Hostname: page-component-6bf8c574d5-2jptb Total loading time: 0 Render date: 2025-02-15T09:25:04.892Z Has data issue: false hasContentIssue false
  • English
  • Français

Time Scales for Dissolution of Calcite Fracture Fillings and Implications for Saturated Zone Radionuclide Transport at Yucca Mountain, Nevada

Published online by Cambridge University Press:  10 February 2011

James R. Winterle  and
William M. Murphy
James R. Winterle
Affiliation:
Center for Nuclear Waste Regulatory Analyses, 6220 Culebra Road, San Antonio, TX 78238
William M. Murphy
Affiliation:
Center for Nuclear Waste Regulatory Analyses, 6220 Culebra Road, San Antonio, TX 78238
Get access

Abstract

An analysis was performed to estimate time scales for dissolution of calcite fracture fillings in the fractured tuff aquifer that underlies Yucca Mountain (YM), Nevada, where groundwater is chemically undersaturated with respect to calcite. The impetus for this analysis originates from speculation that undissolved calcite in the saturated zone is evidence for limited diffusive exchange between fracture and matrix waters. Assuming that matrix diffusion is the rate-limiting process, the time scale for dissolution of calcite fracture fillings depends on the amount of calcite initially deposited, the distance between flowing fractures, the degree of chemical disequilibrium, and the rate of diffusion. Assuming geochemistry of J-13 well water in free-flowing fractures, estimated time scales for complete dissolution of matrix-entrapped calcite range from about 104yr for a 2 mm-thick deposit located I m from a flowing fracture, to over 107 yr for a 2 cm-thick deposit located 100 m from a flowing fracture. We conclude that, given the geochemical and hydrologic characteristics observed at YM, the persistence of calcite minerals over geologic time scales in aquifers where flowing water is under-saturated with calcite does not necessarily preclude matrix diffusion as a dilution mechanism. However, our model suggests that the effective spacing between flowing fractures may be large enough to diminish the overall benefit of matrix diffusion to proposed high-level waste repository performance.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 556: Symposium QQ – Scientific Basis for Nuclear Waste Management XXII , 1999 , 713
Copyright
Copyright © Materials Research Society 1999

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Whelan, J.F., Vaniman, D.T., Stuckless, J.S., and Moscati, R.J. in Proceedings of the Fifth International Conference on High Level Radioactive Waste Management, (American Nuclear Society, Lagrange Park, IL, 1994) pp. 1,573–1,580.Google Scholar
2. Bish, D.L. and Chipera, S.J., Los Alamos National Laboratory Report No. LA-1 1497-MS, 1989.Google Scholar
3. Kerrisk, J.F., Los Alamos National Laboratory Report No. LA-I0929-MS, 1987.Google Scholar
4. Murphy, W.M. in Scientific Basis for Nuclear Waste Management XVIII, edited by Murakami, T. and Ewing, R.E. (Materials Research Society, Pittsburgh, PA, 1995) pp.419–426.Google Scholar
5. Based on EQ3/6 database data0.com.R2, Lawrence Livermore National Laboratory (1995).Google Scholar
6. Archie, G.E., Trans. AIME 146, 54 (1942).Google Scholar
7. Hayduk, W. and Laudie, H., J. AIChE, 20, 611–615 (1974).Google Scholar
8. Thordarson, W., Water-Resources Investigations Report 83-4171, (U.S. Geological Survey, Denver, CO, 1983).Google Scholar
9. Bish, D.L. and Aronson, J.L., Clays and Clay Minerals, 41, 148, (1993).Google Scholar
10. Lobemeyer, D.H., Whitfield, M.S. Jr., Lahoud, R.G., U.S. Geological Survey Open File Report 83-855 (U.S. Geological Survey, Denver, CO, 1983).Google Scholar
11. Geldon, A.L., Water-Resources Investigations Report 94-4177, (U.S. Geological Survey, Denver, CO, 1996).Google Scholar
12. Craig, R.W., and Robison, J.H., Water Resources Investigations Report 84-4248, (U.S. Geological Survey, Denver, CO, 1984).Google Scholar
13. Lobemeyer, D.H., Water-Resources Investigations Report 86-4015, (U.S. Geological Survey, Denver, CO, 1986).Google Scholar
14. Wolery, T.J., EQ3NR User's Guide, UCRL-MA- 110662-Pt.3 (Lawrence Livermore National Laboratory, Livermore, CA, 1992).Google Scholar
15. Rasmuson, A. and Neretnieks, I., Water Resources Research 22, 1247, (1986).Google Scholar
16. Triay, I.R., Meijer, A., Conca, J.L., Kung, K.S., Rundberg, R.S., and Strietelmeier, E.A., Yucca Mountain Site Characterization Project Milestone 3784, (Los Alamos National Laboratory, Los Alamos, NM, 1996).Google Scholar
17. Genuchten, M. Th. van in Hydrogeology of Rocks of Low Permeability, IAH Mem 17 (2) (International Association of Hydrogeologists, Ottowa, Ontario, 1985).Google Scholar