PUREX流程1A槽中锝的走向分析

Distribution of Technetium in 1A Tank of PUREX Process

结合基础研究数据和工艺实验数据,对核燃料后处理PUREX流程共去污槽(1A槽)中锝的走向进行了分析。工艺实验数据表明:1A槽萃取段中TBP对锝与锆的共萃取行为是影响锝走向的主要因素。硝酸浓度会显著影响TBP对锝与锆的共萃取性能,当c(HNO3)<3 mol/L时,提高硝酸浓度可以促进水解的锆解离生成Zr4+,从而促进锆锝共萃取;当c(HNO3)≥3 mol/L时,硝酸可能会参与锆与锝的萃取。在0.5~5 mol/L的范围内,提高硝酸浓度有利于锝的萃取。在1A槽洗涤段硝酸浓度分布相近的条件下,1A槽中锝的走向取决于萃取段硝酸浓度的分布。萃取段硝酸浓度分布不同,将导致进入1A槽有机产品液(1AP)的锝含量比例不同,萃取段硝酸浓度越高,越有利于锝进入1AP。

The distribution of technetium in the co-decontamination tank(1 A tank) of PUREX process was analyzed. The trend of technetium was determined by the co-extraction of Zr-Tc in the section of extraction, which is related with the distribution of nitric acid. The concentration of nitric acid shows significant influence on the co-extraction of technetium and zirconium. At c(HNO3)<3 mol/L, the concentration increase of nitric acid prevents the hydrolysis of Zr4+ to promote the co-extraction of Zr-Tc. At c(HNO3)≥3 mol/L, nitric acid is co-extracted with Zr-Tc. At the range of 0.5-5 mol/L, the nitric acid is in favor of the extraction of technetium. The higher nitric acid concentration makes more technetium to be extracted into organic stream in PUREX process.