Reactor Protection System Probabilistic Risk Assessment Of Daya Bay NPP

The primary function of reactor protection system is to protect the integrity of the three nuclear safety barriers, namely, fuel cladding, primary pressure boundary and containment. When the certain safety limits, determined by the accident studies, are exceeded, The reactor protection system will give the protection signals of reactor trip and/or safeguard actuations, and then the reactor trip system and/or the engineered safety features are actuated.The reactor protection system reliability analysis of Daya Bay NPP is an important branch of the Probabilistic Risk Assessment project of Daya Bay Nuclear Power Plant. The purpose of probabilistic risk assessment of reducing reactor trip is to discover all the signals and the components which can result in reactor trip potentially, to assess the safety and reliability of systematic design , to find the potential design drawbacks and take effective measures to reduce such events.The reactor protection system which we analyze this time is in broad sense. The analytical scope is from the systematic sensors (thermodynamic instrumentation groups and nuclear instrumentation groups ) to the rod cluster control assemblies and the signals of engineered safety feature actuation system.A lot of papers about the report of probabilistic risk assessment of Daya Bay NPP and system manuals has been read by the author and let as the basis. In this paper, based on the reliability analysis methods of Failure Mode and Effect Analysis and Failure Tree Analysis, according to the result of Event Tree Analysis of probabilistic risk assessment report of Daya bay NPP , the top events of the fault treesof reactor protection system and the success criteria were established. By using Risk-Spectrum procedure, the unavailability and the minimal cut-sets (MCS) of the fault trees were obtained. The result of analysis was put into the visual risk analysis software of Daya Bay NPP as the support of data.The reactor protection system reliability analysis is the indispensable branch of the model of probabilistic risk assessment of Daya Bay NPP. The completion of this project will consummate the model of probabilistic risk assessment.