ASNT Industrial Radiography Radiation Safety Practice Test

In which unit is the activity of radioactive material measured?

1. Decays

2. Curies

3. Grays

4. Sieverts

The correct answer is: Curies

The activity of radioactive material is measured in curies. This unit quantifies the amount of radioactive decay occurring in a material over time. Specifically, one curie is defined as the amount of radioactive material that produces 3.7 x 10^10 disintegrations per second, which is approximately the rate of decay of one gram of radium-226. Understanding this unit is critical in fields involving radiation, as it helps communicate the level of radioactivity present in a sample, thereby ensuring proper safety protocols and exposure assessments can be implemented. In contrast, decays describe the process itself rather than a standard unit of measurement; grays quantify absorbed radiation dose, which pertains to the amount of energy deposited in materials; and sieverts measure biological effect from radiation exposure, taking into account the type of radiation and its impact on human health.