Health Physics
August 2010, Volume 99, Number 2
Table 9. Ratio of '’Cs inventory in 1991-1993 and 1978 esti-
Atoll
NWRSdata for
1991-1993
(1 SD)
LLNL data
for 1978
(1 SD)
Ailuk
Alinginae
Alinglapalap
Arno
Aur
Bikar
Ebon
Erikub
Jabat
Jaluit
Jemo Island
Kili Island
Knox
Kwajalein (north)
Kwajalein (south)
Lae
Lib Island
Likiep
Majuro
Maloelap
Mejit Island
Mili
Namorik
Namu
Rongelap Island
(south part of atoll)
Rongerik: Enewetak Island
Taka
Taongi
Ujae
Ujelang
Utrik
Wotho
Wotje
1.1 (0.8)
1.0 (0.7)
1.1 (0.7)
1.2 (0.9)
1.3 (0.6)
nr&
1.2 (0.7)
0.6 (0.4)
0.9 (0.6)
0.7 (0.6)
0.8 (0.5)
0.8 (0.6)
nr
0.8 (0.5)
1.5 (0.7)
1.4 (0.8)
1.2 (0.7)
1.1 (0.7)
1.2 (0.9)
1.5 (0.7)
0.8 (0.4)
0.8 (0.5)
0.9 (0.5)
1.1 (0.7)
0.9 (0.6)
1.1 (0.5)
0.8 (0.5)
—
—
—
nr
—
—
—
—
—
—
—
—
1.3 (na)4
—
—
0.7 (0.3)
1.5 (0.8)
—
1.0 (0.5)
—
—
—
0.8 (0.2)
1.0 (0.8)
0.8 (0.7)
nr
1.1 (0.7)
0.8 (0.5)
1.0 (0.7)
1.1 (0.7)
0.7 (0.4)
1.2 (0.6)
1.1 (0.4)
—
—
0.7 (0.3)
0.9 (0.4)
0.9 (0.5)
—
Arithmetic mean (1 SEM)
1.0 (0.043)
1.0 (0.072)
Weighted mean* (weighted
error on the mean)?
0.93 (0.11)
0.85 (0.12)
a?)
= —
1969).
S/o?) ( (Bevington
g
)
be
b
On
=
1
\ v/a?)
“nr: no reliable measurements; na: not enough information available to
estimate uncertainty.
“Uncertainty in measurements could not be estimated. Ratio used in
arithmetic average but not weighted average.
100 |---|
'8’Cs Deposition Density (kBq m”)
mated from all available data to measured inventories by the
NWRS (Simon and Graham 1997) and LLNL (Robison etal.
1981). The soil sample data obtained for Bikar, Knox, and Taongi
were highly uncertain and not suitable for use in the weighted
mean calculations. Dashes indicate no sample measurementdata
were available for comparison.
I
{i
Ei}
CASTLE-BRAVO
CASTLE-ROMEO
CASTLE-YANKEE
0fesssensanensessenennentensnnens
HITTITE
138
Majuro
Kwajalein
Utrik
ATOLL
Rongelap
Island
Fig. 2. Comparison of Bravo, Romeo, and Yankee deposition
densities (kBq m~’) of '’Cs at Majuro, Kwajalein, Utrik and
Rongelap. Note break in Y-axis between 7 and 18 kBq m”’.
southernmost atolls, which includes the capital of Ma-
juro, was between 1 and 3 kBq m~. The cumulative
deposition at many of the mid-latitude atolls (~10°N)
ranged between 3 and 8 kBq m~.
Here it should be recalled that global fallout '*’Cs,
which is not included in these estimates, was about 0.9
kBq m° across the Marshall Islands implying that the
deposition of '’Cs from regional fallout ranged from
about the same value as global fallout on the most
southern atolls, to about eight times that from global
fallout on the mid-latitude atolls (Kwajalein and nearby
atolls). Although global fallout deposition was responsi-
ble for a large fraction of the '’’Cs measuredin soils at
someofthe atolls, this does not imply the doses that were
received locally from Marshall Island tests were comparable to the doses received from global fallout since, as
discussed in the companion papers by Bouville et al.
(2010) and Simonet al. (2010b), most of the dose from
Marshall Island tests to residents was from short-lived
radionuclides.
For purposes of comparison only, mid-latitude con-
tinental locations (30—40°N)received much higher '’’Cs
deposition from global fallout than did the Marshall
Islands. Based on extrapolation from measurements of
Sr in fallout collectors (Larsen 1983) at numerous
locations worldwide, '°’Cs deposition density from
global fallout in the Marshall Islands was only about
15-20% of that in the mid-latitudes.
atolls, Majuro, Kwajalein, Utrik, and Rongelap, are
compared in Fig. 2. We believe that the deposition
densities at these four atolls represent the overall range of
deposition from regional nuclear testing on inhabited
atolls. The cumulative deposition density of '*’Cs in the
A considerably greater amount of '°’Cs from re-
gional nuclear testing was deposited at Utrik and at the
small uninhabited neighboring atoll of Taka, about
20-30 kBq m~, or about 20 to 30 times the global
fallout deposition of '*’Cs. The '*’Cs deposition on a