Study on Shell Mode Vibration Characteristics of Reactor Core Barrel Based on Analysis of Pressure Vessel Vibration Signal

The vibration state of reactor core barrel is directly related to the safe operation of the core. However, the barrel is under high temperature and high radiation conditions, so it is impossible to measure the barrel vibration by a sensor directly installed on the barrel. In this paper, the accelerometer installed on the pressure vessel is used to indirectly monitor the barrel vibration. The coherence spectrum, auto-power spectrum and cross-power spectrum of vibration signal of pressure vessel with multiple nuclear units are analyzed to provide the shell mode vibration frequency and amplitude of the barrel. As shown by comparison, the analysis results approximate to the measured values from the test of Qinshan NPP Phase II Unit 1. The study results show that the shell mode vibration characteristics of the core barrel can be effectively identified by the monitoring and analysis of the pressure vessel vibration signals, which provides a foundation for the evaluation of the core barrel conditions.