2.2.3 Radiation safety hazards
Many scanners include sensors that take measurements by directing nuclear particles, X-
rays, or laser light at the process. The scanner design includes rigorous safety features to:
• Inform the worker through shutter status indicators of dangerous, open nuclear
and X-ray radiation sources.
• Monitor system mechanical, electrical, and software states through interlocks to
prevent opening of source shutters or discharge of laser sources in an unsafe
manner, for example, when heads are split, receivers are not in place, sources are
not in place, control software is not running, shutter safety lights are not
operational, and so on.
Subsections 2.2.3.1 and 2.2.3.2 describe the nuclear and laser safety hazard conditions.
Subsection 2.2.3.3 describes general radiation safety precautions to be taken when
working around a scanner.
Review those sections with special care, and note any questions that need to be answered
by Honeywell authorized personnel.
2.2.3.1 Nuclear radiation
The measuring head on the scanner typically has a radioactive source with shielding
casing materials and an aperture opening controlled by a shutter system. The shutter
design limits the radiation exposure direction to the receiver system
and, when closed, allows the radiation source to be blocked completely, enabling a safe
working environment for maintenance work on the sensors, head, and scanner.
Nuclear radiation hazard zone
When a radiation sensor is operating, the shutter is open, but the opposing head limits all
but a small amount of radiation that may make its way through the narrow gap between
the heads.
A radiation survey done at 1m (3.28 ft) from the head ensures that radiation levels are
within regulation for these types of devices. However, the small amount of residual
radiation that does exist infers a safe work practice hazard zone of 1m (3.28 ft) around the
scanner heads when the shutters are open (see Figure 20).
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