power of time and meteorological arguments suggest this exponent
soon increases to 2.0 to 2.5 because the rate of eddy diffusion
_dncreases with time. The radioactive decay is assumed to be
proportional to the 1.2 power of time.
Table 6.3 is computed
. under the assumption that the over-allchange is proportional- to
+73:2 and shows the radioactivity expected to be collected under
'.°. the core of the cloud, as a function of time.
It should be
_ borne in mindthat. the activity would be significantly higher in
rain « perhaps a factor of ten or even 100.
TABLE6.3
Estimated Meximun Dry Fallout Expected to be Collected
id
ae
Under MIKE Trade Wind Cloud
Collection Period Maxima Radioactivity
Days After Burst
_ “Start
—_—_—
1
2
3
Neate
h
: S°
i
|
Expected Without Rain
End
.
d/m/ft?/day
2
3
b x 10° |
6x10"
5
7x10°)
k
6
12
2x10
kx 10°
3x 10°
Range Estimated to
Include Approximately
'
50% Likelihood gf Occur-
rence d/m/ft</day
=
108to 107
2x20" to 108
©
5 x 210° x 107
2=—Sti<‘<it~‘*«Sdto
_
x 0"
No range ~- an absolute
Value by assumption.
‘tot to 10°
The last item of the table is shown for comparison with the
greatest radioactivity measured wi
entered the United States, name 104
at Boise, Idaho.
this portion of the cloud
d/m collected 11 to 12 November
:
sO
It should be noted that the computation has ‘not been extended
ceed Std ‘eltahanal ni
-to the first day after burst because it is probably invalidated by
the fallout of large particles.
6.6 _ ASSISTANCE 0
METEOROLOGY
In view of the paucity of weather data aud the lack of an
adequate knowledge of tropical meteorology and turbulent diffusion,
it might be expected that the use of atomic debris as a tracer would
2 53