Plant behavior of a fast breeder reactor under loss of AC power for long period

► This paper describes about evaluation results for the prototype FBR ‘Monju’ during a station blackout as long period as 10 days. ► The reactor can be cooled by three air coolers after the total blackout event. ► The reactor can be cooled if only one loop is intact. ► The temperatures at the outlet of fuel subassemblies become higher when the blackout occurs during the cooling-down process using pony-motors. ► Especially, a high temperature will appear when the blackout occurs between 300 to 1500 s.