Tracer transport in fractured rocks

Conference · Fri Jul 01 04:00:00 EDT 1988

OSTI ID:7056663

Tsang, C F; Tsang, Y W; Hale, F V

Recent interest in the safety of toxic waste underground disposal and nuclear waste geologic repositories has motivated many studies of tracer transport in fractured media. Fractures occur in most geologic formations and introduce a high degree of heterogeneity. Within each fracture, the aperture is not constant in value but strongly varying. Thus for such media, tracer tends to flow through preferred flowpaths or channels within the fractures. Along each of these channels, the aperture is also strongly varying. A detailed analysis is carried out on a 2D single fracture with variable apertures and the flow through channels is demonstrated. The channels defined this way are not rigidly set pathways for tracer transport, but are the preferred flow paths in the sense of stream-tubes in the potential theory. It is shown that such variable-aperture channels can be characterized by an aperture probability distribution function, and not by the exact deterministic geometric locations. We also demonstrate that the 2D tracer transport in a fracture can be calculated by a model of a system of 1D channels characterized by this distribution function only. Due to the channeling character of tracer transport in fractured rock, random point measurements of tracer breakthrough curves may give results with a wide spread in value due to statistical fluctuations. The present paper suggests that such a wide spread can probably be greatly reduced by making line/areal (or multiple) measurements covering a few spatial correlation lengths. 13 refs., 11 figs., 1 tab.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7056663
• Report Number(s): LBL-25657; CONF-880583-5; ON: DE89001258
• Country of Publication: United States
• Language: English

Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal & Storage
053000 -- Nuclear Fuels-- Environmental Aspects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
DATA
FAILURES
FLOW RATE
FLUID FLOW
FRACTURES
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GROUND WATER
HAZARDOUS MATERIALS
HIGH-LEVEL RADIOACTIVE WASTES
HYDROGEN COMPOUNDS
INFORMATION
ISOTOPE APPLICATIONS
MANAGEMENT
MATERIALS
NUMERICAL DATA
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE MANAGEMENT
RADIOACTIVE WASTES
ROCKS
STATISTICAL DATA
TRACER TECHNIQUES
TWO-DIMENSIONAL CALCULATIONS
UNDERGROUND DISPOSAL
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER