原子能科学技术2026，Vol.60Issue(5)：1027-1037,11.DOI:10.7538/yzk.2025.youxian.0531
TBP-正十二烷辐解对黏度影响的分子动力学机制
Molecular Dynamics Mechanisms of Effect of TBP-n-dodecane Radiolysis on Viscosity
摘要
Abstract
To elucidate the molecular mechanism by which radiolysis affects the viscosity of solvents in the Purex process,this study employed molecular dynamics simulations on model systems of long-chain organophosphates with varying degrees of polymerization within TBP-n-dodecane systems,and conducted 60Co gamma irradiation experiments on a 30vol%TBP-n-dodecane mixture solvent.The viscosities of NPT ensembles with different proportions of tributyl phosphate(TBP),n-dodecane,and their long-chain compounds were systematically simulated.According to the theoretical study,the increase in the content of long-chain organophosphate ester degradation products will drive viscosity growth through enhanced molecular entanglement,expanded van der Waals contact area,and directional dipole interactions of P=O bonds.The viscosity shows a linear growth trend(1.86-3.44 mPa·s).The molecular topology exhibits non-monotonic regulation on viscosity:The pure-phase viscosity of the T-C-T structure jumps significantly to 10.06 mPa·s due to the doubling of polar sites;The"lubricant"effect of flexible alkyl chains in the T-C-T-C structure reduces the pure-phase viscosity to 7.74 mPa·s;The viscosity of the T-C-T-C-T pure-phase system rises to 12.78 mPa·s because more TBP groups are locked with each other.This confirms that the increase in the number of TBP groups dominates intermolecular locking and sliding inhibition,and thus determines viscosity behavior.Combined with P element radial distribution function analysis,it is demonstrated that the increase in TBP groups within the molecular topology induces the non-monotonic change in viscosity via an enthalpy-driven mechanism.Furthermore,60Co irradiation experiments reveal that high-dose irradiation forms highly polar topological structures,leading to entropy-enthalpy imbalance,reducing contribution of alkyl chain flexibility,and consequently accelerating viscosity increase.Based on the scientific findings,the engineering risk of pipeline blockage originates from the formation of persistent three-dimensional crosslinked networks during continuous solvent radiolysis via metal coordination,P-O-P crosslinking,and micellar self-assembly.This network formation triggers moisture adsorption and the generation of crud-like precipitates,ultimately obstructing pipelines.Consequently,effective risk mitigation necessitates an integrated approach combining strategies of irradiation dose control,rheological monitoring,and staged chemical treatment(initial washing with 5%NaOH followed by deep treatment with concentrated acid/oxidant).关键词
核燃料后处理/溶剂辐照降解/分子动力学/黏度/有机磷酸酯Key words
nuclear fuel reprocessing/solvent irradiation degradation/molecular dynamics/viscosity/organic phosphate ester分类
能源科技引用本文复制引用
刘佳鑫,杨昕未,董雪,陈勤,纪雷鸣,李磊,金相丞,刘毅,马敬..TBP-正十二烷辐解对黏度影响的分子动力学机制[J].原子能科学技术,2026,60(5):1027-1037,11.基金项目
国家自然科学基金(22478056) （22478056）
中国核电工程有限公司"青年人才"项目(KY24045) （KY24045）
中核集团"星原计划"(CNPE8208) （CNPE8208）
