Seismic Test Analysis Evaluation of Motor-Operated Valve Actuators for Nuclear Power Plant

Abstract

The function of motor-operated valves provided in nuclear power plants during an earthquake has been previously evaluated on the basis of seismic test results; however, since the response acceleration has increased with a recent reassessment of standard earthquake ground motions, it is necessary to evaluate their function during high acceleration earthquakes. In order to carry out seismic test analysis, we examined the compression characteristics of the gaskets in three kinds of representative valves, in terms of the current load and slide coefficient, by element tests. We created an analysis method using the finite element method which used the gasket’s characteristics, and the result of these analyses could explain the loosing and the amplitude of the bolt connecting force and gasket slipping at the time of excitation to the safety side. According to the analysis, the actuator connection part of the motor-operated butterfly valve showed a seismic resistance of 20 × 9.8m/s2 and other parts showed a seismic resistance of 30 × 9.8m/s2.