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 utr/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 °°Co.
This was the
contamination on the buried metal scrap, but the radioisotope
was also found in a soil sample taken from the island. The other
major contributor was +87 G5,
Only small amounts of +25 oh
were present.
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 EXPCSURE RATES
(ur/hr)
Location
1
(Center near
87a,
8° ao
185 oh
Total
As
25.8(39%)
39.4(59%)
1.12%)
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
N
bo
bunker)
(Northeast
(Near lagoon
shore)
(Center on
corner)
4
55.3
western
side)
- 37 -