§ 835.501 Radiological areas.
§ 835.502 High and very high radiation areas.
(a) High radiation areas. One or more of the following features
shall be used for each entrance or access point to a high radiation
area where radiation levels exist such that an individual could
exceed a deep dose equivalent to the whole body of 1 rem (0.01
sievert) in any one hour at 30 centimeters from the source or
from any surface that the radiation penetrates:
(1) A control device that prevents entry to the area when
high radiation levels exist or upon entry causes the radiation
level to be reduced below that level defining a high radiation
(2) A device that functions automatically to prevent use or
operation of the radiation source or field while personnel are
in the area;
(3) A control device that energizes a conspicuous visible
or audible alarm signal so that the individual entering the
high radiation area and the supervisor of the activity are made
aware of the entry;
(4) Entryways that are locked. During periods when access
to the area is required, positive control over each entry is
(5) Continuous direct or electronic surveillance that is capable
of preventing unauthorized entry;
(6) A control device that will automatically generate audible
and visual alarm signals to alert personnel in the area before
use or operation of the radiation source and in sufficient time
to permit evacuation of the area or activation of a secondary
control device that will prevent use or operation of the source.
(b) Very high radiation areas. In addition to the above requirements,
additional measures shall be implemented to ensure individuals
are not able to gain access to very high radiation areas when
dose rates are in excess of the posting requirements of § 835.603(c).
(c) No control(s) shall be established in a high or very high
radiation area that would prevent rapid evacuation of personnel.
Subpart G-Posting and Labeling