Updating of criteria for in-service inspection of Indian PHWRs

Full text: In a period of over four decades, Indian nuclear programme has come a long way, both, in the fields of R and D and power generation. The first generation nuclear reactors apart from generating electricity for the power-starved nation, contribute very significantly in providing very valuable experience feedback. Surveillance and in-service-inspection (ISI) are activities primarily meant to monitor and provide assurance on the health of system, structure and components (SSC) in a nuclear power plant (NPP). With longer years of design life for newer units and management of ageing components and life extension of the existing units, the inputs generated by surveillance and ISI gain added dimensions. In the earlier years, criteria adopted for surveillance and ISI of NPPs was dominated by the theoretical considerations. However, with the phenomenal growth in the technology, availability of wide knowledge base, downward revision in the radiation dose limits for the occupational workers and a high level of public awareness, a need for updating the rationale for surveillance and ISI of NPPs has become necessary. The emerging newer techniques for non-destructive examinations, availability of host of superior materials, application of probabilistic assessment technique etc. could influence the rationale for surveillance and ISI of NPPs. In this paper an attempt is made to briefly discuss the integration of experience feedback with the current knowledge base and, consequently, update the criteria for ISI of Indian NPPs