| Abstract Scope |
Nuclear graphite serves as a moderator, reflector, and structural material in reactors due to its stability under irradiation and high temperatures. It is composed of partially ordered, amorphous, and crystallized carbon, and the behavior of amorphous regions under irradiation is not well understood and can affect dimensional changes. Microstructural evolution in nuclear graphite grade ETU-10 under in-situ electron irradiation was investigated. Observations show that irradiation leads to structural rearrangements, including formation of new basal planes in cracks and distortion of existing basal planes. The ordering of amorphous structures suggests that irradiation results in crystallization. Newly formed basal planes, well-aligned with existing basal planes, developed within cracks, resulting in closure, while other microcracks remained open due to accumulated ring-type defects. These features may be associated with defect accumulation. The results point toward an irradiation-driven ordering mechanism, which may influence irradiation-induced dimensional change and turnaround behavior. |