The definition of a high radiation area is a radiation level that could result in an individual receiving a dose equivalent in excess of:

• A. 0.01 rem (0.1 mSv) in 1 hour at 10 cm from the source
• B. 0.1 rem (1 mSv) in 1 hour at 10 cm from the source
• C. 0.01 rem (0.1 mSv) in 1 hour at 30 cm from the source
• D. 0.1 rem (1 mSv) in 1 hour at 30 cm from the source

Answer: (D)

High radiation area is defined by the potential to deliver a certain exposure rate in a short time at a specified distance from the source. In this context, that threshold is 0.1 rem (1 mSv) in one hour at 30 cm from the source. The option stating 0.1 rem per hour at 30 cm matches this criterion, so it identifies an area where the dose rate could exceed the limit in one hour, triggering the high-radiation designation. The other statements describe either a lower dose rate (0.01 rem) or use distances that don’t align with the defined measurement condition, so they don’t meet the threshold for a high-radiation area.