Precision Validation on the Flaws in Pipe Blocks of Performance Demonstration Inspection for Nuclear Power Plant

The radiographic testing (RT), ultrasonic testing (UT) and anatomical measurement were employed to measure the embodied real flaws in self-developed pipe blocks of performance demonstration inspection (PDI), and the differences between the geometric dimensions and position coordinate parameters of the embodied flaws and the design values were analyzed. The test involved four different specifications of pipe blocks, with a total of 16 defects, all of which are cracks. The results show that the track of embodying weld is eliminated completely, the cracks are featured with natural and high closure, and the tips are distinguishable with no secondary propagation. The embodied crack forms a complete metallurgical bond with the parent body of the block, and there is no abnormal signal reflection interface or secondary flaw in the embodied weld. After RT and UT, it is confirmed that the average absolute value deviation of the geometric size and position coordinates of the defects is less than 2.0 mm, and after anatomical measurement, the average absolute value deviation is less than 1.0 mm. The flaw precision meets the requirement for PDI of nuclear power plant.