at three of them.
A number of transects of the island and
routes around the island were made to obtain measurements
with the portable counters.
The approximate locations of
these measurements are shown in Figure 7.
The portable survey instruments indicated exposure
rates from 10 to 60 ur/hr around the edge of the island and
from 15 to 160 ur/hr near the center {see Table 1).
Isolated
areas had much higher radiation levels, particularly the
northeastern section where exposure rates of over 200 ur/hr
were measured.
The spectrometer measurements indicated that the major
contributor to the radiation field was °°Cco.
This was the
contamination on the buried metal scrap, but the radioisotope
was also found in a soil sample taker from the island. The other
major contributor was ~*’Cs.
were present.
Only small amounts of **°Sb
The exposure rates due to each isotope and its
percentage of the total
is
shown below for each location,
along with the total exposure rates measured with the
ionization chamber.
SPECTROMETER AND IONIZATION CHAMBER EXPOSURE RATES
(ur/hr}
Location
1
(Center near
bunker)
2 (Northeast
ey)
corner)
4
(Near lagoon
shore)
(Center on
western
side)
*87 as
E © a0
8" oH
Total
Aa
25.8(39%)
39.4 (59%)
1.1 (2%)
66. 3
75.5
60.6(33%)
119.5(66%)
2.0(1%)
182.1
204.0
18.1 (50%)
17.2 (48%)
- 6 (2%)
35.9
34.1
55.3