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通过拉曼光谱法研究秦山核电厂一期反应堆内运行后的燃料棒Zr-4合金包壳外表面不同部位氧化膜的晶体结构。结果表明,在燃料棒底端,腐蚀程度相对较低,含有较高含量的四方相,表面也呈致密黑色,随着距底端的距离增加,腐蚀程度增加,外表面由黑白相间过渡到疏松白色,氧化膜中四方相氧化锆含量逐渐减少,逐渐转变为单斜相;在径向上,从氧化膜/金属界面到表面,四方相含量逐渐减少,单斜相氧化锆含量升高。与堆外试验结果类似,即四方相向单斜相氧化锆的转变决定锆合金包壳材料在堆内的抗腐蚀性能,单斜相含量越高,腐蚀速率越高,耐腐蚀性能越差。
Raman spectroscopy was used to study the crystal structure of the oxide film on the outer surface of the fuel rod Zr-4 alloy cladding in the first reactor of Qinshan Nuclear Power Station. The results show that at the bottom of fuel rods, the corrosion level is relatively low with a high content of tetragonal phase, and the surface is also densely black. The corrosion degree increases with the distance from the bottom end, and the outer surface transitions from black and white to loose white , The content of tetragonal zirconia in the oxide film gradually decreases and gradually changes to the monoclinic phase. In the radial direction, the content of tetragonal phase decreases from the oxide film / metal interface to the surface, and the content of monoclinic zirconia increases. Similar to the out-of-pile test result, the transformation of tetragonal phase monoclinic zirconia determines the corrosion resistance of the zirconium alloy cladding material in the reactor. The higher the monoclinic phase content and the higher the corrosion rate, the worse the corrosion resistance.