Abstract
We have updated the radiological dose assessment for Rongela
Rongelap Atoll using data generated from field trips to the atoll
through 1993. The data base used for this dose assessmentis ten fold
that available for the 1982 assessment.
Details of each data base are presented along with details about the m
to calculate the dose from each exposure pathway.
The doses are calculated for a resettlement date of January
maximum annualeffective dose is 0.26 mSv y-! (26 mrem y-1).
‘50-, and 70-y
1,
The es
integral effective doses are 0.0059 Sv (0.59 rem), 0.0082 Sv
and 0.0097 Sv (0.97 rem), respectively. More than 95% of these estimate
due to 137-Cesium (137Cs). About 1.5% of the estimated dose is con
90-Strontium (90Sr), and about the same amount each by 239+240
(239+240Pu), and 241-Americium (241Am).
|
Introduction
On March 1, 1954, a nuclear weapon test,
code-named BRAVO, was conducted at Bikini
Atoll in the northern Marshall Islands. The
explosive yield of the detonation greatly
exceeded expectations, with the result that
radioactive material in the cloud was three-tofive times what was expected. Thus, despite the
attention that was given to meteorology in the
operational planning, moderate to heavy fallout
was experienced at the Rongerik, Rongelap,
Ailinginae, Ailuk, Taka, Mejit, and Utirik
Atolls, located to the east of Bikini. Rongelap
and Utirik were inhabited by Marshallese. A
smail number of Rongelap residents werevisiting .
uninhabited Ailinginae, and a small detachment
of U.S. military personnel were stationed on
Rongerik. These people were removed from ail
four atolis as soon as evacuation resources could
be deployed.
The Rongelap evacuation
commenced about 47 hours after the first arrival
of fallout and was completed within a few hours.
Most. of the acute dose received by these
residents was attributable to many short-lived
radionuclides.
dose.to inhabitants of Rongelap Island from manmade sources.
In 1978, in anticipation of the fermination of
its role as trustee under the Ugited Nations
Trusteeship Agreement, the
United States
government decided to conduct
aerial survey
of several atolls east of Bikini Atoll in the
direction of the BRAVO fallogt pattern to
determine the external gamma-egposure rates.
The survey, known as the No
Islands Radiological Survey (NM
conducted using the USNS
helicopters in which the EG&G
Enewetak and Bikini Atolis indi
terrestrial food chain was potenfi
In contrast, by the time they
returned to their atoll three years later (June,
1957), many of these radionuclides had decayed.
However, some radionuclides with intermediate
half-lifes, such as 55-Iron (95Fe), 65-Zinc (65Zn),
and 60-Cobalt (69Co), did contribute to the dose
people received in the first two or three years
(Lessard et al., 1980a) after their return.
Currently, the long-lived radionuclides, 137Cs,
90Gr, 239+240Py, and 241Am, contribute most of the
possible in the time availablefto (1) provide
data for a preliminary dose asfessment at the