In Indian BWRs, ISI is planned and performed in accordance with the requirements of ASME Boiler and Pressure Vessel Code Section XI which forms an integral part of the technical specification for plant operation. As provided in the reference code section, visual examination, surface examination and/or volumetric examinations are carried out on the components. Visual examinations are either direct or remote using state-of-the-art optical aids. Surface examinations employ penetrant test or magnetic particle test methods. Radiography and ultrasonic methods are used to examine components volumetrically. Uses of remote manipulators are resorted to in cases where direct access for inspection is restricted. Examination coverage is so extensive and regular that the ISI and allied surveillance activities alone consume about eight percent of the plants annual manpower budget. As a result of the systematic implementation of the ISI programme, defects have been detected in time, that is before they cause equipment breakdown or lead to forced plant outages or jeopardize plant safety, for taking corrective actions.

This paper describes the ISI programme underway in the twin- reactor BWR plant at Tarapur, India, and shares the much valuable experience amassed through a quarter century of ISI efforts here. Also explained in the paper are the planning and scheduling of ISI, training of ISI personnel, preparation and qualification of specific NDE procedures, executing the works, results of examinations and a few major challenges overcome in performance of ISI.