Air oxidation of yttrium hydride as a high temperature moderator for thermal neutron spectrum fission reactors

JOURNAL OF NUCLEAR MATERIALS

卷:556

Article

Kane, K.¹  Hu, X.¹  Stack, P.²  Mouche, P.¹  Brigham, B.³  Sooby, E.³  Pint, B.¹ 

[1] Oak Ridge Natl Lab, Mat Sci & Technol Div, Oak Ridge, TN 37831 USA

[2] Univ Akron, Coll Engn, Akron, OH 44325 USA

[3] Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX 78249 USA

关键词: Transformational challenge reactor;    Yttrium hydride;    Metal hydride;    High temperature oxidation;    yttria;    moderator;   

DOI  :  10.1016/j.jnucmat.2021.153166

来源: Elsevier

【 摘 要 】

Yttrium hydride (YHx) is an attractive moderator material for thermal neutron spectrum fission reactors requiring a small reactor core volume and has been selected as the neutron moderator for the Transformational Challenge Reactor (TCR), an advanced gas-cooled microreactor. Before YHx can be used in this application, it is important to understand the material response to off-normal conditions. In the present study, 550-650 degrees C isothermal dry air oxidation was performed to simulate a depressurized loss of force circulation (DLOFC) event. The oxidation was performed using thermogravimetric analysis (TGA) on bulk crack-free YHx coupons. Oxidation studies were also performed on Y coupons to elucidate the impact of H on oxidation. Both the chemistry and distribution of processing impurities were found to strongly affect oxidization behavior on a batch-to-batch basis. Regardless of batch, YHx oxidized at a significantly lower rate than Y at all temperatures, and the lower rate was directly correlated with increased hydride content. Metallic Y exhibited complex exponential kinetics, whereas YHx also exhibited complex kinetics but gained considerably less mass. According to literature reports on protonic and native-ion conductivities of Y2O3 and mass spectrometry analysis of gaseous reaction products formed during the oxidation of YHx, a mechanism for the reduced oxidation rate of yttrium hydride is suggested. (C) 2021 Elsevier B.V. All rights reserved.

【 授权许可】

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