4.7
CALCULATION OF DOSE RATE d FROM OBSERVED
GAMMA FIELD-SAMPLE ACTIVITY RATIO
Schuert (Reference 4) has calculated gamma fields for certain Operation Castle shots
from a relation of the following kind:
d =kI
(4.7)
Where: I = gammaactivity of collected fallout samples per unit area of collecting surface.
k = factor calculated from gamma activity of fallout samples and gamma field
intensities measured at or near the site of fallout collection.
Both measurements refer to H + 4 days.
When the activity is expressed® in units of
mv cm™ 2 Schuert’s data give for the total collector:
0.048 <k =.0.48
:
r hr!
mv cm=2
and for the gumned paper collector:
k = 0.36 22
-1
mv cm~2
Recently Miller (Reference 6) has calculated k using re-evaluation Rad-Safe gamma
field data and values of gamma activity from fallout samples.
From his data for Shot 1:
k = 0.53 + 26 percent (standard error).
For Shot 3:
k = 0.34 + 21 percent.
vs () (@)
A value for k may be caleulated from Equation 4.4 as follows:
= dr
R
I
I =kI
Where: k=dr=
By substitution there results, using values based upon the spectral data for Shots 5 and 6:
k = 0.35
~1
rhrv"
mv cm7?
amma activity
in mv
8 (gamma activity in mr hr-)) = acti
70