针对从乏燃料中有效分离钍-铀循环所产生的镤元素和铀-钚循环所产生的镎元素时面临的困境，本项目拟采用基于第一性原理和分子力场的多尺度模拟方法，研究镤、镎的溶液化学。通过研究镤、镎在溶液体系中的配位化学，包括镤、镎与溶剂、离子强度调节剂、萃取剂的相互作用，探索在溶液中控制镤、镎的种态分布的化学条件。项目对阐明水法和干法分离镤、镎的机制，揭示化学环境影响镤、镎纯化的规律有重要意义。通过研究将提出可行的改善螯合配体性能的设计方案，为发展先进乏燃料后处理技术提供理论支持。

Theoretical studies on the solution chemistry of protactinium (Pa) and neptunium (Np) with multi-scale methods at the first-principle and force field levels are to be carried out to tackle the difficulty in the efficient separation of Pa in the thorium-uranium (Th-U) fuel cyle and Np in the uranium-plutonium (U-Pu) fuel cycle. The project covers the issues of the interactions between Pa/Np and solvent, ions which are used to adjust the ionic strength of solution, polydentate ligands used for the extraction in spent nuclear fuel reprocessing, and the chemical conditions to control the speciation of Pa/Np in the solution phase. Through the theoretical study, mechanisms that govern the separation of Pa/Np in the spent nuclear fuel, both in spent nuclear fuel wet and dry reprocessing, and the influence of the chemical condition will be addressed. Based on the results, potential modifications of the polydentate ligands will be proposed towards a better performance in the separation of Pa/Np in the spent nuclear fuel to contribute to the development of advanced spent nuclear fuel reprocessing.