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Title: Comparison of experimental methods for estimating matrix diffusion coefficients for contaminant transport modeling

Here, diffusion cell and diffusion wafer experiments were conducted to compare methods for estimating effective matrix diffusion coefficients in rock core samples from Pahute Mesa at the Nevada Nuclear Security Site (NNSS). A diffusion wafer method, in which a solute diffuses out of a rock matrix that is pre-saturated with water containing the solute, is presented as a simpler alternative to the traditional through-diffusion (diffusion cell) method. Both methods yielded estimates of effective matrix diffusion coefficients that were within the range of values previously reported for NNSS volcanic rocks. The difference between the estimates of the two methods ranged from 14 to 30%, and there was no systematic high or low bias of one method relative to the other. From a transport modeling perspective, these differences are relatively minor when one considers that other variables (e.g., fracture apertures, fracture spacings) influence matrix diffusion to a greater degree and tend to have greater uncertainty than effective matrix diffusion coefficients. For the same relative random errors in concentration measurements, the diffusion cell method yields effective matrix diffusion coefficient estimates that have less uncertainty than the wafer method. However, the wafer method is easier and less costly to implement and yields estimates moremore » quickly, thus allowing a greater number of samples to be analyzed for the same cost and time. Given the relatively good agreement between the methods, and the lack of any apparent bias between the methods, the diffusion wafer method appears to offer advantages over the diffusion cell method if better statistical representation of a given set of rock samples is desired.« less
Authors:
 [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-26422
Journal ID: ISSN 0169-7722
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Journal of Contaminant Hydrology
Additional Journal Information:
Journal Volume: 209; Journal Issue: C; Journal ID: ISSN 0169-7722
Publisher:
Elsevier
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Environmental Management (EM)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1419758

Telfeyan, Katherine Christina, Ware, Stuart Doug, Reimus, Paul William, and Birdsell, Kay Hanson. Comparison of experimental methods for estimating matrix diffusion coefficients for contaminant transport modeling. United States: N. p., Web. doi:10.1016/j.jconhyd.2018.01.006.
Telfeyan, Katherine Christina, Ware, Stuart Doug, Reimus, Paul William, & Birdsell, Kay Hanson. Comparison of experimental methods for estimating matrix diffusion coefficients for contaminant transport modeling. United States. doi:10.1016/j.jconhyd.2018.01.006.
Telfeyan, Katherine Christina, Ware, Stuart Doug, Reimus, Paul William, and Birdsell, Kay Hanson. 2018. "Comparison of experimental methods for estimating matrix diffusion coefficients for contaminant transport modeling". United States. doi:10.1016/j.jconhyd.2018.01.006.
@article{osti_1419758,
title = {Comparison of experimental methods for estimating matrix diffusion coefficients for contaminant transport modeling},
author = {Telfeyan, Katherine Christina and Ware, Stuart Doug and Reimus, Paul William and Birdsell, Kay Hanson},
abstractNote = {Here, diffusion cell and diffusion wafer experiments were conducted to compare methods for estimating effective matrix diffusion coefficients in rock core samples from Pahute Mesa at the Nevada Nuclear Security Site (NNSS). A diffusion wafer method, in which a solute diffuses out of a rock matrix that is pre-saturated with water containing the solute, is presented as a simpler alternative to the traditional through-diffusion (diffusion cell) method. Both methods yielded estimates of effective matrix diffusion coefficients that were within the range of values previously reported for NNSS volcanic rocks. The difference between the estimates of the two methods ranged from 14 to 30%, and there was no systematic high or low bias of one method relative to the other. From a transport modeling perspective, these differences are relatively minor when one considers that other variables (e.g., fracture apertures, fracture spacings) influence matrix diffusion to a greater degree and tend to have greater uncertainty than effective matrix diffusion coefficients. For the same relative random errors in concentration measurements, the diffusion cell method yields effective matrix diffusion coefficient estimates that have less uncertainty than the wafer method. However, the wafer method is easier and less costly to implement and yields estimates more quickly, thus allowing a greater number of samples to be analyzed for the same cost and time. Given the relatively good agreement between the methods, and the lack of any apparent bias between the methods, the diffusion wafer method appears to offer advantages over the diffusion cell method if better statistical representation of a given set of rock samples is desired.},
doi = {10.1016/j.jconhyd.2018.01.006},
journal = {Journal of Contaminant Hydrology},
number = C,
volume = 209,
place = {United States},
year = {2018},
month = {1}
}