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Contaminant Release from Solidified Radioactive Wastes Buried in Unsaturated Sediments: Lysimeter Study
Author(s) -
Jones T. L.,
Serne R. J.
Publication year - 1995
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1995.00472425002400060004x
Subject(s) - lysimeter , leachate , leaching (pedology) , portland cement , environmental science , radioactive waste , waste management , environmental chemistry , cement , lessivage , hazardous waste , chemistry , soil water , nuclear chemistry , metallurgy , materials science , soil science , engineering
A lysimeter facility has been used since 1984 to monitor the leaching of buried waste forms under natural, arid conditions. The facility includes 10 bare‐soil lysimeters (183 cm diam. by 305 cm deep) containing buried waste forms solidified with Portland III cement, masonry cement, bitumen, and vinyl‐ester styrene. From 1984 through 1992, an average of 45 cm of water (27% of area precipitation) have leached through the lysimeters. To date, tritium, 60 Co, and 137 Cs have been identified in the lysimeter leachate samples. From 1984 through 1992, >4000 µCi of tritium, representing 76 and 71% of inventory (not decay corrected), have been leached from the two waste forms containing tritium. Cobalt‐60 (<0.1% of original Co inventories) has been found in the leachate from each of all six of the waste forms that originally contained >1 mCi of inventory. Mobile Co is believed to be chelated with organic compounds, such as EDTA, present in the waste. Trace amounts of 137 Cs have occasionally been identified in leachate from two waste forms since 1991. Qualitatively, the field leaching results confirm laboratory studies, suggesting that tritium is readily leached from cement, and that 60 Co is generally leached more from cement than from vinyl‐ester styrene. These data suggest that empirical source‐term models should predict leaching based on the amount of water flowing past the waste form, not based on time.