Code development for core disruptive accidents in sodium-cooled fast reactors

Koshizuka, Seiichi*; Liu, J.*; Morita, Koji*; Arima, Tatsumi*; Zhang, S.*; Tobita, Yoshiharu; Yamano, Hidemasa   ; Ito, Takahiro*; Naito, Masanori*; Shirakawa, Noriyuki*; Hosoda, Seigo*; Uehara, Yasushi*; Yamamoto, Yuichi*; Himi, Masashi*; Kozakai, Hiroshi*; Hirano, Etsujo*; Shimizu, Sensuke*; Oue, Masaya*

A computer code, named COMPASS (Computer Code with Moving Particle Semi-implicit for Reactor Safety Analysis), is being developed for various complex phenomena of core disruptive accidents (CDAs) in sodium-cooled fast reactors (SFRs). Theoretical studies are performed about a unified algorithm for compressible and incompressible flows, fluid flow with solid debris, and algorithm improvement for free surface flows. Code verification and validation procedures are established by exploiting the past experiences in those of SIMMER-III code. COMPASS will be used for separated phenomena in CDAs, while the whole core will be analyzed by SIMMER-III. COMPASS is expected to clarify the detailed process in duct wall failure and fuel discharge to avoid re-criticality during CDAs in large size SFRs.