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Tracer transport in fractures: analysis of field data based on a variable - aperture channel model

Technical Report:

Abstract

A variable-aperture channel model is used as the basis to interpret data from a three-year tracer transport experiment in fractured rocks. The data come from the so-called Stripa-3D experiment performed by Neretnieks and coworkers. Within the framework of the variable-aperture channel conceptual model, tracers are envisioned as travelling along a number of variable-aperture flow channels, whose properties are related to the mean b{sup -} and standard deviation {sigma}{sub b} of the fracture aperture distribution. Two methods are developed to address the presence of strong time variation of the tracer injection flow rate in this experiment. The first approximates the early part of the injection history by an exponential decay function and is applicable to the early time tracer breakthrough data. The second is a deconvolution method involving the use of Toeplitz matrices and is applicable over the complete period of variable injection of the tracers. Both methods give consistent results. These results include not only estimates of b and {sigma}, but also ranges of Peclet numbers, dispersivity and an estimate of the number of channels involved in the tracer transport. An interesting and surprising observation is that the data indicate that the Peclet number increases with the mean travel time:  More>>
Authors:
Tsang, C F; Tsang, Y W; Hale, F V [1] 
  1. LBL, Univ. of California, CA (United States)
Publication Date:
Jun 01, 1991
Product Type:
Technical Report
Report Number:
STRIPA-TR-91-14
Reference Number:
SCA: 540250; 052002; PA: AIX-23:010995; SN: 92000637733
Resource Relation:
Other Information: PBD: Jun 1991
Subject:
54 ENVIRONMENTAL SCIENCES; 12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; GEOLOGIC FRACTURES; HYDRAULIC CONDUCTIVITY; TRACER TECHNIQUES; APERTURES; DISPERSIONS; EXPERIMENTAL DATA; FLOW RATE; RADIOACTIVE WASTE DISPOSAL; UNDERGROUND DISPOSAL; 540250; 052002; SITE RESOURCE AND USE STUDIES; WASTE DISPOSAL AND STORAGE
OSTI ID:
10111371
Research Organizations:
Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
Other: ON: DE92613500; TRN: SE9100235010995
Availability:
OSTI; NTIS (US Sales Only); INIS
Submitting Site:
SWDN
Size:
63 p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Tsang, C F, Tsang, Y W, and Hale, F V. Tracer transport in fractures: analysis of field data based on a variable - aperture channel model. Sweden: N. p., 1991. Web.
Tsang, C F, Tsang, Y W, & Hale, F V. Tracer transport in fractures: analysis of field data based on a variable - aperture channel model. Sweden.
Tsang, C F, Tsang, Y W, and Hale, F V. 1991. "Tracer transport in fractures: analysis of field data based on a variable - aperture channel model." Sweden.
@misc{etde_10111371,
title = {Tracer transport in fractures: analysis of field data based on a variable - aperture channel model}
author = {Tsang, C F, Tsang, Y W, and Hale, F V}
abstractNote = {A variable-aperture channel model is used as the basis to interpret data from a three-year tracer transport experiment in fractured rocks. The data come from the so-called Stripa-3D experiment performed by Neretnieks and coworkers. Within the framework of the variable-aperture channel conceptual model, tracers are envisioned as travelling along a number of variable-aperture flow channels, whose properties are related to the mean b{sup -} and standard deviation {sigma}{sub b} of the fracture aperture distribution. Two methods are developed to address the presence of strong time variation of the tracer injection flow rate in this experiment. The first approximates the early part of the injection history by an exponential decay function and is applicable to the early time tracer breakthrough data. The second is a deconvolution method involving the use of Toeplitz matrices and is applicable over the complete period of variable injection of the tracers. Both methods give consistent results. These results include not only estimates of b and {sigma}, but also ranges of Peclet numbers, dispersivity and an estimate of the number of channels involved in the tracer transport. An interesting and surprising observation is that the data indicate that the Peclet number increases with the mean travel time: i.e., dispersivity decreasing with mean travel time. This trend is consistent with calculated results of tracer transport in multiple variable-aperture fractures in series. The meaning of this trend is discussed in terms of the strong heterogeneity of the flow system. (au) (22 refs.).}
place = {Sweden}
year = {1991}
month = {Jun}
}