Research on Reactor Cavity Cooling System (RCCS) with passive safety features

Takamatsu, Kuniyoshi  ; Funatani, Shumpei*; Banno, Masaki*

After Fukushima Daiichi nuclear disaster, 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, the decay heat can be passively removed for a long time, even forever if the heat removal capacity of the RCCS is sufficient.