Modeling and load follow simulation of CPR1000 Nuclear Power Plant implementing Mechanical Shim control strategy

Abstract

Load follow operation without changing soluble boron concentration is desirable for reasons of economic efficiency, automatic control capability and effluent reduction. Many researchers have investigated the implementations of Mechanical Shim (MSHIM) strategy to different types of Pressurized Water Reactors (PWRs) to achieve this goal. However, their studies mainly focused on reactor core calculations. This paper presents the modeling and load follow simulation of the CPR1000 Nuclear Power Plant (NPP) implementing MSHIM operation and control strategy in MATLAB/Simulink environment. The whole plant model consists of the Nuclear Steam Supply System (NSSS) and the Balance of Plant (BOP) system. The NSSS model consisting of the one-dimensional nodal reactor core model, nonequilibrium three-region pressurizer model and nonlinear, time-dependent lumped parameters U-Tube Steam Generator (UTSG) model was first developed. The BOP system model including dynamic models of key components, piping lines and valves was also developed. These models were then integrated in MATLAB/Simulink according to their coupled relationships with relevant control systems built to obtain the whole plant simulation model. Based on this model, the typical 12-3-6-3/100-50-100 daily load follow maneuvers with constant soluble boron concentrations at the Beginning of Cycle (BOC) and End of Cycle (EOC) were simulated under the MSHIM control strategy. The simulation results have demonstrated the feasibility and safety of the CPR1000 NPP implementing MSHIM control strategy to achieve daily load follow operations at both BOC and EOC. This study could offer a reference to the engineering application of MSHIM control strategy as well as whole plant simulations of PWRs.