Uranium solubility in aluminosilicate melts of the Na₂O-CaO-Al₂O₃-SiO₂ system with two different Na/Ca ratios was studied at temperatures of 1250–1400°C and under various redox conditions. A closed thermochemical reactor was used to control the alkali metal activity (sodium oxide content) and the oxygen fugacity imposing the reducing environment on the glass melt (10⁻⁵ atm < fO₂ < 10⁻¹⁵ atm). The compositions of the quenched glasses were analyzed by scanning electron microscopy and electron probe microanalysis. It appeared that uranium solubility decreased with decreasing oxygen fugacity, elucidating the roles of the different valences of uranium. To account for the respective effects of theses valences, we proposed a method to determine the proportion of each uranium oxidation state in the glass sample. The coexisting U^VI, U^V, and U^IV species have been characterized for the first time in glass samples using U M₄ edge high energy resolution X-ray absorption near-edge structure. Results showed that the lowest solubility values, of approximately 1 mol% UO₂, were obtained under strongly reducing conditions, and thus with U^IV as the main valence. Under higher oxygen fugacity, uranium solubility was controlled and drastically enhanced by the U^VI concentration in the melt.

研究了在两种不同Na / Ca比的Na ₂ O-CaO-Al ₂ O ₃ -SiO ₂系统的硅铝酸盐熔体中铀的溶解度，温度为1250-1400°C，并且在各种氧化还原条件下进行。使用封闭的热化学反应器来控制碱金属活性（氧化钠含量）和氧气逸度，将还原环境置于玻璃熔体上（10 ^-5 atm <fO ₂ <10 ^-15atm）。通过扫描电子显微镜和电子探针显微分析来分析淬火玻璃的组成。似乎铀溶解度随着氧逸度的降低而降低，从而阐明了不同价态铀的作用。考虑到这些价的各自影响，我们提出了一种确定玻璃样品中每种铀氧化态比例的方法。在使用UM ₄边缘高能量分辨率X射线吸收近边缘结构的玻璃样品中，首次对共存的U ^VI，U ^V和U ^IV物种进行了表征。结果表明最低的溶解度值约为1 mol％UO ₂，是在强烈还原条件下获得的，因此以U ^IV为主要价。在较高的氧气逸度下，通过熔体中的U ^VI浓度可控制并大大提高铀的溶解度。