In this method of Nondestructive testing the penetration property of X-ray and Gamma rays to detect the discontinuities. The object to be inspected is placed between the radiation source and a piece of film. X-rays or gamma rays pass through the object. The object will stop some of the radiation. Thicker and denser area will stop more of the radiation and show on the film lighter than thinner or less dense area. Most weld defects will show on the film darker than the surrounding area.