Synthesis of modeling and simulation techniques for the in-vessel thermal-hydraulics analysis in decay heat removal system operation

Tanaka, Masaaki ; Hamase, Erina ; Li, S.*; Endo, Junji*; Gerschenfeld, A.*; Gorsse, Y.*; Imamura, Akira*; Imamura, Tomo*; Yoshimura, Kazuo ; Ezure, Toshiki 

For the safety enhancement of sodium-cooled fast reactor (SFR), diverse decay heat removal systems (DHRSs) are required. The direct reactor auxiliary cooling system with the dipped-type direct heat exchanger (D-DHX) in the hot plenum of the reactor vessel (RV) is recognized as one of the most promising systems at normal operating conditions and accident conditions. This paper attempted the synthesis of computational fluid dynamics (CFD) modeling and simulation techniques to evaluate the core coolability under the complicated thermal-hydraulics phenomena in the D-DHX operation. The investigation of review and gap analysis of respective experiences on CFD analyses regarding the sodium test facility named PLANDTL-1 in JAEA, ASTRID as an innovative SFR in CEA, and a pool-type demonstration SFR in Japan in MFBR was made to provide consensus on an appropriate CFD analysis model of the RV, including the fuel sub-assembly and inter-wrapper gap in the core.