Study of Bottom Reflooding in a Narrow Rectangular Channel

Bottom reflooding is the third phase when a large-break loss-of-coolant accident occurs. Due to the complexity and importance, especially in a distinct narrow rectangular channel, various research methods can be utilized to understand the whole process. Test facility is established to figure out the thermal-hydraulic behaviors during bottom reflooding, and the acquisition of accurate solid temperature is essential. The inverse heat transfer problem method is applied to take full advantage of experimental data. In addition, a bottom reflooding transient (BRT) code is utilized to calculate various parameters conveniently. A three-dimensional heat conduction equation for a transient state is solved implicitly to obtain solid temperature distribution, surface heat flux, and heat transfer coefficient at the cooling surface. The simulation results of the BRT code are compared with that of RELAP5, an available system code, and the experimental results. A conclusion that can be derived is that the BRT code shows good applicability of simulating bottom reflooding in a narrow rectangular channel.