Control strategy research and controllers design of the China lead alloy cooled reactor

•A model for the reactor for CLEAR-IB was developed.•A PI controller was designed to keep the power following the set value.•A control strategy was adopted to control water average temperature of HX.•Dynamic simulation of the whole system was performed.

This paper considers the control strategy and the controllers design of a subcritical 10 MWth China lead alloy cooled reactor (CLEAR-IB). The model for the main components of the reactor and the most relevant interactions among them is developed to investigate the dynamic and control characteristics of the plant. It comprises of the primary system with lead bismuth eutectic (LBE) as the coolant, the secondary circuit with sub-cooled water as the coolant and the associated air cooling system for an effective rejection of thermal power to the environment as a final heat sink. The simulation results have been compared with the design data and the calculated data by Relap5 code, which shows that the proposed model is accurate enough to describe the dynamic behaviors of the plant in spite of its simplicity. A Proportional-Integral (PI) controller is designed to keep the power following the set value as quickly as possible. To keep the average temperature of sub-cooled water in the heat exchangers (HXs) constant, a control strategy based on a simultaneous feed-forward and feedback scheme has been adopted. Based on the developed model and control strategy, dynamic simulation of the whole system in cases of step changes of external source and load is performed, which demonstrated that the developed control system for the CLEAR-IB can provide superior reactor control capabilities due to the efficiency of the control strategy adopted.