Speaker
Description
In nuclear fuels, thin-film diffusion barriers are essential for preventing the release of radioactive fission products (FPs). Silicon carbide (SiC), which serves as the primary diffusion barrier layer, is exposed to various FPs along with helium (He) generated as a result of alpha decay of actinide elements and neutronic transmutation. Therefore, this study investigates the role of He in the migration of silver (Ag) and cesium (Cs) pre-implanted into SiC. Single-crystalline 6H-SiC samples were separately implanted with 360 keV Ag ions and 200 keV Cs ions to a fluence of 2×10¹⁶ ions/cm² at room temperature (RT). The individually implanted samples were subsequently co-implanted with 17 keV He ions to a fluence of 1×10¹⁷ ions/cm² at RT. The Ag-implanted, Cs-implanted, Ag+He co-implanted, and Cs+He co-implanted samples were then annealed at 1100 °C for 5 hours in a vacuum tube furnace. Rutherford backscattering spectrometry (RBS) was used to analyze the migration behavior of Ag and Cs in SiC. Channeling RBS, Raman spectroscopy, and transmission electron microscopy (TEM) were employed to investigate the thickness of the damaged layer, microstructural changes induced by implantation, and the formation of He bubbles, respectively. Ag and Cs implantation resulted in the formation of an amorphous layer, while subsequent He implantation increased the thickness of this amorphous region. Annealing induced recrystallization in all samples; however, some graphitization was observed in the Ag+He and Cs+He co-implanted samples. No migration of Ag or Cs was detected after annealing. Compared to the behavior of Ag in polycrystalline SiC, where rapid Ag migration and significant loss were observed after annealing at 1100 °C, the results demonstrate that 6H-SiC effectively retains Ag and Cs. These findings confirm the critical role of SiC microstructure in controlling the migration of fission products.
| Apply for student award at which level: | MSc |
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| Consent on use of personal information: Abstract Submission | Yes, I ACCEPT |