SCANNER SAFETY AND LOCAL CONTROLS
Table 4 summarizes nuclear and X-ray radiation hazards, warnings, and safety precautions
to be used in systems with a nuclear- or X-ray-based sensor (radiation hazard zone < 1 m
(3.28 ft) from heads).
Table. 4. Nuclear and X-ray Radiation Hazard Precautions
Green indicator OFF
Red indicator ON
Indicates that a radiation shutter switch is open.
Indicates radiation shutter commanded open.
Work in this area < 1 m (3.28 ft) from head exposes the
worker to trace amounts of radiation from sensors
while heads are aligned.
Work in this area < 1 m (3.28 ft) from
head requires closure of all shutters
first. Do not look into or insert body
parts into gap.
Green indicator ON
Red indicator OFF
Indicates that all shutters are closed.
Indicates radiation shutter commanded closed.
No nuclear radiation exposure hazard.
Normal maintenance work may be
done on scanner, head and sensors in
this area. Highest level of safety
control when
Interlock key is removed by person
doing maintenance work.
Green indicator ON
Red indicator ON
Indicates all shutters are closed.
Indicates a shutter open command is active.
Not a normal operating mode when persistent. May
occur briefly during shutter open sequence, or if a
shutter cannot open, for example, due to lack of air
pressure.
If red is ON, operator must always assume radiation
and act accordingly.
No nuclear radiation exposure
hazard. Troubleshoot radiation
warning system if state is persistent.
Green indicator OFF
Red indicator OFF
Indicates shutter may be open.
Indicates no active shutter open command.
Not a normal operating mode. May occur if a shutter is
stuck open, power is off, or if green light circuit is not
functioning properly. Nuclear radiation exposure
hazard may be present.
Assume nuclear radiation exposure
hazard may be present. Do not split
heads. Troubleshoot radiation
warning system.
2.2.3.2 Laser Radiation
Laser radiation-based sensors do not use a shutter for emissions control; they are not
related to the red and green shutter safety indicators on the head or user panels.
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