Evaluation of the three-dimensional natural circulation heat removal characteristics in sodium-cooled fast reactor

Endo, Junji*; Oyama, Kazuhiro*; Watanabe, Osamu*; Doda, Norihiro  

Adoption of natural circulation decay heat removal system is being investigated for commercialized sodium-cooled fast reactors. In this study, CFD simulations of primary heat transport systems including a core and decay heat removal systems in a loss-of-offsite-power event were conducted to evaluate the influence of thermal stratification and natural convection phenomena in the core upper plenum primary and the heat transport piping on the decay heat removal. From the simulation results, it was confirmed that the core is stably cooled by natural circulation, although drift occurs in the flow in the cold led pipes during the transition from forced to natural circulation.