Development of ABWR Feedwater Pump and Controller Model

This work developed a stand-alone ABWR (Advanced Boiled Water Reactor) feedwater pump and controller model which was incorporated with a simplified reactor vessel and steam line model. The purpose of this work is to improve the existing model in PCTran-ABWR, a nuclear power plant (NPP) simulation code. INER has been using this computer code as an NPP simulation model for Software Safety Analysis (SSA) and software Fault Injection (FI) of digital instrumentation and control (I&C) research for years. The feedwater pump model includes three turbine-driven feed water pumps and one motor-driven feed water pump. The feedwater controller includes a one-element / three-element water level controller and a specific feedwater speed controller for each feedwater pump. The feed water turbines are driven by the steam from main steam line. As a result, the reactor dome pressure can affect the driving force of the three turbine-driven feed water pumps. It means if the dome pressure becomes low enough, the turbine-driven feed water pumps cannot function normally. The reactor dome pressure transient also affects the pressure difference of feedwater pump discharge pressure and the reactor dome pressure, which can actually affect the feedwater flow rate and reactor water level. The time-lag of feedwater control valve is also considered in this model. Hence, the slower response of turbine-driven feed water pump than that of motor-driven feed water pump can be observed. A number of test cases namely step change of dome pressure, load rejection, and four tests of feedwater pumps transfer were performed in this work to demonstrate the feasibility of dynamic response of this model. Therefore, this model will be implemented into the existing PCTran-ABWR plant simulation code to improve the response of feedwater pump and controller model. This stand-alone model can also be a feedwater control strategy tool to observe the possible responses of various feedwater control architectures.