For such inspection method, 128 and 256-channel phased array system has been developed for the inspection of weldment of internal components such as core shroud and the piping to the jet pump.

In the case of core shroud, array probe has 256 elements and a length of about 200mm along the array direction. Then the simultaneous B-scan imaging of three different beam directions, which is normal beam inspection and angle beam inspections from opposite side of weldment, can be carried out. In this system, only the mechanical scanning along the weld line is required for the complete inspection of weldment. Furthermore, TOFD inspection and imaging can be carried out by the use of electrical element scanning capability, which selects the partial elements as the transmitting or receiving element.

In the recent application of phased array, 128-channel system has used for the inspection of the weldment of the piping which is connected from the feed water nozzle to jet pump. In this case, HAZ region near the weldment of 8 mm thickness pipe wall has inspect and imaged automatically.

As the result of these experiments, It was established that phased array system has high performance for detecting and sizing the defect as the inspection system for the BWR internal components.