The prescribed standards ensure an adequate margin of safety so that NPPs can be operated without undue radiological risks to the plant personnel and members of the public. Nevertheless, it is necessary to develop emergency response plans so that in case of any eventuality, however unlikely, no undue radiological risk to plant personnel and public is incurred. All NPPs have established and documented emergency procedures by having an on-site as well as an on-site emergency preparedness plan. The role, responsibilities and action plans for various agencies required to act during an emergency are detailed in these plans. Specific requirements with respect to emergency preparedness in NPPs have been formulated by AERB.
NPPs are generally sited in a relatively low-population zone. An exclusion zone around the plant is established, which is under the exclusive control of the operating organization, and no public habitation is permitted in the area. The dose limits to a member of the public, under normal operating conditions and under design basis accident conditions specified, are applied at the boundary of this exclusion zone. A Sterilized Zone beyond the exclusion radius is also established. The Emergency Planning Zone is the zone defined around the plant up to a 16-km radius and provides for the basic geographical framework for decision making on implementing measures as part of a graded response in the event of an off-site emergency. This zone is examined in great detail while drawing up an offsite emergency plan and arranging logistics for the same. In case of an accident, the emergency measures consist of emergency actions in respect of notification, alerting personnel, assessment of situation, corrective actions, mitigation, protection and control of contamination.
The Environmental Survey Laboratories installed at all Nuclear Power Plant sites are well equipped for the assessment of radioactivity in various environmental matrices in and around the regions of the NPPS during normal operation. They play an important role during a nuclear emergency by assessing the impact of the emergency. Environmental monitoring is carried out with special focus on the affected sector so as to help decide the plan of action and suggest countermeasures, if required.