Development of in-service inspection priorities for pressurized water reactor high-pressure injection system components

The multiyear program entitled Nondestructive Evaluation Reliability for In-Service Inspection of Light Water Reactors, sponsored by the US Nuclear Regulatory Commission, is being conducted at the Pacific Northwest Laboratory. The goals of the program are to determine the reliability of current in-service inspection of pressure boundary systems and components and to develop recommendations that can ensure a suitably high inspection reliability. The long-term objective is to develop recommendations for improved in-service inspections. In meeting program objectives, a risk-based method has been developed to guide the development of inspection plans. The method uses results of probabilistic risk assessment and failure modes and effects analysis techniques to identify and prioritize the most risk-important systems and components for inspection at nuclear power plants. The Surry Nuclear Power Station Unit 1 was selected for demonstrating the methodology. The specific system addressed in this study was the high-pressure injection/recirculation (HPI/R) system. The results provide a risk-based ranking of components within the HPI/R system, which can be used to guide the development of improved inspection plans for nuclear power plants. This work will subsequently be used in supporting the revisions of the American Society of Mechanical Engineer's codes and standards