When information is needed to plan surveys or other aspects of the
collection effort, the fallout prediction establishes an outline of the
expected hazard that can be used for this purpose. Fallout prediction is a
procedure used to estimate the probable areas of radiological contamination
from a nuclear burst before actual arrival of fallout. The detailed fallout
prediction is normally prepared by the NBCE. It is based upon 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 when received. Using a current wind vector plot, the NBCE can prepare
a detailed fallout prediction for dissemination within minutes after
receiving required nuclear burst information.
The completed prediction delineates two zones of hazard.
A detailed fallout
prediction must contain the following information.
(1) Identification of grid north (GN), map scale, GZ coordinates, and
date-time of burst.
(2) Two radial lines, drawn from the ground zero point at azimuths
determined from the wind vector plot and radioactive cloud and stem
parameters, dependent on yield.
If wind speeds are below 8 KMPH, the
fallout prediction is considered a special case, and you will have a
(3) Two downwind arcs, representing the downwind distances of Zone I
and Zone II.
(4) A circle drawn around GZ with a radius equal to the stabilized
(5) Two tangents drawn from the ground zero circle to the points of
intersection of the two radial lines with the Zone I arc.
(6) One or more time-of-arrival arcs (dashed), representing the
expected time of arrival of fallout as it moves downwind from ground zero.
Only those time-of-arrival arcs that are located within the zones are
normally indicated on the fallout prediction (Figure 3-1).
within the tactical operations center (TOC) and elsewhere, as required. The
report to other staff agencies both within and outside the TOC and to
higher, adjacent, and subordinate units, as appropriate and indicated in the