Evaluation of Flow-Guide Effects in a Sodium-cooled Pool Type Reactor

Under a mid- and long-term nuclear R and D program, various conceptual design options for a sodium-cooled fast reactor have been proposed to fulfill the safety criteria and secure a reliable decay heat removal performance. Every design option has its own features to enhance and secure a decay heat removal performance. In the recently proposed reactor pool design for a 600MWe demonstration reactor, DHX was positioned in the hot pool, and the baffle plate was removed. The one of the important design points in this concept is the flow-guide, which induces stack effects. A stack effect is the phenomenon caused by pressure and temperature differentials, which results in fluid being drawn through the stack. In this geometry, the flow-guide is installed in the hot pool and partially divides the hot pool into two regions, a UIS region and annular region. In this study, the effects of the flow-guide on cooling performance of the reactor pool are investigated numerically. A complex geometrical arrangement in the reactor pool was modeled in COMMIX-1AR/P using a porous-medium approach. In order to estimate the effects of flow-guide in the reactor pool, an imaginary reactor having the same geometry except the flow-guide is modeled additionally. The overall thermal-hydraulic behaviors in the reactor pool have been evaluated at a transient state condition as well as a steady state condition and the effects of flow-guide are analyzed