Health Physics Questions and Answers - Question 27

Question 27: Do licensees have to post controlled areas (outside the restricted area) as airborne radioactivity areas if derived air concentrations (DAC) are exceeded?

Answer: Yes, if the airborne radioactivity is indoors. If the airborne radioactivity is outdoors, the answer depends on the particular situation. In certain situations the licensee may need to identify and delineate an outdoor airborne radioactivity area. For example posting would be required in a small area, accessible to workers, in the immediate vicinity of a vent on the outside of a building, exhausting air containing concentrations of radioactive materials in excess of the DACs specified in Appendix B to 10 CFR Part 20.

(References: 10 CFR 20.1003, 10 CFR 20.1902)