Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
塩津 弘之; 伊藤 裕人*; 杉山 智之; 丸山 結
Annals of Nuclear Energy, 163, p.108587_1 - 108587_9, 2021/12
被引用回数：0 パーセンタイル：0.01(Nuclear Science & Technology)In the late phase of severe accident in light water reactor nuclear power station, re-mobilization of fission products (FPs) has a significant impact on the source term because most portion of FPs is retained in reactor coolant system and/or containment vessel. Recently, VERDON-2 experiment showed noticeable re-vaporization, which was one of the re-mobilization phenomena, of iodine under air ingress condition, but this mechanism has not been identified yet. The present study numerically investigated the FPs behaviors in VERDON-2 experiment with the mechanistic FPs transport analysis code incorporating thermodynamic chemical equilibrium model in order to further understand nature for FPs behavior, especially iodine re-vaporization under air ingress condition. Consequently, this analysis reproduced the deposition profile of cesium, one of important FPs in the source term, along the thermal gradient tube (TGT) in the experiment, which revealed that cesium was transported as CsOH in early phase of FP release from fuel, and then formed Cs
MoO
and CsTe after the release of molybdenum and tellurium was activated. Regarding iodine as another important FP, formation of CsI was predicted in steam condition. The CsI was transported and partly deposited and condensed onto the TGTs and other components of the VERDON facility. Under the air ingress condition, the present analysis showed the agreement for iodine re-vaporization in the experiment and revealed its mechanism; the deposits of iodide were chemical re-vaporized as molecular iodine (I) gas by redox reaction with competitive elements such as molybdenum, chromium and tellurium.
塩津 弘之; 伊藤 裕人*; 石川 淳; 杉山 智之; 丸山 結
Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 6 Pages, 2018/11
The VERDON-2 experiment for FPs transport in steam environment was analyzed with the mechanistic FPs transport code incorporating thermodynamic chemical equilibrium model in order to assess its predictive capability for transport behavior of key FPs, especially for highly volatile FPs such as Cs and I. The present analysis reproduced well the Cs deposition profile obtained from the experiment, which revealed that Cs was transported as CsOH in early phase of FP release from fuel, and then formed CsMoO after increasing Mo release. On the other hand, the deposition peak of I was predicted to appear at 720 K, which was significantly higher than the experimental result at 600 K. This discrepancy was potentially caused by the following two points: lack of the other stable species in thermodynamics database for thermodynamic chemical equilibrium model, or failure of chemical equilibrium assumption for iodide species.
塩津 弘之; 伊藤 裕人*; 杉山 智之; 丸山 結
no journal, ,
水蒸気雰囲気での大規模FP放出・移行挙動実験であるVERDON-2実験について、化学平衡を仮定するFP移行挙動評価コードVICTORIA2.0を用いた解析を実施し、平衡論に基づいたCsおよびIに係る化学挙動予測機能の評価を行った。解析の結果、平衡論により高温領域でのCs化学挙動を定性的に評価できることを明らかにした。一方で、Iや低温領域でのCs化学挙動では実験結果との定性的な一致が見られず、手法に課題があることが示された。
