Health Physics Questions and Answers - Question 106

Question 106:

(a) Are there no limits on airborne radioactivity concentrations in the controlled area, other than de facto limits for public dose to keep dose rates less than 2 mrem in an hour?

(b) Would stack effluents creating temporary airborne radioactivity concentrations greater than DAC levels in the controlled areas be allowed, as long as the public dose criteria of 10 CFR 20.1301 are met?

(c) It appears that these areas would not need to be "posted" or controlled, since there are not any 10 CFR Part 20 airborne radioactivity concentration limits for controlled areas. Is this correct?


(a) There are no limits on concentrations of airborne radioactive materials in controlled areas that are expressed in terms of concentrations. However, both the occupational dose limits (for individuals who receive an occupational dose in a controlled area) and the dose limits for an individual member of the public (when in a controlled area) indirectly limit the concentrations of radioactive material in controlled areas. Note that for members of the public the 100 mrem in a year limit applies. The 2 mrem in an hour limit does not apply in a controlled area. This limit applies only in an unrestricted area.

(b) Yes.

(c) There may be "airborne radioactivity areas" within controlled areas that need to be posted. See the answer to Question 27.

(Reference: 10 CFR 20.1301, 10 CFR 20.1201)

Page Last Reviewed/Updated Tuesday, October 31, 2017