ASNT Industrial Radiography Radiation Safety Practice Test

What would be the exposure rate at 1 ft from a source with 30 Ci of Iridium and a gamma constant of 5.2 R/h/Ci?

1. 30 R/h

2. 156 R/h

3. 66.7 R/h

4. 5.2 R/h

The correct answer is: 156 R/h

To determine the exposure rate at a specified distance from a radioactive source, you multiply the activity of the source (in curies) by the gamma constant (in R/h/Ci). In this case, the radioactive source has an activity of 30 Ci, and the gamma constant is 5.2 R/h/Ci. Calculating the exposure rate involves the following formula: Exposure Rate = (Activity in Ci) × (Gamma Constant in R/h/Ci) Substituting the given values: Exposure Rate = 30 Ci × 5.2 R/h/Ci = 156 R/h This result indicates that at a distance of one foot from the source, the exposure rate would indeed be 156 R/h. This calculation demonstrates how the activity of the source and the gamma constant directly contribute to determining the radiation exposure levels in radiological safety practices. Understanding how to apply these factors is essential for professionals working with radioactive materials, ensuring both compliance with safety regulations and the protection of individuals from excessive radiation exposure.