AUTOMATIC REACTOR POWER-CONTROL FOR A PRESSURIZED WATER-REACTOR

An automatic reactor power control system is presented for a pressuriz ed water reactor (PWR). The associated reactor control strategy is cal led ''mode K.'' The new system implements a heavy-worth bank dedicated to axial shape control, independent of the existing regulating banks. The heavy bank provides a monotonic relationship between its motion a nd the axial shape change, which allows automatic control of the axial power distribution. Thus, the mode K enables precise regulation of bo th the reactivity and the power distribution, by using double closed-l oop control of the reactor coolant temperature and the axial power dif ference. Automatic reactor power control permits the nuclear power pla nt to accommodate the load-follow operations, including frequency cont rol to respond to the grid requirements. The mode K reactor control co ncepts were tested using simulation responses of a Korean standardized 1000-MW(electric) PWR. The simulation results illustrate that the mod e K would be a practical reactor power control strategy for the increa sed automation of nuclear plants.