ICONE23-1248 DEVELOPMENT OF A FAST SIMULATION PROGRAM FOR AP1000 NUCLEAR STEAM SUPPLY SYSTEM

Abstract

The AP1000 nuclear steam supply system (NSSS) contains the reactor core and the reactor coolant system (RCS). The RCS is made up of two vertical U-tube steam generators (UTSG), four canned motor reactor coolant pumps, and one pressurizer. The energy released in the fission reaction is removed from the reactor core and transferred to the secondary side of the steam generators for power generation by RCS. In this paper, the dynamic responses and control characteristics of the AP1000 NSSS have been studied through dynamic modeling and simulation. First, a nodal core model was used to describe the core thermal power transient. A non-equilibrium two-regions-three-volumes pressurizer model and a lumped parameter dynamic model with moving boundary for the U-tube steam generator were developed based on the fundamental conversation of mass, energy and momentum. Then, the developed models, the relevant NSSS control systems, and the feedwater system of UTSG were implemented using MATLAB/SIMULINK to develop a fast simulation program of AP1000 NSSS. Based on the developed simulation program, the typical Mechanical Shim (MSHIM) load follow, 10% step load change and 5%/min ramp load change simulations were performed. The simulation results have demonstrated that the trend of transient responses agrees well with the general physical rules, and the reactor power and other key system parameters are well-controlled by the NSSS control systems. Thus, the develop simulation program can be used for dynamic simulations and control studies of AP1000 NSSS. Moreover, with the adoption of modular programming techniques, the developed simulation program facilitates easy modification, runs quickly, and can be easily applied to other large pressurizer water reactors in the futures.