Colloid-facilitated radionuclide transport in fractured porous rock

Journal Article · Tue Dec 31 04:00:00 EST 1996 · Waste Management

DOI:https://doi.org/10.1016/S0956-053X(96)00074-8· OSTI ID:449454

Baek, I; Pitt, Jr, W W ^[1]

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1. Texas A and M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

Disposal in geological media is being considered for the long-term isolation of high-level radioactive waste. In this study, a full-equilibrium model was developed to describe the transport and fate of the radionuclides in the fracture. Sorption onto the rock matrix, fracture surface and sorption onto mobile and immobile colloids are included. The effect of colloidal particle size was also considered. Mass partition mechanisms between the colloids and solid matrix and between colloid and contaminant are represented by local equilibrium. In the three-phase system, the three parameters, the retardation coefficient, the hydrodynamic dispersion coefficient and fracture width, are modified to include the equilibrium distribution coefficient of a contaminant with a carrier. In the three-phase model, much smaller retardation and hydrodynamic dispersion coefficients are obtained and the effect of the fracture width is larger. Much faster transport of contaminant has resulted mainly because the radionuclides attached to colloidal particles are not subject to retardation by diffusion into the rock matrix. With the additional consideration of colloidal particle sizes, these effects become ever larger. Numerical solutions for the model were obtained using a fully implicit finite difference scheme. A significant sensitivity to model parameters was discovered, and, in particular, the equilibrium distribution coefficients between a contaminant and the carrier were found to be the most important factors.

• OSTI ID: 449454
• Journal Information: Waste Management, Journal Name: Waste Management Journal Issue: 4 Vol. 16; ISSN WAMAE2; ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
COLLOIDS
GEOLOGIC FRACTURES
HIGH-LEVEL RADIOACTIVE WASTES
MATHEMATICAL MODELS
RADIOACTIVE WASTE DISPOSAL
RADIONUCLIDE MIGRATION
SORPTIVE PROPERTIES