Oxidation-induced geochemical changes in trench leachates from the Maxey Flats low-level radioactive waste disposal site

Journal Article · Sat Feb 01 04:00:00 EST 1986 · Nucl. Technol.; (United States)

OSTI ID:6077766

Dayal, R; Pietrzak, R F; Clinton, J H

A knowledge of extra-trench processes related to oxidation-induced geochemical changes that are likely to occur when iron-rich, anoxic trench waters encounter an oxidizing environment along a redox gradient is essential for modeling radionuclide transport at low-level waste (LLW) disposal sites. The results of laboratory oxidation experiments on several trench leachates from the Maxey Flats site show that, upon oxidation, a series of geochemical changes were initiated that resulted in a drastically different solute geochemistry, involving oxidation of ferrous iron and subsequent precipitation of ferric oxyhydroxide, changes in alkalinity and acidity, a drastic increase in redox potential (Eh), and generally relatively little change in the concentrations of /sup 60/Co, /sup 137/Cs, and /sup 85/Sr in solution. The observations made in this study have important geochemical implications for the modeling of LLW sites in that the source term as an input parameter cannot be assumed to be constant, both spatially and temporally. The acid-generating potential and buffering capacity of an anoxic source term are important geochemical controls that maintain a balance between acidity and alkalinity and largely determine the nature and extent of oxidation-induced geochemical changes likely to occur along a redox gradient. The presence of organic chelating agents can alter the source term geochemistry to such an extent that authigenic ferric oxyhydroxide, which represents a geochemical discontinuity at the redox interface along leachate migration paths, proves to be a relatively ineffective sink for radionuclides.

• Research Organization: Brookhaven National Lab., Dept. of Nuclear Energy, Upton, NY 11973
• OSTI ID: 6077766
• Journal Information: Nucl. Technol.; (United States), Journal Name: Nucl. Technol.; (United States) Vol. 72:2; ISSN NUTYB
• Country of Publication: United States
• Language: English

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54 ENVIRONMENTAL SCIENCES
ACID NEUTRALIZING CAPACITY
ALKALI METAL ISOTOPES
ALKALINE EARTH ISOTOPES
ANOXIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CESIUM 137
CESIUM ISOTOPES
CHEMICAL REACTIONS
CHEMISTRY
COBALT 60
COBALT ISOTOPES
DAYS LIVING RADIOISOTOPES
DISPERSIONS
ECOLOGICAL CONCENTRATION
ELECTRON CAPTURE RADIOISOTOPES
ENVIRONMENTAL TRANSPORT
EVEN-ODD NUCLEI
GEOCHEMISTRY
GROUND WATER
HOURS LIVING RADIOISOTOPES
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LEACHATES
LOW-LEVEL RADIOACTIVE WASTES
MANAGEMENT
MASS TRANSFER
MATERIALS
MINUTES LIVING RADIOISOTOPES
MIXTURES
NUCLEAR FACILITIES
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXIDATION
OXYGEN COMPOUNDS
PH VALUE
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE FACILITIES
RADIOACTIVE WASTES
RADIOECOLOGICAL CONCENTRATION
RADIOISOTOPES
RADIONUCLIDE MIGRATION
REDOX REACTIONS
SOLUTIONS
SOURCE TERMS
STRONTIUM 85
STRONTIUM ISOTOPES
UNDERGROUND DISPOSAL
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER
WATER CHEMISTRY
YEARS LIVING RADIOISOTOPES