Preliminary Experiment of U-Shaped Heat Pipe as Passive Cooling System in High Temperature Gas-Cooled Reactor Cooling Tank

Abstract

When station blackout occurs on high temperature gas-cooled reactor, the decay heat will be absorbed by a residual heat dissipation system (known as cooling tank) which connected to the reactor cavity cooling system. The U-shaped heat pipe as passive cooling system is proposed as new feature of technology to absorb the decay heat in the high temperature gas-cooled reactor cooling tank, and to keep the water remains in its operating temperature and level. This research objective is to know thermal resistance of U-shaped heat pipe scale model based on variation of heat load and coolant velocity. The influence of water temperature in the circulating thermostatic bath as heat load on evaporator section and air velocity which flowed into the horizontal condenser fin were investigated experimentally. The heat loads were varied at water temperature of 45, 50, and 60°C. The air velocities were varied at 0.45, 0.83, and 1.06 m/s. The experiment result showed the lowest thermal resistance of 0.000027±0.0000000593 °C/W when U-shaped heat pipe was operated at hot water temperature of 60°C and air velocity of 1.06 m/s. The investigation result can be used as a model and initial knowledge to design large scale of U-shaped heat pipe as a passive cooling system in cooling tanks connected to high temperature gas-cooled reactor cavity cooling system. This result is also useful regarding to the thermal management of passive cooling process in cooling tank and it can improve the nuclear safety and be able to overcome the thermal problems caused by station blackout in high temperature gas-cooled reactor.