A pilot application of risk-based methods to establish inservice inspection priorities for nuclear components

As part of the Nondestructive Evaluation Reliability Program, sponsored by the Nuclear Regulatory Commission at the Pacific Northwest Laboratory, a methodology has been developed for establishing inservice inspection priorities for nuclear power plant components. The method uses results of probabilistic risk assessment in combination with the techniques of failure modes and effects analysis to identify and prioritize the most risk-important systems and components for inspection at nuclear power plants. Surry Nuclear Power Station, Unit 1 was selected for demonstrating the methodology. The specific systems selected for analysis were the reactor pressure vessel, the reactor coolant, the low pressure injection including the accumulators, and the auxiliary feedwater. The results included in this paper provide a risk-based ranking of components, which can be used to establish a prioritization of the components and a basis for developing improved inservice inspection plans at nuclear power plants