Characterization and structural integrity tests of ex-service steam generator tubes at Ontario Power Generation

The Canadian Nuclear Standard CSA N285.4 requires the periodic metallurgical examination of removed ex-service steam generator tubes. This paper describes the practices used for the characterization and structural integrity tests of ex-service steam generator tubes at Ontario Power Generation (OPG). It shows that there is no degradation of mechanical properties of Monel 400 tubes after 7–18 effective full power years (EFPY) of operation and Incoloy 800 tubes after more than 10 EFPY of operation.