The species of Np and Pu under the geological disposal conditionsare studied by the calculation method. Using the geochemistry model EQ3/6, the species of Np and Pu in groundwater, engineered barriers balanced water are investigated. Input parameters including all the environment factors such as temperature, pH, Eh and CO2 concentration, are studied to show the effects on the species. The calculated results provide useful information for the lab work.%采用EQ3/6地球化学模式和计算方法研究了放射性废物处置中Np和Pu在地下水和工程屏障平衡水中的化学形态,计算分析了温度、浓度、pH值、Eh值、CO2等对上述2个元素形态的影响。结果表明,地下水中Np的形态主要有4种:NpO2+,NpO2CO3-,NpO2OH和Np(OH)5-,当CO32-质量浓度高时,Np主要以NpO2(CO3)23-存在。pH值对Np形态的影响主要表现在上述4种形态分布的相对比例及OH-与CO32-的竞争配合作用。Eh值低于0.2V时,Np主要为四价;0.2~0.7V时,五价为主;大于0.7V时,出现六价。Pu的形态主要为Pu(OH)5-。CO32-的质量浓度对四价钚的形态分布不产生影响,但CO32-却与Pu(Ⅵ)有很强的配合能力。Eh值低于-0.5V时,Pu主要为三价;-0.4~0.6V时,五价为主;大于0.7V时,六价为主。
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