NEA CODAP Project Topical Report: A Review of the "Post-1998" Experience with Thermal Fatigue in Heavy Water and Light Water Reactor Piping Components


Since its inception in 2002, the operating experience with thermal fatigue mechanisms has been an intrinsic aspect of the technical scope of CODAP, which is a joint database project within the Committee on the Safety of Nuclear Installations (CSNI). This sixth topical report documents the results of thermal fatigue operating experience evaluations performed by the CODAP management board (MB). The technical emphasis is on the lessons learnt since the publication of the report “Specialist Meeting on Experience with Thermal Fatigue in light-water reactor (LWR) Piping by Mixing and Stratification” (NEA/CSNI/R(98)8).

This report highlights the need for close co-operation between plant designer and plant owner and, among plant personnel, between maintenance and operation staff to keep the risk of thermal fatigue under control. This sixth topical report addresses the accrued thermal fatigue operating experience since 1998 and the different programmes to monitor and mitigate thermal fatigue damage in nuclear power plant piping. The CODAP MB identified 254 pipe failures attributed to thermal fatigue. Of the total data subset, 31% (or 80 events) occurred after 1998. The insights and lessons learnt from evaluating the post-1998 operating experience is the subject of the sixth CODAP topical report.