Shielding factors for vehicles to gamma radiation from activity deposited on structures and ground surfaces.

This paper describes a measuring procedure for the determination of shielding factors for vehicles passing through areas that have been contaminated by activity released to the atmosphere from a reactor accident. In open areas the radiation field arises from an infinite plane source. In urban areas the radiation field consists of the contribution from fallout deposited on a road and on the buildings lying at both sides of the road. It is assumed that these buildings will attenuate completely the radiation from fallout deposited behind the building. A simulated radiation field from fallout has been approximated by a point source that has been placed in a matrix around and above the vehicle. From measurements on different vehicles with and without passengers shielding factors are recommended for ordinary cars and buses in both urban and open areas, and areas with single family houses.