Analysis Of Natural Circulation Instability In The Passive Residual Heat Removal System For Molten Salt Reactor

The passive residual heat system is one of the most important systems to ensure the safety of the molten-salt reactor when it is normal or accident.Based on the passive residual heat system of molten salt reactor,this paper designed and built two sets of experimental equipment for the water cooled passive residual heat system of the molten salt reactor.The flow and heat transfer process of the system is studied through experiments.The flow instabilities in the system are analyzed and summarized,which provide a basis for the design and optimization of the passive residual heat removal system of molten salt reactor.Based on the purpose and content of the study,we carried out experiments on natural circulation,subcooled boiling,steady natural circulation,saturated boiling heat transfer and unsteady flow.Based on the experimental data,the heat transfer characteristics of the passive residual heat removal system in molten salt reactor and the effect of flow instabilities on the thermal hydraulic characteristics of the system are analyzed and studied.According to the mathematical model,the heat transfer process in the system is calculated theoretically,and the theoretical calculation results are compared with the experimental values.The experimental results show that the residual heat removal system of molten salt reactor can well meet the requirements of residual heat removal,and safely and reliably generate the heat generated by molten salt.When the system runs,there will be two kinds of flow instabilities,intermittent fountain and density wave oscillation.The experimental results show that increasing the heating power of the system and increasing the inlet temperature of the central tube can significantly avoid the flow instability in the experiment.In order to ensure the quick and safe operation of the water cooled passive residual heat removal system of molten salt reactor,it is suggested that the system is in a low power operation for a long time and the molten salt is in a hot standby state with molten state.The theoretical calculation results show that the agreement with the experimental values is very good.The error of the two is within 16%,and the instability of the flow in the experiment is verified.