High Radiation Area is defined as

• A. An area where radiation exposure is present but below regulatory limits.
• B. An area enclosed by lead shielding where no radiation can escape.
• C. An area accessible to personnel in which there exists radiation at such levels that a major portion of the body could receive in any one hour a dose in excess of 100 millirem.
• D. An area where exposure exceeds 2 rem per hour.

Answer: (C)

High Radiation Area is defined as an area accessible to personnel in which there exists radiation at levels that could deliver in any one hour a dose to a major portion of the body in excess of 100 millirem. This 100 mrem per hour threshold is what triggers stronger access controls, monitoring, and posting to limit who enters and for how long. In practice, areas below that dose rate aren’t considered high radiation areas, and a shielded enclosure is designed to keep radiation from escaping rather than define an area people work in. If the dose rate were as high as 2 rem per hour, that would be a much higher category of radiation area, requiring even stricter controls.