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Radiography Testing (RT) is one of the very early methods of NDT. Initially it was used for medical applications while soon its usefulness as an inspection method for critical constructions was revealed. It is about electromagnetic rays of high penetrability. -X rays and –γ rays differ only to their way of producing them.
- X-rays are produced when rapidly travelling electrodes collide to a material of high atomic number.
- -γ Rays are produced spontaneously by radioactive isotopes. Such materials are Ir192 and Co60.
The method is based on the fact that the –X or –γ rays penetrate at a different rate the materials. The amount of the outcoming rays depends on the penetrated thickness, the atomic number of the material and the density of the material. A radiographic film is put behind the test piece. There the radiographic image shall be revealed, which depends on the absorption degree of the piece tested.
High training is required, not only for the correct implementation of the method but also for the safe conduction of the test. In any case, special protection measures must be implemented and the international radiation protection measures must be followed.
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