the Bravo crater.
instrument bunker.
Off the southern tip is an isolated concrete
The radiation levels on the island were about 15 ur/hr.
High tides must frequently wash across the island.
Consequentiy,
there is little retention of radioactive materials, but
traces are still found due to the close proximity of the
tests.
Samples cf sand from the island and some bottom sediments
from the Bravo crater were taken for gamma spectral analysis.
The sand exhibited mostly °°co, **’cs, and **®sb activity.
-~
€°Co appeared to be responsible for abcut 60% cf the exposure
rate, **’cs about 30% of the exposure rate, and **5 sph and
other elements the remainder.
The bottom sediment sample,
while containing all of the above isotopes, also contained
considerable *°”’ Bi activity.
The major contributor was again
©°Co.
I.
Nam
Nam,
the third largest island,
northwest part of the atoll.
is alsc located in the
This island exhibited yet
another variation of the atoll topography, which caused each
island to seem markedly different in appearance.
Nam has
large open areas covered with fimbrisytiis and ipomea vines.
Messerschmidia trees,
unsurrounded by thick underbrush,
able to spread out and achieve large sizes.
of birds were nesting on the island.
A great number
Radiation levels were found to vary widely on Nam.
bone ey
prem,
addition,
were
In
special problems were presented by pieces of highly
active scrap metal scattered about the island.
One piece of
metal found half-buried near the center of the island
approached the activity of a typical laboratory ©" Co
calibration source - ~500 ur/hr at 1 meter.
it is possible
that a large number of these metal artifacts are in the
soil of this island due to its close proximity to testing
areas.
\
A full set of radiation measurements was performed on
Nam.
Ionization chamber measurements were made at four
widely separated locations with spectrometer measurements