After the average dose rate has been determined, entry times that will keep
computed on the basis of calculated stay times; or total doses can be
computed for specified entry times and stay times. These calculations are
made in the manner described in the following paragraphs.
is necessary to know the time of entry into the area, the average dose rate
along the route, and the time of stay within the area. Use the total dose
(fallout) nomogram in Figure 5-2 and the methods in Part B for these
In crossing, the average dose rate is equal to one-half the maximum dose
rate encountered on the route. If the maximum dose rate encountered is 60
R1avg = 1/2 R1max = 1/2 x 60 cGyph = 30 cGyph.
In using Figure 5-2, the average dose rate must be normalized (taken back)
to H + 1. Refer to pages 5-6 through 5-8 on the decay nomogram and average
dose rate for determining dose rate at H + 1 and by using Figure 5-1.
follow the procedure below.
1. Calculate the average dose rate.
R1avg = 1/2 R1max.
2. Normalize R1avg to H + 1, unless the dose rate data have already
Eden referenced to H + 1.
3. Calculate the time required to cross the fallout area.
The length of the route within the 20 cGyph (H + 1) contour line is the
4. Find the outside dose, using Figure 5-2 on page 5-12.
5. Calculate the inside dose (ID = OD x TF).
If shielding is involved,
obtain TF from Figure 5-3 on page 5-16.