Environmental geochemistry of chelating agents and radionuclide - chelate complexes. Final report

Technical Report · Tue Oct 28 04:00:00 EST 1980

OSTI ID:5100385

Means, J L; Alexander, C A

The disposal of chelated radioactive waste is discussed. Chelating agents are used in decontamination because they form very selective and strong complexes with nuerous radionuclides. However, if environmentally-persistent chelated wastes are disposed without pretreatment to eliminate the chelating agents, increased radionuclide migration rates from the disposal sites may occur. The environmental chemistry of the three most common aminopolycarboxylic acid chelating agents, NTA (nitrilotriacetic acid), EDTA (ethylenediaminetetraacetic acid), and DTPA (diethylenetriaminepentaacetic acid) is reviewed. Increased solubility and/or migration of radionuclides by chelating agents used in decontamination operations have been observed at two different radioactive waste burial grounds, Oak Ridge and Maxey Flats. These observations suggest that the practice of disposing chelated radioactive wastes should be re-evaluated. Three different technical options for disposing chelated low-level radioactive wastes are proposed: (1) bind the solidified chelated waste in some kind of polymeric organic matrix that has a slow each rate and bury the waste in a dry disposal site; (2) substitute biodegradable chelating agents in the decontamination reagent for the chelating agents that are persistent in the environment; and (3) chemically or thermally degrade the chelating agents in the waste prior to disposal. We feel that surprisingly little attention has been given to an obvious procedure for the disposal of chelated radioactive wastes: chemically or thermally degrading the chelating agent prior to disposal. Any of the above three options might in fact be a satisfactory approach to the disposal of chelated wastes. However, we suggest that the burial of chelating agents such as EDTA be avoided and that option (3) be given more consideration. 100 references, 6 figures, 4 tables.

• Research Organization: Battelle Columbus Labs., OH (USA)
• DOE Contract Number: W-7405-ENG-92
• OSTI ID: 5100385
• Report Number(s): BMI-X-701; ON: DE84010690
• Country of Publication: United States
• Language: English

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54 ENVIRONMENTAL SCIENCES
ACTINIDES
AMINO ACIDS
BIODEGRADATION
CARBOXYLIC ACIDS
CHELATING AGENTS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DOCUMENT TYPES
DRUGS
DTPA
EDTA
ELEMENTS
ENVIRONMENTAL TRANSPORT
GEOCHEMISTRY
GROUND WATER
HYDROGEN COMPOUNDS
MANAGEMENT
MASS TRANSFER
METALS
NTA
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
RADIOACTIVE WASTE DISPOSAL
RADIONUCLIDE MIGRATION
RADIOPROTECTIVE SUBSTANCES
REVIEWS
SOILS
SOLUBILITY
WASTE DISPOSAL
WASTE MANAGEMENT
WATER