Experimental study on influences of cooling systems on natural circulation cooling behavior in reactor vessel of sodium-cooled fast reactors under severe accident conditions

Sasaki, Keisuke; Aizawa, Kosuke ; Ezure, Toshiki ; Tanaka, Masaaki  

For the safety enhancement of sodium-cooled fast reactors, water experiments were carried out in a reactor vessel (RV) model with dipped type direct reactor auxiliary cooling system heat exchanger (DHX), penetrated type DHX, and reactor vessel wall cooler have been conducted individually to clarify the thermal-hydraulic characteristics in decay heat removal operation by obtaining temperature distributions inside the RV model, during a long-term cooling phase of severe accident. As the results, the characteristics in the RV each cooling system operation were clarified through the comparison of temperature distributions among the different cooling systems.