Study on cooling process of decay heat removal systems in a reactor vessel of sodium-cooled fast reactor under severe accident

Tsuji, Mitsuyo 

To elucidate the core cooling systems of a sodium-cooled fast reactor under severe accident, PIV experiments were carried out by using scaled water experimental facility simulating the condition of uniformly-accumulated debris on the core catcher, measured the natural convection flow field in starting up the submerged type DHX. The authors confirmed the specific flow patterns that low temperature fluid flowed down along the core wall and flowed into lower plenum, and the fluid was heated on the core catcher and elevated toward the center of reactor core, then some vortexes were formed by the mutual interaction due to the down-flow of low temperature fluid and up-flow of elevated temperature fluid. Furthermore, the equivalent flow field and the maximum flow velocity were observed compared with the existing knowledge.