GIVEN:

R1 = 200 cGyph Ts = H + 1.5 hours Te = 1 hr.

FIND:

D.

SOLUTION:

On Figure 5-2, connect H + 1.5 hours on the Te scale and 1

hour on the Ts scale with the hairline. Pivot the hairline at

its point of intersection with the index scale to 200 cGyph on

the dose rate (R1) scale. Read D = 90 cGy on the total dose

(D) scale.

ANSWER:

90 cGy.

GIVEN:

D = 20 cGy

R1 = 100 cGyph

TS = 1 hour.

FIND:

Te.

SOLUTION:

On Figure 5-2, connect 20 cGy on the D scale and 100 cGyph on

the R1 scale with the hairline.

Pivot the hairline at its

point of intersection with the index scale to 1 hour on the Ts

scale. Read Te = 3.4 hours on the Te scale.

ANSWER:

H + 3.4 hours.

By 24 hours after burst, the change in the rate of decay is so low that it

is relatively insignificant.

Therefore, in making estimates of the total

dose to be received when entry into the contaminated area is later than H+24

hours, the total dose is obtained by multiplying the dose rate at entry time

by the stay time (in hours). Symbolically, this is written--

D = RTe x Ts, where: D = Total dose,

RTe = Dose rate at time of entry, and Ts = Time of stay.

The calculations above and the nomograms in Figures 5-1 and 5-2 are valid

only if the dose rate reading is made after the radioactive particles have

ceased falling.

For example, a dose rate reading made 1 hour after the

burst while fallout is still arriving is not valid for determining what the

dose rate will be at a later time, since there is no way to determine how

much more fallout will arrive.

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