In any five consecutive days, a dose exceeding how many millirem defines a Radiation Area?

• A. 50 millirem
• B. 100 millirem
• C. 5 millirem
• D. 150 millirem

Answer: (B)

In radiation protection, areas are categorized by the potential dose a person could receive over a defined time. For a Radiation Area, the criterion is a total dose that could exceed a specific limit over any five consecutive days. The defined threshold is 100 millirem. So if someone could accumulate more than 100 millirem in five days, that area is designated as a Radiation Area. This five-day window matches a typical workweek and helps determine when extra controls, monitoring, or postings are needed.

Why this value fits: 100 millirem is high enough to warrant additional protection measures beyond ordinary areas, yet not so high as to blanket many spaces with stringent controls. The other numbers don’t set the official threshold: 50 and 5 millirem are below the standard limit, while 150 millirem would also exceed the limit, but the defined threshold itself is 100 millirem.