大亚湾核电站汽轮机转子末级叶片是采用GEC-A设计制造的MARKII型叶片枞树型叶根。由于GEC-A未改进前的末级叶片在其它电厂发现过裂纹，大亚湾核电站很早就开始实施反馈性预防检查，但需要拆除末级叶片，而一次拆装检查需要8~9 d，成为核电厂常规换料大修中的关键瓶径，并可能产生因拆卸而带来的机械损伤风险。因此，找到延长低压缸拆装叶片的周期的方法，将可以实现在保证核电厂汽轮机组可靠性的同时进一步提高经济性。通过多年的调研及试验，相控阵超声波原位检查技术可以满足此目的，并已在现场得到成功应用。

In Daya Bay nuclear plant, the type of the last stage blade of turbine rotor is MARKⅡ vertical tree root, which is designed by GEC-A. In some plants, cracks were found on the rotor blades of old type, which were not improved before by GEC-A. For that reason, Daya Bay nuclear plant began feedback preventive inspection in a very early time. But there is a problem that it has to tear down all the rotor blades before inspection each time, so the inspection will cost about 8~9 days and become the critical path of the refueling outage, whats more, it may cause the risk of mechanical damage. Therefore, to extend the cycle time of the low-pressure cylinder blades disassembly can further improve the economy of the steam turbine and keep the nuclear power plant steam turbine maintaining a reliable. Through years of researches and experiments, in-situ phased array ultrasonic inspection techniques can meet the requirement, and it has been successfully used practically.