Risk-Informed Disposition of Primary Heat Transport Piping Subject to Local Wall Loss
9th International Conference on CANDU® Maintenance - 2011 December 04-06

Presented at:
9th International Conference on CANDU® Maintenance
2011 December 04-06
Toronto, Canada
Session Title:
Fitness for Service Session C3

Xinjian Duan (Candu Energy Inc.)
Min Wang (Candu Energy Inc.)
James Wang (Candu Energy Inc.)
Michael Kozluk (Independent Consultant)


Fitness-for-service assessment is required in accordance with CSA-N285.4 if the extent of piping local wall loss exceeds the limits specified for the design of the piping component, which in general is equated to 12.5% of the nominal wall thickness.  This paper presents a comprehensive and robust risk-informed disposition of local wall loss in two example outlet feeders in accordance with the requirements of the Industry’s Fitness-For-Service Guidelines for Feeders.  The deterministic structural assessment is used to demonstrate that the component is fit-for-service, while the probabilistic assessment is performed as an alternative approach to demonstrate the extremely low probability of rupture due to local wall loss in terms of the reliability index using the first-order second-moment reliability method.

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