a large abundance of !37C€s relative to other gamma emitting nuclides no
effort was made to correct the readings obtained from the scintillators

whicn were caiv>rated against !97Cs,
The islands can pe divided into essentially three domains:
1,

Beach «rea - uniformly low background of approximately
10 uR/nr.

2.

‘Village Area - located along lagoon side of the island.

For

purposes of this report two sets of data were obtained:
a.

From lagoon road to approximately 250 feet inland
the mean background was 52 pR/hr.

Db.

From lagoon road to beach - 35 yR/hr.

Considering

these two areas together the mean background would
be 44 yR/hr.
3.

Interior - used for agriculture.

This was considered to

include the area within the perimeter road, excluding the
village area.

The mean background was 86 ,,R/hr.

Experience obtained during the clearing operation indicates that total
removal of the vegetative cover and turning of the soil as occurred
during the grading of the perimeter and cross island roads resuits
in a rapid reduction of the measured exposure rate.

If it is assumed

that the village area will be essentially cleared and covered with
crushed coral

as is customary,

it would sean that an expected reduction

of the mean exposure rate by a factor of two would be a conservative
estimate.

Figures 19 and 20 show the integrated exposure for the village and interior areas.

(The beach is assumed constant at <10uR/hr).

By making

assumptions as to the residence time in each domain, the external gamma
dose may be estimated.

If the following assumptions for residence time shovn in Table 5 are
taken, the intearal

(at anv aqe) dose to children born on Bikini

would be the figures shown in Table 6,

33

in 1970

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