Divide the average transmission factor for the fallout shelters (As) by the average
transmission factor during evacuation of the area (Ae).
Determine the multiplication factor. Enter the vertical axis of Figure S-40 in the
Supplemental Booklet at the value determined in Step 1. Move horizontally along the As
value to the Ae curve. Move straight down to the horizontal axis and read the multiplication
Calculate the Optimum Exit Time. Multiply the multiplication factor by the evacuation time
(Tev). The product is the optimum time in hours after detonation that the unit should leave
its shelters and evacuate the area.
Mathematically, this can be expressed as:
Optimum Exit Time = Multiplication factor x Tev.
EXAMPLE PROBLEM: A platoon is occupying an area that received fallout from a nuclear burst. The
personnel are in foxholes (TF 0.1). The platoon will evacuate the fallout area in 2 1/2-ton trucks (TF
0.6). It will take the personnel 1 hour to load into the trucks and leave the area.
For ratios of
that are close to or greater than 0.5,
the unit should evacuate the fallout area as soon as possible. If the optimum
exit time is estimated to be before the actual arrival of fallout, the unit should evacuate the area as soon
as possible after fallout is complete and an uncontaminated area is available. Leaving the contaminated