Cohn, Robertson, Conard
(figure 1). Gejen, an uninhabited northern island. received the highest dose.
2.000 1; Rongclap (from which it was necessary to evacuate the mbhabitants)
received an intermediate dose of 175 rand Utirik Island to the east received
14 r in the first 2 davs. The dose rate on the Rongclap Atoll, as measured
a9 €09
2°
TTS
ATOLL
o
at INGIN
ATOLL
50
STATUTE MILES
0°
—
ee
RONGERIK
RONGELAP ATOLL
ATOLL
100
50
|
©ar
BIKAR ATOLL O16;aN
12°
°
UTIRIK ATOLL
&
TAKA ATOLLU UTIRIK
ISLAND
200
_
166°
168°
!
170°
4
10°
Ficure 1}, Isodose lines of estimated pattern of radioactive fallout. Pacific Proving
Grounds. March 1. 1954 The numbers on the map represent the doses that would nave
neem Tecencd over approuumatelh 48 hour without shielding The dose. above wiuch
sumnval is unkkely ws $00 1. and below winch survival is probable is 200 1 ifrom
Cronkite et af, 1956.
initially and over a 5-vear period. is presented in table 1. The values of dose
rate at }] vear varicc from 0.5 mr/hr on Rongelap Island to 3.0 mr/hr on
Kabclle Island. These values represent averages, as the levels of activity were
not uniform on each island. The rapid fal] in gammaactivity over the first 2-vear
period reflects the high percentageof short-lived radioisotopes which contnbute
Tape 1. Average gamma dose rates on Marshall Islands following nuclear detonation
of March 1, 1954 {from Held, 1958)
Gammaexposurelevels Rongcla Atoll
imr/her at 3 ft above ground)
Rongelap Island
Jan. V5 5eee
Oct. 1955
JOH 1956eee
0.5
2.0
0.2
0.4
Pade W957 neeeeecceeernee
0.07
March 1939 ow veces teen
0.035
March 1958 oe
Aug. 1958 nee
Eniaetok Iskand
Kabelle Island
3.0
12
0.029
0.058
0.067
0.076
0.048
308
6.20
0.14
0.16
0.10