Experimental and numerical studies on performance of passive decay heat removal by a water cooling panel from a high-temperature gas-cooled reactor

An experiment was carried out to simulate passive decay heat removal from a high-temperature gas-cooled reactor based on water cooling panel system. T he experiment is aimed at investigating the temperature distribution of the system and the effectiveness of decay heat removal. The experimental appar atus consists of a pressure vessel of Im in diameter and 3 m in height, bri stling with nineteen stand pipes atop and containing internal heaters with a maximum heating rate of 100 kW to simulate the decay heat of the core The pressure vessel is surrounded by the water cooling panels in an air-filled cavity; which resembles the actual reactor installation. The computational code THANPACST2 was benchmarked by the experimental data to verify its num erical methods including a newly-proposed axi-symmetrical model of the thre e-dimensional structures of the stand pipes by porous body cells. Under the conditions of helium gas pressure of 0.47 MPa and temperatures up to 430 d egrees C in the pressure vessel, the temperatures of the critical spots nea r the top of the pressure vessel, where peak temperatures appeared, were es timated within discrepancies between -25 and +70 degrees C from the experim ental data. The heat transferred to the cooling panel was estimated to be 4 .1% less than the experimental value.