Study on the Flow and Heat Transfer Characteristics of the Passive Containment Cooling System Under DBC
Expanding the application scenario of the passive safety system,simplifying the design of safety systems and support systems,and improving the economy of plant is one of the main objectives of optimization and innovation of three-loop PWR.Using the passive containment cooling system(PCS)to cope with DBC is an important technical option.PCS can effectively remove the heat in the containment under DBC,to make sure that the temperature,pressure and corresponding release of radioactivity from the containment are under the limiting requirements.RELAP/SCDAP-SIM was used to the PCS model of three-loop PWR,and the flow and heat transfer characteristics of the system during DBC were studied.The key factors of effecting feasibility of the PCS coping with DBC were analyzed.The results show that,the number of heat exchanger tubes should increase about 2.5 times comparing with severe accident condition to cope with the DBC without changing the form of the heat exchanger.The arrangement of the PCS in the containment becomes the key limiting factor of its feasibility.The diameter and wall thickness of the heat transfer tubes have little influence on the natural circulation capacity and heat transfer power of the system.The distance between the heat exchanger and cooling pool should not be too high,otherwise effective natural circulation cannot be established.The condensation heat transfer coefficient had significant influence on the heat transfer power of the system.It is necessary to carry out corresponding experiments to obtain the heat transfer coefficient which is more consistent with the practical conditions.The results provide reference for the design of system and heat exchanger and engineering verification of the PCS to cope with the DBC.
Passive containment cooling systemFlow and heat transfer characteristicDBC
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