ae
.
IV.
SUMMARY AND CONCLUSIONS
An intensive external radiation survey of Bikini Atoll
was carried out during April and May of 1967.
Total exposure
rates were found to vary considerably from island to island
and from site to site on a given island.
Levels measured
oe
RO
over soil ranged from less than 10 ur/hr to over 500 ur/hr.
(External gamma radiation levels in the United States due to
naturally occurring emitters in the soil range from 0 to
about 20 wr/hr.})
On Bikini and Eneu Islands the major
contributor by far to the total exposure rate was found to
be ~*’cs with minor but Significant contributions from 8° Co
On Nam and other islands closer to blast sites
and **®sb.
°°Co was the main contributor with important contributions
from **° sb,
1°2@™Mpn,
and sometimes
**"Cs.
Other
isoto es,
including 2°" Bi, *© 5 Bu, *S? hu, = 5 on, 1°SRh, +°Rh, 4 Ce,
239 P
and #47 am, were aiso detected occasionally as was
u.
The range of radiation levels on each island are summarized
below.
SUMMARY OF RADIATION LEVELS -
GAMMA EXPOSURE RATES
Gir/hr)
Island
Exposure Rate
Range
Bikini
10-120
Weathered Areas
16-30
Close-to-Shore
20-40
Island Center
Hot Spots
50-80
80-120+
Eneu
2-10
Nam
10-330
Outer Edge
ne
Island Center
N.E. Corner
Bokantuak, Iomelan,
Rojkere, Eonjebi
LO-30
Major
Contributors
*87 Gs
*87 as
°°co, **’cs
15-150
110-330
3-10
—~ 40 -
*