Degradation of partially immersed glass: A new perspective

The International Simple Glass (ISG) is a six-component borosilicate glass which was developed as a reference for international collaborative studies on high level nuclear waste encapsulation. Its corrosion behaviour is typically examined when it is immersed in a leaching solution, or when it is exp...

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Bibliographic Details
Published in:Journal of nuclear materials 2018-05, Vol.503, p.56-65
Main Authors: Chinnam, R.K., Fossati, P.C.M., Lee, W.E.
Format: Article
Language:English
Subjects:
Borosilicate glass
Chemical precipitation
Condensates
Condensed Matter
Corrosion
Corrosion mechanisms
Corrosion tests
Degradation
Glass
Leaching
Materials Science
Nuclear chemistry
Physics
Protective coatings
Radioactive wastes
Radioactivity
Silica
Steady state
Storage conditions
Supersaturation
Water film
Water vapor
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Summary:The International Simple Glass (ISG) is a six-component borosilicate glass which was developed as a reference for international collaborative studies on high level nuclear waste encapsulation. Its corrosion behaviour is typically examined when it is immersed in a leaching solution, or when it is exposed to water vapour. In this study, an alternative situation is considered in which the glass is only partially immersed for 7 weeks at a temperature of 90 °C. In this case, half of the glass sample is directly in the solution itself, and the other half is in contact with a water film formed by condensation of water vapour that evaporated from the solution. This results in a different degradation behaviour compared to standard tests in which the material is fully immersed. In particular, whilst in standard tests the system reaches a steady state with a very low alteration rate thanks to the formation of a protective gel layer, in partially-immersed tests this steady state could not be reached because of the continuous alteration from the condensate water film. The constant input of ions from the emerged part of the sample caused a supersaturation of the solution, which resulted in early precipitation of secondary crystalline phases. This setup mimics storage conditions once small amounts of water have entered a glass waste form containing canister. It offers a more realistic outlook of corrosion mechanisms happening in such situations than standard fully-immersed corrosion tests.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2018.02.040