Fission products silver, palladium, and cadmium identification in neutron-irradiated SiC TRISO particles using a Cs-Corrected HRTEM

Electron microscopy investigations of selected coated particles from the first advanced gas reactor experiment at Idaho National Laboratory provided important information on fission product distribution and chemical composition in the silicon-carbide (SiC) layer. Silver precipitates were nano-sized,...

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Bibliographic Details
Published in:Journal of nuclear materials 2016-08, Vol.476 (C), p.93-101
Main Authors: van Rooyen, I.J., Olivier, E.J., Neethling, J.H.
Format: Article
Language:English
Subjects:
Cadmium
Fission products
Grain boundaries
Information dissemination
Irradiation
Palladium
Silicon carbide
Silver
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Summary:Electron microscopy investigations of selected coated particles from the first advanced gas reactor experiment at Idaho National Laboratory provided important information on fission product distribution and chemical composition in the silicon-carbide (SiC) layer. Silver precipitates were nano-sized, and therefore high-resolution transmission electron microscopy (HRTEM) was used to provide more information at the atomic level. Based on gamma-ray analysis, this particle which was irradiated to an average burnup of 19.38% fissions per initial metal atom, may have released as much as 10% of its available Ag-110 m inventory during irradiation. The HRTEM investigation focused on silver, palladium, and cadmium due to interest in silver transport mechanisms and possible correlation with palladium and silver previously found. Palladium, silver, and cadmium were found to co-exist in some of the SiC grain boundaries and triple junctions. This study confirmed palladium both at inter and intragranular sites. Phosphor was identified in SiC grain boundaries and triple points. •First high resolution electron microscopy fission product nano-structural locations of irradiated TRISO coated particles.•Pd observed inside SiC grains in proximity to planar defects e.g. stacking faults.•Ag co-exists with Pd and Cd only may suggest a Pd-assisted transport mechanism.•First finding of neutron transmutation product P, in SiC layer of TRISO coated particles. No direct link to Ag transport.•No significant Pd corrosion of SiC observed even at this high resolution images.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2016.04.010