摘要
将氧化物乏燃料直接电解还原为粗金属的过程是目前以"电解还原-电解精炼"为特征的主流干法后处理流程的重要步骤。二氧化铀(UO_2)是乏燃料的最主要成分,将致密的UO_2芯块转化为八氧化三铀(U_3O_8)粉末后,再进行电化学还原能有效提高还原速率。因此,以U_2O_8为研究对象,开展其在氯化锂(LiCl)熔盐中的电解还原机理研究,对于后处理干法流程的开发具有重要的现实意义。本研究在650℃的氯化锂(LiCl)熔盐中,采用循环伏安法和恒电位电解法,研究了U_3O_8的电解还原行为。并且对于电解后的样品,运用XRD、SEM等手段,分析了其组成和形貌,并推测了相应的还原机理。
Direct reduction of spent oxide fuel to mix-metal is the key step of an important dry reprocessing process,which is feature with "Electroreduction-Electrorefinning".UO_2 is the main component in spent fuel.The transform of compact UO_2 pellet to U_3O_8 powder could effectively improve the electroreduction rate.Therefore,taking U_3O_8 as research object,studying its electrochemical behaviors during the electroredction process has certain practical significance for the development of this process.In this paper,the electroreduction behaviors of U_3O_8 in molten LiCl(650℃) were studied using cyclic voltammetry,constant potential electrolysis technology.The after-electrolysis products were analyzed by XRD and SEM.Finally,and a reduction mechanism was also proposed.
引文
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