Browsing by Author "White, JT"

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    Structural and phase evolution in U3Si2 during steam corrosion
    (Elsevier, 2022-08-01) Liu, J; Burr, PA; White, JT; Peterson, VK; Dayal, P; Baldwin, C; Wakeham, D; Gregg, DJ; Sooby, ES; Obbard, EG
    U3Si2 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 2b interstitial site of U3Si2Hx and moves to 8j for x ≥ 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 °C and preference for the 8j site. Above 375 °C, formation of UO2, U3Si5 and USi3 take place in the grain boundaries and bulk. Hydriding occurs in bulk and precedes other reactions. © 2022 Published by Elsevier Ltd.
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    Thermal expansion and steam oxidation of uranium mononitride analysed via in situ neutron diffraction
    (Elsevier B. V., 2023-03) Liu, J; Gasparrini, C; White, JT; Johnson, KD; Lopes, DA; Peterson, VK; Studer, AJ; Griffiths, GJ; Lumpkin, GR; Wenman, MR; Burr, PA; Sooby, ES; Obbard, EG
    In situ neutron powder diffraction experiments are applied to physical, kinetic, and microstructural characterization of uranium mononitride as a promising light water reactor fuel material. The temperature-variable coefficient of thermal expansion and isotropic Debye Waller factors are obtained by sequential Rietveld refinement over 499–1873 K. Oxidation of a UN pellet (95.2% density) under flow of 11 mg/min D2O is observed to initiate above 623 K and the rate increases by a factor of approximately 10 from 673 to 773 K, with activation energy 50.6 ± 1.3 kJ/mol; uranium oxide is the only solid corrosion product. Crown Copyright © 2022 Published by Elsevier B.V.