Fuzzy logic control for improved pressurizer systems in nuclear power plants

• Improved performance of the pressurizer system in a CANDU nuclear power plant (NPP).
• Inventory control for the pressurizer system in NPP.
• Compare fuzzy logic with PID in pressurizer system in NPP.
• Develop a fuzzy controller to regulate the pressurizer inventory control.
• Compare control performance with current proportional controller used at NPP.

The pressurizer system in a CANDU nuclear power plant is responsible for maintaining the pressure of the primary heat transport system to ensure the plant is operated within its safe operating envelope. The inventory control for the pressurizer system use a combination of level sensors, feed valves and bleed valves to ensure that there is adequate room in the pressurizer to accommodate any swell or shrinkage in the PHT system. The Darlington Nuclear Generating Station (DNGS) in Ontario, Canada currently uses a proportional controller for the bleed and feed valves to regulate the pressurizer inventory control which can result in large coolant level overshoot along with excessive settling times. The purpose of this paper is to develop a fuzzy controller to regulate the pressurizer inventory control and compare its performance to the current proportional controller used at DNGS. The simulation of the pressurizer inventory control system shows the fuzzy controller performs better than the proportional controller in terms of settling time and overshoot.