American Society for Nondestructive Testing (ASNT) Radiographic Testing Practice Test

Cobalt-60 (Co-60) is a radioactive isotope commonly used in nondestructive testing due to its ability to emit gamma rays. Gamma radiation is a form of high-energy electromagnetic radiation, similar to X-rays but generally more penetrating. The gamma rays emitted by Co-60 are effective for radiographic testing as they can penetrate various materials, allowing for the examination of internal structures without causing damage to the specimen.

In the context of nondestructive testing, gamma rays are preferred for their deep penetration capabilities, making them suitable for inspecting thick materials. The choice of Co-60 is particularly beneficial as it has a half-life of about 5.27 years, providing a stable source of radiation that can deliver consistent results over time.

Other types of radiation such as alpha and beta particles have characteristics and energies that limit their effectiveness in this application. Alpha particles, which are heavy and positively charged, have very low penetration power and would not be useful for imaging internal features of materials. Beta particles, being electrons, are slightly more penetrating than alpha particles but still do not have the penetrating power or the imaging capabilities offered by gamma radiation. X-rays, while also effective, are generally derived from different sources and do not utilize isotopes like Co-60