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U.S. Department of Energy
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Mobilization of actinides from disposal trenches by natural organic matter

Conference ·
OSTI ID:126709
;  [1];  [2]
  1. Oak Ridge National Lab., TN (United States)
  2. Institute of Freshwater Ecology, Ambleside (United Kingdom)
The mechanisms and rates of transport of transuranic (TRU) radionuclides in groundwater at ORNL are being examined to determine the potential role of colloids or natural organic matter (NOM) in radionuclide migration. Radionuclides outside shallow TRU disposal trenches were not associated with inorganic colloids; none of the alpha-emitting radionuclides were retained by a 3000 molecular weight (approximately 1-nm) filter. The radionuclides did appear to be complexed with NOM in the groundwater; both NOM and the radioactivity adsorbed to-and co-eluted from-DEAE anion exchange resin. Results of geochemical speciation modeling also suggest that a substantial fraction of the {sup 241}Am and {sup 244}Cm in the groundwater would be predicted to be complexed. with NOM. It is postulated that increased recharge from rain storms during the winter (1) causes the rising water to intersect the shallow trenches, while (2) mobilizing NOM from the soil profile, which complexes and co-transports the actinides in he waste. This conceptual model is being evaluated in field tracer tests. Rare earth elements, such as europium, will be injected into the TRU trenches as nonradioactive analogs that have chemistry and transport properties similar to the actinides migrating from the trenches.
OSTI ID:
126709
Report Number(s):
CONF-950402--
Country of Publication:
United States
Language:
English