Host: The Japan Society of Mechanical Engineers
Name : The 30th International Conference on Nuclear Engineering (ICONE30)
Date : May 21, 2023 - May 26, 2023
if the residual heat of the core cannot be exported in time after a severe accident, the temperature of the fuel element will continue to rise until melting occurs. The core melting is ejected into the lower head of the Reactor Pressure Vessel (RPV) and reacts violently with the residual coolant in the lower head. As a result, a debris bed is formed. The debris bed is a porous structure composed of particles of different sizes. Due to the continuous fission reaction in the debris bed, decay heat is released. Therefore, it needs to keep cooling, otherwise it may melt again. In this paper, the pool boiling phenomenon of porous debris bed is investigated, the two-phase flow and boiling heat transfer calculation model of porous medium with internal heat source is established. Inside, the conservation equations of flow and heat transfer are established for porous debris bed. For the flow resistance, the drag force between gas and liquid in continuous fluid is considered, and the flow resistance of solid to fluid in porous medium area is considered. The heat transfer model takes into account the heat transfer between solid liquid and solid gas, as well as the heat and mass transfer between gas and liquid. At last, the proposed models are validated by using the existing literature data, and the results show that the developed calculation model has a certain accuracy. Furthermore, the effect of different operation condition and structural parameters are discussed.
