between altitudes h, and h,, as shown in Figure 3.1, is superimposed on the instrumenta-~
tion array for 0.5, 1, 2, 3, 4, and 5 minutes after zero time.
The midpoint altitude
‘
(hy + h,)/2, is given for each of these times.
of windspeed and direction estimates
confirmation
as
serves
only
not
fortunately,
This,
for the fallout period, but also allows some rough assessmentof vertical activity distribu-
tion within the cloud.
For the source strength of fission products at 2.4 minutes, Reference 4 gives a value
For the Shot Fig debris at H+ 2.4 minutes, assuming 1.45 = 10% fis/kt.
.
It will be assumed that dose rate as a function of distance from a point source in air can
be described with fair accuracy by
_ §
I= Re e
uv
|
I = dose rate, r/hr
= range, meters
a constant that is proportional to source strength
ww
Where:
_=-R/320
If all the fission products from Shot Fig were concentrated at a single point directly over
the ¥CV barge at 2.4 minutes. the height of the point source necessary to produce the average measured dose rate of
¢omputed from the above is
Reference to Figure 3.4 shows that, at 2.4 minutes
about the
midpoint for the lower of the two puffs that made up the visible cloud (see also Figure 3.2).
This result indicates that the lower part of the visible cloud contained the bulk of the activity.
3.7 CRATER DATA
The two RAMS detectors that were pulled into the crater at H+ 10 minutes were appar~
ently damaged by an electrical transient phenomenon and failed at zero time. However,
dose rates near and within the crater lip were recorded at plus 3.5, plus 18, and plus 47
hours. Results are shown in Figure 3.12. The crater appeared to be contained within the
NTS soil.
A survey was made of the Fig crater on 21 August (D+3 days). Results are summarized
in Figure 3.13. The ledge shown about 4 feet below the crater lip was caused by a cave-in,
which may have been the result of postshot rain.
3.8 PLUTONIUM CONTAMINATION
Several sticky pans were returned to Sandia Laboratory for plutonium analysis by radiochemistry. In Table 3.3, results are listed together with gamma dose rates that were inferred by gamma-counting the same pans. The ratio of the two results is also shown. The
indication is that gamma dose-rate measurement is a poor way to estimate plutonium contamination at a given location. If there were no fractionation between fission products and
plutonium, the ratio would be expected to be ahout 0.06 r/hr/ugm/m?’.
Most of the ratios
are very much higher than this, indicating a larger particle size for fission products than
42