What is the minimum distance for personnel for Radiation Hazard - HF3 & 4?

• A. 15 feet
• B. 3 feet
• C. 130 feet
• D. 50 feet

Answer: (A)

Minimum distance from a Radiation Hazard area for HF3 & HF4 is fifteen feet. This distance is set because radiation exposure falls off with distance, roughly following the inverse-square relationship, so moving farther away dramatically reduces dose. Fifteen feet keeps personnel within allowable exposure limits during routine operations, while shorter distances—such as three feet—would push dose above safe levels. Distances like fifty or one hundred thirty feet exceed the required minimum and aren’t needed to meet the safety standard, though they would reduce exposure even further. HF3 & HF4 indicate higher hazard, so a clear, established standoff like fifteen feet is used to balance safety with practical work.