PREDICTION OF SUBSURFACE-DETONATION FALLOUT
343
The debris disks tracked earthward are defined as follows: In each
cloud (main cloud and base surge), 11 disks of particle size r, are defined at each isobaricsurface p, such that
In ry = In ry ~ 7p (nr, Ing)
where I is equal to 0, 1, 2,..., 10; r, is the radius of the largest particle modeled in the cloud; and r, is the radius of the smallest particle
modeled in the cloud, The term p, is equal to p, — [P/10(p3 — Py)],
where P is equal to 0, 1, 2,..., 10; p, is the pressure at the base of
the cloud at the time of cloud stabilization; and p,, is the pressure at
the top of the cloud at the time of cloud stabilization.
The (H + 1)-hr external gamma dose rate (for a height 3 ft above
an infinite plane) is calculated by using the method of Batten, Iglehart,
and Rapp’! modified to account for the effect of normal shear and
lateral eddy-diffusive disk growth.
The following quantities are calculated in the model and are output
in the indicated modes:*
. Cathode-ray~tube
Printout
Position of surface zero
,
(H + 1)-hr dose rate at the predicted ground posi-
tion of each disk centroid for each cloud
Predicted ground position of each. disk centroid
for each cloud
Envelope containing the areaaffected by the fallout from each cloud
Time of beginning and end of fallout deposition at
each ground-positioncentroid for each cloud
Isopleths of the (H + 1)-hr dose rate for any
_.. Specifled interval.of.dose rate(each contribut—--ing cloud and totalpattern)
_.(H+.1)-hrdose rate as afunctionof distance
ns
the hot Tine {each<cloudanddtotal pattern)
. display
x
x
-
x
x
x
|
Xx
Sntee
.
x
Xx
DIAGNOSTIC CALCULATION FOR SEDAN
For calibration of the cratering fallout model on the Sedan shot,
the obServed shot-time winds, the observed cloud geometry of the main
cloud and the base surge, the estimated F, = 10%, and the appropriate
fission yield were input to the model. A first guess of the 12 activity —
particle size parameters, to be discussed later, was also input to the
* About 0.25 min of IBM 7094 computer time is required for the calculations
for a two-cloud nuclear-cratering fallout problem, and 2.4 min of Livermore
Advanced Research Computer time is required for the cathode-ray-tube displays indicated above.