Reactor feedwater control device

During rated operation where water is supplied on an automatic operation mode by using two ordinary feedwater pumps in parallel, if abnormality should occur in one of the ordinary feedwater pumps and the flowrate is decreased, the flowrate of the other ordinary feedwater pump is increased in accordance with an instruction from a water level control device in order to compensate the reduction of the flowrate of the feedwater, which results in imbalance in the flowrates between the ordinary feedwater pumps. When the imbalance is increased to more than a predetermined value, imbalance signals with respect to the ordinary feedwater pumps are outputted. Ordinary feedwater pump trip signals are outputted based on the imbalance signals. As a result, an automatic starting interlock for existent back-up feedwater pump is operated to compensate the feedwater flow rate of the tripped ordinary feedwater pump by the operation of the back-up feedwater pump, so that the necessary feedwater flow rate is maintained to avoid reactor scram due to reduction of the reactor water level. (I.S.)