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which ese the residue of bamb elemsnts and surface msterials,
Soil and water, rade redicactive by ececcpanying radiation
fields. Debris {s sucked Nigh into the atzosvhere by eftes
winds of the explosion. ‘where this radiosctive detris wil}
fell is a mejor pre-shot considerations end pricerily invluences
the decision to detonate a nuclear explosion et a certain tise.
The area over woich radicactive debris is spread end the
intensity of fali-out on the ground ere determined by the yield
of the explosion as well es by wind pattern since the larges
the yield, the more surface materials ere sucked up into the
¢loud and the more fission framments are eveileble. The relaetionship between yield and fall-out is known only qualitatively.
4.
PRE-SHOT IXNSORMATION:
The operational espects of the
BRAVO experience were planneq and conceived in the lisht af
experience geined fran sreviamisoperations.
These factors ware
considered:
Be The basis for ferecasting whate fallout will ¢o
is experiencs gained from overseas test operations CROSSROADS,
SaNDSTONE, GREENEOUSS and IVY and to a certain extent fros tests
at the Neveda Frovins Ground. Prior to the firing of BRATO,
rm
only ons mezaton yield device (IVY-NIn=)-had been detam ted.
Aithough conscientious efforts were cade to docucent the fallout from LIKE, only about 5% of the
tal debris could ever be
accounted for.
‘
The technique used for forecasting fallout pat-
terns is to consider the cloud as a szell area source (adsut a
15 mile radius); then edd vectorially 7arecast winds frac the
surface to approxzimetely 100,000 feet. The nezt step is to
outline an area on the sround where fealiout is expected.
Teis
ares is computed by taking into consideration perticle aize,
diffusion into the atmosphere, wind pattern, yleld and source
radins. Such patterns have been largely canfizrmed by experiqg
ence in Nevada es well as by the meager data availiable hers.
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¢. The Surface redex was plosted,
th ap fasuresce
factor eddad, i.e., smaller particles thes previous experlesce
indicated necessary were considered.
Tris doubled distsoces
from ground zerp woers fallout was predicted to occur.
ad. The upwind intensity of radiation levels at various distenceg was monsidered to be of the sase order of sageitude es for IVY-.T%S.
Sadietion versus distance lines were
transposed to Bikini atoll.
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