Research and development of probabilistic risk assessment methodology of external hazard combinations; Identification of hazard combinations in terms of impacts on SFR air cooling decay heat removal system

Okano, Yasushi; Yamano, Hidemasa   ; Takata, Takashi  ; Nishino, Hiroyuki  ; Kurisaka, Kenichi 

External hazard related to meteorological phenomena may impact on decay heat removal system using ambient air as an ultimate heat sink such as in sodium-cooled fast reactor system. This study identify the combination of external hazards to be considered and the items to be quantified for probabilistic risk assessment from the view point of strength and affecting duration of the hazard in case that secondary external hazard which has predicted appearance frequency overlaps after an primary external hazard which is very rare but high consequence.