Radiographic Testing (RT), or industrial radiography, is a nondestructive testing (NDT) method of testing materials to detect hidden flaws. The ability of short wavelength electromagnetic radiation (high energy photons) are used which penetrate various metals.
Either an X-ray machine or a radioactive source (Ir-192, Co-60 and Se 75), can be used as a source of photons.
This peaceful use of Atomic Energy. The Radio Isotopes are unstable elements manufactured in a Nuclear reactor .Radioisotopes emits Gamma rays in the process to come to a stable position .These gamma rays are used to scan welding in steel and other metals as these rays can penetrate 9 inches of steel. The Industrial Radiography films are used to get exposed when placed on the joint and radiation source on the other side. Any defect in the joint can be viewed on the exposed and process film by placing over the illuminated film viewer. There are many types of Radioisotopes Source having different energy. Gamma rays continuously get emitted each having different half life. These sources are chosen according to the type of requirement. Mostly Ir192 and co60 are mostly used in Industrial Radiography. Industrial X ray machines are also used for Radiography. The basic difference is G-rays comes out of the nucleus of the Radio Isotope while X-rays comes out of the orbit electrons knocked out by fast impinging ions in cathode ray tube. As the x rays and Gamma rays have penetration and absorption quality it is used in radiography for testing various types of jobs like welding ,casting ,forging etc .
Because of Ill effects of Radiation on human body the Safety precautions are taken as per the rules laid down by The Department of Atomic Energy Who monitors the radiation dose received by a radiation worker every month. If a Radiation worker receives more dose than the prescribed dose due to faulty working or by accident, it must be reported to A.E.R.B. after investigation by the site in charge certified by A.E.R.B. Radiographers are also given training and certification by AERB who authorize him to handle the source. Gamma Rays or X rays follow the laws of light. Radiation strength is measured in Becquerel while earlier unit was Ci (Curie).