The Department of Atomic Energy conducted a district-wide emergency exercise around the Kalpakkam nuclear complex as a mandatory regulatory drill ahead of full-power operations at the country’s Prototype Fast Breeder Reactor (PFBR), which achieved first criticality in April. The PFBR is a 500 megawatt (MW) prototype at Kalpakkam and the exercise was intended to validate off-site response plans and coordination among civil and technical agencies. The exercise was mandated once every three years by the Atomic Energy Regulatory Board (AERB) and simulated an off-site radiological emergency originating at the PFBR in order to test coordination between the Department of Atomic Energy (DAE) and Chengalpattu disaster management machinery. Scenario management focused on notification, public safety measures and interagency communication across the affected district. The seven-hour drill was led by the District Disaster Management Agency under Chengalpattu Collector M Veerappan, who served as Incident Commander, with technical support from the Kalpakkam Emergency Committee. The committee was headed by SB Selvakumaran, Station Director of the Madras Atomic Power Station and Site Emergency Director, and included Allu Ananth, Station Director of the PFBR, overseeing technical response activities and safety protocols. Police, health, fire, agriculture and transport departments participated alongside the National Disaster Response Force (NDRF) Arakkonam unit, and local agencies practised evacuation, medical triage and traffic management measures. Around 15 observers from national and state disaster management agencies, the Nuclear Power Corporation of India Ltd (NPCIL) and Bhavini monitored the exercise and assessed readiness ahead of the scheduled full-power operations. The exercise also examined medical surge capacity, contamination control procedures and public information dissemination to ensure district resilience, and drill controllers evaluated resource mobilisation and interagency decision making. The monitoring agencies prepared a post exercise appraisal to identify strengths and areas for improvement as final preparations progress for sustained full-power operations at the reactor.