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FOLOER Enrwelat
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ENEWETOK DOSE ASSESSMENT REVIEW
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EC Watson
File/LB
409837
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I have reviewed the methodology and results of calculations performed by Lawrence
Livermore Laboratory for future inhabitants of Enewetok Atoll.
In general,
I concur with their methods and conclusions. However, I have some questions
and suggestions for the next draft of the LLL document.
T used slightly mocified versions of our computer codes PABLM and iMAXI to
calculate 30- and 50-year accumulated doses and maximum annual doses. I also
used the code DACRIN to try to duplicate some inhalation dose results. I needed
to modify the first two codes in order to accommodate the specific diet of the
Harshall Islands. The codes PABLM and MAX] basically incorporate the recommendcations of ICRP-2, and DACRIN uses the ICRP Task Group on Lung Dynamics model. I
took plant concentration to soil concentration ratio data from the LLL document
where available, and assumed conservative values elsewhere.
The doses calculated are for an adult male only. I did not have time to modify
the codes further for children and women. I.did reduce the masses of al] organs
by a uniform 15°) to account for the smaller size of Marshall Islanders from the
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standard man.
I attempted to incorporate as many of the Livermore assumptions
as I could, to try to follow their exposure scenarios. All ingestion doses
therefore allow an €0-year period initially during which no radionuclides are
ingested.
I did calculate external irradiation doses based on soil concentrations, even
though this was really not necessary since the reported values were based on
actual measurements.
results.
I was able to come comfortingly close ‘+10%) to their
Livermore reports only contributions from ©°Co and ?3’Cs + 0.
Our
program indicated a small calculated contribution from !°2Eu, but never more than
a few percent.
Since it has a short halflife, it is probably not worth worrying
about.
There is not sufficient data presented in the LLL rough draft to predict doses
from isotopes of plutonium, even though they do present dose results.
I believe
they may have predicted plutonium concentrations based on a Pu/Am ratio, but no
confirmations of this appears in the report.
There is not sufficient data presented in the LLL report to predict inhalation
doses from any radionuclide.
No resuspension data is given for the inhalation
pathway.
I have used a resuspension factor of 10-’m-!, based on work by Anspaugh,
and allowed only the top centimeter of soil to be available for resuspension.
Since the inhalation doses vary directly with resuspension, these are somewhat
arbitrary values.
Though the initia] inhalation doses are relatively small, at
long times they will come to be the controlling pathway. The remaining radio-
nuclides (actinides) contribute mainly via the inhalation pathway.