It is one of history’s great ironies that nuclear energy—arguably among humanity’s most profound technological achievements—remains burdened with the shadow of destruction. The association is not without reason; it was forged in the searing memory of the Hiroshima bombing on 6 August 1945, during the final stages of World War II, when the atom first revealed its terrifying power. And yet, in the decades since, that same force has quietly transformed into one of the cleanest and most sustainable sources of electricity we know. When India’s Fast Breeder Reactor at Kalpakkam recently went critical, it stirred in me a cascade of memories—most vividly, my visit in 2007 to the reactor ‘Bhavani’ as part of President A. P. J. Abdul Kalam’s entourage.

I remember standing before a structure of such immense scale and complexity—its vast volumes of reinforced concrete and steel descending deep underground, layers engineered, cooled and shielded to contain a force that, once critical, cannot simply be switched off—that it redefined my sense of what human endeavour can achieve. Today, when public celebrations often gather around bridges and skyscrapers, I am struck by how little we recognise these deeper infrastructures that sustain civilisation. We have grown accustomed to admiring the visible and the ornate, while remaining largely unaware of the invisible forces—and the monumental systems, buried beneath our feet—that quietly hold our world together.

At the foundation of this journey stands Homi J. Bhabha—a visionary who not only imagined India’s atomic future but also built the institutions to realise it. With the support of the Tata Trusts and the visionary backing of J. R. D. Tata, he established the Tata Institute of Fundamental Research in 1945, laying the foundation for India’s advanced scientific research ecosystem. In 1954, he articulated the three-stage nuclear programme, a uniquely Indian strategy designed to convert limited uranium and abundant thorium into long-term energy security. His untimely death on 24 January 1966, in the crash of Air India Flight 101, bound for London and lost over Mont Blanc in the Alps, did not extinguish this vision. It endured—quietly, persistently—through generations of scientists, and through a political leadership that grasped the long arc of national interest. That the first stage now stands effectively realised in April 2026 is not merely a technical milestone; it is a civilisational marker of patience, continuity and resolve. 

The elegance of Homi J. Bhabha’s vision lies in its alignment with India’s natural endowment. With modest uranium reserves but vast thorium deposits, the programme unfolds in three deliberate stages: heavy-water reactors using natural uranium; fast breeder reactors that multiply fissile material, a material that can split and release energy to sustain a nuclear chain reaction; and, finally, thorium-based systems capable of sustaining energy production for centuries. For a country of over a billion people, the demand for energy at scale is not a choice but a necessity—one that cannot be met without harnessing the power of the atom. This is not just an energy strategy; it is a blueprint for sovereignty—transforming scarcity into abundance through science.

Yet, within this design lies a deeper strategic insight. The world remains fundamentally dependent on uranium—a resource India possesses only in limited measure—while thorium, abundant along India’s coasts, remains largely untapped globally. Bhabha’s pathway recognised that thorium cannot release energy on its own; it must first be ‘awakened’. During the fast breeder stage, plutonium is produced, which in turn serves as the trigger, converting thorium into uranium-233—a fissile material capable of sustaining a nuclear chain reaction. In this elegant act of scientific alchemy, India turns its constraint into strength: using what is scarce to unlock what is abundant, and thereby securing an energy future that is not only self-reliant but potentially inexhaustible.

Yet such a vision was never destined for haste. The programme’s long gestation arises from its very architecture. Each stage depends on the successful completion of the one before it; the second cannot proceed without the first, nor the third without the second. The technologies involved are among the most complex humanity has attempted. Fast breeder reactors operate under high neutron flux and demanding engineering conditions, while thorium must first be converted into uranium-233 through a multi-step fuel cycle before it becomes usable as nuclear fuel. Every step demands precision, validation and time. 

To this intrinsic difficulty was added the weight of history. After the Smiling Buddha, India faced decades of technological isolation under regimes such as the Nuclear Suppliers Group. What many nations could access through global collaboration, India had to build painstakingly from first principles. This constraint undoubtedly slowed progress, but it also forged a rare kind of resilience. The programme that emerged is not derivative; it is deeply indigenous—shaped by necessity, refined through persistence, and strengthened by self-reliance. If anywhere in the world there exists a nuclear programme that can truly claim to be homegrown in spirit and substance, it is India’s.

History reminds us that science has often advanced through the movement of minds across borders. Albert Einstein, an immigrant to the United States, reshaped modern physics; Enrico Fermi, Leo Szilard and Edward Teller were among those who carried Europe’s intellectual legacy into America’s nuclear enterprise. India’s journey, by contrast, unfolded largely without such external inflows—its strength arising from within. In that sense, its achievement is not only technological but civilisational: a demonstration that sustained vision, even under constraint, can build capabilities as profound as any assembled through the advantages of global mobility.

Hereafter, the future moves forward with quiet certainty. With the breeder stage going critical at Kalpakkam, India begins to multiply its fissile resources, preparing the ground for the thorium era. In the coming decades, thorium-based reactor technologies are expected to progress from experimental stages to potential deployment, positioning India among the leading nations in industrialising this fuel cycle. In parallel, nuclear energy is likely to integrate with renewables, helping anchor a stable, clean energy grid. Beyond its borders, India may emerge as a provider of nuclear technologies and frameworks for the Global South—offering not just systems, but a philosophy of building under constraint. 

In reflecting on the journey so far, I consider myself deeply fortunate to have met R. Chidambaram and Anil Kakodkar on several occasions and to have experienced their warmth and affection. As a mechanical engineer, I was struck when Kakodkar Sahib shared that he, too, came from the same discipline. Verghese Kurien, himself a mechanical engineer, embodied the same truth—that excellence is not confined by formal training. Perhaps that is the quiet law of great endeavour: those who surrender to the work before them often transcend their own boundaries, as if carried forward by a larger current of energy.

I have also been privileged to share a long-standing association with Sudhakar Potluri, who devoted a lifetime to atomic energy and later served as Chairman of the Electronics Corporation of India Limited. From him, I gained an appreciation of the extraordinary electronic engineering that underlies nuclear power—the seamless conversion of heat into steam, the precise running of turbines, and the generation of electricity in systems where ‘never a fault’ is not merely an ideal but an uncompromising necessity. As for me, my journey has been modest; I remain a small fry in the presence of such towering individuals, grateful simply to have been a fellow traveller in a boat steered by Dr. Kalam—much like an isotope held in careful balance.