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Where
y = KT of bomb
ms 15 er
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o# Total activity of loud
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cj * Activity of cloudthatcomes in contact with |rain,
And it. is assuned that rain is“tuice as* eefictenta *scavengerof radioactivityme
as sand, and that the radioactive fall-out area would be only. half of the -
average shown in the Figures for sand fall-out to account for cloud aotion
;
during fall-out, In view of the data shown in the inclosed Figures and Tables,’
it becomes evidentrain scavenging has been greatly overestimated in both Ander~-,
son's (5) and in Holzman's (6) reports, Reference 6 overestimates the radio- .: “
active hazard due to rain scavenging because it underestimates both the heights ;j
reached by 10 KT "tactical" atomic bombs and the magnitude of the horizontal
diffusion rate of the atomic cloud.
Holzman ‘clearly recognizes ‘the limitations °!r
of his assumption of the diffusion rate becase he says of the diffusion rate, = '
"This assunption is the weakest of all",
From the data presentedin this re-‘port it is estimated that the redioactive contamination “due. ‘to the scavenging ~
action of rain cannot produce a hazardto life provided the.‘atomic cloud is"
1 hour dd or older, It may be possibleto deposit on. the surface of theground ~
approximately 100r integrated life time dose of radioactivity. if the fifteen minute old cloud of a 1 to 2 KT atomic bombis completely scavenged out by™
rain in a short while after detonation, but the contamineted srea will be con oo
fined to within 1 to 5 miles of ground zero. From the tactical point of view: __
this would be a bonus effect. It is difficult to {magine how rain could possibly.
produce hazardous contamination at distances greater than100 miles from ground °
zero under any circumstances or regardless of the ounbder of 10 KT "tactical® . a
bombs used. Anderson (5) overestinates the fadioactive ‘contaminationprinarily|
because he assumes rain could originate above the mushrodm cloud | ‘from a. 20K:
atomic bomb.
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