25 May 2005
sufficient to allow the inspection system to scan a large stationary vehicle and
To increase throughput, provide a longer inspection lane for operation of a
portable system that scans stationary vehicles. This will allow the system to
scan several vehicles at one time.
Provide no canopy over the inspection area planned or dedicated for use by the
portable equipment unless the clear height is a minimum of 22 ft (6.7 m).
Site all permanent facilities or guard posts such that they would remain outside
of the exclusion zone. A shielding wall may be required if there are occupied
buildings or areas near the detector.
Site all permanent facilities such that they are not in the direction of travel of the
radiation beam unless the distance between the inspection vehicle and the
facility is at least 300 ft (90m.) The intent is to insure that the 100 mR / year
radiation dose limit is not exceeded for personnel who may be in the direction
of travel of the radiation. This distance can be reduced to 75.5 ft (23 m) if a 12
in (305 mm) wide x 8 ft (2.4 m) high (minimum) concrete shielding wall is
provided between the radiation source and any facility of concern. The
determination of exclusion zones should also consider oblique scan angles,
which some inspection systems can employ.
7-3.3.3 Fixed / Portable Vehicle X-Ray Inspection Systems (Imaging)
There is a wide range of fixed vehicle inspection systems. The systems operate in a
manner very similar to the mobile systems. The types of systems can be categorized
Stationary Target Vehicle - transmission source and detector travel past the
target on a rail system or similar platform;
Controlled Target Vehicle - vehicle is moved through a fixed inspection system
on a platen or gantry transport, on a rail system, or similar device; and
A Portal system - with a fixed inspection system where vehicles pass-through
Examples of these systems are illustrated in Figures 7-4 to 7-6. The space
requirements vary from minimal for the portal system to significant for a transport or
stationary vehicle system. As encountered for the mobile inspection systems, exclusion
zones may be required for the fixed systems. For illustration purposes, the exclusion
zones and/or radiation levels associated with the SAIC VACIS II and AS&E Shaped
Energy ISO Search systems are provided in Figures 7-7 to 7-9. Note that the VACIS II
exclusion zones depend on the type of radioactive isotope used and the presence of a
shielding wall. Some systems have no exclusion zone outside of the actual scan area.
In no case are the vehicle operators to remain in the vehicle during a scan. The
operator is either to exit the vehicle or the vehicle is positioned such that the operator is
outside the scan area prior to the scan initiating.