Conversion factors for a mobile survey method by car in the Chernobyl area.

Conversion factors for the purpose of mobile survey by car in the Chernobyl area have been evaluated using simulation calculations. In the calculations, the width of road is assumed as being 4 m, 10 m and 20 m and the surrounding area is divided into ten zones contaminated homogeneously by 137Cs with different depth profiles in the ground. The air kerma contribution from all zones to the road is simulated. A conversion factor is calculated by dividing the air kerma rate in typical land-use adjacent to the road by that on the road. Conversion factors in various land uses around the roads are examined. The calculated conversion factors agree with the conversion factors measured in the Chernobyl area within an accuracy of 20%. Further, basic data, needed for composing conversion factors appropriate to other contaminated regions with different depth distributions from the Chernobyl area, are also indicated.