Regulatory and safety aspects of Control Room design in Indian NPPs - criteria & practices

The design of Control Room in Nuclear Power Plants (NPPs) ensures that the operator is informed with accurate, complete and timely status of the plant equipment and applicable systems, notwithstanding the means for operating the plant safely under all Design Basis Events. The Control Room panels consist of several components arranged in a sequential fashion that are helpful in monitoring and control of various plant system parameters. The information provided on the panels is grouped suitably so as to add to the convenience of the operator. Human Machine Interface (HMI) aspects of the Control Room and its panels are based on anthropometrics and ergonomic considerations to provide the operator means to operate the plant in a safe and efficient manner. Over the years the Control Room of NPPs has undergone various stages of modernization moving in lockstep with advances in Control & Instrumentation technology. This includes replacement and segregation of panel components, introduction of Computer Based Systems (CBS) leading to superior operator interfacing and reduction of panel instrumentation and changes in over-all design layout at par with international standards. Nevertheless, in the fast evolving scenario, the Control Room design process poses new challenges for the industry and regulators in assuring safety, reliability and quality requirements. The criteria and requirements to assess the qualitative reliability and safety aspects of such design are laid out in various codes/guides viz. AERB/SC/D, AERB/SG/D-4 & D-20 as well as other international regulatory documents (IEC 964). Safety assessment of Control Room designs encompasses all the aspects affecting accessibility and habitability of the Control Room, HMI and other important factors like presence of fire, smoke, toxic gases & radioactivity, along with possible adverse effects of Electromagnetic Interference (EMI). The paper enumerates regulatory criteria and practices followed for a compreh- nsive design review of Control Room of Indian NPPs, along with a brief study of the evolving design scenario on Control Rooms of Indian PHWRs together with the international practices followed and the corresponding regulatory requirements for the new generation reactors.