Characteristics of pressure buildup from local fuel-coolant interactions in a simulated molten fuel pool, 2; Numerical analyses using SIMMER-III

Cheng, S.; Matsuba, Kenichi  ; Isozaki, Mikio; Kamiyama, Kenji  ; Suzuki, Toru; Tobita, Yoshiharu

In this study, motivated by acquiring further evidence for understanding the characteristics of pressure buildup from local fuel-coolant interactions in a simulated molten fuel pool, SIMMER-III, an advanced fast reactor safety analysis code, is utilized for analyses. It is found that, similar to previous reported experimental analyses, the water volume and melt temperature are observable to have remarkable impact on the interaction, while the role of water subcooling seems to be less prominent. In addition, from the numerical runs performed it is also recognized that the most probable reason leading to the limited pressurization for a given melt and water temperature within the non-film boiling range, even under a condition of comparatively larger volume of water delivered into the pool, should be due to an isolation effect of vapor bubbles generated at the water-melt interface. Knowledge and data gained from this study might be utilized for potential empirical-model development as well as future investigations using reactor materials.