ATWS Accident Analysis for AP1000 Nuclear Power Plant

According to the analysis of all the anticipated transients without scram（ATWS） for AP1000 plant,it was determined that the loss of normal feedwater ATWS event is the limiting ATWS.Based on several sensitivity studies,the diverse actuation system（DAS） was improved as follow:low SG wide range water level setpoint implement the steam dump isolation and CMTs actuation,and then trip the RCP immediately.The final cases have been analyzed assuming the new DAS ATWS protection logic,and the results of analysis show that:considering the limiting MTC for the whole AP1000 plant life,the RCS peak pressure of LNFW ATWS meets the acceptance criteria with considerable margin.