​At long last: On Kalpakkam reactor criticality, India’s regulatory regime

India's three-stage nuclear power programme, conceptualised by Dr. Homi Bhabha, aims to secure long-term energy independence by ultimately utilising the country's vast thorium reserves. Stage 1 involves Pressurised Heavy Water Reactors, while Stage 2 transitions to Fast Breeder Reactors, such as the 500 MWe Prototype Fast Breeder Reactor at Kalpakkam. Breeder reactors are technologically unique because they generate more fissile material than they consume by transmuting depleted uranium and spent plutonium into usable fuel. Achieving criticality—the state of a self-sustaining nuclear chain reaction—at the Kalpakkam facility is a landmark event. However, this milestone is marred by a 16-year delay and massive cost overruns, emphasizing the need for improved project execution before India can realistically progress to the final thorium-based Stage 3.

As India targets a net-zero economy by 2070, nuclear power provides an indispensable, zero-emission baseload power supply (constant and reliable electricity) to complement intermittent renewables. Currently contributing just over 3% to the national grid, nuclear energy is remarkably land-efficient, requiring only 6% of the footprint needed for equivalent solar capacity. This high power density helps resolve the inherent conflict between large-scale renewable expansion and biodiversity conservation by preventing the conversion of green cover. Despite these environmental merits, the economic viability of nuclear expansion requires strict scrutiny. With the Kalpakkam reactor's final cost ballooning to over ₹8,181 crore, policymakers must continually evaluate the nuclear paradigm against the rapidly falling levelised costs of solar and wind power to ensure efficient allocation of scarce public capital.

The impending expansion of India's nuclear sector necessitates an urgent overhaul of its institutional and regulatory architecture. Historically, the safety regulator, the Atomic Energy Regulatory Board, and the developmental agency, the Department of Atomic Energy, have both reported to the Atomic Energy Commission. This structure creates an inherent conflict of interest, as the Atomic Energy Commission acts simultaneously as the promoter and the regulator of atomic energy. The recent enactment of the SHANTI Act, 2025 marks a paradigm shift by allowing limited private participation and laying the groundwork for Small Modular Reactors. To secure public trust, ensure safety, and attract global investment in this new era of private operations, India must eliminate this administrative short-circuit and grant complete statutory and functional independence to its nuclear safety watchdog.