Kaiga Unit-1 Completes Major Life Extension Overhaul, Showcasing India’s Nuclear Engineering Capability

India’s nuclear power programme has achieved a significant engineering milestone with the completion of a major refurbishment programme at Kaiga Atomic Power Station Unit-1, involving En-Mass Coolant Channel Replacement (EMCCR) and feeder replacement works.

The 220 MW Pressurised Heavy Water Reactor (PHWR) unit, operated by the Nuclear Power Corporation of India Limited (NPCIL), underwent an extensive life-extension programme aimed at replacing ageing reactor components and preparing the unit for extended operation. Kaiga Unit-1 is among India’s early indigenous PHWRs and has played an important role in demonstrating the reliability and maturity of Indian nuclear technology.

The reactor was shut down in April 2025 for the major overhaul, which involved replacement of critical reactor components including the ageing coolant channels and associated feeder systems. These systems are essential parts of PHWR technology, carrying pressurised heavy-water coolant through the reactor core and ensuring efficient heat removal during operation.

Replacement of Coolant Channels — A Complex Nuclear Engineering Challenge

In a PHWR reactor, coolant channels contain the fuel bundles and pressure tubes through which heavy-water coolant circulates. Over decades of operation, these components experience radiation exposure, material ageing and operational stresses, requiring periodic inspection, maintenance and replacement.

The En-Mass Coolant Channel Replacement (EMCCR) process involves removing the existing coolant channel assemblies and installing new pressure tubes, calandria tubes and related components. The operation requires extremely high precision because these components form the heart of the reactor core structure.

Such refurbishment projects are among the most complex activities undertaken in the nuclear sector, requiring specialised tools, advanced engineering techniques and strict adherence to nuclear safety standards.

Fresh Fuel Loaded After Completion of Major Overhaul

After completion of the refurbishment activities, Kaiga Unit-1 entered the restart preparation phase with the loading of the first new fuel bundles into the newly installed channels on 13 September 2026.

The fresh fuel loading marked a major step towards restarting the reactor after its extensive modernisation programme. The achievement reflects the capability of Indian nuclear engineers in carrying out large-scale reactor refurbishment and life-extension projects.

The successful completion of the work demonstrates India’s growing expertise in maintaining and extending the operational life of its indigenous PHWR fleet.

Strengthening India’s Indigenous Nuclear Power Programme

Kaiga Atomic Power Station in Karnataka’s Uttara Kannada district is one of India’s important nuclear power facilities operated by NPCIL. The station has contributed significantly to India’s nuclear electricity generation programme through its indigenous PHWR technology.

Life-extension programmes such as EMCCR are important for countries operating mature nuclear fleets, as they allow existing reactors to continue producing clean electricity while maintaining high safety standards.

By replacing ageing reactor components and upgrading critical systems, such projects improve reliability, extend operational life and preserve valuable nuclear infrastructure and expertise.

Another Milestone After Kaiga’s Record Operational Achievement

Kaiga Unit-1 has previously achieved international recognition for operational performance. Between 2016 and 2018, the reactor operated continuously for 962 days, setting a world record for uninterrupted operation of a nuclear power reactor at that time.

The completion of the latest life-extension programme adds another important milestone to Kaiga’s history. While the exact description of the project as a “world first” would require confirmation from NPCIL or the Department of Atomic Energy, the scale and complexity of the EMCCR and feeder replacement work represent a major achievement in nuclear engineering.

The successful refurbishment of Kaiga Unit-1 highlights India’s ability to undertake complex reactor modernisation programmes and strengthens the long-term foundation of the country’s indigenous nuclear energy programme.

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