Reactor Feedwater Pump Control System

Abstract

An object of the present invention is to provide a reactor feedwater pump control system, wherein when a condensate pump is tripped, the decrease in feedwater flow of feedwater supplied to a steam generator is minimized to suppress the decrease in water level of the steam generator, and at the same time preventing operating condensate pumps from continuing a run out operation. The feedwater pump control system is provided with a feedwater supply system, which includes a plurality of condensate pumps disposed in parallel for boosting condensate water from a condenser; a plurality of reactor feedwater pumps disposed in parallel for further boosting and supplying the condensate water to a steam generator; and variable frequency power supply systems each for driving an electric motor of the reactor feedwater pump at an adjustable speed.

1 . A reactor feedwater pump control system provided with a feedwater supply system, the feedwater supply system comprising:
 a plurality of condensate pumps disposed in parallel for boosting condensate water from a condenser;   a plurality of reactor feedwater pumps disposed in parallel for further boosting and supplying the condensate water to a steam generator; and   variable frequency power supply systems each for driving an electric motor of the reactor feedwater pump at an adjustable speed, the variable frequency power supply systems in the feedwater supply system receive frequency control instruction to thereby control the rotational speeds of the reactor feedwater pumps;   wherein:   the reactor feedwater pump control system includes:   control for tripping means for, when it is detected that one of the operating condensate pumps has been tripped, changing a maximum flow limit value for the frequency control instruction to the variable frequency power supply systems, in order to change a flow to the run out flow which is operational only for a short-time transition; and   control for returning means for, when it is detected that a standby pump for the condensate pump has started up, changing the maximum flow limit value from the run out flow to the normal operating flow.   
     
     
         2 . The reactor feedwater pump control system according to  claim 1 , wherein:
 the feedwater supply system includes pressure detection means for detecting discharge pressure of the condensate pumps; and   the reactor feedwater pump control system receives the discharge pressure of the condensate pumps from the pressure detection means, detects start-up of the standby condensate pump by comparison operation of the discharge pressure and pump start-up characteristics.   
     
     
         3 . The reactor feedwater pump control system according to  claim 1 , wherein:
 the feedwater supply system includes rotational speed detection means for detecting the rotational speeds of the condensate pumps; and   the reactor feedwater pump control system receives the rotational speeds of the condensate pumps from the rotational speed detection means, detects the start-up of the standby condensate pump by comparison of the rotational speeds and the pump start-up characteristics.   
     
     
         4 . The reactor feedwater pump control system according to  claim 1 , wherein:
 the reactor feedwater pump control system includes the control for tripping means, and control means for, when it is detected that the standby pump for the condensate pump has not started up, changing the maximum flow limit value from the run out flow to the normal operation flow obtained by condensate pumps that are continuously operating.   
     
     
         5 . The reactor feedwater pump control system according to  claim 4 , wherein:
 the reactor feedwater pump control system includes control means for, when it is detected that the standby pump for the condensate pump has not started up, outputting an   instruction to an automatic power regulator of the steam generator to request the automatic power regulator to decrease the power of the steam generator.   
     
     
         6 . The reactor feedwater pump control system according to  claim 5 , wherein:
 the reactor feedwater pump control system includes control means for, when it is detected that the standby pump for the condensate pump has not started up, changing the number of operating reactor feedwater pumps in such a manner that the number of operating reactor feedwater pumps becomes equivalent to the number of condensate pumps that are continuously operating.   
     
     
         7 . The reactor feedwater pump control system according to  claim 2 , wherein:
 the reactor feedwater pump control system includes the control for tripping means, and control means for, when it is detected that the standby pump for the condensate pump has not started up, changing the maximum flow limit value from the run out flow to the normal operation flow obtained by condensate pumps that are continuously operating.   
     
     
         8 . The reactor feedwater pump control system according to  claim 3 , wherein:
 the reactor feedwater pump control system includes the control for tripping means, and control means for, when it is detected that the standby pump for the condensate pump has not started up, changing the maximum flow limit value from the run out flow to the normal operation flow obtained by condensate pumps that are continuously operating.