[en] The use of state of art digital instrumentation and control (I and C) in safety and safety related systems (like reactor power regulation, reactor shutdown etc.) in nuclear power plants has gained importance due to the performance in terms of accuracy, computational capabilities and data archiving capability for future diagnosis. Added advantages in computer based systems are fault tolerance, self-testing, signal validation capability and process system diagnostics. But, uncertainty exists about the quality, reliability, performance and security of such software based nuclear instrumentation which poses new challenges for the nuclear industry and regulators in using them for safety and safety related systems. Therefore, it becomes mandatory to demonstrate that these systems are reliable, safe and secure. To obtain adequate confidence in licensing them for use in NPPs, digital I and C were deployed gradually from monitoring system to control system (i.e. non-safety, safety related and lastly safety systems). Based upon the experience over a decade, AERB safety guide AERB/SG/D-25 was prepared to prescribe the criteria and requirements to assess the qualitative reliability of digital I and C. The detail regulatory requirements for the use of FPGA and CPLD in nuclear applications are being worked out for addition in this document. This paper elaborates gradual deployment of digital I and C system in Indian NPPs. It covers the AERB approach for regulatory review and audit process for digital I and C as recommended in AERB safety guide AERB/SG/D-25. Further, aspects like Configuration Management (due to operation feedback, introduction of additional features and obsolescence), use of software developer tools and security of the digital I and C systems are mentioned. (author)

[en] Highlights: • The safety framework for Indian nuclear power programme (NPP). • Key aspects of development of regulations requirements and guidance. • Safety enhancements of NPPs. • Safety review of new technologies for NPP. - Abstract: The Atomic Energy Regulatory Board (AERB) is the regulatory body in India for ensuring that the use of ionizing radiation and nuclear energy does not cause undue risk to the health of workers, members of the public and to the environment. AERB is responsible for prescribing and enforcing of rules, regulations and requirements pertaining to safety of nuclear and radiation facilities and radiological safety. This paper describes the regulatory process followed by AERB for ensuring the safety of nuclear power plants (NPPs) during their construction as well as operation. The regulatory process for nuclear and radiation safety in the country had evolved organically, over a long period since the beginning of the nuclear program in the country, addressing the requirements and situations of the applications of the technology in the country. Some of the recent initiatives taken by AERB in this direction are brought out. In the coming days AERB is expected to face new challenges such as coping with the demands of a fast growing nuclear power program, simultaneous review of a large number of new projects of diverse designs and long term operation of the existing NPPs. The paper also gives some insights into how AERB is preparing itself to address these future challenges.