Experimental on Transient Heating and Cooling of Natural Circulation Flow using A FASSIP-02 Large Scale Experimental Facility

The Fukushima Daiichi nuclear plant accident in 2011 has provided important information about the failure of the active cooling system if the installation does not have electrical power. So that research on the phenomenon of natural circulation flow through passive cooling systems is an essential topic in improving the safety management of nuclear power plants in the world. However, research on natural circulation flow experimentally using large-scale facilities has not been widely carried out. This research aims to analyze the natural circulation flow rate phenomenon under transient heating and transient cooling conditions. The research method was conducted experimentally using the FASSIP-02 Test Loop, a largescale experimental facility with a head height of 9.1 meters. Experiments were carried out by varying the temperature setting in the heat source (WHT), respectively, at 60 oC, 70 oC, and 80 oC. The results showed that the flow regime formed was in a turbulent flow regime, with the Reynolds numbers being 9352, 12634, and 17370, respectively, for variations in temperature settings of 60 oC, 70 oC, and 80 oC.