ia?)
w
ct
ing Program resulted
in
local and regional fallout contamination of islands in the
central Pacific basin,
as Micronesia.
ern Marshall
as
the actual
Most er this contamination affected the North-
Islands of eastern Micronesia,
test
a
oO
proximity to t}
we
in an area which is generically known
m.
sites
or which were
which cither served
in relatively close
Since all of the Marshall
Islands
are low
coral islands or atolls, the natural radioactivity content of
their soil is among the lowest on earth; and their natural
radiation environment is cominated by the contribution of cosmic rays.
In contrast,
the high
islands of the Caroline groups,
to the west of the MNarsnalls, are characterized by voicanic
soils having a significant complement of radionuclides in the
uranium and thorium chains.
Several field trips by SGEP
Division personnel to Micronesia between 1975 and 1980 have
afrorded opportunities to study the natural radiation environments of the coral atolls of the Marshalls and several high
islands
in the Carolines;
and to evaluate the contributions of
fallout fission and activation products to the inventories
The analytical methods
of soil radioactivity in these locations.
employed included in situ gamma spectrometry and exposure rate
measurements with pressurized ion chamber survey instruments.
These measurments were supplemented by laboratory analyses of
soil samples.
The results of these studies have indicated that
significant contributicns
from radioactive
ated in situ with relative ease on coral
fallout can be evalu-
islands.
In contrast,
the higher natural radioactivity content of high island soiis,