India's nuclear nursery tucked on the coast of the Arabian Sea is 57 years old, but going strong, showing no signs of ageing or retiring.
Standing inside the control room of Tarapur Atomic Power Station Units 1 and 2 is like stepping into a living chapter of India's scientific history. The blinking panels, humming systems and vigilant operators are not merely running a power plant. They are keeping alive the facility that laid the foundation of India's commercial nuclear power programme nearly six decades ago. The newly refurbished control room looks in mint condition, smelling of fresh paint.
Fifty seven years after it first began producing electricity, Tarapur Atomic Power Station Unit 1 continues to operate as the world's oldest commercial nuclear reactor. For India, it is much more than an engineering marvel. It is the place where the country's journey from nuclear novice to a nation with end to end capabilities in atomic energy truly began.
Inside the control room, surrounded by decades of technological evolution, Vinay Thatte, Station Director of Tarapur Atomic Power Station 1 and 2, Nuclear Power Corporation of India Limited (NPCIL) reflects on a journey that has defined much of his professional life. A mechanical engineer who has spent more than 37 years at the station, Thatte speaks about the reactor with unmistakable affection.
"It is my family. It is my child. It is a pious place for me," Thatte says very humbly.
Vinay Thatte, Station Director of Tarapur Atomic Power Station 1 and 2
That emotional connection is understandable. Over the decades, Thatte has witnessed Tarapur evolve from an imported technology dependent on foreign suppliers into a highly indigenised facility sustained by Indian engineering and manufacturing capabilities.
The origins of the station date back to the early years of India's nuclear ambitions. Constructed as a turnkey project with equipment supplied by General Electric, and Bechtel of the United States, construction began in 1964. Both reactors achieved criticality in 1968 and entered commercial operation in 1969.
At the time, Tarapur stood in what was largely an undeveloped region. Transportation networks were limited. Infrastructure was sparse. Yet the project moved ahead at remarkable speed. Within five years, both units had become commercial power producers.
What emerged was India's first large scale commercial nuclear power station, a facility that would become the training ground for generations of engineers and scientists.
Today, the station continues to generate electricity at a remarkably competitive tariff. According to Thatte, the plant currently sells power at around Rs 3.31 per unit, making it one of the cheapest sources of electricity available in India.
There is a fascinating historical contrast. When the station first began operations, power generated by Tarapur reportedly cost only six paise per unit. Nearly six decades later, despite inflation, technology upgrades and extensive safety enhancements, the plant remains among the country's most economical producers of electricity.
Equally important, it produces electricity without emitting carbon-dioxide during operation.
But longevity does not happen by accident. Keeping a reactor built in the 1960s running safely in the 2020s demands constant vigilance, continuous upgrades and a willingness to learn from global experience.
Tarapur's survival story is also a story of adaptation.
The station underwent major safety enhancements after each of the world's most significant nuclear accidents.
Following the Three Mile Island accident in the United States in 1979, operator training became a major focus. Additional systems were introduced to reduce the possibility of human error affecting reactor operations.
After the Chernobyl disaster in 1986, further improvements were implemented to strengthen reactor safety and operational reliability.
Later, extensive design reviews conducted during the early 2000s led to another wave of modernisation. Shared systems were separated into independent systems for each reactor unit. Additional emergency diesel generators were installed. Power supplies and safety related equipment were further strengthened.
Then came Fukushima.
The 2011 accident in Japan transformed safety thinking across the global nuclear industry. Tarapur was no exception.
According to Thatte, one of the most significant post Fukushima upgrades involved the installation of a nitrogen inerting system inside the primary containment. The purpose was straightforward but powerful. By eliminating oxygen from containment structures, conditions that could potentially lead to hydrogen explosions are greatly reduced. Tsunami water protection gates were also installed and additional generators were put in place.
The plant also installed containment filtered vent systems. These systems provide operators with additional tools to manage containment pressure safely during extreme situations.
The changes required detailed engineering reviews, especially because integrating new systems into a plant built nearly six decades ago is never simple.
