Simulation of early phase radioactivity of CPR1000 plant under LOCAs based on RELAP5-3D core engineering simulator

In this study, the radioactivity of noble gases during loss of coolant accidents in containment is simulated by using CPR1000 nuclear power plant simulator in Ningde Fujian China. A simple fission product release model along with two real-time simulation methods are used for the modeling of the radioactivity transportation in the containment. In addition, an accurate method to simplify multi-nuclides into a single equivalent nuclide is presented. The characteristics of the lumped parameter method and the distributed parameter method for modeling containments are compared. Meanwhile, a shortcoming of the current containment modeling tool in the 3KeyMaster platform is discussed. The simulation results of noble gases gap release fractions are in agreement with the results of Sandia National Laboratories in SAND2008-6664 for high burnup cores.