characteristic of the alkaline solution of Ca(OH), but the pH of the water-surface -burst
fallout was about the same as ocean water, 7.5 to 7.7.
Approximately 25 percent of the particulate matter was not radioactive. The e-aluation of this number is uncertain due to the possible introduction of dust into collector
trays. One sample from Site How indicated that 345 percent of the activity was assoviated
with particles greater than 225 microns in diameter. A iarge traction of the activity was
also found to be associated with very-small particles, but these could have been the result of particle break-up in the sizing procedure.
Radicautographs of particles revealed
1000
oi
a
Particle Diameter, microns
+
100
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ao
64900680! O2
08
:
2
$
19
2
w’w
4
650
60
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96
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oe
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Percentage of Particles with Smaller Diameter
Figure 3.11 Cumulative particle-size distribution.
some with activity only on the surface, others with activity irregularly distributed, and
still others that were radioactive throughout. The angular-shaped particles usually had
the activity on the surface, whereas the uniformly radioactive particles had a spheroidal
shape. The average particle density was 2.4 gm/cm’.
Samples collected on aerosol filters after Shot 1 revealed the same types of particulate: angular with surface activity and spheroidal with a volume-distributed activity. A
water leaching only removed 24 percent of the activity, whereas about 96 percent was
removed by weak acetic acid. Aerosol samples were collected aboard the ships (YAG’s)
stationed in the fallout zone during Shots 2 and 4. The activity appears to have arrived
principally in water droplets.
,
Chemical analysis of the samples was used to separate the fallout composition into
coral, sea-water, and device contributions by evaluating the Ca, Na, and Fe content of
52