SREL Reprint #2523
A
review of plutonium releases from the
T.
G. Hinton, J. E. Pinder, II
University,
of Georgia, Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA
Abstract
This
chapter reviews two decades of research on plutonium in terrestrial and aquatic
environments of the Savannah River Site (SRS). a nuclear production facility
covering 800 km2 of South Carolina. USA.
Sources and quantities of Po released over the facility's 40 years of
operation are summarized. Some 160
GBq of 238Pu and 239pu were released in isotopic ratios
that allowed researchers to distinguish site emissions from global fallout.
The ratios also proved to be a powerful tool useful for identifying major
pathways through which Pu moved in the environment.
Two major lines of research are reviewed; one examining Pu transport
through agricultural systems typical of the southeastern United States, the
other examining Pu dynamics within lake systems. Regardless of the crop studied, Pu contamination of plants
was dominated by the retention of Pu-bearing particles on plant surfaces from
direct deposition and resuspension, rather than root uptake and translocation of
Flu within the plant. Lar2e-scale
commercial harvesting of contaminated agricultural crops revealed that
mechanized harvest in increased Pu contamination of crops.
Differences in Pu concentrations among crops were due largely to external
plant morphologies that affected soil loading.
Studies on Pu transport in aquatic systems showed that over 99% of the Pu
inventory was within lake sediments. Persistent
and complex annual cycles still exist for Flu within the lake systems studied.
some 20 years after the contamination event.
Field studies and modeling helped discern the relative importance of
anoxic remobilization from the sediments, hydrologic mixing and sedimentation on
the Pu cycle within lakes. Remobilization
of Pu in the winter appears to contribute more to the seasonal cycle than does
the more commonly observed mechanism of remobilization in summer anoxic waters
due to associated Fe-Mn redox phenomena. Doses
to humans from Pu releases were also reviewed and found to be less than those
acquired from naturally occurring radionuclides or from 137Cs
releases. Maximum dose equivalents
(85 µSv) to an individual at the site boundary would have occurred in
1955 and the population dose due to releases that occurred from 1954 to 1989 was
7 person-Sv.
SREL Reprint #2523
Hinton, T. G.,
and J. E. Pinder, III. 2001. A review of plutonium releases from the Savannah
River Site, subsequent behavior within terrestrial and aquatic environments and
the resulting dose to humans. p. 413-435. In
Proceedings of the Second International Symposium Plutonium in the Environment,
edited by A. Kudo. Elsevier, Kyoto University, Osaka, Japan.
