Abstract
To meet the safety design criteria (SDC) and contributing to the establishment of the safety design guideline (SDG) for a Generation-IV Sodium-cooled fast reactor (SFR), the heat removal function of JSFR was enhanced to avoid loss of the function even if any internal events exceeding design bases or severe external events happen. As a countermeasure against loss of reactor level (LORL) type event, double failure of reactor vessel (RV) and guard vessel (GV) is prevented by securing a margin to earthquake resistant performance and a reliability of RV and GV. Furthermore, direct reactor auxiliary cooling system (DRACS) is extended functionally to keep heat removal capability even if siphon break occurs by multiple leakages on the primary cooling circuit. Against loss of heat sink (LOHS) type event, effective measures are enhancement of natural circulation function of DRACS and primary reactor auxiliary cooling system (PRACS), application of accident management and introduction of auxiliary core cooling system independent from DRACS and PRACS to prevent loss of all heat removal function from severe external events. It is important that RV melt-through can be practically eliminated by these design measure to achieve in-vessel retention (IVR) without significant core damage in the loss of heat removal type events.
