Transmission Electron Microscopy Investigation of Krypton Bubbles in Polycrystalline CeO₂

To gain an understanding of gas bubble transport in oxide nuclear fuel, this paper uses polycrystalline CeO₂, composed of both nanograins and micrograins, as a surrogate material for UO₂. The CeO₂ was implanted with 150-keV Kr ions up to a dose of 1 × 10¹⁶ ions/cm² at 600°C. Transmission electron microscopy characterizations of small Kr bubbles in nanograin and micrograin regions were compared. The grain boundary acted as an efficient defect sink, as evidenced by smaller bubbles and a lower bubble density in the nanograin region as compared to the micrograin region.