Following an improvised nuclear device (IND) attack, many of the characteristics of the IND
will not be immediately clear. Key, initially uncertain, parameters that will significantly
influence the fallout plume include detonation location, height of burst, and device yield. Even if
both surface and high altitude meteorology were known perfectly, these uncertainties mean that
early calculations of the nature of the fallout plume will likely be in error. As the response
progresses, observations and radiation measurements on the ground and in the air must be
directed toward identification of burst conditions and ground truth regarding the extent of fallout
areas. This situational assessment will provide the basis for guiding responder rescue operations
near hazard zones and for informing evacuation strategies for individuals within fallout areas.
The information requirements that provide the basis for effective evacuation away from the
highest dose regions of the fallout hazard area can be quite demanding. The exemplary point
analyses indicate that significant reductions in evacuation effectiveness can occur if fallout
plume projections are just a few degrees in error. This can be contrasted with current guidance
for fallout area operations proposed in earlier program meetings with first responder
communities.
14
This guidance, based on a keyhole-shaped exclusion area, is illustrated in Figure
25. The buffer areas reflecting uncertainties in initial modeling of the fallout plume have not
been quantified in this or earlier studies. The size of the buffer zone depends on weapon,
detonation location, meteorological conditions, and the quality of the model used in making the
plume estimates.