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Title: Chemical characteristics, migration and fate of radionuclides at commercial shallow-land burial sites. [Maxey Flats, KY]

Conference ·
OSTI ID:6105268

The subsurface migration of radionuclides has been studied at a commercial, shallow-land burial site of low-level nuclear waste at Maxey Flats, Kentucky. A variety of radionuclides including /sup 3/H, /sup 238,239,240/Pu, /sup 60/Co, /sup 137/Cs and /sup 90/Sr have migrated short distances on-site (meters to tens of meters). A number of the mobile radionuclides, notably plutonium and /sup 60/Co, appear to exist as anionic species with organic properties. As a result, we have studied the organic chemistry of radioactive leachates pumped from a number of waste burial trenches throughout the site. The major aim of the organic research is to elucidate the role of organic compounds in mediating the subsurface migration of the mobile radionuclides in groundwater. A survey study of the hydrophilic and hydrophobic organic content of the waste leachates has revealed that organic compounds are readily leached from the buried waste. Organic chelating agents like EDTA, HEDTA, and ED3A are the major hydrophilic organic compounds in the leachates, their concentrations ranging from 78 ppB to 19.5 ppM. A number of carboxylic acids are also present in the leachates, ranging from 671 ppB to 8.8 ppM, collectively. A variety of hydrophobic organic compounds including barbiturates and other aromatic compounds, presumably waste-derived, are also present in the leachates, generally at much lower ppB concentrations. A detailed chemical speciation study, aimed at determining whether any of the organic compounds identified in the survey study are associated with the mobile radionuclides, was undertaken using leachate from one of the waste trenches. It is clear that EDTA is chelated to plutonium and /sup 60/Co in the leachate, potentially mobilizing these radionuclides. Other radionuclides, /sup 137/Cs and /sup 90/Sr, may be associated with polar organic compounds such as carboxylic acids.

Research Organization:
Pacific Northwest Lab., Richland, WA (USA)
DOE Contract Number:
AC06-76RL01830
OSTI ID:
6105268
Report Number(s):
PNL-SA-12707; CONF-8409115-20; ON: TI86007713
Resource Relation:
Conference: 6. annual Low-Level Waste Management Program participants' information meeting, Denver, CO, USA, 11 Sep 1984
Country of Publication:
United States
Language:
English