Method of controlling bypass flow rate in FBR type reactors

Purpose: To perform a rapid and smooth start-up of auxiliary core cooling system (ACCS) by operating separation valves so that the flow rates to the ACCS do not exceed a predetermined peak value. Method: A secondary sodium coolant circuit for transmitting heats by way of an intermediate heat exchanger to a steam system, and an ACCS for bypassing to the steam generator in the sodium coolant circuit are provided. The flow rate in the ACCS for bypassing to the steam generator is controlled by the operation of valves for separating the steam generator from the secondary sodium coolant circuit. The separation valves are adapted such that the closing velocity is continuously or discontinuously changed as the valve opening degree decreases to thereby control the flow rates in the ACCS below a predetermined controlled value. (Moriyama, K.)