Purex流程1A槽中Pu(Ⅵ)行为的计算机模拟

在乏燃料后处理Purex流程中，共去污循环的安全稳定运行是整个生产过程的关键之一。Pu(Ⅵ)在TBP中的分配系数比Pu(Ⅳ)的低而易导致钚流失。文章采用计算机模拟1A萃取槽中UO²⁺₂、HNO₃、Pu⁴⁺、PuO²⁺₂的运行。计算结果表明，Pu(Ⅵ)的流失是造成钚收率降低的主要因素之一，提高Pu(Ⅵ)的收率能够有效提高钚产品的收率。当1AF中ρ(U)＝225g/L、c(HNO₃)＝3.0mol/L、ρ(Pu)＝2.20g/L，1AS中c(HNO₃)＝3.0mol/L，1AX为30％TBP/煤油，流比1AF∶1AS∶1AX＝1.25∶0.75∶3.00时，为使1A萃取槽中钚的收率不低于99.9%，应控制1AF料液中Pu(Ⅵ)量（占总Pu百分数）不超过7%。

Behavior of Pu(Ⅵ) in Codecontamination (1A) of Purex Process by Computer Simulation

Computer code was presented to simulate the codecontamination (1A) of Purex solvent extraction process. The code can deal with four ingredients (UO_2~(2+) , HNO_3, Pu~(4+) , PuO_2~(2+) ) and the concentration profiles were modeled to evaluate the process condition of 1A. The experimental concentration profiles were fitted well with the calculated results. The simulated results show that the losses of Pu ( Ⅵ) to the aqueous raffinate are one of important factors for total plutonium losses. When the feed solution is 3. 0 mol/L HNO_3 solution containing 225 g/L uranium and 2. 20 g/L Pu, the solvent stream is 30% TBP/kerosene, the scrub feed is 3. 0 mol/L HNO_3 solution and the flow ratios of 1AF: 1AS: 1AX is 1. 25: 0.75: 3. 00, the percent of Pu(Ⅵ) (occupies total Pu) in 1AF should be less then 7% in order to reach over 99. 9% plutonium recycled.