Irradiation induced structural changes in the coating layers of TRISO fuel

The impact of 160 keV Ne ion irradiation on TRISO fuel surrogate samples was investigated, focusing on structural transformations in the buffer, transition, and the IPyC layers. Using various TEM techniques we analyzed the structural changes in the vicinity of the buffer-IPyC interface. The anisotropy texture analysis was based on the orientation distribution of the carbon (002) planes, determined from angular intensity variations along the (002) diffraction rings in SAED patterns, for both unirradiated and irradiated buffer, transition, and IPyC layers. We observed increasing texture up to 25-35 DPA followed by amorphization above 35-40 DPA. Using energy dispersive spectroscopy we observed a distinctive double peak in the Ne concentration profile within the buffer layer. The results indicate that the structure evolves significantly during irradiation and that these changes likely induce different ion penetration depths resulting abnormal Ne concentration profile. SRIM simulations provide complementary insights into the depth-dependent Ne concentration and DPA profiles. This research highlights the significant structural changes induced by Ne ion irradiation and the unique characteristics of the buffer layer's response.