Report on series 2A reflood experiment

Series 2A reflood experiment was carried out from February to April 1975 to obtain thermo-hydrodynamic data during reflood phase of a typical PWR. The main test conditions are as follows: - direct water injection into the simulated core at constant flow rate - operation under an atmospheric pressure, and - temperature of heater rods up to 6000C. Study of the data showed that several heat transfer phases exist in the core, i.e. adiabatic, droplet-dispersed vapor flow, film boiling, quench, and nucleate boiling phase. The relation between heat transfer phases and heat transfer coefficients was discussed qualitatively, and the following phenomena were found out: Pressure oscillation exists in the core, and it has large influence upon heat transfer coeficient characteristic as well as heater rod surface temperature response, and the inlet water velocity influences the carry over fraction. (auth.)