SGTR analysis on CPR1000 with a passive safety system

As the development of the nuclear industry, passive technology turns out to be a remarkable characteristic in the design of advanced nuclear power plants. Since the 20th century, much effort has been given to the passive technology, and a number of evolutionary passive systems have been developed. The CPR1000 plant, which is one kind of mature pressurized water plants in China, is proposed to be improved with some passive systems to enhance safety. The proposed passive systems include: (1) the RMT (reactor makeup tank); (2) the ACC (accumulator); (3) the IRWST (in-containment refueling water storage tank); (4) the PEFS (passive emergency feed water system), which is installed on the secondary side of SGs; (5) the PDS (passive depressurization system). In modifying the passive safety system, it is found that the actuation conditions of the passive safety system and the accident assumptions bring great effects on the accidental mitigation. It is necessary to study the influence induced by them. In this paper, the transient phenomenon of SGTR is analyzed to show the process in the modification of the actuation conditions and the assumptions. Finally, the most proper assumptions and actuation conditions are determined. Through the sensitivity analysis, it is found that the RMTs' and PEFSs' behaviors bring a great impact on the accident transient. The strong mutual effect between each passive safety component in the SGTR is the reason of choosing this accident to analyze in this paper.