干法后处理熔盐电解精炼过程数学模型研究  

Mathematical Model of Dry Reprocessing Electrorefining of Molten Salt

作　　者：王赛 林如山[1] 李康祎 钟振亚 钱宾杰 张磊[1] 唐洪彬[1] WANG Sai;LIN Rushan;LI Kangyi;ZHONG Zhenya;QIAN Binjie;ZHANG Lei;TANG Hongbin(Department of Radiochemistry,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院放射化学研究所,北京102413

出　　处：《原子能科学技术》2024年第1期23-32,共10页Atomic Energy Science and Technology

摘　　要：熔盐电解精炼是乏燃料干法后处理的核心工艺单元,通过数学模型探索高温熔盐电解精炼过程的化学与电化学变化,可为电解精炼工艺优化和设备设计提供参考依据。本文基于电化学热力学及物质传递公式建立了乏燃料熔盐电解精炼过程的数学模型,以铀钚锆三元合金燃料为研究对象,计算了燃料中关键元素的电极电势、分电流及物料分布随时间的变化。采用向后差分法对物料分布变化方程进行离散,通过文献实验数据对建立的数学模型进行了准确性验证。结果表明,模拟计算所得阴极沉积铀产品与实验数据的相对误差为2.80%,所建数学模型具有较好的拟合性。同时采用所建模型模拟计算了电流强度对乏燃料电解精炼过程的影响,结果表明电解速率与电流强度呈正比,不改变钚铀锆的溶解和沉积顺序。Molten salt electrorefining is the core process unit of spent fuel dry reprocessing,and the chemical and electrochemical changes of high-temperature molten salt electrorefining process can be explored through mathematical model research,which can provide a reference basis for electrorefining process optimization and equipment design.In this paper,based on electrochemical thermodynamics and material transport formulas,a mathematical model of the electrorefining process of molten salt in spent fuel was established,and the changes of electrode potential,partial current and material distribution of key elements in spent fuel with time were calculated.The central difference method was used to discretize the material distribution change equation and obtain the oscillation result.The backward difference method of discrete material distribution change equation was used to verify the accuracy of the established mathematical model through literature experimental data.The results show that the relative error between simulated uranium product deposited at the cathode and the experimental data is 2.80%,which shows that the mathematical model has good fit.During electrorefining,there are two mutations in the anode potential,indicating complete dissolution of Pu and complete dissolution of U separately.At the same time as the electrochemical dissolution of Pu,a displacement reaction occurs with UCl 3 in the molten salt,so that the anode division current of Pu is larger than the input current.The order of dissolution of the three elements at the anode is Pu>U>Zr.U elements are deposited in large quantities at the cathode,and the deposition rate slows down after Zr dissolved at the anode.The concentration of elements in molten salt varies with the electrorefining process.In the simulated time range,the concentration of U element decreases to a certain extent at first,and the concentration of Pu element increases with time,and then the concentration of the two elements remains almost unchanged.The molar concentration of Zr element

关 键 词：乏燃料 干法后处理 熔盐电解精炼 数学模型 物料分布变化 

分 类 号：TL244[核科学技术—核燃料循环与材料]