Modeling of boiling water reactor feedwater control algorithms

A RELAP5/MOD3.1 model of a boiling water reactor and an interface originall y developed as a real-time test platform for the Browns Ferry Unit 2 feedwa ter control system and turbine governors have been expanded to include feed water heater systems and controls and to change the reactor recirculation p ump controls from the current fluid-coupled drive to a future variable spee d drive. The expanded model includes feedwater heater shell-side components , associated piping, steam supplies, and condensers, and allows simulation of the Fox-boro digital feedwater heater level control system. The model wa s updated to RELAP5/MOD3.1.1, while the interface was expanded to handle ad ditional communications and operator actions. The simulated feedwater heate r level controls were tuned and benchmarked; benchmarking was performed aga inst steady-state data at various power levels from plant hear balance data . After the model was benchmarked, various transients were simulated to ide ntify potential flaws in the feedwater heater level control system.