wo
minimize external exposur2.
2 survey
or Bikini Atoll was tropcsed.
Tians
zie ‘see acknowledgement) ana the sup-
“<nitiai
called for aerial surveys <=o
tort of the =ERDA Researcn Vessei,
Liktanur,
ierermine external zamma -eveis cn ail
islands in the atoil aleng with zround
surveys using scintillatisn counters
from June 15 througn June 24,
1975.
The casic plans
for the i975 Bikini
survey are outlined below.
and thermoiuminescent dosimeters
(TLD).
imphasis was to te placed on
3ikini and Eneu Islands,
residence islands.
SURVEY PROGRAM OF BIKINI SOIL AND
GAMMA EXPOSURE RATE
zhe prime
In addition,
there
vas to te a rather large scale effort
Survey of Gamma-Exposure Rate
The program for the measurement of
to sample the soil and vegetation to
Zamma-ray exposure rates conducted on
evaluate the potential csse via the
the ground was designed to examine in
terrestrial pathway.
detail the geographical variability of
Ir was feit thac
this was an especially inportanc zoal
the exposure rates on Bikini and Eneu
in view of the significance of the
Islands,
contribution of the food chain to the
measured during previous visits.
and verify exposure-rates
total dose estimated at Znewetrak
Methods and Measurements
Atol.+
For a number of reasons,
A Baird-Atomic scintillation detec
the scale
of the pvrogram had to be reduced from
tor, which consists of a 2.5-cm-diam
that originally planned.
x 3.9-cem-long NaI crystal with a
Manpower and
support were reduced, and the aerial
ratemeter readout was used.
survey was temporally deferred,
instrument was calibrated with a
leaving
The
13765
the entire program of measuring the
point source in the primary calibra-
external dose levels on Bikini and
tion range of the National Environmen-
Eneu Islands to be accomplished by
tal Research Center, Las Vegas, Nevada.
ground crews.”
While the response of this instrument
The emphasis of this
reduced effort was toward the external
is energy-dependent, our experience at
gamma measurements on Bikini and Eneu
Enewetak showed that this was not a
Islands.
food chain pathways was iess extensive
serious limitation because of the
137
than we had hoped, we maintained a
background on the atoll.
smaller scale program designed to help
a Reuter-Stokes high pressure toniza-
assess the potential dose via inges-
tion chamber.
tion pathways.
the radiation-induced ionization within
Although the sampling of the
The 1975 Bikini survey
was conducted with the help of 20 peo-
-3j-
dominance of
Cs in the radiation
We also used
The current produced by
the chamber is measured bv a sensitive