dilution of radioactive fallout material in the ocean and Bikinf Ligoon. The
difficult job of deep-mooring 14 to 17 skiffs in the open ocean to the north
of Bikini Atoll was accomplished. The skiff stations were used for fallout
collection.
Collecting stations were instrumented on islands of Bikini Atoll, two
YFNB's and three rafts anchored in the lagoon, and on three manned ships.
Samples collected and studied from early times with respect to gamma and
beta activity were al.o analyzed for chemical and radiochemical composition,
and determinations were made of certain of their physical properties, including distribution of particle size. It is certain that this effort will provide a basis for the improvement of theorics describing the formation, dispersion, and over-all characteristics of fallout.
Four P2V-5 aircraft were used to survey gamma radiation from fallout-
contaminated ocean arcas. The data were used to direct su-vey vessels
and for determining contours in producing land-equivalent fallout patterns.
Fallout samples collected from a number of land stations were subjected ta radiophysical and radiochemical measurements to d termine better
the characteristics ci in-close fallout material. A gamma-rate meter sus-
pended from a helicopter was successfully used to measure dose-rate con-
tours. A few stations were instrumented in an effort to evaluate the roll of
the base surge in transport of radioactive material.
Five B-d7B aircraft were used to collect data on radiation dose and
aircraft contamination resulting from early penetrations into the clouds and
stems of thermonuclear detonations. Twenty-seven penetrations of six
radiation clouds!
“were mace at times ranging
from 20 to 78 miffafter detonation and at altifudes from 20,000 to 59. 000
ft. The dose rate in the stem was found to be less than the dose rate in
the cloud by a factor of 5 to 10. Important information for operational
usage was obtained.
Sufficient data on gamma exposure as : function of distance from the
point of detonation of various high-yield deviccs were obtained so that it
will eventually be possible to conclude dosage contours and the validity of
scaling laws.
A reasonable picture of the initial and the
.dual gamma intensities
as a function of time after the detonation of high-yield devices shouid be
ootained upon postoperational data analysis.
Several types of building surfaces were exposed at various orientations
to fallout on the bows of two of the collection ships. Contamination on all
events was so low that it was not possible to make good decontamination
studies. Surfaces exposed to high fallout fields from
‘8 (Tewa)
ended with very little contamination; however, this initself may give data
for the radiological recovery of military installations constructed from such
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