Risk-Informed Inservice Inspection Evaluation in Daya Bay Nuclear Power Plant

This paper describes in detail the methodology and implementation process of the risk-informed inservice inspection evaluation in Daya Bay nuclear power plant. The risk-informed inservice inspection evaluation is used to optimize the current inservice inspection of the residual heat removal system in Daya Bay unit 1. After optimization, the inspection location and numbers change. The assessment results show that the risk-informed inspection method is effective. It can focus on the risk significant locations, decrease the inspection numbers and the staff occupation doses, and the public health and safety are maintained and improved. The risk-informed inservice inspection does not only simply decrease the inspection numbers or change the inspection methods, but also pays more attention to the risk significant pipe segments. Risk-informed inservice inspection evaluation makes the inspection based on the degradation mechanism, i.e. cause-based, to improve the inspection effectiveness. In the end, some key issues about the risk-informed inservice inspection evaluation process are discussed and suggestions are proposed on its application.