Study on Numerical Simulation for Thermal-Hydraulic Phenomena of Multiphase, Multicomponent Flows; Transient Vaporization/Condensation Phenomena in Multicomponent System,1

Morita, Koji*; Matsumoto, Tatsuya*; Fukuda, Kenji*; Tobita, Yoshiharu; Yamano, Hidemasa   ; Konishi, Kensuke ; Sato, Ikkenn 

It is one of the important problems for more reliable reactor safety evaluation to improve numerical simulation techniques for involved thermal-hydraulic phenomena of multiphase, multicomponent flows in core disruptive accidents.In the present joint research, physical model development and experimental investigation were conducted for transient condensation phenomena of a vapor bubble with noncondensable gases to improve applicability of a fast-reactor safety analysis code for the phase-transition phenomena in multicomponent systems.In this fiscal year, preliminary experiments using noncondensable gas were performed for the transient bubble condensation phenomena, and then basic data were obtained for large-scale bubble behavior without condensation.In addition, a multiple-scale flow-regime model treating large-scale bubbles was newly proposed for the fast-reactor safety analysis code and applied to the analysis of the preliminary experiments successfully.