Ω焊缝是CPR1000机组控制棒驱动机构(CRDM)上连接不同部位的不锈钢金属焊缝,其完整程度对于CRDM的良好运行起着十分重要的作用。阐述了针对Ω焊缝研发的自动化超声波水浸聚焦技术，确定了包括检测波型、探头频率、晶片尺寸及水层厚度等检测参数,并通过实际试块的检测试验，表明该技术可实现对CPR1000机组CRDM Ω焊缝的质量检测。

Canopy welds (Ω) in CRDM housing are welded seals joining stainless material and playing an important role in leak-proof for CRDM housing. The paper firstly summarizes and outlines the development of the immersion ultrasonic inspection techniques for canopy welds, and then determines the test parameters such as wave type, probe frequency, wafer dimension and layer thickness , and finally carries out the verification test. And through the test it proves that the technique could meet the test requirements of canopy welds (Ω) in CRDM housing.