Abstract
The probabilistic safety analysis method is an effective tool to demonstrate the balance of design and identify the vulnerabilities. It can provide technical support for the design optimization of nuclear power plant. A nuclear power plant in China specially designed the reactor cavity injection system (RCI) with both active and passive trains to mitigate the severe accident with core damaged. When the core damage accident occurs, the melt debris in the lower head can be cooled by RCI with water injection to the outside surface of the reactor vessel, thereby maintaining the integrity of the vessel and realizing the core melt in-vessel retention (IVR). This paper will introduce the design of the cavity injection system, and use the PSA method to establish a model of the system. Then the reliability of the system and its contribution to the large release frequency will be discussed, the vulnerability of the system will be identified. System design optimization recommendations will be proposed based on PSA results, and the results comparison between the optimization scheme and the original design is discussed. It can be concluded that in the design process of NPP, risk-informed methods should be considered as an important technical support tool.
