Radionuclide migration in fractured porous rock: Analytical solution for a kinetic solubility-limited dissolution model

Journal Article · Mon Nov 01 04:00:00 EST 1993 · Nuclear Technology; (United States)

OSTI ID:6032961

Li, Shihhai; Chiou, Sheanlang ^[1]

---

1. National Tsing-Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Nuclear Engineering

An analytical solution based on Laplace transforms is developed for the problem of radionuclide transport along a discrete planar fracture in porous rock. The solution takes into account advective transport in the fracture, longitudinal hydrodynamic dispersion in the fracture along the fracture axis, molecular diffusion from the fracture into the rock matrix, sorption within the rock matrix, sorption onto the surface of the fracture, and radioactive decay. The longitudinal hydrodynamic dispersion in the fracture along the fracture axis, molecular diffusion from the fracture into the rock matrix, sorption within the rock matrix, sorption onto the surface of the fracture, and radioactive decay. The longitudinal-dispersion-free solution, which is of closed form, is also reported. The initial radionuclide concentrations in both the fracture and the rock matrix are assumed to be zero. A kinetic solubility-limited dissolution model is used as the inlet boundary condition. In addition to the radionuclide concentrations in both the fracture and the rock matrix, the mass flux in fracture is provided. The analytical solution is in the form of a single integral that is evaluated by a Gauss-Legendre quadrature for each point in space and time. As the dissolution rate constant approaches infinity, the inlet boundary condition of the kinetic solubility-limited dissolution model can be replaced by the boundary condition of constant concentration, as is shown by numerical illustration. Restated, the constant concentration boundary condition represents a conservative upper limit to the solubility-limited dissolution rate. Diffusion into the rock matrix enhances the dissolution rate, even though it can also enhance the retardation of solute transport in fracture.

• OSTI ID: 6032961
• Journal Information: Nuclear Technology; (United States), Journal Name: Nuclear Technology; (United States) Vol. 104:2; ISSN 0029-5450; ISSN NUTYBB
• Country of Publication: United States
• Language: English

Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal & Storage
053002 -- Nuclear Fuels-- Environmental Aspects-- Radioactive Effluents-- (1992-)
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
54 ENVIRONMENTAL SCIENCES
540300 -- Environment
Aquatic-- (1990-)
ANALYTICAL SOLUTION
DISSOLUTION
ECOLOGICAL CONCENTRATION
ENVIRONMENTAL TRANSPORT
FRACTURED RESERVOIRS
HIGH-LEVEL RADIOACTIVE WASTES
INTEGRAL TRANSFORMATIONS
LAPLACE TRANSFORMATION
MANAGEMENT
MASS TRANSFER
MATERIALS
POROUS MATERIALS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE MANAGEMENT
RADIOACTIVE WASTES
RADIONUCLIDE MIGRATION
SOLUBILITY
TRANSFORMATIONS
UNDERGROUND DISPOSAL
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES