Investigation of the structure and chemical nature of Pd fission product agglomerations in irradiated TRISO particle SiC

JOURNAL OF NUCLEAR MATERIALS

卷:532

Article

Olivier, E. J.¹  Neethling, J. H.¹  van Rooyen, I. J.² 

[1] Nelson Mandela Univ, Ctr HRTEM, Phys Dept, Port Elizabeth, South Africa

[2] Idaho Natl Lab, Fuel Design & Dev Dept, Idaho Falls, ID USA

关键词: TRISO particle;    Fission product;    Diffusion;    Transmission electron microscopy;    Dislocation core;   

DOI  :  10.1016/j.jnucmat.2020.152043

来源: Elsevier

【 摘 要 】

Tristructural-isotropic (TRISO)-coated fuel particles are used in high-temperature gas-cooled nuclear reactors. Although the polycrystalline 3C-SiC layer acts as the main barrier to fission product release, post-irradiation examinations have shown that certain metallic fission products are found on the outside of the TRISO coated particle, with no observable evidence of micro-cracks or mechanical failure. In this study, an atomic resolution transmission electron microscopy investigation of a SiC layer from a neutron irradiated (19.38% fissions per initial metal atom average burnup; 1072 degrees C time-averaged temperature) TRISO-coated particle from the first fuel irradiation experiment as part of the US DOE Advanced Gas Reactor Fuel Qualification and Development (AGR) Program, was conducted. The fission product Pd was found to be present at dislocation cores associated with twins, stacking faults, and their intersections as atomic scale silicide inclusions. EELS elemental quantification of the silicide region showed a reduction of C and increase of Si in the Pd containing inclusion. Pd was also observed as distributed along grain boundaries down to the atomic scale. The local corrosion and dissociation of C from Pd containing grain boundary agglomerations was observed at the atomic level. Elemental quantification of atomically dispersed Pd grain boundary regions using EELS spectrum imaging similarly showed a measurable decrease in C concentration at Pd regions and an increase in Si concentration. (C) 2020 Elsevier B.V. All rights reserved.

【 授权许可】

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