Design Method of Sphere Parameters for Passive Activation Device of Independent Heat Exchanger in Sodium-Cooled Fast Reactor

As the switch for the residual heat removal system of the independent heat exchanger in an integrated sodium-cooled fast reactor, the passive start-up device (PSD) is a critical component ensuring reactor safety in the event of a malfunction. The weight and dimensions of the sphere inside the PSD determine its ability to open and close. By analyzing the relationship between the forces acting on the sphere, the pressure loss of the device, and the inlet velocity, a design method for the PSD sphere parameters was established. To verify the reliability of this design method, a flow field simulation model of the PSD was built. The forces acting on the sphere and the pressure loss of the device under different inlet velocities were simulated and the variation patterns were analyzed. The simulation results show that the sphere parameters determined using this design method can meet the opening and closing requirements of the passive start-up device.