Lesson 2/Learning Event 8
Radiological Contour Lines.
In the construction
of the radiological contamination overlay, proper
consideration must be given to factors which locally affect the contamination pattern. This is
particularly true between points in an aerial survey. These factors include, among others, presence of
terrain features such as bluffs or cuts, heavily built-up or wooded areas, and bodies of water. For
example, a large river will carry away the fallout which lands in it, leaving its path relatively free of
contamination. Similarly, the contamination hazard near a lake will be lower than expected since the
fallout particles will sink to the boom and the water will provide shielding. In wooded or built-up areas,
a measure of the reduction of dose rate can be obtained by using the transmission factors for these areas.
Dose-rate contour lines depicting the contamination hazard in an area can be drawn when all the dose-
rate information in the area is posted. This process is accomplished by
Determining the H + 1 dose-rate contour lines to be plotted (for example, 20, 30, 100, 300, 1000
Determining the points along the various survey routes, course legs, and near monitoring
locations where the desired dose rates are located; interpolate linearly between dose rates, if
necessary (figure 22 on page 77).
Connecting all the points having the same dose rates with a smooth line. Use all plotted
monitoring data as additional guides in constructing these contours.
Operations in a nuclear environment will require frequent exchange of radiological intelligence.
Radiological contamination overlays may be disseminated by any of the following methods, arranged in
order of preference:
Electrical Transmission of Hard Copy. Because of its speed and accuracy, the preferred method for
(for example, facsimile). Facsimile devices are normally available at division and higher headquarters.
These devices will be used to transmit contamination overlays to lateral and higher commands.
NBC 5 Report. When hard copy channels
of electrical communications are not available, the
radiological contamination chart is transformed into a series of readings and coordinates for
transmission with the NBC 5 (Nuclear) Report as prescribed in STANAG 2103.