Abstract
Decay heat removal system using a dipped-type direct heat exchanger (DHX) is recognized as a promising system from the viewpoint of the safety enhancement of sodium cooled fast reactors including severe accident situations. In this study, a steady state sodium experiment 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 and to provide validation data for evaluation method based on numerical approaches. 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.
