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Author Sawatsky, N. G.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES ♦ GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE ♦ ENVIRONMENTAL SCIENCES ♦ DIFFUSION ♦ MATHEMATICAL MODELS ♦ IODIDES ♦ RADIOACTIVE WASTE DISPOSAL ♦ EVALUATION ♦ BENTONITE ♦ CANDU TYPE REACTORS ♦ EXPERIMENTAL DATA ♦ IODINE 129 ♦ UNDERGROUND DISPOSAL ♦ BETA DECAY RADIOISOTOPES ♦ BETA-MINUS DECAY RADIOISOTOPES ♦ CLAYS ♦ DATA ♦ HALIDES ♦ HALOGEN COMPOUNDS ♦ HEAVY WATER MODERATED REACTORS ♦ INFORMATION ♦ INORGANIC ION EXCHANGERS ♦ INTERMEDIATE MASS NUCLEI ♦ INTERNAL CONVERSION RADIOISOTOPES ♦ IODINE COMPOUNDS ♦ IODINE ISOTOPES ♦ ION EXCHANGE MATERIALS ♦ ISOTOPES ♦ MANAGEMENT ♦ MATERIALS ♦ NUCLEI ♦ NUMERICAL DATA ♦ ODD-EVEN NUCLEI ♦ PRESSURE TUBE REACTORS ♦ RADIOACTIVE WASTE MANAGEMENT ♦ RADIOISOTOPES ♦ REACTORS ♦ THERMAL REACTORS ♦ WASTE DISPOSAL ♦ WASTE MANAGEMENT ♦ YEARS LIVING RADIOISOTOPES ♦ Nuclear Fuels- Waste Disposal & Storage ♦ Mathematics & Computers ♦ Environment, Terrestrial- Radioactive Materials Monitoring & Transport- (1990-)
Abstract Diffusion coefficients, D, are critical parameters for predicting migration rates and fluxes of contaminants through dense bentonite-based barrier materials used in many waste containment strategies. Values of D were determined for I[sup [minus]] ([sup 129]I is a relatively long-lived radionuclide present in high-level nuclear fuel waste) in saturated bentonite using both transient and steady-state techniques. The bentonite was compacted to dry densities, [rho][sub b], ranging from 0.9 to 1.6 Mg m[sup [minus]3], and saturated with a synthetic groundwater solution having an ionic strength of 0.22. Two different D values were determined: an apparent diffusion coefficient, D[sub a] defined as D[sub o][tau], and an effective diffusion coefficient, D[sub a], defined as D[sub o][tau]n[sub e] where D[sub o] is the diffusion coefficient in pure bulk solution, [tau] the tortuosity factor and n[sub e], the fraction of the porosity of the saturated clay that is available for diffusion. There appears to be a critical [rho][sub b] value for this clay of [approx] 1.4 Mg m[sup [minus]3], beyond which the flux of [sup 129]I from the clay can be markedly decreased. By compacting a bentonitic barrier material to a density greater than the critical value, the potential hazard associated with the long-term disposal of nuclear fuel waste that contains [sup 129]I can be decreased. 30 refs., 6 figs., 1 tab.
ISSN 03615995
Educational Use Research
Learning Resource Type Article
Publisher Place United States
Journal Soil Science Society of America Journal
Volume Number 56
Issue Number 5


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