Design of pumped up heater drain system

We have designed the pumped up heater drain system for Advanced Boiling Water Reactor(ABWR) Plant, and adopted the system to Kashiwazaki-Kariwa Unit no.7 of Tokyo Electric Power Co.,Inc.(TEPCO) to improve the plant heat rate based on the study of the system reliability especially in the transient mode. After the transient operation, ex. Load Rejection, there is a possibility that the drain may be flushed in the pump inlet side pipe. To prevent the drain flush in the pipe upstream to the pump ,we designed the pumped up heater drain system with the cooling of the drain in the pump inlet side pipe by injecting condensate water which temperature is relative lower than the pump inlet drain. We can keep the pump inlet pressure higher than required value by using this cooling system even in the big transient mode. During the start up test we checked the system response and the reliability of the heater drain pumped up system under the big transient mode. We confirmed the performance of the pumps and the system satisfied the design requirement. (author)