Files in this item



application/pdf9953170.pdf (7MB)Restricted to U of Illinois
(no description provided)PDF


Title:The Development and Application of Reactive Transport Modeling Techniques to Study Radionuclide Migration at Yucca Mountain, Nevada
Author(s):Viswanathan, Hari Selvi
Doctoral Committee Chair(s):Valocchi, Albert J.
Department / Program:Civl and Environmental Engineering
Discipline:Civl and Environmental Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Abstract:Yucca Mountain, Nevada has been chosen as a possible site for the first high level radioactive waste repository in the United States. As part of the site investigation studies, we need to make scientifically rigorous estimations of radionuclide migration in the event of a repository breach. Performance assessment models used to make these estimations are computationally intensive. We have developed two reactive transport modeling techniques to simulate radionuclide transport at Yucca Mountain: (1) the selective coupling approach applied to the convection-dispersion-reaction (CDR) model and (2) a reactive streamtube approach (RST). These models were designed to capture the important processes that influence radionuclide migration while being computationally efficient. The conventional method of modeling reactive transport models is to solve a coupled set of multi-dimensional partial differential equations for the relevant chemical components in the system. We have developed an iterative solution technique, denoted the selective coupling method, that represents a versatile alternative to traditional uncoupled iterative techniques and the fully coupled global implicit method. We show that selective coupling results in computational and memory savings relative to these approaches. We develop RST as an alternative to the CDR method for solving large two- or three-dimensional reactive transport simulations for cases in which one is interested in predicting the flux across a specific control plane. In the RST method, the multidimensional problem is reduced to a series of one-dimensional transport simulations along streamlines. The key assumption with RST is that mixing at the control plane approximates the transverse dispersion between streamlines. We compare the CDR and RST approaches for several scenarios that are relevant to the Yucca Mountain Project. For example, we apply the CDR and RST approaches to model an ongoing field experiment called the Unsaturated Zone Transport Test.
Issue Date:1999
Description:144 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1999.
Other Identifier(s):(MiAaPQ)AAI9953170
Date Available in IDEALS:2015-09-25
Date Deposited:1999

This item appears in the following Collection(s)

Item Statistics