What function do shielding blocks serve when the source is not in use?

• A. They reduce radiation leakage from the source in non-active states.
• B. They measure activity.
• C. They increase decay rate.
• D. They cool the source.

Answer: (A)

Shielding blocks are used to minimize exposure by absorbing or blocking radiation when the source is not in use. The goal is to prevent leakage and stray radiation from reaching personnel during idle periods, maintenance, or transport. These blocks, usually made of dense material like lead, are placed between the source and occupied areas to attenuate the emitted photons and keep dose rates low. They don’t measure activity, don’t change the decay rate, and don’t provide cooling—they simply reduce the amount of radiation that escapes or leaks when the source isn’t being actively used.