Lesson 2/Learning Event 4
Ground radiological survey are normally performed by personnel mounted in wheeled or tracked
vehicles. The radiological information can also be obtained by personnel on foot, but because of the
resultant high radiation doses to personnel, foot surveys should be conducted only under exceptional
circumstances. Armored vehicles reduce doses received by personnel and will be used whenever
possible. All echelons can perform ground surveys within their areas of responsibility, using regularly
assigned personnel and equipment
Techniques for Ground Radiological Surveys
As noted above, the techniques used to conduct ground surveys include the point technique, the route
technique, and the preselected dose-rate technique. Each of these is discussed in the following
paragraphs.
Point Technique. In using the point technique, the ground dose rate is determined at a selected point of
particular operational concern. The reading can be obtained by dismounting from the vehicle and taking
a direct ground dose-rate reading or by taking the dose-rate readings inside the vehicle. From the
standpoint of accuracy, the first method is preferred. If the dose rate is taken inside the vehicle, the
ground dose rate will be determined by the control party by using a correlation factor. When obtaining
readings, while dismounted, monitors should move away from the vehicle a distance of at least 10
meters to make final readings. This procedure prevents undue shielding of the radiation field by the
vehicle.
Route Technique. In using the route technique, dose-rate readings are taken inside the vehicle at
selected distance intervals between check points along a designated route. Ground dose rates will be
determined by the control party by using a correlation factor. Most ground surveys are performed by
use of the route technique. A route survey is used when the route itself is of operational concern.
Preselected Dose-Rate Technique. In using the preselected dose-rate technique, locations of
preselected dose rates are determined along assigned routes. This technique is normally employed only
for survey of old fallout contamination (after H + 48 hours) or radiological agent contamination where
the decay is very slow. In these situations, dose rates and locations can be plotted directly without
further processing.
In practice, most ground radiological surveys combine the route and point survey techniques.
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