There have been several models developed either for laboratory
reference or for test control conditions.
They have been assessed re-
cently by the Armed Forces Special Weapons Projectt2/ and the summation
of the various fall-out models is presented here in its entirety from
that report:
Armed Forces Special Weapons Project Method
This method is based on ground surveys at JANGLE (surface) and
CASTLE Bravo, end consists of "idealized" contours which follow a
single scaling wind direction.
Abrupt wind shears and unusual
weather conditions are not easily handled.
The method is suitable
for planning purposes only, not for post-shot analysis.
An order-
of-magnitude contour can be drawn for any weapon yield between 0.1
KT and 100 M? in two or three minutes by trained personnel.
Air Research and Development Command Method
The model assumes that 90% of the bomb debris activity is in
the stem of the stabilized cloud, and 10% is in the muskroon.
Mean effective particle sizes are assumed for the cloud and parts
of the stem, and Stokes' law fall rates for spherical particles are
used.
Wind and weather conditions are allowed for.
The method
is calibrated to CASTLE Bravo, but is adaptable over a wide range
of yields.
A problem solution requires several hours by trained
personnel.
Army Signal Corps Method
The model divides a hypothetical stabilized bomb cloud consisting of superposed cylinders into dise or cylindrical wafers or
compartments, each associated with a particular particle size category and fall rate.
Each disc is then brought to the ground accord-
ing to the winds acting on it, and ground values are then summed
over all the discs to obtain contours.
A different model must be
generated for each weapon yield, and for different localities:
a
Armed Forces Special Weapons Project, Fall-out Symposium (Confidential) AFSWP-895, January 1955, SECRET Restricted Data
51