Abstract
The thesis focuses on the improvements and modifications of the PCTRAN-ABWR, a simulation code for the Lungmen Nuclear Power Plant, about the Emergency Core Cooling system (ECCS). The methodology to modify the PCTRAN-ABWR code and to improve its process flow and pressure model and the heat exchanger model can be examples for future modifications. The ECCS system includes of three subsystems, the Reactor Core Isolation Cooling subsystem, High Pressure Core Flooder subsystem and Residual Heat Removal subsystem. The approaches of the thesis are as followings:(1)Three independent divisions of ECCS are established.(2)The essential operation modes and interlock logics of ECCS system are improved.(3)The Thermal-Hydraulic relationships among the ECCS, the reactor core model and the containment are clarified.(4)The models for the process flow and pressure drop of ECCS are improved.(5)The RHR heat exchanger model is improved. As benchmarks of the ECCS modifications, the TRACG Benchmark Transient Analysis for the LUNGMEN Simulator Validation Project [1] and the SAFER/GESTR-Loss of Coolant Accident Analysis [2] are utilized. The discussions on the cases of LOCA and the impacts due to the delay of SCRAM time and the failure of the ECCS on the case of loss of all feedwater flow can be examples for future analysis.