toa
and 24d ay were expected
pCi/eg and 0.06 pCi/g.
to
As expected,
contribute at most a few percent
the profile samples showed a wide
to the total exposure rates.
range of activity distributions as
This
was confirmed by Ge(Li) gamma
a function of depth on the two
spectral analyses of several
islands.
hundred soil samples collected on
are difficult to make,
both islands during the June 1975
on Bikini Island usually decreased
survey.
with depth in the first few centi-
The detailed results of
Fven though generalizations
the activities
the soil survey will be published
meters with a relaxation length of
in a subsequent report.
about 5 cm (the depth at which the
In summary,
the soil survey included the random
activity is et, or 37% of the surface
collection of two types of soil
activity).
samples on each island:
activities were relatively low and
and profile.
surface
Each surface sample
On Eneu Island,
the
uniform throughout the full range
consisted of two L5-cm-deep cores.
of depths sampled.
Profile samples were obtained from
data in conjunction with the data of
the sidewall of a trench dug for
Beck et al.," we estimated the
60
37
the purpose.
median
On Bikini Island
the
average
"Cs and 606, activities
to
the
Cs and
Using these
Co contributions
total gamma-ray
exposure
rates
exhibited by the 15-cm-deep core
over the two islands to be 94% and
samples were 41 pCi/g and 0.74 pCi/g,
6Z,
respectively; while on Eneu Island,
were assumed to be valid over
the corresponding values were 2.5
remaining islands of the atoll.
respectively.
These percentages
the
External D ose Estimation
In addition to the gamma-ray
exposure rates, we need
reasonable selection of possible
to consider
conditions
that would cover
the range
the expected living patterns of the
of doses that could be received by
future inhabitants in order to
any Sizeable segment of the popula-
evaluate the external dose problem.
tion.
Of course,
experiences during the Enewetak
many uncertainties are
These were based upon our
1
,
;
inherent in the prediction of
sutvey
future Living patterns.
with personnel from the Trust
the following cases,
Table 1,
However,
shown in
.
as well as on discussions
Territory of the Pacific Islands.
Suggestions have also been solicited
have been chosen as a
~14-