Simulation Study of Turbine Trips Without Scram for CPR1000 Nuclear Power Plant Employing MSHIM Control

Abstract In nuclear power plant operations, several signals may trigger the closure of turbine valve, known as turbine trips. It is desirable that these turbine trips would not cause reactor scram to avoid iodine pit and thus save time and work to restart the reactor. This study investigated the turbine trip without scram transients of CPR1000 Nuclear Power Plant (NPP) implementing Mechanical Shim control system. The Nuclear Steam Supply System (NSSS) consisting of the one-dimensional reactor core model, the nonequilibrium three-region pressurizer model, the nonlinear dynamic model of U-tube steam generator was first modeled. The Balance of Plant (BOP) model including the turbine model, the condenser model, the reheater model and the deaerator model was then established. Based on that, the full-scope simulation platform of CPR1000 NPP was constructed with relevant control systems integrated on MATLAB/Simulink. Meanwhile, the protection system of CPR1000 was also considered in which different real-time protection signals will be collected and processed, and once there is one or more signals were triggered, the protection system will be triggered and shut down the reactor for safety reasons. Finally, the most serious turbine trip transient from 100% Full Power (FP) were initiated and simulated. Results showed that this CPR1000 NPP configured MSHIM control can withstand the above transient as well as provide enough safety margins without leading to a reactor scram.