Since the portable units are entirely self-contained they require no land based power or other
facilities. If an entry control facility or truck inspection station design is to incorporate a
portable vehicle inspection system similar to those illustrated above, but the system is
unspecified the following recommendations regarding site development should be followed.
Provide a 10.7 m wide x 33.5 m long paved inspection area for use by the portable
equipment. This provides enough width for the inspection system and the lane of
travel for the vehicles to be inspected. The length is sufficient to allow the inspection
system to scan a large stationary vehicle and maneuver.
To increase throughput a longer inspection lane can be provided 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 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 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 23 m if a 305 mm wide x 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.
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 as follows:
Stationary Target Vehicle, transmission source and detector travel past the target on a
rail system or similar platform
Target Vehicle is moved through a fixed inspection system on a platen or gantry
transport, on a rail system, or similar device
A Portal system, with a fixed inspection system where vehicles pass-through the
Examples of these systems are illustrated in Figures 7.5 - 7.7. The space requirements vary
from minimal for the portal system to significant for a transport or stationary vehicle system.
Illustrations of these systems are shown below. 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 7.8- 7.10. Note that the VACIS II
exclusion zones depend on the type of radioactive isotope utilized and the presence of a
shielding wall. Some systems will 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.