Modern electron microscopy techniques were used to conduct a thorough study of an irradiated urania fuel pellet microstructure to attempt at an understanding of high burnup structure formation in this material. The fuel was irradiated at low power to high burnups in a light water reactor, proving ideal for this purpose. Examination of grain size and orientation with strict spatial selectivity across the fuel pellet radius allowed for capturing the progression of the restructuring process, from its onset to full completion. Based on this information, the polygonization mechanism was shown to be responsible for restructuring, involving formation of low-angle grain boundaries with their initiation occurring at the original high-angle grain boundaries of the as-fabricated pellet and at the gas bubble-matrix interfaces. The low-angle character of boundaries between the subdivided grains disappeared in the fully developed high burnup structure, likely due to creep deformation in the pellet.

现代电子显微镜技术被用来对辐照过的尿素燃料芯块的微观结构进行彻底的研究，以试图了解这种材料中高燃耗结构的形成。在轻水反应堆中以低功率将燃料辐射至高燃耗，证明是理想的选择。在整个燃料颗粒半径上具有严格的空间选择性的晶粒尺寸和取向检查，可以捕获从开始到完全完成的重组过程。根据这些信息，多边形化机制被证明是负责重组的，涉及低角度晶界的形成，其起始发生在预制颗粒的原始高角度晶界和气泡-基质界面处。 。