Experimental Investigation on the Survival of Cooling Tube in Molten Pool

Abstract An experimental facility was established to verify the structural integrity of the cooling tube under an intense thermal shock formed by the molten corium. The vertical cooling tube specimen made by stainless steel has a diameter of 80mm and a thickness of 10mm, and it is positioned at the center of the test section. The bottom of the tube was connected with a water tank, then the water level and temperature in the tube could be adjusted by changing the relative height of the tank, and the top of the tube was opened to discharge the vapor to the air. The C/K-type thermocouples located at the outer-surface of tube were used to record time that melt interacted with tube, also used to estimate the deep of molten pool. In this study, the simulant material ZrO2 was melted by using the cold crucible technique, then the liquid melt about 70kg was discharged into the test section. The experimental results implies that as soon as the melt contacted with the cooling tube, the ZrO2-crust with the low thermal conductivity was formed around the tube, and it will be significantly decreased the temperature on the inner and outer wall of cooling tube. So, the local maximum temperature in outer wall was near the melting point of stainless steel, the structural integrity of cooling tube was still kept.