Verification of RT Crystal Diffraction Image of the Centrifugal Casting Tube for PWR Coolant System

On RT testing of centrifugal casting pipe of CPR1000 PWR coolant system, an image on the film with a large area of black and white, and with unclear edge boundary was found. The image was also characteristic of irregular patch or defect image. Through a variety of physical and chemical methods and non-destructive examination methods for exclusion and verification and by comparing it with the defect image of typical casting defect map, it was verified that the image was the non-defect image caused by the crystal diffraction, and following on its formation mechanism was analyzed.