부산대학교 도서관

The effects of both nuclear energy loss and electronic energy loss need to be taken into consideration in the ceramic-based waste forms under repository environment. However, the irradiation responses of ceramic-based waste forms to each type of energy loss are somewhat different. In this study, the microstructure evolutions of ultrafine nano and micro Gd 2 Zr 2 O 7 -based waste forms were systematically studied under predominant electronic energy loss simulated by multi-energy He+ irradiation, and compared to those under predominant nuclear energy loss. The results reveal that the fewer He bubble chains, ribbon-like He bubbles and smaller microcracks were observed in the irradiated nano-grained sample. Additionally, nano-grained sample displayed a lower degree of amorphization and higher atomic order compared to micro-grained samples when subjected to predominant electronic energy loss. Moreover, the irradiation dominated by nuclear energy loss can easily induce the grain growth of nano-grained Gd 2 Zr 2 O 7 -based waste form, but in the present study this phenomenon was not observed under multi-energy He+ irradiation. Consequently, under predominant electronic energy loss, the thermodynamic instability and driving force for grain growth due to excess surface energy in the ultrafine nano sample can be suppressed. As a result, the sample demonstrated enhanced irradiation resistance due to the more efficient absorption and elimination of defects at grain boundaries induced by electronic excitation. We elucidated that enhanced irradiation resistance of the waste forms by tailoring the grain size requires the consideration of the effects of electronic energy loss and nuclear energy loss, which can provide guidance for the design and optimization of highly irradiation-resistant nuclear waste forms. [ABSTRACT FROM AUTHOR]