Yet perhaps the most remarkable chapter in Tarapur's recent history is the massive refurbishment project that has effectively given the reactor a new lease of life.
Engineers describe it as one of the most technically demanding upgrades ever undertaken at the facility. Thatte calls it conducting an open heart surgery on an operating nuclear reactor.
The comparison is apt.
At the heart of the operation was the replacement of critical reactor recirculation piping. This system plays a vital role in moving water through the reactor and helping extract heat from the reactor core.
Routine inspections revealed indications in certain weld joints. While these indications did not represent cracks or leaks, engineers decided to proactively replace the system with one made from superior materials.
The replacement system uses advanced low carbon nitrogen steel, a material renowned for its strength and resistance.
Executing the replacement, however, was a daunting challenge.
The piping was located in areas with significant radiation fields. Accessing it required the removal of ducts, structural supports, cable trays and numerous other components. Only after clearing these obstacles could engineers reach the piping itself.
Success depended on preparation.
Engineers first built a complete replica of the system outside the reactor area. Every component was recreated millimetre by millimetre. Teams repeatedly practised the operation, developed specialised tools and refined procedures before carrying them into the actual plant.
Much of the work made use of both robotic systems and human expertise.
Lead shielding blocks were fabricated to quickly isolate active radiation areas. Automated cutting and welding machines were developed locally. Remote handling systems were created for particularly challenging tasks.
The effort represented a showcase for Indian engineering innovation. "It requires a lot of planning and a lot of mock ups," Thatte explains.
The result is a revitalised reactor ready for decades of continued operation.
One of the significant achievements behind Tarapur's longevity has been India's growing ability to replace imported technologies with indigenous alternatives.
When the station began operations, spare parts and components largely depended on external suppliers.
That dependence gradually became a strategic concern.
Beginning in the late 1980s, Indian organisations including Bhabha Atomic Research Centre, Mumbai, Indira Gandhi Centre for Atomic Research, Kalpakkam and domestic industry partners worked together to localise critical components.
Today, Thatte says, most systems have been successfully indigenised.
The same story can be seen in fuel supply.
There was a period when international restrictions created challenges for obtaining fuel. After the 1974 Pokhran atomic explosion, USA decided to stall fuel supplies to Tarapur. To address these pressures, India developed domestic fuel production capabilities through the Nuclear Fuel Complex.
According to Thatte, fuel availability is no longer a concern. "There is no shortage of fuel," he says confidently.
Spent fuel management has also evolved. Used fuel is initially stored in specially designed pools inside the reactor building before being transferred to larger away from reactor storage facilities. These facilities provide safe long term storage capacity while ensuring stringent safety standards. India is unable to re-process the spent fuel from Tarapur 1 and 2 because of safeguards issues.
Looking ahead, perhaps the most remarkable fact about Tarapur is that engineers believe its story is far from over.
Based on detailed health assessments of structures, systems and equipment, Thatte believes the reactor can potentially continue operating for at least another twenty years. The station has presently sought a five year life extension, extendable to ten years after a safety review by the regulator.
That would take one of the world's oldest operating reactors well past its sixth decade of service. Taking Tarapur into a senior citizen category of atomic plants, a true rarity.
More importantly, it would continue contributing to India's rapidly expanding nuclear ambitions.
The Government of India has set a target of 100 gigawatts of nuclear power capacity by 2047. Achieving that vision will require many new reactors. But it will also require preserving institutional knowledge, engineering expertise and safety culture built over generations.
Much of that heritage was born at Tarapur. That is why this station occupies such a unique place in India's scientific landscape.
It is not merely a nuclear power plant. It is the birthplace of India's commercial nuclear energy programme, the training ground of thousands of engineers and the proving ground where India learned how to build, maintain and eventually master complex nuclear technologies.
As operators monitor reactor systems inside the control room and veteran engineers train the next generation, Tarapur continues writing its new India story.
For a facility that began its journey in the 1960s, the future still looks remarkably bright.
The world's oldest operational commercial nuclear reactor is not preparing for retirement.
After a remarkable refurbishment and decades of continuous modernisation, it is preparing for yet another chapter in India's clean energy journey.
