LiCl-KCl熔盐体系中UCl_(3)的合成研究  

Reaction Mechanism of Uranium Metal and Cadmium Chloride in LiCl-KCl Eutectic Molten Salt

作　　者：肖益群 曾国智 刘思京 姚本林 何辉[1] 叶国安[1] 李斌[1] XIAO Yiqun;ZENG Guozhi;LIU Sijing;YAO Benlin;HE Hui;YE Guoan;LI Bin(China Institute of Atomic Energy,Beijing 102413,China;China Guangdong Nuclear Power Corporation(Huizhou)Co.,Ltd.,Huizhou 516003,China;Harbin Engineering University,Harbin 150001,China)

机构地区：[1]中国原子能科学研究院,北京102413 [2]中广核惠州核电有限公司,广东惠州516003 [3]哈尔滨工程大学,黑龙江哈尔滨150001

出　　处：《原子能科学技术》2025年第S1期173-181,共9页Atomic Energy Science and Technology

基　　金：中核集团集中研发项目;中国原子能科学研究院青年英才基金(YC232505001003)。

摘　　要：为充分掌握LiCl-KCl熔盐体系中,氯化镉(CdCl_(2))与金属铀(U)反应生成高浓度三氯化铀(UCl_(3))的过程及其机理,本文基于快堆乏燃料高燃耗、高超铀元素含量等特点,针对高浓度UCl_(3)的合成需求,采用热力学计算、电化学监测和原位吸收光谱技术,分析该反应的热力学可行性、反应动力学及UCl_(3)的合成机制。结果表明,500℃下,CdCl_(2)能有效氧化金属铀,生成U^(3+),进而形成UCl_(3),副产物为金属镉。热力学计算和实验验证表明,反应主要生成UCl_(3),未观察到高价铀化物(如UCl_(4)、UCl_(5)等)的生成。随着反应的进行,熔盐中UCl_(3)含量逐渐增加,而Cd^(2+)含量不断降低,最终达到平衡。电化学测试和原位吸收光谱法结果表明,UCl_(3)为主要产物,且没有出现明显的U^(4+)或U^(5+)等高价铀物质。在实验过程中,通过反应优化,成功制备了高浓度(50.86%)UCl_(3)的LiCl-KCl熔盐体系,并通过稀释方法,获得了适用于电解精炼的初始熔盐。以上结果表明,CdCl_(2)与金属铀反应生成高浓度UCl_(3)的方法是可行的,可为乏燃料电解精炼工艺的LiCl-KCl-UCl_(3)熔盐体系制备提供理论和技术支持。The synthesis of high-concentration uranium trichloride(UCl_(3))was investigated through the reaction of cadmium chloride(CdCl_(2))with metallic uranium(U)in a LiCl-KCl eutectic molten salt system.This process is particularly relevant to nuclear fuel reprocessing,as the production of UCl_(3)is essential for efficient uranium electrorefining.The study aims to investigate the thermodynamic feasibility,reaction dynamics,and synthesis mechanism of UCl_(3)in LiCl-KCl molten salt system.Thermodynamic calculations were performed to predict the likely reaction pathways and the equilibrium conditions.Electrochemical monitoring and in-situ absorption spectroscopy were employed to observe the concentration changes of uranium and cadmium species during the reaction.The experimental results demonstrate that CdCl_(2)is capable of oxidizing metallic uranium to U^(3+),leading to the formation of UCl_(3).Metallic cadmium(Cd)is produced as a byproduct.As the reaction proceeded,the concentration of UCl_(3)in the molten salt increases steadily,while the concentration of Cd^(2+)decreases over time.The process reaches equilibrium after a certain period.Thermodynamic calculations confirm that the reaction is energetically favorable for the formation of UCl_(3).No higher-valent uranium compounds,such as UCl_(4)or UCl_(5),are observed in the reaction,which is consistent with the experimental data.The electrochemical analysis reveals a clear transition in the oxidation states of uranium,from U to U^(3+),as the reaction progressed.In addition,in-situ absorption spectroscopy was used to monitor the formation of UCl_(3)in real-time.The results confirm that UCl_(3)is the dominant product formed during the reaction.No significant formation of U^(4+)or U^(5+)is detected,further validating the thermodynamic predictions.The formation of UCl_(3)is accompanied by a gradual decrease in the concentration of Cd^(2+),which is reduced to metallic Cd and deposited at the bottom of the reaction vessel.The high concentration of UCl_(3)(50.86%)is successful

关 键 词：LiCl-KCl熔盐 UCl_(3) 氯化镉 金属铀 电化学监测 原位吸收光谱 

分 类 号：TL241.2[核科学技术—核燃料循环与材料]