Host: The Japan Society of Mechanical Engineers
Name : The 27th International Conference on Nuclear Engineering (ICONE27)
Date : May 19, 2019 - May 24, 2019
For AP1000 NPP, the connection weld between the steam generator and main pump is the only butt weld for the main equipment. This weld works in high temperature, high pressure, high vibration etc.. It has important significance and necessity to ensure its integrity by in-service inspection. The outlet nozzle of the steam generator is a highly radioactive area and is usually inspected from the outside. According to requirements of ASME-2004, ultrasonic inspection should be carried out more than 1/3 of thickness from inner wall , so ultrasonic probes must approach the weld from inner wall of the nozzle, one kind of special inspection equipment should be developed. It is difficult to design the inspection equipment because of the high irradiation environment, risk of internal contamination, small inlet size for equipment, large nozzle diameter to be inspected. Besides, it has a long distance between equipment installation and inspected weld, and is crossed-axis in space. In order to meet inspection needs, developed inspection equipment has 10 moving joints and multiple parts, each part is connected by fast connection structure. Installation personnel install inspection equipment outside of the steam generator manhole, then remotely control 10 moving joints to achieve inspection equipment's carrying, positioning, fixing and scan process, completing ultrasonic testing of the weld internally. Inspection equipment has been applied to Unit 1 and 2 of Sanmen NPP and Unit 2 of Haiyang NPP in China.
