Development of numerical simulation method to evaluate two-phase flow behavior in spent fuel pool, 1; Numerical simulation method for two-phase flow with water surface

Yoshida, Hiroyuki  ; Nagatake, Taku ; Nemoto, Yoshiyuki  ; Kaji, Yoshiyuki  

In the Fukushima Daiichi Nuclear Power Plant accident, loss of cooling system for spent fuel pool (SFP) occurred and occurrence of heat-up of the spent fuel was concerned. Therefore, safety measures for the SFP cooling are required in Japan. As one of the safety measures for the accidents in the SFP, a portable spray system is considered. To confirm applicability of portable spray cooling systems as the safety measure, a capability of spray cooling has to be evaluated. To evaluate applicability of this safety measure, thermal-hydraulic behavior of two-phase flow must be evaluated. To evaluate two-phase flow behavior, dispersed flow, the counter current flow limiting (CCFL), and film flow, the numerical simulation method for two-phase flow behavior in the SFP has been developed in this research. The developed method is based on a 3-dimensional two-fluid model simulation code ACE-3D. To evaluate two-phase flow behavior in the SFP, the water surface simulation and dispersed flow simulation functions are introduced to the ACE-3D. To evaluate water surface behavior, the advanced interface tracking method developed by the JAEA is modified and used in this simulation method. In this presentation, the outline of the numerical simulation method related to water surface behavior introduced to the ACE-3D is reported.