Purex流程铀钚分离工艺中锝对镎走向的影响

在HNO3-U(Ⅳ)-N2H4-Tc(Ⅶ)-Np(Ⅴ)体系中,Np(Ⅴ)迅速还原为Np(Ⅳ)。对比研究表明,Tc是该体系中Np(Ⅴ)迅速还原的主要原因。该体系中的主要反应是U(Ⅳ)将Tc(Ⅶ)还原为Tc(Ⅳ),进而Tc(Ⅳ)将Np(Ⅴ)还原为Np(Ⅳ)。本文通过串级和台架实验研究了该体系中锝对镎走向的影响。结果表明,Np(Ⅴ)的还原速度随HNO3浓度、初始Tc浓度的增大和温度的升高而加快。在模拟Purex流程铀钚分离工艺的条件下,试管串级和微型混合澄清槽台架实验结果表明,提高1AP料液中Tc(Ⅶ)的浓度、升高反应温度,Np进入1BU中的百分含量增加。

Influence of Technetium on Routing of Neptunium in U/Pu Separation Stage in Purex Process

It was found that in the nitric acid solution containing U(Ⅳ), hydrazine, Tc(Ⅶ) and Np(Ⅴ), Np(Ⅴ) was reduced to Np(Ⅳ) quickly. The main reason of the fast reduction of Np(Ⅴ) was due to Tc(Ⅳ), which was produced by the reduction of Tc(Ⅶ) in the presence of U(Ⅳ). The routing of Np in U/Pu separation stage was studied by tube cascade experiments and bench scale experiments at a miniature mixing settler set. The results show that nearly 67.7% of Np goes into 1BU in the presence of Tc in the 1AP, but approximately 27.0% of Np goes into the 1BU in the absence of Tc. The amount of Np going into 1BU increases with the reaction temperature and the concentration of Tc(Ⅶ) in 1AP.