CODAP Database Project: 20 Years of International Collaboration on Passive Component Operating Experience and Materials Degradation

Abstract of the technical paper/presentation presented at:
CNS CANDU Maintenance & Nuclear Component Conference
April 23-26, 2023

Prepared by:
Jovica Riznic
Canadian Nuclear Safety Commission

Abstract

The structural integrity of piping systems is crucial to the continuous and safe operation of nuclear power plants. Across all designs, the pressure boundary and its related piping and components form one of the many levels of defence in this respect.  It is therefore necessary to identify, understand, evaluate and catalogue all the degradation mechanisms and failures that affect various piping systems and components across all nuclear power plants (NPPs). The year 2022 marked 20 years of the OECD NEA collaborative event database project, which collects information on passive metallic component degradation and failure. The project is referred to as the Component Operational Experience, Degradation and Ageing Programme (CODAP). The scope of the database includes primary heat transport system piping components, the reactor vessel and its internals, main process and standby safety systems, support systems, and non-safety-related components whose degradation or failure can have a significant operational impact.

This presentation will discuss selected results from studies of temporal trends in pipe failure rates:

• The CODAP database event population had expanded to more than 5100 records by the end of 2022. The total event population has resulted from 12,505 reactor years of operation: 85% pipe failure events and 15% non-piping passive component failures.
• Trends and patterns in material degradation over more than five decades of nuclear power plant operation have been identified and analyzed, with the results published as topical reports that are available from the NEA website. Topical reports discuss a range of issues, from Flow Accelerated Corrosion (FAC) in commercial nuclear power plants to the thermal fatigue operational experience and material degradation in periods of extended and long-term operation.
• The use of CODAP/OPEX and knowledge databases can and has resulted in several significant inspection changes at NPPs worldwide. For example, Canada has already utilized CODAP to address thermal stratification and piping material fatigue issues. In addition, Canada proposed a methodology to separate piping and non-piping passive system reliability parameters as a function of plant design and age. Korea has collected and used information for piping failure events to identify sites of potential concern in their in-service inspection programs. The US NRC used the CODAP data in their studies of Estimating Loss-of-Coolant Accident (LOCA) Frequencies.

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