Session: 4.3 - Nuclear Power

Paper Number: 118881

118881 - Codap Programme- Twenty Years of International Collaboration in Collecting Operating Experience 

CODAP Programme-  Twenty Years of International Collaboration in collecting Operating Experience

Since 2002, the OECD/NEA has operated an event database project that collects information on passive metallic component degradation and failures. The scope of the database includes primary system piping components, reactor pressure vessel internals (“reactor components”), main process and standby safety systems, and support systems (i.e., ASME Code Class 1, 2 and 3, or equivalent) components, as well as non-safety-related (non-Code) components whose degradation or failure can have significant operational impact. With an initial focus on piping systems components (the OPDE Project) the scope of the project in 2011 was expanded to also address the reactor pressure vessel and internals as well as certain other metallic passive components that are susceptible to damage or degradation. In recognition of the expanded scope, the Management Board (MB) approved the transition of OPDE to a new, expanded “Component Operational Experience, Degradation & Ageing Program” (CODAP). Fatigue mechanisms have caused significant nuclear power plant operability challenges including forced reactor shutdowns and extended outages. Since the 1970s, major research and development efforts have been devoted to better understand the underlying physical phenomena in order to prevent re-occurrences and to the development of fatigue management programs that ensure the long-term structural integrity of piping pressure boundary components. Recent operating experience data point to new technical challenges and the need for additional research. The new fatigue related challenges include, but are not limited to, evidence of thermal fatigue in locations believed to have been mitigated twenty or thirty years ago through piping design solutions implemented to resolve potential cracking and through-wall leakages. Also among the new challenges are potential limitations or “gaps” in existing fatigue management guidelines that have resulted in out-of-scope inspection locations degrading and failing due to fatigue mechanisms. In this presentation we will review the results of evaluations of the accrued thermal fatigue operating experience since 1998 and the different national programs to monitor and mitigate thermal fatigue damage in nuclear power plant piping. The CODAP database contains 254 pipe failures attributed to thermal fatigue. Of the total data subset, about 31% (or 80 events) occurred post 1998.

The specific objectives of this presentation are as follows: Brief overview of significant historical events; i.e. events that occurred prior to 1999 and that resulted in industry and regulatory actions, Based on the information stored in the CODAP event database, summarize the insights and results of root cause evaluations of thermal fatigue events that have occurred since the publication of NEA/CSNI/R(1998). Demonstrate how to use the thermal fatigue failure data in CODAP to draw qualitative and quantitative insights about structural reliability and integrity management. Provide some international level conclusions and recommendations for helping the work of member countries to decrease the number of fatigue failures and their risks to safe operation

Presenting Author: Jovica Riznic Canadian Nuclear Safety Commission

Presenting Author Biography: Within International nuclear regulatory community, Dr Jovica Riznic is best known for his contribution to research in thermal hydraulics and its application to components fitness-for-service and effective regulation of nuclear power plants, particularly related to steam generators as one of the key safety significant components. Active in professional societies, particularly in ASME, Jovica Riznic has served the engineering profession and community with distinction and exceptional dedication; he is current Chair of the ASME Nuclear Engineering Division’s Executive Committee (2022-2023. One of his the most prominent recent ASME activities have been with the International Conference on Nuclear Engineering (ICONE) where he served as a track lead organizer since 1998, and currently is the Conference Co-Chair for the ICONE-30 to be held in Kyoto, Japan.