ASNT Industrial Radiography Radiation Safety Practice Test

If one half-value layer of lead is 0.19 in., how many half-value layers are in a 0.57 in. thick lead sheet?

1. 1.5

2. 2

3. 3

4. 4

The correct answer is: 3

To determine how many half-value layers are in a 0.57 in. thick lead sheet when one half-value layer (HVL) of lead is 0.19 in., you would divide the total thickness of the lead sheet by the thickness of one half-value layer. The calculation involves dividing the thickness of the lead sheet (0.57 in.) by the thickness of one half-value layer (0.19 in.). Performing this calculation: 0.57 in. ÷ 0.19 in. = 3 This result indicates that there are 3 half-value layers in the 0.57 in. thick lead sheet. Each half-value layer represents the thickness of material required to reduce the radiation exposure by half. Therefore, in this scenario, a 0.57 in. thick lead sheet indeed corresponds to three full half-value layers, effectively functioning to attenuate the radiation significantly over that distance. This fundamental principle of radiation shielding is crucial in ensuring proper safety and protection measures in industrial radiography and related fields.