[2N20-23] high temperature gas-cooled rector

[2N22] New reactor cavity cooling system (RCCS) having passive safety features

Comparison methodology between a real RCCS and a scale-down heat removal test facility

＊Kuniyoshi Takamatsu¹, Tatsuya Matsumoto², Koji Morita² (1.Japan Atomic Energy Agency, 2.Kyushu University)

Keywords:RCCS, Passive safety, HTGR, HTTR, VHTR, Radiation, Natural convection, Core meltdown, LOCA

After Fukushima Daiichi nuclear disaster by TEPCO, a cooling system to prevent core damage became more important from the perspective of defense in depth. Therefore, a new, highly efficient RCCS with passive safety features without a requirement for electricity and mechanical drive is proposed. Employing the air as the working fluid and the ambient air as the ultimate heat sink, the new RCCS design strongly reduces the possibility of losing the heat sink for decay heat removal. The RCCS can always stably and passively remove a part of the released heat at the rated operation and the decay heat after reactor shutdown. Specifically, emergency power generators are not necessary and the decay heat can be passively removed for a long time, even forever if the heat removal capacity of the RCCS is sufficient. Moreover, we can also define the experimental conditions on radiation and natural convection for a scale-down heat removal test facility.