Numerical analysis for fission product behavior in VERDON-2 experiment

VERDON-2実験における核分裂生成物の移行挙動に関する数値解析

塩津 弘之  ; 伊藤 裕人*; 杉山 智之 ; 丸山 結 

Shiotsu, Hiroyuki; Ito, Hiroto*; Sugiyama, Tomoyuki; Maruyama, Yu

The VERDON-2 experiment for fission products (FPs) transport under steam condition was analyzed with the mechanistic FPs transport code based on thermodynamic chemical equilibrium model in order to understand their behavior, especially for Cs and I with high volatility. Furthermore, the chemical model was validated for improve source term evaluation method with consideration of chemistry. The present analysis reproduced well the Cs distribution obtained from the experiment, which revealed that Cs transported as CsOH in early phase of FP release from fuel, and then form CsMoO after Mo release. On the other hand, the I deposition peak was predicted at a higher temperature than experimental result, which was observed at 600 K in the experiment and at 720 K in the analysis. This discrepancy was potentially caused by following two points: lack of the other stable species in thermodynamics database for chemical equilibrium model, or failure of chemical equilibrium assumption for iodide species. These results suggest that FPs transport code with thermodynamic chemical equilibrium model can evaluate Cs behavior as CsOH and CsMoO species and not currently available on the evaluation for I behavior.