Question 218: 10 CFR 20.1601 (a) (1) says that the control
devices must cause the radiation level to be reduced "upon
entry." (a) Must the devices preclude authorized or
unauthorized entry? (b) At what point must the control
devices activate, when a person passes the final 30 cm
before, or entry itself?
Answer: (a) 10 CFR 20.1601 (a) requires that entrance or
access points to a high radiation area have "one or more"
of the listed features to preclude excessive radiation
exposure to an individual. The control device in
subparagraph (1) stipulates only that it cause the
radiation level to be reduced so that an individual, upon
entry, could not receive 100 mrem in an hour within 30 cm
of an accessible area of the source. This paragraph does
not distinguish between "authorized" or "unauthorized."
(b) The control device must activate "upon entry into the
area" at the "entrance or access point." (Reference: 10
CFR 20.1601)