Study on decay heat removal in sodium-cooled fast reactors; In-vessel cooling characteristics by direct heat exchanger

Ezure, Toshiki ; Onojima, Takamitsu; Tanaka, Masaaki  ; Kameyama, Yuri*

As a part of safety enhancement of sodium-cooled fast reactors, experiments was carried out using PLANDTL-2 facility to grasp the core cooling behavior only relying on the natural circulation inside the vessel using dipped-type DHX. As the result, temperature distributions in the core were quantitatively grasped under a situation where cold coolant from DHX penetrated the core. Furthermore, it was observed that temperature distribution at the middle height of core became flat due to the flow redistribution among heating channels resulting from the buoyancy balance between channels.