Fallout prediction is a procedure of estimating probable areas of
radiological contamination from a nuclear burst before the actual arrival of
fallout. The detailed fallout prediction is normally prepared by the NBCE.
It is based on data for a specific yield, or target analysis information,
and upper air wind data. The upper air wind data are rapidly processed into
a fallout wind vector plot each time they are received. With a current wind
vector plot, the NBCC can have a detailed fallout prediction ready for
dissemination in a matter of minutes after required nuclear burst
information is available.
To competently prepare a detailed fallout prediction, it is necessary to
perform steps as follow:
Step 1. Preparation of Fallout Wind Vector Plot.
The fallout wind vector plot is prepared each time new upper air
wind data are received.
Every prediction made from the current
fallout wind vector plot should be prepared on a separate overlay,
so that the current fallout wind vector plot may be saved for
further use.
The fallout wind vector plot may be drawn to any
convenient map scale.
Step 2. Determination of Nuclear Burst Information.
A convenient worksheet for recording data for the detailed fallout
prediction method is shown in Figure 3-3.
This worksheet may be
reproduced locally. Nuclear burst information is recorded on lines
a through e.
Step 3. Determination of Cloud Parameters.
Cloud parameters are read from Figure 3-4.
Enter Figure 3-4 with
the yield by placing a hairline so that the values on the left yield
index scale and on the right yield index scale are the same. Read
all parameters under the hairline.
Cloud parameter values are
recorded on lines f through j of the worksheet.
Step 4. Initial Determination of Lateral Limits of the Fallout Prediction.
Mark points representing the cloud-top height, cloud-bottom height,
and two-thirds stem height on the fallout wind vector plot; and draw
radial lines from the ground zero point through these height points
(interpolate linearly between the wind vectors if necessary).
Disregard all wind vectors below the
CM5206
3-8
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