United States Nuclear Regulatory Commission - Protecting People and the Environment

Health Physics Questions and Answers - Question 48

Question 48: In 10 CFR 20.1301 (a) (2), does ". . . 0.002 rem (0.02 mSv) in any one hour" apply to the dose in any single hour or can it apply to the average over a discrete period of time.

Answer: The phrase "0.002 rem in any one hour" means a cumulative dose of 0.002 rem in any period of 60 consecutive minutes regardless of the dose rates within that 60-min. period. It does not mean a dose rate, in units of rems per hour, obtained by averaging over a time period greater than, or less than, one hour.

(Reference: 10 CFR 20.1301 (a) (2))

Page Last Reviewed/Updated Thursday, September 24, 2015