventional methods. Some guidelines for an accurate determination of decay ratios are also presented.
社団法人日本原子力学会の論文
2005-02-25