Abstract
The Lungmen nuclear power plant, owned by Taiwan Power Company and scheduled to be in commercial operation on 2011, is a GE-designed ABWR. The annular region in the lower downcomer of reactor pressure vessel accommodates ten reactor internal pumps (RIPs), which can provide core flow rate up to 111% rated. For safety concern, further more studies on thermal hydraulic characteristics of RIPs are needed. However, there is little information available on the limiting transient analyses of the highest or lowest core flow operation of ABWR. The first purpose of this study is to model the recirculation flow control system (RFCS) and investigate its effect on the system transient behavior forLungmenadvanced boiling water reactor (ABWR) plant. The second purpose of this study is to perform a transient analysis for the limiting pressurization events identified in the Final Safety Analysis Report (FSAR) of the Lungmen Advanced Boiling Water Reactor (ABWR) plant, using a thermal-hydraulic code different from that used in the Lungmen FSAR. The analysis results of key system parameters´ responses are then compared with those shown in the FSAR. This work also serves as an independent check and verification of the FSAR analysis result. The four transients selected are: (1) one reactor internal pump (RIP) trip, and (2) loss of feedwater heating. (3) Load Rejection with No Bypass, and (4) One Single Turbine Control Valve Closure (Fast Closure Model). These four transients are simulated and △CPR (Delta Critical Power Ratio) are caculated in this study, using the RETRAN-02 System Model in order to perform the verification of the FSAR transient analysis. The Analysis results show that the difference of the parameters′ response between the cases of automatic RFCS and manual RFCS can be predicted and identified clearly. The thermal limit parameters (ΔCPR) of the two transients for the automatic RFCS and manual RFCS cases have also been calculated using the RETRAN-02 hot channel model and CPR calculation methodology developed in this study. In general, the good agreement between the RETRAN-02 calculation and the FSAR results for the transient response of the core power, the core inlet flow, the system pressure, and the core inlet enthalpy is an indication that the △CPR is expected to be in good agreement with the FSAR △CPR results if the fuel vender CPR correlation is employed for the determination of CPR. Based on this, it is expected that the RETRAN-02 model developed in this study can be employed to support operational transient analysis if the model is benchmarked further with the appropriate data, e.g., the Lungmen plant power test data, etc.