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?
Answer: (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)