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“-APFFNDIXV."TOENCLOSURE2
Bricf£ Summary of the Radivivgical Status of the Bikini Atoll
t
A
CONF
32 dw 38 only
D TO BE UNCLASSIFIED
AUTHORITY: DOE/SA-20
BY BRo—SCHED? , DATE:
B- 2, 611900
Philip F. Gustafson
Fallout Studies Branch
Division of Biology and Medicine
G-l6-Fut
.
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
“ulin eziort was devoted to the measurement of ambient radiation levels using
‘severai types of detectors.
The external radiation field was mapped in con-
»iderabic detail on Bikini and Eneu Islands, and less thoroughly on the
cemainaer of the atoll.
The various radionuclides and their ‘concentrations
which cave rise to the observed radiation field were determined from field
gamma-ray spectrometry.
Representative samples of local plants and énimals
waach might be eaten 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, if they return to the
aio.i.
Background radiation on the atoll is, due almost exclusivelyto
cosmic radiation, and there are only trace amounts of the naturally occurring
racioelements in the area.
Except in the immediate vicinity of nuclear
aetonations, the composition of the residual gamma-ray radioactivity was
c.milar throughout the atoll, consisting of about 70% 137¢s,
zi. 6000, and 10%
1254,
.
Variations in intensity were observed from place
to place; Eneu was the least contaminated, followed by Bikini Island itself.
A dose gradient existed across Bikini, with lowest levels on the beach are
ait highest values in the heavily overgrown interior.
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