Study on cooling process of decay heat removal systems in a reactor vessel of sodium-cooled fast reactor by scaled water experiments, 6; Thermal hydraulics behavior under operations of multiple decay heat removal systems

Tsuji, Mitsuyo ; Aizawa, Kosuke ; Kobayashi, Jun ; Kurihara, Akikazu 

Thermal-hydraulic phenomena driven by natural circulation in a reactor vessel was investigated by using scaled model water experiments simulating a reactor vessel in order to enforce of safety and optimize design and operation of decay heat removal systems under normal operation and severe accident conditions. This report shows temperature and PIV measurement results of natural convection flow field in the reactor vessel under operations of dipped-type DHX and penetrated-type DHX. From the experimental result, it was conformed that the effect of the operation of the penetrated-type DHX on the natural convection behavior in the reactor vessel including the cooling of core and debris on core catcher.