为了保证核电站反应堆控制棒组件的正常使用，采用水浸脉冲反射回波超声检测技术，应用FFT（快速傅里叶变换）获得壁厚信号的谐振频率，根据壁厚信号的谐振频率计算壁厚，从而得到检测区域内的缺陷信息。在已知壁厚的试验棒上验证这种方法，得到的壁厚数据的精度较高，能较好地实现反应堆控制棒组件的超声检测。

It was necessary to detect the defects of Rod Cluster Control Assembly used in nuclear power plant reactor for its normal operation. The immersion pulse-echo technique was applied, from which the resonance frequency of the UT signal was obtained by performing FFT. After that, the defects information within the area of inspection can be analyzed from the UT signal. The method was validated on a calibration block whose thickness was known. The accuracy was high and the uncertainty was within the allowable range. With the help of this method, the ultrasonic inspection for Rod Cluster Control Assembly can be realized well.