Experimental Investigation of Hot Block Rewetting Process during Nuclear Reactor Emergency Cooling

An experimental investigation was carried out to simulate the process of emergency cooling rewetting of the hot block such as molten material and pressure vessel wall in nuclear reactor core under the serious accident.According to the present experimental study,the liquid spatters can pre-cool the hot block;the heat transfer in the y direction has been enhanced with the increasing liquid level and the central temperature cooling speed is very high.The experiments reveal the nonlinear relationship between the center temperature dropping speed and the liquid level increasing speed,and it shows an U-shape trend which suggests that a minimum center temperature dropping speed exists during rewetting with a certain liquid level increasing speed which should be avoid.With higher initial temperature,the temperature dropping speed is affected by the initial temperature mildly.