ae
cS cea n nae ‘y
tantalum pellets were used.
The work deals with the ultimate size of
particles resulting from disintegration of the test pellets and with the
extent to which such hazardous particles might become airborne with
varying wind velocity.
o
The humidity at which tantalum pellets are disintegrated has
no effect on the particle size, although it does affect the rate of disintegration, higher humidities producing more rapid disintegration.
Particle-size distributions and quantities of airborne tantalum were
determined in wind-tunnel tests.
At a wind speed of 10 mi/hr, 7% of the
tantalum became airborne, and 99% of this airborme material was found to
be 1l3u, or smaller, in size.
In small-scale field tests, contamination
of a desert area with the test agent resulted in no detectable airborne
radioactive material at wind velocities up to 20 mi/br.
With wind
velocities of 25 mi/br and simultaneous distwrbance of the area by
vehicular movement, radioactivity was noted 200 ft downwind of the area
to the extent of only 5 x 10710,¢/cc.
CRLR - 188
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RADIOACTIVE PARTICLE STUDIES INSIDE AIRCRAFT (UKP-8).
(Operation UPSHOT-KNOTHOLE)
John M. Roady and Nicholas 5. Capasso, 11 June 1953.
CONFIDENTIAL
Samples were taken of air entering the cockpits of F-80 drone
aircraft that penetrated the atomic clouds a short time after the
detonation of two of the airburst shots of Operation UPSHOT-KNOTHOLE.
Particulate matter in the sampled air was collected on the slides of a
five-stage cascade impactor and on a millipore filter attached to the
effluent end of the impactor.
This report records the test setup employed
for evaluation of the potential inhalation hazard to which aircraft crews
would be subject on passing through an atomic-bomb cloud.
For such evaluation it was necessary to collect4& suitable
sample of the cloud particulate matter of the size range in which lung
retention is a maximum (0.ly to 10, diam).
The collection was made ina
manner that made possible the determination of: (1) concentration of alpha
and beta activity in the air; (2) particle-size distribution and activity
vs particle size,
(3)
specific activity of individual particles in the
specific size range, (4) total activity of air in the cockpit at peak
concentration, and (5) the rate of dilution of this air by clean air upon
emergence from the cloud.
measurements were made.
The samples were later analyzed, and supporting
The final report of this work appeared as CRIR-299 and WI-71T.
eee.
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