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arXiv · 2202.07181

Structural and phase evolution in U$_3$Si$_2$ during steam corrosion

Jiatu Liu·Patrick A. Burr·Joshua T. White·Vanessa K. Peterson·Pranesh Dayal·Christopher Baldwin·Deborah Wakeham·Daniel J. Gregg·Elizabeth S. Sooby·Edward G. Obbard
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Abstract

U$_3$Si$_2$ nuclear fuel is corroded in deuterated steam with in situ neutron diffraction. Density functional theory is coupled with rigorous thermodynamic description of the hydride including gas/solid entropy contributions. H absorbs in the 2$b$ interstitial site of U$_3$Si$_2$H$_x$ and moves to 8$j$ for $x\ge 0.5$. Hydriding forces lattice expansion and change in $a/c$ ratio linked to site preference. Rietveld refinement tracks the corrosion reactions at 350-500 \deg C and preference for the 8j site. Above 375 \deg C, formation of UO$_2$, U$_3$Si$_5$ and USi$_3$ take place in the grain boundaries and bulk. Hydriding occurs in bulk and precedes other reactions.

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Jiatu Liu, Patrick A. Burr, Joshua T. White, Vanessa K. Peterson, Pranesh Dayal, Christopher Baldwin, Deborah Wakeham, Daniel J. Gregg, Elizabeth S. Sooby, Edward G. Obbard. 2022-02-15. Structural and phase evolution in U$_3$Si$_2$ during steam corrosion. https://arxiv.org/abs/2202.07181

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