为了降低238 PuO2的中子发射率,制备出满足要求的放射性同位素热源材料,采用CeO2模拟238 PuO2进行氧同位素置换反应实验研究,确定了氧同位素置换工艺的最佳参数.实验结果表明,H216 O和CeO2氧同位素置换最适宜的温度为700℃,置换反应平衡时间为15 min,置换次数为15次,压力对置换反应影响较小.置换后的CeO2样品中18 O丰度由0.204％下降至0.026％,最大置换率达到89.7％.

The separation of tridentate actinides from lanthanides and that between Am(III) and Cm(III) is one of the most challenging tasks in the process of partitioning-transmutation of nuclear waste. Herein, we report a novel tridentate N-N-O hybrid ligand, i.e., N-ethyl-N-tolyl-2-amide-1,10-phenanthroline (ETPhenAm), for the selective extraction toward Am(III)/Cm(III) over Eu(III) from HNO3 solutions. ETPhenAm in 3-nitrotrifluorotoluene has excellent Am(III) extraction ability and Am(III)/Eu(III) separation performance. Notably, the good selectivity of ETPhenAm toward Am(III) over Cm(III) suggests that ETPhenAm exhibits good ionic radius selectivity in the interaction with the intraseries cations such as Am(III) and Cm(III). Extractive complexes of formula M(NO3)3L and M(NO3)3L2 (M = Am, Cm, and Eu) are identified in the extraction system. HNO3 concentration in the aqueous phase heavily affects the composition of the extractive species in the organic phase because of the strong basicity of ETPhenAm. Extraction observations are validated by determining the protonation constants of the ligand and the reaction equilibrium constants for the generation of complexes M(NO3)3L and M(NO3)3L2 (M = Nd and Eu) in CH3OH/10%(v)H2O solution. The structures of complexes M(NO3)3L and M(NO3)3L2 are confirmed through X-ray diffraction of compounds [La(NO3)3(ETPhenAm)2] (I), [Nd(NO3)2(ETPhenAm)2]NO3 (II), and [Eu(NO3)2(ETPhenAm)2]NO3 center dot[Eu(NO3)3(ETPhenAm)(CH3OH)]center dot 2CH3OH (III).

The density functional theory (DFT) method was used to study the coordination of a series of N,N-dialkylamides with Pa(v) to shed light on the inherent principles for screening amide extractants of Pa(v) from aqueous solution.

In recent decades, N-heterocyclic ligands have been extensively used in the separation of lanthanides/ actinides, whereas the selective extraction of amercium or curium has been very challenging. Using density functional theory calculations, this study is devoted to the investigation of the binding affinity of a series of modelling pyridine ligands with Am-III and Cm-III. The structure-property correlations between the amercium and curium systems and the binding affinity were obtained, and promising strategies for efficient separation of Am-III/Cm-III were proposed.

The binding affinity of AmIII/CmIII to a series of pyridines under different concentrations of nitrate were investigated by density functional theory calculations.

Due to the enormous threat of protactinium to the environment and human health, its disposal and chemistry have long been important topics in nuclear science. [PaO(H2O)6]3+ is proposed as the predominant species in hydrous and acidic solutions, but little is known about its formation mechanism. In this study, density functional theory (DFT) calculations demonstrate a water coordination-proton transfer-water dissociation mechanism for the formation of PaO3+ in hydrous solutions. First, Pa(V) ion preferentially forms hydrated complexes with a coordination number of 10. Through hydrogen bonding, water molecules in the second coordination sphere easily capture two protons on the same coordinated H2O ligand to form [PaO(H2O)9]3+. Water dissociation then occurs to generate the final [PaO(H2O)6]3+, which is the thermodynamic product of Pa(V) in hydrous solutions.

A borate ester bonding agent with a five-membered ring was synthesized via a one-pot process using borate acid,ethylene glycol and1,2,4-butanetriol as raw materials. Its structure was characterized by FTIR,11B NMR,1H NMR and MS. The hydrolysis reaction kinetics of the synthesized borate ester in normal temperature water and in saturated water vapor was investigated by an on-line IR analysis method. The hydrolysis reaction kinetic model was established. The results show that the hydrolysis of the synthesized borate ester under above-mentioned two conditions is the pseudo-first order reaction. The reaction rate constant and half life of the borate ester are 2. 3 × 10- 5s- 1and 8. 4 h in normal temperature water,2. 96 × 10- 7s- 1and 27 d in saturated water vapor,respectively. The addition of 0. 2% borate ester makes the tensile strength of RDX / HTPB explosive increase from 0. 80 MPa to 1. 44 MPa and the compressive strength increase from 5. 04 MPa to 13. 27 MPa,proving that the synthesized borate ester has good bonding effect.