中文摘要：

实验模拟核反应堆堆芯失水后堆芯熔融物和被加热压力容器壁等热块再淹没时的应急冷却过程。实验研究发现，液滴飞溅对热块钢板起到了预冷作用，在淹没液位上升的过程中，热块纵向导热越来越强，被淹没位置具有很高的中心冷却速率；热块被淹没位置的中心冷却速率并不随浸没速率单调变化，而是在一定区间内呈起伏变化，这说明在某个淹没速率下存在一个最小中心冷却速率的区问，因此在进行应急冷却时要避免这个区间；在高温情况下，冷却的初始温度对中心冷却速率影响不大。

英文摘要：

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.