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Observation by Sem/edxs of Leached Layers on SRL-165 Glass from 5-Year MIIT Test

Published online by Cambridge University Press:  01 January 1992

Pedro B. Macedo
Affiliation:
Vitreous State Laboratory, The Catholic University of America, Washington, D.C., 20064
Andrew C. Buechele
Affiliation:
Vitreous State Laboratory, The Catholic University of America, Washington, D.C., 20064
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Abstract

Long-term tests on the durability of nuclear waste glasses, both under laboratory conditions and in actual burial environments, have shown that after periods of several months or years the rates of glass corrosion can show unexpected increases. In burial tests in brine environments the growth of the thickness of the surface layer during years 3 to 5 as revealed by SIMS and SEM measurements was found to be faster than expected on the basis of findings during the first 2 years. In this paper we report on our SEM-EDXS observations of a 5 year burial sample of SRL-165 glass from the MIIT test, and compare our findings to those of other studies, especially SIMS measurements. Our average thickness measurement for the leached layer at the glass-metal interface is 3.70 μm, but wide variation is observed, as well as evidence of partial loss of the leached layer in some areas. A thicker, better retained layer is observed on the glass-brine interface near the core heater averaging 8 to 12 μm in thickness with occasional local attack producing leached layers of greater depth, in one case nearly 40 μm. These findings show that it is important to extend durability tests to long periods in order to establish a reliable basis for predictive modeling of long-term glass durability.

Type
Research Article
Copyright
Copyright © Materials Research Society 1993

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References

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