in wind-sensitive contours which have only relative values.
Actual
values may be fitted to the contours as a result of one or more
post-shot survey readings taken in the contaminated area.
A prob-
lem solution requires something more than an hour for personnel
familiar with the method.
U.S. Naval Radiological Defense Laboratory Method
This is a wind and weather dependent system which essumes the
bulk of the radioactive material originates in the lower portion
of the mushroom, and utilizes an aerodynamic particle fall rate
which varies considerably with the altitude of the particle.
A
problem solution requires several hours by personnel familiar with
the method.
The RAND Corporation Method
The method gives wind and weather-sensitive contours, based on
an assumed particle size distribution and the hypothesis that 90%
of the fission product radioactivity falls out from the mishroom
cloud and 10% from the stem.
An aerodynamic rate of fall is used
which is somewhat different. from that used by NRDL, but which also
varies markedly with altitude.
amount of hand calculation.
A problem solution requires a great
The method has also been programmed
for machine solution.
Technical Operations, Inc. Method
The method utilizes an inverted cone cloud model, the NRDL
assumption of particle size distribution, and fall rates which
increase with increase in altitude.
A problem solution requires
somewhat more than an hour, utilizing trained personnel.
There are two general categories into which the fall-out models
can be placed.
The first cetegory is that of a rough approximation
which will furnish Military or Civil Defense officials with a knowledge
of the approximate direction and area of the fall-out field from an
estimate of the yield and winds.
Such methods must be amenable to
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