Title: Experimental Study on Kinetic Oxidation of Graphite IG-110 by Steam

Abstract

Graphite is proposed for use in High-temperature Gas-cooled Reactors (HTGRs) as the fuel matrix, neutron moderator/reflector, and core structural material. One important property of nuclear grade graphite is their resistance to oxidation in high-temperature environment. Extensive investigation has been performed in the literature for graphite oxidation by air. However, available experimental data are still limited for graphite oxidation by steam under conditions comparable to a postulated steam ingress accident in HTGRs. In this study, the oxidation rate of graphite IG-110 by steam was measured at temperatures from 850 to 1100 °C with the steam partial pressure varying from 0.5 to 20.0 kPa and the hydrogen partial pressure varying from 0 to 2.0 kPa. Further analysis confirms the oxidation process in this present study is dominated by the chemical kinetics, which lends credit to the data for being used to develop numerical models. It was observed that the increase of the kinetic oxidation rate with the steam partial pressure tends to become less apparent if the steam partial pressure keeps increasing. In addition, it was found that the partitioning of hydrogen inhibits the graphite-steam reaction process even with the steam partial pressure up to 20.0 kPa. However, this inhibiting effect startsmore » to become saturated when the hydrogen partial pressure exceeds 1.0 kPa. The oxidation rates were fitted to the conventional Langmuir-Hinshelwood (LH) and Boltzmann-enhanced Langmuir-Hinshelwood (BLH) models by a multivariable optimization algorithm. The BLH model exhibits a better accuracy than the LH model within the specified experimental conditions. The predicted oxidation rate using the BLH model shows a mean relative difference of about 24% with the maximum difference of about 55% when compared with our experimental data.« less

Authors:

Wang, Chengqi ^[1]; Sun, Xiaodong  ^[1]

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+ Show Author Affiliations

1. University of Michigan

Publication Date:

Sun Jan 01 00:00:00 EST 2023

Research Org.:

Univ. of Michigan, Ann Arbor, MI (United States)

Sponsoring Org.:

USDOE Office of Nuclear Energy (NE)

Contributing Org.:

Idaho National Laboratory

OSTI Identifier:

1974508

Alternate Identifier(s):

OSTI ID: 1987918

Grant/Contract Number:  

NE0008782

Resource Type:

Accepted Manuscript

Journal Name:

Nuclear Engineering and Design

Additional Journal Information:

Journal Volume: 410; Journal ID: ISSN 0029-5493

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

Nuclear graphite, IG-110, HTGR, Graphite oxidation, Graphite-steam reaction