控制棒驱动机构（CRDM）是核电站控制反应堆功率的重要组成部件，该部件的耐压壳焊缝长期处于高温、高压、高辐射环境，需定期进行在役检测，而欧洲先进压水堆（EPR）机组的CRDM耐压壳的连接形式与CPR1000机组有很大区别，其下部耐压壳的检测要求也从目视和声发射检测变为超声检测。针对其异种金属焊缝和薄壁厚的特点，以及特殊的空间布置和辐射环境，开展了CRDM异种金属焊缝自动超声检测技术的研究。介绍了超声检测工艺和自动检测装置，在带有缺陷的模拟试块和核电现场部件上进行了试验。试验结果表明，开发的自动超声检测工艺可有效检出模拟试块中的缺陷，自动超声检测装置能满足现场检测要求。

The control rod driving mechanism (CRDM) is an important component of nuclear power plant, and the structure and connection form of the European Pressurized Reactor (EPR) CRDM are quite different from those of the CPR1000 Reactor. The change of CRDM pressure housing inspection method from visual and acoustic emission inspection to ultrasonic test was therefore required. According to the characteristics of its dissimilar metal welds and thin wall thickness, as well as the special space arrangement and radiation environment, the automatic ultrasonic inspection technology of CRDM dissimilar metal welds was studied. In this paper, ultrasonic testing technology and automatic inspection device are introduced. The test results show that the developed automatic ultrasonic inspection technique can effectively detect the defects in the simulated test blocks and the automatic ultrasonic inspection device can meet the requirements of field inspection.