Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1565730 | Journal of Nuclear Materials | 2013 | 11 Pages |
Abstract
One of the most severe accident scenarios anticipated for VHTRs is an air ingress accident caused by a pipe break. Graphite oxidation could be severe under these conditions. In this work, the oxidation rate of NBG-18 nuclear-grade graphite was studied thermogravimetrically for different oxygen concentrations and with temperatures from 873 to 1873Â K. A semi-empirical Arrhenius rate equation was developed for the temperature range of 873-1023Â K. The activation energy of NBG-18 was 187Â kJ/mol and the order of reaction was 1.25. The penetration depth of oxidant was about 3-4Â mm for NBG-18 oxidized at 973Â K. Increased porosity and changes in external geometry became more prominent at higher temperatures from about 1173 to 1873Â K. The surface of oxidized NBG-18 was characterized by SEM, EDS, FTIR and XPS.
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Physical Sciences and Engineering
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Nuclear Energy and Engineering
Authors
Jo Jo Lee, Tushar K. Ghosh, Sudarshan K. Loyalka,