ASNT Industrial Radiography Radiation Safety Practice Test

What type of radiation does a sealed source emit?

1. X-rays

2. Alpha particles

3. Beta particles

4. Gamma rays

The correct answer is: Gamma rays

A sealed source typically emits gamma rays, which are high-energy electromagnetic radiation. These sources are designed to contain radioactive materials that emit radiation while remaining encapsulated, preventing the release of radioactive substances into the environment. Gamma radiation is particularly prevalent because it can travel long distances and penetrate various materials, making it useful for industrial radiography applications, where it is utilized to inspect the integrity of materials and structures. This property of gamma rays allows them to effectively penetrate the materials being examined while minimizing the exposure to personnel when proper safety protocols are followed. In the context of sealed sources, while alpha and beta particles can also be emitted by certain radioactive isotopes, their use is limited because they have much lower penetration abilities compared to gamma rays. Alpha particles, for instance, can be stopped by a sheet of paper, while beta particles can be stopped by plastic or a few millimeters of aluminum. Hence, the primary choice for sealed sources in industrial applications leans toward gamma emitters due to their effectiveness and ease of use.