After the average dose rate has been determined, entry times that will keep

the total dose below a specified maximum (operation exposure guide) can be

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.

In calculating the total dose to be received in crossing a fallout area, it

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

calculations.

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

cGyph, then,

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.

In calculating the total dose to be received when crossing a fallout area,

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

distance used.

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.