The rate of internal energy changes on u-shape heat exchanger inside water cooling tank of FASSIP-02 test loop base on variation temperature in heating area

The accident at the nuclear power plant in Fukushima, Dai-ichi, Japan, proves the failure of an active cooling system that uses pumps. Thus, using a passive cooling system to improve the safety of reactor operation is necessary, especially if there is no power at the plant during an accident. Research and development of passive cooling system technology have been carried out in Indonesia since 2011, one of which is by building the FASSIP-02 Test Strand, a large-scale experimental facility. The main components of the FASSIP-02 Test Strand consist of a piping system, expansion tank, water cooling tank, U-shape type heat exchanger, and water heater tank. The occurrence of natural circulation flow rate during operation is determined by the change in the internal energy of each component. Thus, the purpose of this research is to focus on the rate of change of inte rnal energy in a U-shape type heat exchanger based on changes in water temperature in the heating tank. The research method was carried out experimentally by varying the water temperature setting at steady conditions in the heating tank from 70 oC, 80 oC, and 90 oC. After obtaining the temperature and mass flow rate data, the internal energy change is calculated. The calculation results show the relationship between the rate of change of internal energy in the U-shape heat exchanger based on variations in the temperature setting of the heating water at a steady-state, indicating the higher the temperature, the more significant the change in internal energy that occurs, the internal energy changed from 5690 W, 7363 W, and 9768 W. Energy internal increased of 41.75% from the water temperature setting of 70 oC to 90 oC.