Reactor Physics Considerations for Use of Yttrium Hydride Moderator

Brian J. Ade; Benjamin R. Betzler; Joseph R. Burns; Christopher W. Chapman; Jianwei Hu

doi:10.1080/00295639.2022.2035157

Reactor Physics Considerations for Use of Yttrium Hydride Moderator

Brian J. Ade, Benjamin R. Betzler, Joseph R. Burns, Christopher W. Chapman, Jianwei Hu

Research output: Contribution to journal › Article › peer-review

10 Scopus citations

Abstract

Recent developments in manufacturing large metal hydrides are enabling their use as a moderator for advanced reactor designs. Yttrium hydride (YH_x) is particularly attractive for small reactor designs because of its ability to retain a high hydrogen density at elevated temperatures. Design iteration for the Transformational Challenge Reactor (TCR), which uses a YH_1.85 moderator, revealed positive moderator temperature coefficients. A positive temperature coefficient for YH_x is expected regardless of the core design, however, the positive moderator coefficient exceeded that of the negative fuel temperature coefficient in some early TCR design iterations. The cause of the positive moderator coefficient is analyzed, and conditions for which positive temperature coefficients would be expected are identified for a number of fuel and moderator geometry layouts for dense tristructural isotropic/silicon carbide fuel and UO₂ fuel.

Original language	English
Pages (from-to)	1539-1558
Number of pages	20
Journal	Nuclear Science and Engineering
Volume	196
Issue number	12
DOIs	https://doi.org/10.1080/00295639.2022.2035157
State	Published - 2022

Funding

This work was supported by the U.S. Department of Energy Office of Nuclear Energy Transformational Challenge Reactor Program. Special thanks to Xuniung Hu for yttrium hydride production and for providing information on the material and Kurt Terrani for initiating and guiding the initial portion of this work.

Funders	Funder number
U.S. Department of Energy

Keywords

TRISO
Yttrium hydride
microreactor
reactivity coefficient
zirconium hydride

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10.1080/00295639.2022.2035157

Cite this

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title = "Reactor Physics Considerations for Use of Yttrium Hydride Moderator",

abstract = "Recent developments in manufacturing large metal hydrides are enabling their use as a moderator for advanced reactor designs. Yttrium hydride (YHx) is particularly attractive for small reactor designs because of its ability to retain a high hydrogen density at elevated temperatures. Design iteration for the Transformational Challenge Reactor (TCR), which uses a YH1.85 moderator, revealed positive moderator temperature coefficients. A positive temperature coefficient for YHx is expected regardless of the core design, however, the positive moderator coefficient exceeded that of the negative fuel temperature coefficient in some early TCR design iterations. The cause of the positive moderator coefficient is analyzed, and conditions for which positive temperature coefficients would be expected are identified for a number of fuel and moderator geometry layouts for dense tristructural isotropic/silicon carbide fuel and UO2 fuel.",

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AB - Recent developments in manufacturing large metal hydrides are enabling their use as a moderator for advanced reactor designs. Yttrium hydride (YHx) is particularly attractive for small reactor designs because of its ability to retain a high hydrogen density at elevated temperatures. Design iteration for the Transformational Challenge Reactor (TCR), which uses a YH1.85 moderator, revealed positive moderator temperature coefficients. A positive temperature coefficient for YHx is expected regardless of the core design, however, the positive moderator coefficient exceeded that of the negative fuel temperature coefficient in some early TCR design iterations. The cause of the positive moderator coefficient is analyzed, and conditions for which positive temperature coefficients would be expected are identified for a number of fuel and moderator geometry layouts for dense tristructural isotropic/silicon carbide fuel and UO2 fuel.

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Reactor Physics Considerations for Use of Yttrium Hydride Moderator

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