Seismic analysis of PWR control rod drop with the CRDAC scram performance code

This paper presents the seismic analysis method based on the CRDAC code which developed by China Nuclear Power Technology Research Institute (CNPRI). Both the scram time and the seismic response have been calculated, such as the maximum pressure in the guide thimble, impact forces to the spider spring, and friction forces to the absorber rod. According to the design requirements of the third-generation nuclear power plants, safety shutdown earthquake (SSE) and operating basis earthquake (OBE) for the horizontal response need to satisfy 0.3 g and 0.15 g, respectively. Therefore, the maximum accelerations of both the input and the initial horizontal deformation of a fuel assembly have been taken into account in this paper. After several sensitive analyses, it is found that the CRDAC code is a powerful tool for the design of control rods and fuel assemblies.