In-Service Inspection - A Vital Role in Monitoring & Health Assessment of Nuclear Pressure Vessels, Piping & Components at Tarapur Atomic Power Station-1&2, NPCIL

Tarapur Atomic Power Station is a twin unit Boiling Water Reactors (BWRs) built in 1960's and presently operating at 160MWe. TAPS has completed 36 years of successful commercial operation and is continuing to provide safe, economic and reliable power supply. The design life of Tarapur nuclear reactors is 40 Effective Full Power Years (EFPY). So far TAPS has completed about 20EFPY for each reactor. In order to estimate the healthiness of nuclear components, a comprehensive study was made by the station in consultation with design group of NPCIL. In-Service Inspection (ISI) substantially enhances confidence in component performance. Consolidated inspection early in service life provides greater assurance of component's integrity. Periodic in service inspection provides vital information in the form of Haw characterization for assessment of structural integrity. This paper describes various degradation mechanisms (SCC, IGSCC, TGSCC, EC, F AC etc.,) identified for critical components, their method of detection, methodologies followed for In-Service inspection and developmental activities to assess the integrity of nuclear reactor vessels, piping & components for continued service. Also a comprehensive examination carried out on Structures, Systems and Components (SSCs) as part of plant ageing management programme is also discussed.