-—
7h
wr
137¢s contributed 76° to 78 percent
Of these three isotopes
695 and 1256p,
of the total exposure rate and 60¢0 and 125s, each contributed about 10 to
12 percent. These resuits were in agreemenc with gamma field estimates derived from soil sampling data. Also identified at levels tog, low to significantly contribute to the total exposure fate were 155Eu,
Eu, 24lam, and
possibly 106gh,
Table 1
tat
ar
Gamma Radiation Rates in Bikini Atoll
.
mR/hr
fi
The TLD results on the O Transect showed the same trend as in Figure 72,
although these values are slightly higher on the average.
Table Ll shows a summary of the range of exposure rates on Bikini, the
levels applicable to various locations, and the major contributor to the gamma
radiation levels.
Bikini vegetation clearing
experiment
a
planting coconut trees and other food plants could have some effect on population exposures if radionuclides in plants contribute significantly to the external radiation field, A vegetation clearing experiment was planned and conducted on Bikini. The area chosen for the experiment was near the center of
the istand. The dense vegetation at this location, mainly scaevola, was about
three meters high, At a point marked by a stake a complete set of spectro-
Island Center
“OBO. pos
’
Eneu
“o_o
002-.010
omens
137 ¢5
Nam
-O10~ .330
600, 13Tes
Outer Edge
-O10- .030
N.E. Corner
-110-.330
;
.
Rojkere, Eonjebi
oole.020
"006-010
was cleared to 3 meters, 6 meters, and 9 meters radius.
Eneman
001-257
These measurements were repeated as a circular area
Bikdrin, Lele
The radiation levels
At the request of the Trust Territory District Agriculturist, vegetation
The amount of vegetation removed from this smalt
The results of the experiment indicate that clearing vegetation has little
immediate effect on total exposure rate, However, subsequent weathering of
the same as before.
“p03 +030
1010-235
Lukoj
oJ
.
Eneu is the second largest island in the atoll. It containa many buildings
and several steel towers and is less heavily overgrown with scrub vegetation
There was easy access to the interior of the island and a road
along the lagoon shore was quite visible.
Portable instrument measurements
were made along this road and along a path parallel to the ocean shore on the
other side of the island.
Spectrometer and ionization chamber measurements
were made at two places on the lagoon side of the island.
along the Lagoon road to remain about two weeks.
060-.200
°
Jelete
Oroken
.060-.130
.015-.045
Bokdrolul
Bokbata
Aomen-Iroi,) Complex:
-020- .050
-010-,030
.010~ .035
Bokaetoktok
Enew
than Bikini.
-003-.235
East Enidrik
West Enidrik
;
Aomen
Lomilik
;
a
Odrik, Iroij
*
60¢
1
;
.005-.020
.020- .330
-O10-.040
TLD's were placed
*No soil satple or field spectra measurements.
o»
Rh
020+ 057)
Enidrik
area was very large amounting to almost 2,500 kilograms.
0
.
oe ero
West, Eneman
These results give an indication of potential
cleared areas and termination of cycling of radionuclides through scrub plants
could lead to lower radiation levels. The cleared area was resurveyed two
weeks later upon return to Bikini.
The radiation Level was found to be about
"00 7s
East Eneman
removed during the vegetation clearing experiment was separated as to type,
agricultural productivity.
,
-003-.010
Bokantuak, Tomelan,
Aerokoj, Aerokojlol
weighed, and data recorded.
7
.O15-.150
meter, ionization chamber, and portable instrument measurements were made bechanged very little as the area was cleared,
137¢s
0-080
.
Aeroko, -Eneman Complex:
fore any clearing began.
.
"Ooon obo
Island Center
The planned clearing of scrub vegetation on Bikini to make space for
Contributors
.OL0-.120
Hot Spots
greater
ter.
Range
Weathered Areas
Close-to-Share
A separate value is not given for the beta-gamma measure-
=
-
Bikini
’
ments since even at ground level the gamma and beta-gamma values were essential ly the same. One exception was an area near the mid-point of the 1 Traneect
where the beta-gamma levels were consistently higher but not significantly
‘
Ma jor
Exposure Rate
island
1255)
”
;
6%0, 125,
102m»,
B00, 1253.)
l
;
,
Oemn
*
*
*
60%o, 137f¢s
*
60cq, 1255,
*