The impact of the matrix and buffer properties on residual stresses in TRISO particles during manufacture and early life

Inyang-Udoh, Udeme, Battistini, Angelo, Jones, Lloyd, Leide, Alex, Wenman, Mark R. and Haynes, Thomas (2026) The impact of the matrix and buffer properties on residual stresses in TRISO particles during manufacture and early life. Journal of Nuclear Materials, 620. ISSN 0022-3115

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Abstract

A three-dimensional finite-element model was developed using Abaqus to simulate the fabrication and initial power ramp-up of a tri-structural isotropic (TRISO) particle, featuring a UO2 kernel, encapsulated in either a SiC or graphite matrix. After sintering, the residual compressive hoop stress in the SiC coating layer reached -540 MPa when encapsulated in a graphite matrix, 94 MPa more compressive than in a SiC matrix. However, following the initial power ramp-up, the predicted compressive hoop stresses in the SiC layer of a particle embedded in a SiC matrix (-388 MPa) were significantly greater than in a graphite matrix (-222 MPa), emphasizing the matrix material's critical role in the stress state of the SiC layer. Model validation attempts were made with the experimental measurements of the residual stresses of a zirconia-kernel surrogate particle. We found that in a fully-bonded surrogate TRISO particle, the stress state of the SiC layer is highly sensitive to the buffer porosity with compressive SiC layer hoop stresses ranging from up to -1.06 GPa at a porosity of 0.14 to -0.77 GPa at a porosity of 0.60. Partial kernel/buffer delamination simulations revealed a significantly varied geometric stress distribution, with tensile stresses reaching up to +54 MPa and compressive stresses up to -546 MPa at different axes of the sectioned plane in the model. This finding suggests that contrary to the common assumption of complete delamination at the kernel/buffer interface during fabrication, partial delamination is a more plausible explanation for the high compressive stresses observed in the SiC layer experimentally.

Item Type:	Article
Additional Information:	Data availability: Data will be made available on request. Funding information: Mr Inyang-Udoh acknowledges support from the University of East Anglia, Faculty of Science PhD Studentship; Nuclear Innovation and Research Office; and the Department for Energy Security and Net Zero. Dr Battistini acknowledges financial support from the Engineering & Physical Sciences Research Council Nuclear Energy Futures Centre for Doctoral Training (grant EP/S023844/1) and the UK National Nuclear Laboratory. Dr Leide acknowledges support by the Royal Academy of Engineering under the Research Fellowship programme. Dr Haynes acknowledges support from Nuclear Innovation and Research Office; and the Department for Energy Security and Net Zero. The research presented in this paper was carried out on the High-Performance Computing Cluster supported by the Research and Specialist Computing Support service at the University of East Anglia.
Faculty \ School:	Faculty of Science > School of Engineering, Mathematics and Physics
UEA Research Groups:	Faculty of Science > Research Groups > Sustainable Energy
Depositing User:	LivePure Connector
Date Deposited:	16 Dec 2025 15:30
Last Modified:	16 Dec 2025 15:30
URI:	https://ueaeprints.uea.ac.uk/id/eprint/101425
DOI:	10.1016/j.jnucmat.2025.156311

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