Numerical simulation of breakup characteristics of sodium liquid jet

Sun, G.*; Yamashita, Susumu   ; Okawa, Tomio*; Yoshida, Hiroyuki  

When coolant leak occurs in sodium-cooled fast reactors, liquid sodium jet ejected from damaged piping can impact solid surfaces such as floors, generating splashing droplets. These droplets significantly increase the contact area between sodium and atmosphere, thereby intensifying combustion reactions. The quantity and size of splashing droplets, which influence the contact area, depend on the state of the jet during impact. Therefore, understanding the falling behavior of the jet is crucial. In this study, the breakup characteristics were analyzed to investigate the applicability of the numerical fluid dynamics simulation code JUPITER to the falling behavior of liquid sodium jets. The simulation results were similar to the extrapolated values from the empirical equations obtained from the experimental results with alternative fluids. Prospects for applying JUPITER to the analysis of sodium jet falling behavior were obtained.