ナトリウム冷却高速炉の崩壊熱除去システム運用時の炉内熱流動解析評価手法整備; 燃料集合体間ギャップ部の熱流動解析モデルの予備検討

Development of numerical estimation method for thermal hydraulics in reactor vessel of sodium-cooled fast reactor under decay heat removal system operation conditions; Investigation of thermal hydraulic modeling in gap between fuel subassemblies

田中 正暁  ; 菊地 紀宏  ; 浜瀬 枝里菜 ; 村上 諭*; 藤崎 竜也*; 今井 康友*

Tanaka, Masaaki; Kikuchi, Norihiro; Hamase, Erina; Murakami, Satoshi*; Fujisaki, Tatsuya*; Imai, Yasutomo*

ナトリウム冷却高速炉の安全性強化の観点から極めて有効な方策である自然循環崩壊熱除去時において、事故時を含むあらゆる条件下で原子炉容器内の熱流動場を予測できる解析評価手法の構築が重要となっている。そこで、燃料集合体間のギャップ部に存在するナトリウムの流れによる炉心冷却効果を評価するため、原子炉上部プレナム部での熱流動との相互作用を考慮可能な伝熱流動解析モデルを検討し、既往ナトリウム試験(PLANDTL-1)を対象に解析を実施し、その妥当性を確認した結果を報告する。

For safety enhancement of sodium-cooled fast reactor, decay heat removal system (DHRS) by using the natural circulation without depending on the pump as the mechanical equipment is recognized as one of the most effective method. The numerical estimation method which can predict thermal hydraulic phenomena in the reactor vessel during DHRS operation is necessarily required. In this study, appropriate modeling to predict the inter wrapper flow which is caused in the gap between fuel subassemblies is preliminary investigated. The validation of the numerical results is carried out in comparison with the measured temperature data in the scaled sodium test facility named PLANDTL-1. Through the simulation, potential applicability of the gap model using the correlation equations to simulate the thermal hydraulics behavior of the inter-wrapper flow in the core is indicated.