4.
Total Dose Received in an Induced Area.
The Total Dose Nomogram in Figure 5-10 is used for predicting total dose to
be received while in an induced radiation area. This nomogram relates total
dose (D), R1 dose rate, stay time (Ts), and entry time (Te). The two scales
at the left show total dose and R1 dose rate. There are two time-of-stay
scales to the right of the index line. The index scale is a pivoting line
which is used as an intermediate step between D and R1 and Ts and Te. The
extreme right scale shows time of entry. The left scale is for Soil Types
II and IV and the right scale is for Soil Types I and III.
Remember the Total Dose Nomogram, Figure 5-10, is never used to find R1.
Soil Types II and IV under stay time are used for total dose calculations if
the soil type is not known.
If the soil type is known, the appropriate
scale under stay time is used. It is possible to find any one value on the
Total Dose Nomogram if the other three are given, as illustrated in the
following problems.
b. Example Problems.
These problems are concerned with techniques only. They do not consider the
impact the dose or dose rates might have on operations in a contaminated
areas.
Problem 1.
GIVEN:
R1 = 140 cGyph
Te = H + 6 hours
Ts = 1 hour
Soil Type II.
FIND:
D.
SOLUTION:
Since no soil type is indicated, use Soil Types II and IV
scale under stay time.
On the nomogram in Figure 5-10,
connect H + 6 hours on the Te scale with 1 hour on the Ts
scale (Soil Types II and IV) with the hairline. Pivot the
hairline at its point of intersection with the index scale
to 140 cGyph on the R1 scale. Read 72 cGy on the D scale
5-33
CM5206
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