STEM-EDS analysis of fission products in neutron-irradiated TRISO fuel particles from AGR-1 experiment
| Autor: | I.J. van Rooyen, Bin Leng, Kumar Sridharan, Yaqiao Wu, Izabela Szlufarska |
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| Rok vydání: | 2016 |
| Předmět: |
Void (astronomy)
Fission products Nuclear fission product Nuclear and High Energy Physics Materials science Metallurgy Energy-dispersive X-ray spectroscopy 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences 010305 fluids & plasmas Materials Science(all) Nuclear Energy and Engineering 0103 physical sciences Scanning transmission electron microscopy General Materials Science Neutron Grain boundary Pyrolytic carbon 0210 nano-technology |
| Zdroj: | Journal of Nuclear Materials. 475:62-70 |
| ISSN: | 0022-3115 |
| DOI: | 10.1016/j.jnucmat.2016.03.008 |
| Popis: | Historic and recent post-irradiation-examination from the German AVR and Advanced Gas Reactor Fuel Development and Qualification Project have shown that 110 m Ag is released from intact tristructural isotropic (TRISO) fuel. Although TRISO fuel particle research has been performed over the last few decades, little is known about how metallic fission products are transported through the SiC layer, and it was not until March 2013 that Ag was first identified in the SiC layer of a neutron-irradiated TRISO fuel particle. The existence of Pd- and Ag-rich grain boundary precipitates, triple junction precipitates, and Pd nano-sized intragranular precipitates in neutron-irradiated TRISO particle coatings was investigated using Scanning Transmission Electron Microscopy and Energy Dispersive Spectroscopy analysis to obtain more information on the chemical composition of the fission product precipitates. A U-rich fission product honeycomb shape precipitate network was found near a micron-sized precipitate in a SiC grain about ∼5 μm from the SiC-inner pyrolytic carbon interlayer, indicating a possible intragranular transport path for uranium. A single Ag-Pd nano-sized precipitate was found inside a SiC grain, and this is the first research showing such finding in irradiated SiC. This finding may possibly suggest a possible Pd-assisted intragranular transport mechanism for Ag and may be related to void or dislocation networks inside SiC grains. Preliminary semi-quantitative analysis indicated the micron-sized precipitates to be Pd2Si2U with carbon existing inside these precipitates. However, the results of such analysis for nano-sized precipitates may be influenced by the SiC matrix. The results reported in this paper confirm the co-existence of Cd with Ag in triple points reported previously. |
| Databáze: | OpenAIRE |
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