Development of separation-coefficient estimation method using numerical simulation for the behavior of ions

Horiguchi, Naoki   ; Yoshida, Hiroyuki  ; Kitatsuji, Yoshihiro  ; Fukumori, Mai*; Hasegawa, Makoto*; Kishimoto, Tadafumi*

A Li-7 enriched pH adjuster is essential for water quality control on PWRs. As the required Li-7 enrichment technology, we have developed the multi-channel counter-current electrophoresis (MCCCE) method. Here, Li-7 enrichment using the MCCCE method is to separate Li-7 and Li-6 ions moving in an aqueous solution by different velocities through electric and flow fields. As a part of the development, we have developed a numerical simulation method to understand the behavior of ions. In the numerical method, we calculate electric and flow fields using finite volume methods and the movement of an ion as a mass particle to reproduce the behavior of Li ions. Comparison of the numerical simulation with the experiment is required to validate the numerical simulation, but it is impossible to track ions individually and evaluate their behavior in the experiment. Then, we focused on separation coefficient estimated in the experiments. In this work, we applied the numerical method to the behavior of ions in a simulated channel and estimated the separation coefficient for validation. The separation coefficient is generally estimated using concentration ratios of Li-7 and Li-6, but we estimated the separation coefficient using the ratios of the numbers of ions, which equal to the concentration ratios. Then, we conducted a sensitivity analysis of the separation coefficient by changing the applied voltage and reproduced the change trend of the experiment.