Water is a common fluid using as coolant for most of nuclear power plants due to low cost, wide availability, and high heat capacity. In the Fukushima Daiichi accident caused by the tsunami following a powerful earthquake on 11th March 2011, the loss of heat sink occurred. Seawater, which had been considered as an alternative coolant before, was eventually injected into the nuclear reactor for more than one week as an emergency measure. Studying the characteristics of heat transfer with the seawater received more attentions after the Fukushima Daiichi accident. The differences of hydrodynamic properties such as density, dynamic viscosity, surface tension, and kinematic viscosity, between deionized water and seawater are not significant, however, different behaviors exhibit in the boiling process. Compared to water, the diameter of bubbles in seawater during pool boiling would be smaller than in water. To improve the safety of a nuclear reactor power plant, mechanisms of the heat transfer using seawater as an alternative emergency coolant should be studied thoroughly. In this research, the scenario of a loss-of-coolant accident (LOCA) in nuclear power plants is simulated by a sudden shutdown manually of the circulation pump in the original forced circulation loop. The natural convection boiling after this sudden shutdown in an annulus with a 1 meter heater installed concentrically and vertically is studied experimentally at 1 atm. The tap water, DI water and seawater will be used as the coolant. The wall temperature responses are estimated by nine thermocouples embedded inside the heater with different elevations and angle. The bulk fluid temperature is estimated by the average temperature measurements at the beginning of the heated section and the ending of the test section. The local heat transfer coefficients along the heated section are compared among different working fluids. The various boiling behaviors of 3 working fluids are record by a high speed camera with LED lights. The effect of the heat fluxes is studied by the measured oscillations of wall temperatures on different axial locations along the heater.


Experimental Study of Boiling Characteristics of Seawater After an Accidental Shutdown of the Pump

Division / Sponsors: 
Power Division & Nuclear Engineering Division (NED)

Power Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2020/volume/83747

International Conference on Nuclear Engineering
Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE2020/volume/83761

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