Study on heat transfer characteristics of one side heated vertical channel for the vessel cooling system of VHTR

The Very High Temperature Reactor (VHTR) is a next generation nuclear reactor system. It has the characteristic that the thermal capacity of the core is so large. Therefore, even if the depressurization accident occurs and the reactor power goes up instantly, the temperature of the core will change slowly. The VHTR system can passively remove the decay heat of the core by natural convection and radiation from the surface of the reactor pressure vessel (RPV). The objectives of this study is to investigate the heat transfer characteristics of natural convection of an one-side heated vertical rectangular channel inserting porous materials with high porosity and to develop the passive cooling system for the VHTR. We carried out the experiment and numerical analysis using the one-side heated vertical rectangular channel. The heat transfer and fluid flow characteristics of the natural convection cooling were analyzed using the commercial CFD code. The result shows that the amount of removed heat inserting the copper wire (porosity = 0.9964) was about 8% higher than that without the copper wire. (author)