Dynamic simulation and control studies of CPR1000 reactor core with advanced MSHIM control strategy

The advanced mechanical shim (MSHIM) control system and a typical ΔT protection system are built on MATLAB/Simulink for the CPR1000 reactor core to verify the feasibility and evaluate the safety margin of the reactor in transient conditions without boron adjustment. The simulation platform consists of a 1D dynamic nodal reactor core model, xenon-iodine dynamics model, power control system, AO control system, over temperature ΔT (OTΔT) protection system and over power ΔT (OPΔT) protection system. Based on this platform, three typical operational transients, namely the step increase in load from 90% FP to 100% FP, the 5% FP/min ramp load change from 30% FP to 100% FP and the 12-3-6-3 daily load follow are simulated to study the control effect of the new control system and assess the safety margins during these processes. The simulation results demonstrate that the MSHIM control system has satisfactory regulation capability for the CPR1000 reactor core in these operational transients with no actuation of the protection system and certain safety margins. The results also indicate that the MSHIM control strategy is a good alternative to MODE-G for CPR1000 to improve the performance of the core control system, which could be important references for the further engineering practice.