High resolution transmission electron microscopy (TEM) observations, nano-diffraction and nano-area energy dispersive X-ray spectroscopy (EDX) analyses were carried out in the outer region of high burnup UO2 pellets. Samples were prepared from the outer low temperature region of UO2 pellets, which had been irradiated to the pellet average burnups of 30 and 49 GWd/t in BWRs and 83 GWd/t in a test reactor under a pressurized water reactor (PWR) condition (1 GWd/t = 2.5 × 1019 fissions/cm3). Lattice images and nano-area EDX results indicate the presence of 4-10 nm size Xe bubbles with five-metal particles of Mo-Tc-Ru-Rh-Pd. Nano-diffraction patterns from bubbles show two different new patterns other than that of matrix UO2. From the Xe/U proportion obtained by the EDX peak and nano-diffraction patterns, it was suggested that Xe in the small bubbles existed as a solid or in a near solid state at very high pressure.
|ジャーナル||Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms|
|出版ステータス||出版済み - 5月 1998|
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