Appendix 14
Gamma Radiation Measurements on Bikini Island, 1974
External gamma exposure rate measurements were made by N. A. Greenhouse
and V. A. Nelson in the village area on Bikini Island during December 1974.
The measurements were made with a Reuter-Stokes environmental radiation monitor, model RSS-111, which uses a pressurized ion chamber as a detector.
The
response of this instrument is relatively independent of gamma-ray energy
(+5%) for incident photons from about 0.2 to 4 MeV.
(The largest contributor to the gamma background at Bikini is 137cs with a gamma energy of 0.667
MeV.)
The results, which include cosmic-ray background (%4 LR/hr; +35 mR/yr),
are given in the table below.
Measurements made through the interior of Bikini Island along the "center
baseline" road indicated gamma exposure rates from 3 to 6 times as high as
the village averages. A detailed survey of the interior is planned for early
1975.
Location
Gamma exposure rate 1 m above
floor or ground, uR/hr
Annual gamma exposure, mR
Inside
Inside
Back yard
Back yard
House #4
7.8
13.2
68
116
House #20
8.0
7.7
70
67
House #28
9.3
15.5
81
136
House #40
9.3
15.5
81
136
75
114
Average
~ 154 -