SREL Reprint #2442
Apparent
decline of the sediment 137CS
inventory of an abandoned reactor cooling reservoir:
Gregory
P. Lewis, Barbara E. Taylor, John E.
Pinder III,
Savannah
River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA
Received
19 April 1999; received in revised form 12 November 1999; accepted 29 November
1999
Abstract
In
lakes and reservoirs, variability among
sediment samples can mask temporal changes in radionuclide inventories.
For Pond B, an abandoned reactor cooling reservoir in South Carolina,
USA, we determined if a decline in the sediment 137CS
inventory beyond radioactive decay
could be detected over a 10-yr interval. Because
the 95% confidence interval for the decay-corrected change in inventory (-7.7%
to + 0.8% yr-1) included 0, we could not conclusively determine that
a change in inventory beyond radioactive decay had occurred.
Given the sample size of 30 pairs of sediment cores, the minimum change
that could be detected reliably would have been -5.8% yr-1. By
contrast, we estimate that the average export of 137Cs
in surface water over the 10-yr
interval was <0.6% yr-1. For
lakes and reservoirs with low rates of radionuclide export, hundreds to
thousands of sediment cores may be required to detect changes in radionuclide
inventories beyond radioactive decay over time spans less than several decades.
© 2000 Elsevier Science Ltd. All
rights reserved.
Keywords:
SREL
Reprint #2442
Lewis,
G.P., B.E. Taylor, J.E. Pinder, III, and P.M. Dixon. 2000. Apparent decline of
the sediment
137
Cs inventory of an abandoned reactor
cooling reservoir: export or
uncertainty? Journal of Environmental Radioactivity 49:293-306.
