To assess the long-term leaching behaviour of UO2, the main constituent of spent nuclear fuel, the oxidative dissolution of UO2 pellets was studied at high H2O2 exposures ranging from 0.33 mol m-2 to 1.36 mol m-2. The experiments were performed in aqueous media containing 10 mM HCO3- where the pellets were exposed to H2O2 three consecutive times. The results indicate that the dissolution yield (amount of dissolved uranium per consumed H2O2) at high H2O2 exposures is significantly lower compared to previous studies of both pellets and powders and decreases for each H2O2 addition for a given pellet. This implies a change in redox reactivity, which is attributed to irreversible alteration of the pellet surface. Surface characterization after the exposure to H2O2, by SEM, XRD and Raman spectroscopy shows, that the surface of all pellets is significantly oxidized.

中文翻译：

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关于UO2氧化还原反应性随H2O2暴露量的变化。

为了评估乏核燃料主要成分UO2的长期浸出行为，研究了在0.33 mol m-2至1.36 mol m-2的高H2O2暴露下UO2颗粒的氧化溶解。实验是在含有10 mM HCO3-的水性介质中进行的，将沉淀连续3次暴露于H2O2中。结果表明，与先前对颗粒和粉末的研究相比，在高H2O2暴露下的溶出量（每消耗的H2O2溶解的铀量）显着降低，对于给定的颗粒，每次添加H2O2都会降低溶出量。这意味着氧化还原反应性的变化，这归因于颗粒表面的不可逆改变。SEM，XRD和拉曼光谱表明，暴露于H2O2后的表面表征表明：