Fig. 1. Traditional operation scheme of PWR NSSS control system

Fig. 2. Control system set point decision scheme

Fig. 3. Diagram of setpoint optimization method

Fig. 4. Schematic diagram of a PWR system

Fig. 5. Flowchart of overall process for setpoint optimization

Fig. 6. Flowchart of optimization process based on PSO

Fig. 7. Intelligent decision setpoint optimization results (color online) (a) Decision setpoint optimization process, (b) Average temperature setpoint in primary loop, (c) Fluid level setpoint in pressurizer, (d) Fluid level setpoint in steam generator

Fig. 8. Simulation responses under two setpoint schemes (a) Steam turbine power, (b) Average coolant temperature in primary loop, (c) Pressurizer fluid level, (d) Pressurizer pressure, (e) Steam generator fluid level, (f) Steam pressure

Fig. 9. Simulation responses of main actuators under two setpoint schemes (a) Rod positions of R rods and power compensation rod, (b) Opening of feedwater valves