Bypass Flows in Control Rod Channels of the HTR-PM

Abstract

A large amount of graphite blocks were served as the construction material, the neutron reflectors and also shaped as several helium flow paths in the HTR-PM reactor core. A majority of helium flowed through the pebble bed to bring out the huge fission heat, while a minority might flow in varieties of gaps between graphite blocks without being heated enough. In our previous papers, the method of combined flow network and CFD was established to analyze several bypass flows in HTR-PM. In current paper, we focused on bypass flows in control rod channels by introducing the flow network there and several CFD simulations of complicated flow paths. The inlet and outlet of the control rod channels were discussed for with various sizes to clarify their effect on bypass flow rate. Besides, horizontal gap flows between piles of graphite reflectors were also considered as one kind of bypass flow paths influencing the flow rate in control rod channels. The size distributions of these horizontal bypass flow paths were assumed to be consistent from top to bottom. With the existence of the horizontal flows, the flow rate in the control rod channels was also affected.