A comparison of the performance of nuclear waste glasses by modeling [electronic resource].

Published:: Richland, Wash. : Pacific Northwest Laboratory, 1988.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Additional Creators:: Pacific Northwest Laboratory and United States. Department of Energy. Office of Scientific and Technical Information

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Summary:

Through a combination of data collection and computer modeling, the dissolution mechanism of nuclear waste glasses has been investigated and more clearly defined. Glass dissolution can be described as a dissolution/precipitation process in which glass dissolves in aqueous solution and solids precipitate as the solubility products are exceeded. The dissolution process is controlled by activity of the rate-limiting specie H/sub 4/SiO/sub 4/. As a concentration of H/sub 4/SiO/sub 4/ increases, the rate of dissolution decreases until a final reaction rate is reached. Between the forward reaction rate (early time) and final reaction rate (very long time), glasses may exhibit an intermediate root time dependence caused by a transport resistance for the diffusion of H/sub 4/SiO/sub 4/ within the gel layer on the glass surface. In this report, three glasses are studied: JSS-A, PNL 76-68, and SRL-131. Data from static and dynamic leach tests are assembled, plotted, and successfully modeled. The kinetic parameters for these glasses are reported. With four parameters derived from experiments for each glass, the model can be used to calculate the effects of changes in the initial composition of the water contacting the glass. The effects of convective flow can also be modeled. Furthermore, glasses of different compositions can be readily compared. 49 refs., 27 figs., 5 tabs.

Report Numbers:

E 1.99:pnl-6698
pnl-6698

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Note:

Published through SciTech Connect.
12/01/1988.
"pnl-6698"
"DE89004739"
Grambow, B.; Strachan, D.M.

Funding Information:

AC06-76RL01830

View MARC record | catkey: 14418159