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INTRODUCTION
Fallout research continues to seek a theoretical workiag model
that will describe in detaii ihe mechanism of fallout. Aside fromthis
long-range problem,, consideration must be given to making available
a working tool that will meet the seeds of the military for solving fallout problems in the field, Such consideration requires a simplified
rapid system capable of producing gualitative if not quantitative rescits.
Within a program studying fallout at a recent weapons test opera- tion there was a fallout forecasting assignment that had many aspects of
the practical field prablern yet, at the same time, requiredqaantitative
results for use in reducing other cata. This program needed positioning
data such that three ships cou'd be located properly in the fallout to obtain
data on its parameters. Also, aerial und oceanographic survey projects
Fequired knowledge of the fallout to instigate their navigational procedures,
properly.
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At this operation the Task Force employed a fallout prediction unit
for determining the safe time to detonate the test devices. A}though
many of their techniques for forecasting were similar to those described
in this report, their problem was of a different nature than that of the
fallout program. Several of their methods were unique in that portable
analog computers were tested as field instruments, Thése computers
permitted consideration of many complex parameters, One, in particular, obtained essentially an instantaneous solution to the problem oace
the meteorological data were available.
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To meet these requireménts a technique for rapid fallout forecasting was developed which not only satisfied the needs of the fallout program
but also was accurate enough tc allow comparison between the meteorological aspects of model work and the results obtained from surface
measurements. This technique was restricted te describing quantitatively
the perimeter of the fallout, the axis of the "hot line,and to determining
the time of arrival cf fallout throughout whe pattern, No attempt was made
to quantitate the expected levels of gamma activity or to develop radiation
contour lines.