APPENDIX V
Brief Summary of the Radiological Status of the Bikini Atoll
Philip F. Gustafson
Fallout Studies Branch
Division of Biology and Medicin
May 1968
A number of radiological surveys of Bikini Atoll have been made since
1946.
The most recent survey was conducted in April and May 1967.
The
main cf£ort was devoted to the measurement of ambient radiation levels using
several types of detectors.
The external radiation field was mapped in con-
siderable detail on Bikini and Eneu Islands, and less thoroughly on the
remainder of the atoll.
The various radionuclides and their concentrations
which gave rise to the observed radiation field were determined from field
gamma-ray spectrometry.
Representative samples of local plants and animals
which might be caten by the returning natives were collected and have been
analyzed for radioactivity.
The results of the 1967 survey provide a basis for making reasonable
estimates of the total
(external plus internal) radiation exposure which
the Bikinians might receive over the coming years,
atoll.
if they return to the
Background radiation on the atoll is due almost exclusively to
cosmic radiation, and there are only trace amounts of the naturally occurring
radioclements
in the area.
Except
in the
immediate vicinity of nuclear
detonations, the composition of the residual gamma-ray radioactivity was
similar throughout the atoll, consisting of about 70% 137 cg,
20% 0066, and 10% 12385,
to pJace; Eneu was
the
Variations in intensity were observed from place
least contaminated,
followed by Bilcini Island itselr.
A dose gradient existed across Bikini, with lowest
levels on the beach areas,
and highest values in the heavily overgrown interior.
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