UNCLASSIFIED
eames en ome See ee De
be evaluated.
Physical observation could detail the state of the material
as it landed at the station.
Chemical treatment would allow the separation
and measurement of soluble salts and seawater-insoluble ones which were
to be defined as "insoluble solids." Radiological evaluation would assess
the particle radioactivity. These experimental values then would define
the physical state of the particles, particle size, density, particle spe-
cific activity, total activity, and’mass of fallout per unit area.
Assessment
of
Physical Properties
Visual observations made in the shielded laboratory confirmed the
slurry droplet nature of the fallout. Crystalline materials were observed
to be suspended in the liquid portion of the droplets.. The characteristic
cubic shape of sodium chloride was detected. After the dissolution of
soluble halides, an insoluble-solids component remained on the film.
It was apparent that the slurry droplets contained three major constituents:
water, Soluble sea salts, and insoluble solids from the environmental
materials (Fig. 1).
MeasurementofHalideContent
The reagent film for particle halide analysis utilized a commercial
gelatin film in whichcolloidal red silver dichromate was precipitated
by a special method,! Soluble halides deposited on the film were later
dissolved by saturated hot water vapor and diffused into the gel structure
where they were precipitated as silver salts.
A microscope measure-
ment of the reaction area yielded, by calibration, the weight of halides
reported as sodium chloride, The yneasurable range of sodium chloride
by this method is from 10" to 10%
Be
Measurementof Content
Water
When a droplet strikes the reagent film it spreads to a certain con-
stant degree related to the volume of water in the droplet, 5 Insoluble
solids within each fallout slurry droplet outlined this maximum spread
on the collecting film. A calibration curve was constructed giving the
volume of water in a slurry droplet as a function of the area cevered
by the insoluble-solids trace, This area has been termed the "slurry
artifact.'"' The smallest water volume measurable by this technique is
about 107! ¢c¢,
2a