Probabilistic Safety Analysis For Small LOCA On Primary Coolant Piping Of Tianwan Nuclear Power Plant

For nuclear power plants, security is the foundation of the existence and development. So, all experts of related fields conduct a study on the plants, understand their weak links and take effective measures to ensure nuclear safety, which is important practical significance. Further, safety analysis is playing a more important role for nuclear power plants.The PSA classification in plants have been understood and the analysis methods of PSA have been discussed by studying current development of PSA in domestic and foreign and main contents of PSA in nuclear power plants. Meanwhile, Probabilistic Safety Analysis for Small LOCA on Primary Coolant Piping of Tianwan Nuclear Power Plant has been researched in this thesis.Firstly, combination with the phenomenon description of accident of small LOCA on primary coolant piping, requirements on safety functions and their realization ways had been studied after the accident occurred, the event sequences were modeled by adopting small event tree method, and a mathematical model of core damage has been deduced. Secondly, the failures of the security functions were modeled by adopting the fault tree method, and some assumptions of the systems have been done in the process of the establishment of FTA. Finally, the functional failure of the containment spray system has been found that it was the biggest contribution to the core damaged by identifying the models and reducing the probability of failure of this system was the effective ways and means to minimize the probability of damage to the core of this initial event.