摘要
钍基熔盐堆裂变产物钕的电解分离对于熔盐堆的长期稳定运行、提高燃料利用率、减少放射性废物等具有重要意义。针对熔盐环境中钕的电解分离特性,本研究分析了793~853 K温度范围内NdF_(3)在FLiNaK(物质的量比46.5∶11.5∶42)熔盐体系中的电化学行为和热力学特性。实验结果表明,Nd(Ⅲ)在惰性钨电极上还原为钕金属是一步还原,即Nd(Ⅲ)+3e^(-)→Nd(0)。利用循环伏安法测定熔盐中Nd(Ⅲ)离子的扩散系数(D),显示D随温度升高而增大,获得Nd(Ⅲ)的扩散活化能为115.23 kJ/mol。基于开路计时电位曲线测定了Nd(Ⅲ)/Nd(0)体系在793~853 K温度范围的平衡电位(E^(eq))和标准电极电位(E^(*0))。同时,在793 K温度下开展Nd的脉冲电解沉积实验。X射线衍射分析证实了沉积产物为金属Nd。电感耦合等离子体发射光谱仪对电解前后的熔体分析结果显示,熔盐中钕离子含量的明显降低进一步确认了Nd(Ⅲ)电沉积的发生。
The electrolytic separation of neodymium(Nd),a fission product in Thorium-based Molten Salt Reactors(TMSR),is crucial for ensuring long-term reactor stability,enhancing fuel utilization,and minimizing radioactive waste.Considering the electrolytic separation characteristics of neodymium in a molten salt environment,this study investigates the electrochemical behavior and thermodynamic properties of NdF_(3) in a FLiNaK(mol ratio:46.5∶11.5∶42)molten salt system within the temperature range of 793 K to 853 K.The experimental results demonstrated that the reduction of Nd(Ⅲ)to metallic neodymium on an inert tungsten electrode occurs via a single-step process,represented as Nd(Ⅲ)+3e⁻→Nd(0).The diffusion coefficient(D)of Nd(Ⅲ)ions in molten salt was determined using cyclic voltammetry.It was observed that D increased with rising temperature,and the diffusion activation energy of Nd(Ⅲ)ions was calculated to be 115.23 kJ/mol.The equilibrium potential(E^(eq))and standard electrode potential(E^(*0))of the Nd(Ⅲ)/Nd(0)system were determined within the temperature range of 793 K to 853 K based on the open-circuit chronopotentiometric curve.Additionally,pulsed electrolytic deposition of neodymium was conducted at 793 K.X-ray diffraction analysis confirmed that the deposited product was metallic neodymium.Inductively coupled plasma optical emission spectrometry analysis of the molten salt before and after electrolysis revealed a significant decrease in the concentration of neodymium ions,further confirming the occurrence of Nd(Ⅲ)electrodeposition.
作者
雷敏
郑博文
徐彤彤
郭少强
邱杰
LEI Min;ZHENG Bowen;XU Tongtong;GUO Shaoqiang;QIU Jie(School of Nuclear Science and Technology,Xi'an Jiaotong University,Xi'an 710049,China;China Institute of Radiation Protection,Taiyuan 030000,China;School of Energy and Power Engineering,Xi'an Jiaotong University,Xi'an 710049,China)
出处
《辐射研究与辐射工艺学报》
2025年第6期16-28,共13页
Journal of Radiation Research and Radiation Processing
基金
陕西省科研项目(2023SYJ18)。
