eee
°
.
=,
(
eee (
om:
c
-i-=o>
ie
—
“
.
.
en
fe
.
*
oo,a
ae
L4
Se ke
ete
o ay
.
.
es
aera
However, it is more difficult to determine the diffusion rate.“In order to get:
some idea of the turbulent diffusion of the atomic cloud it will be assumed that =
at H*15 minutes the total cross-sectional area of an atomic cloud from a ‘nominal3.
bomb is approximately 10 to 15 square miles. -Figure 1 and Table III indicate £x-. :
that the radioactive fall-out from TUMBLER/SN&PPER shotno.' 5 was spread over 3.22%
17,000 square miles.
The. fall-out began at H+l hour at a distance of 50 to -ne
75 miles from Ground Zero, at +2 hours within 100 t6 150 miles} and (at He3 2 ais
hours within 150 to 200 miles from ground zero. Obviously some correction should}.
be applied for the motion of the cloud during the first one to “two hours. It” ok
will be assumed that this effect has a value as high as a factor of 2,
In view 7
of this it will be assuned that the total cross-sectional area of the atomic'~ - *:
cloud from-shot 5 would be reduced to awlue between 5000 and 10,000 square.
_ miles.
The average cross-sectional area of the +3 hour atomic cloud of a as
nominal bomb would be approximately 5000 square miles,
ss
This means that in - “
three hours, the atomic cloud has increased in cross-sectional. area Trom 10 to 15 square miles to nearly 5000 square miles.If the cloud ia assumed to be , ex
spherical, then the radiusof the cloud is multiplied by _a factor of BE
due to turbulent diffusion (including shear), provided the. diffusionrate isl é
constant (where t is time in hours after detonation), ~ This’ méans that at Hel 3
hours the cross-sectional area of the cloud would be 1700 square.‘niles vand at
two hours the area. would be approxinately 3400 square miles, =? “a
ve:
: E.
Waxtaum Heiphte Reached by Atomic Cloudsas Compéredtethe. Average’
Heights "here Rain Originates it ¢
a4
4
os
Rt
-
exploded during test operations. Theresults.areY summarized, in Table VIT.Then
RANGER data was obtained from the Los.Alamos’ Report of Operation RANGER,| Volume=
Iv (Secret-Restricted Bata).
From a study. ofthe cloudheights itseens seytousst
that 1 to 2 KT bombs will rise from 10,000 to 20,000 ft.msl,
It will be. assumed;
thatthe atomic clouds of 1 to. 2 KT bombs will be completely ‘enveloped bythe =. Fé
normal rains. It will be assumed that the cloud from 3 to 5 KT bombs will rise.”“3
from 15,000 to 30, ooo ft. msl, hence only in 50% of the ‘cases ‘will rain “succeed.
in “completely covering all of the atomic cloud, It will be”"assumed that” 5 to =:
10 KT bombs willrise: to 25,000 to 40,000 fts" msl and only. gecasionally,will?:
rain come in contact with all of the atomic “cloud. In the’ case of a nominal. °v
‘bomb. (20KT) it will be aSsumedthat.rain will“come “ta ‘contactjmainly |with the*. a.
stem of the cloud,- _It should be noted “that, ‘the’“volumeof the,aushroom cloudis ei
ro a
Ate
normally five to ten tines thevolume of ‘the.stem.” For high_airdrops (2000to|
3000 ft. above ‘terrain for nominal bombs) the stem would be_negligible |to none. F L
existent., For tower shots (100 to 300 ft. towers) the, stemmayhave approxti~ *.:
.
nately 10% of the total bomb activity. | Based upon ‘these, considerations it is.
“<e
possible to evaluate the radioective hazard produced by.“the” Scavenging‘action= © oe
of rain on the H+land H+4 hour old atomic clouds from bombs.of. different, yields?
fhe values obtained are tabuleted in Table VIII. The multiplicationfactorate2&
re
St
BATH Nat neat
~
GP we
3
hepwy “ aed
PEt
oy
to obtain the scavenging action of rain from the ‘available Gata” on the ‘Scavenging!
action of sang were obteined” using the folloning -relation:’