Water vapor oxidation behaviors of nuclear graphite IG-110 for a postulated accident scenario in high temperature gas-cooled reactors

Water leakage in accidental conditions of high temperature gas-cooled reactors is one of the most critical problems that can compromise the integrity of different nuclear components. In this study, oxidation behaviors of nuclear graphite IG-110 in water ingress accidental conditions were investigate...

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Bibliographic Details
Published in:Carbon (New York) 2020-08, Vol.164 (C), p.251-260
Main Authors: Cho, Yi Je, Lu, Kathy
Format: Article
Language:English
Subjects:
Accidents
Atmosphere
Graphite
High temperature
High temperature gas cooled reactors
Nuclear engineering
Nuclear reactors
Nuclear safety
Oxidation
Oxidation tests
Oxidizing agents
Pore formation
Porosity
Reactors
Temperature dependence
Water vapor
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Summary:Water leakage in accidental conditions of high temperature gas-cooled reactors is one of the most critical problems that can compromise the integrity of different nuclear components. In this study, oxidation behaviors of nuclear graphite IG-110 in water ingress accidental conditions were investigated. Mass loss and oxidation rates were evaluated after oxidation tests at temperatures up to 1400 °C in an Ar-20 vol% H2O mixed atmosphere. The activation energy decreased from 318.6 to 148.9 kJ/mol with temperature, indicating two different oxidation regimes. The cross-sections of the oxidized samples were systematically characterized. The corresponding logarithmic porosity profiles showed a temperature dependency. Pore formation moved toward near-surface regions with increasing temperature and preferential binder oxidation, with filler particle degradation. Furthermore, oxidant concentration profiles and oxidation depths were estimated using a theoretical model and compared with the experimental results. This work provides important benchmark data and safety analysis guidance for the accident scenario in high temperature gas-cooled reactors. [Display omitted]
ISSN:0008-6223
1873-3891
DOI:10.1016/j.carbon.2020.04.004