Np、Pu在黄土地下水系统中的反应路径模拟

放射性核素在土壤和地下水中的迁移行为对于核废物处置的安全有着非常重要的影响。目前研究放射性核素在土壤和地下水中的迁移行为通常有两类模式，水力学模式和地球化学模式，其中反应路径模拟方法作为地球化学模式中的重要内容，不仅能给出系统平衡时的物质浓度，更重要的是它能够给出系统从非平衡到平衡这一变化的过程。本文概要阐述了反应路径模拟的原理及EQ3／6程序的特征，以中国辐射防护研究院野外试验场为例，使用EQ3／6程序对Np、Pu在黄土地下水中的反应路径进行了模拟，给出了Np、Pu在涉及水一岩不可逆反应的黄土一地下水系统，局域趋于平衡过程中系统的化学组成随反应进度的变化，与已有实验结果进行了比对。

Reaction path simulation on Np and Pu in loess-groundwater system

The migration behavior of radionuclides in soil and groundwater has a great impact on safety of nuclear waste disposal. Usually, there are two kinds of models to study the migration behavior of radionuclides in soil and groundwater system at present: hydraulic model and geochemical model, As an important part of the geochemical model, the reaction path simulation method can be used to not only the material concentration of the system in equilibrium, but also the change process of the system from disequilibrium to equilibrium. In this paper, principle of the reaction path simulation and characteristic of program EQ3/6 are summarized. Then, with an example of CIRP's field test site, the reaction path of Np and Pu in loess-groundwater system is simulated using program EQ3/6, and the chemical component variation of Np and Pu in the course of irreversible water-rock reaction reaching local equilibrium with the reaction process is investigated. A comparison is also presented between simulated and measured results.