Hostname: page-component-7479d7b7d-fwgfc Total loading time: 0 Render date: 2024-07-12T10:37:12.086Z Has data issue: false hasContentIssue false
  • English
  • Français

The Effect of Groundwater Flow on Release Rate Behavior of Borosilicate Glass

Published online by Cambridge University Press:  26 February 2011

M. J. Apted  and
R. Adiga
M. J. Apted
Affiliation:
Pacific Northwest Laboratory, P. O. Box 999, Richland, WA 99352
R. Adiga
Affiliation:
University of Florida, Gainesville, Florida 32611
Get access

Abstract

A simple open-system model is used to evaluate the effect of groundwater flow on borosilicate glass dissolution. With appropriate assumptions, the mass balance equation is: dc/dt=R-kfc;R=k(ceq-c)

where c is the concentration of dissolved species i, t is time, kf is the flushing frequency (i.e., volumetric flow rate divided by fixed pore volume), and R is the normalized rate of dissolution. A first-order dependence of R on departure of c from the equilibrium saturation concentration, Ceq, is also assumed. Results from steady-state (dc/dt = 0; c = css = constant) static and dynamic flow tests on a borosilicate glass at 90°C were used to calculate R and the dissolution rate constant, k, as a function of flow rate. The calculated results of the model are in good agreement with independent measurements.

There are three important conclusions. First, even the slowest flow rate used (0.1 ml/hr) corresponds to a high flow rate with respect to the intrinsic dissolution rate of the glass and expected repository flow conditions. Second, previous release models that scale radionuclide release rate directly to solubility concentration may overestimate release at high flow rates. This is because previous models fail to account for the pronounced decrease in steady-state solution concentration at the solid interface with increasing flow rate. Third, increased flow rate accelerates the glass dissolution rate without changing the reaction mechanism. This effect is attributable to constant replenishment of undersaturated solution at the glass surface and an apparent increase in the dissolution rate constant with increasing flow rate.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 44: Symposium N – Scientific Basis for Nuclear Waste Management VIII , 1984 , 163
Copyright
Copyright © Materials Research Society 1985

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

1. Strachan, D.M., “Effects of Flow Rate on the Leaching of Nuclear Waste Glass.” Advances in Ceramics. 8 (1984) 12–18.Google Scholar
2. Barkatt, A., Gibson, B.C. and Brandys, M., “A Kinetic Model of Nuclear Waste Glass Dissolution,” this volume (1985).CrossRefGoogle Scholar
3. Machiels, A.J. and Pescatore, C., “Modelling of Waste Form Leaching. Part II: Mechanistic Modelling of Nuclear Waste Form Leaching by Aqueous Solutions.” ONWI/E512-06000-2, Office of Nuclear Waste Isolation, Battelle Columbus Labs., Columbus, OH (1982).Google Scholar
4. Macedo, P.B., Barkatt, A. and Simmons, J.H., “A Flow Model for the Kinetics of Dissolution of Nuclear Waste Glasses.” Nucl. Chem. Waste Manage., 2 (1982) pp. 151–164.Google Scholar
5. Wallace, R.M. and Wicks, G. G., “Leaching Chemistry of Defense Borosilicate Glass.” Scientific Basis for Nuclear Waste Management VI, ed. Brookins, D.G. (North-Holland, New York, 1983) pp. 23–28.Google Scholar
6. Coles, D.G. and Apted, M.J., “The Behavior of 99Tc in Doped-Glass/Basalt Hydrothermal Interactions Tests.” Scientific Basis for Nuclear Waste Management VII, Vol.26, ed. McVay, G.L. (North-Holland, New York, 1984) pp. 129–136.Google Scholar
7. Jantzen, C.M., “Methods of Simulating Low Redox Potential (Eh) for a Basalt Repository.” Scientific Basis for Nuclear Waste Management VII, Vol. 26, ed. McVay, G.L. (North-Holland, New York, 1984) pp. 613–621.Google Scholar
8. Berner, R.A., “Rate Control of Mineral Dissolution Under Earth Surface Conditions.” Am. J. Sci. 278 (1978) 1235–1252.CrossRefGoogle Scholar
9. Barkatt, A., Macedo, P.B. and Montrose, C.J., “Mechanisms of Defense Waste Glass Corrosion: Dissolution of Glass Matrix.” In Final Report of the Defense High-Level Waste Leaching Mechanisms Program, Mendel, J.E., compiler. PNL-5157, Pacific Northwest Laboratory, Richland, WA (1984).Google Scholar
10. Adiga, R., Clark, D.E. and Akomer, E.P., “Effects of Flow Parameters on the Leaching of Nuclear Waste Glasses,” this volume (1985).CrossRefGoogle Scholar
11. Paces, T., “Reversible Control of Aqueous Aluminum and Silica During the Irreversible Evolution of Natural Waters,” Geochim. Cosmochim. Acta 42 (1978) 1487–1493.CrossRefGoogle Scholar
12. Zavoshy, S.J., Chambre, P.L. and Pigford, T.H., “Waste Package Mass Transfer Rates in a Geologic Repository,” this volume (1985).CrossRefGoogle Scholar
13. Grambow, B. and Strachan, D.M., “Leach Testing of Waste Glasses Undef' Near-Saturation Conditions,” Scientific Basis for Nuclear Waste Management VII, Vol.26, ed. McVay, G.L. (North-Holland, New York, 1984) pp. 623–634.Google Scholar
14. Chambre, P.L. and Pigford, T.H., “Prediction of Waste Performance in a Geologic Repository,” Scientific Basis for Nuclear Waste Management VII, Vol. 26, ed. McVay, G.L. (North-Holland, New York, 1984) pp. 985–1008.Google Scholar
15. Apted, M.J., McVay, G.L. and Wald, J.W., “Dissolution of Specific Radionuclides: Actinide Release.” In Final Report of the Defense High-Level Waste Leaching Mechanisms Program, Mendel, J.E., compiler. PNL-5157, Pacific Northwest Laboratory, Richland, WA (1984).Google Scholar
16. National Academy of Sciences, “A Study of the Isolation System for Geologic Disposal of Radioactive Wastes.” (National Academy Press, Washington, DC, 1983).Google Scholar
17. Rimstidt, J.D. and Barnes, H.L., “The Kinetics of Silica-Water Reactions.” Geochim. Cosmochim. Acta 44 (1980) 1683–1699.CrossRefGoogle Scholar
18. Dibble, W.E. Jr. and Potter, J.M., “Effect of Fluid Flow Rates onGeochemical Processes.” SPE-10994, Society of Petroleum Engineers of AIME, Dallas, TX (1982).Google Scholar
19. Pohl, D.C. and Liou, J.G., “Flow-Through Reaction of Basalt Glass and Seawater at 300°C and 200°C, 250 Bars Pressure.” In Fourth International symposium on Water-Rock Interaction, ed. Seki, Y.. (Okayama University, Misasa, Japan, 1983).Google Scholar
20. Dibble, W.E. Jr. and Tiller, W.A., “Kinetic Model of Zeolite Paragenesis in Tuffaceous Sediments.” Clay and Clay Minerals 29 (1981) 323–330.CrossRefGoogle Scholar
21. Grambow, B., “A General Rate Equation for Nuclear Waste Glass Corrosion,” his volumbe (1985).CrossRefGoogle Scholar