India’s journey to avail itself of clean and potent sources of energy to meet its growing demands has led the country to focus on nuclear energy. For this, India is concentrating on both fundamental forms of reactor – fission and fusion. While fission reactors have been operating in India for decades and there is a wealth of national expertise on how to operate these reactors, fusion reactors are still emerging and are technically challenging at the moment.
However, India’s role in the ITER global fusion reactor programme could allow India to harness clean energy for its own growth and also lay the foundation for future nuclear fusion energy industry in India. Prime Minister Narendra Modi’s visit to the project site in France in 2025 further makes the ITER project an important subject of discussion.
India’s ITER Journey
India is an active participant in the global International Thermonuclear Experimental Reactor (ITER) – a 35-country joint milestone project and world’s first commercial-scale fusion reactor project. ITER is being developed as a major step forward to fusion-generated emissions-free electricity.
Within the total share of manufacturing and construction process, India received 9% of the ITER project work that comprises a total of Rs.10,000 crore (US$1.17bn).
India has already supplied the cryostat, the world’s largest high-vacuum pressure chamber. India was also responsible for the construction of the top lid and central disk for the cryostat which was to be assembled and welded on site in a dedicated workshop in France. The upper cylinder was to be assembled and aligned prior to the welding process. The cryostat will operate at very low temperatures facilitating the cooling of the superconducting magnets and are necessary for the fusion reactor to operate successfully. The cryostat will also be the largest vacuum vessel ever built out of stainless steel. But this technology has not been bereft of engineering challenges owing to the huge size and intricate specifications. In July 2023 India completed the lower cylinder of the cryostat and the fabrication of the base.

India’s contribution is also noteworthy for its role in the Cooling Water System (CWS) for the ITER project. The CWS has four sub-systems: the Tomakak Cooling Water System (TCWS), the Component Cooling Water System (CCWS), the Chilled Water System (CWS), and the Heat Rejection System (HRS). India was involved in the three subsystems CCWS, CWS and HRS from design to engineering, manufacturing, procurement, and testing of the components and systems.
The delivery of equipment and components that included delivered a cooling tower rated at a 510 MWth heat rejection capacity, plate type heat exchangers, water cooled chillers, pumps, electrical motors, cables, water polishing units, stop log gates and others were completed in 2021.
Prior to this, India also completed the procurement and in-wall shielding blocks and accompanying support ribs, brackets, and fasteners in 2020 and manufacturing work is also in completion mode. In addition, India is responsible for the development of the Diagnostic Neutral Beam (DNB) to diagnose the helium ash content in the used deuterium-tritium fuel using plasma phase. This diagnostic tool is crucial to the ITER project.
India’s fusion players
Indian conglomerate Larsen and Toubro was a partner and major contractor in the ITER project which ranged from cryostat fabrication and developing the cooling water systems that include systems like heat exchangers, cooling towers, water polishing units, pressurisers, pump sets, piping, strainers, valves. The Indian Domestic Agency was tasked with the procurement and delivery of in-wall shielding package while manufacturing was the responsibility of M/S Avasarala Technologies Limited (ATL) and Larsen and Toubro.
Radio frequency heating sources are being developed in the city of Gandhinagar. This development is not without challenges as there is a need to establish integrated performance that is safe and reliable. The process needs to be capable of being repeated easily even in harsh conditions. These RF heating sources are meant for the Ion Cyclotron Heating and Current Drive system which is an external heating system for the ITER Plasma.
In 2024, Larsen and Toubro has also been awarded port positioning alignment and welding.
According to ITER Director General Bernard Bigot, India “agreed to supply 9% of the value to the construction cost. There are different components, and diversity of equipment. Due to their size and precision, some are pushing frontiers of knowledge, and some are very innovative.”
Needless to say, the project is helping India gain experience and expertise in one of the most crucial and complicated technologies associated with fusion reactor technology. This expertise is being gained not only in research and development activities but also in designing, handling and transporting the equipment safely.
Why fusion?
While other forms of renewable energy exist like solar and wind, they are dependent on the availability of the source of energy in adequate amounts. Cloudy days and calm winds dampen the reliability of those renewable energy sources. There are many places in the world where solar panels and wind-powered turbines would not be as effective due to the climate. For example, during the monsoon season from June to October, Meghalaya, India experiences the highest rainfall in the world. Strong winds could trigger an automatic shutoff feature of wind turbines, which can be damaged and the persistent cloud during these humid summer months precludes a reliable solar supply.
COVID and ITER
COVID affected supply chain mechanisms across the globe and the ITER project was no exception. The ITER was supposed to create the first plasma by 2025, but there is a delay due to COVID-19 in that initiative resulting in a cost overrun too. Nevertheless, India has reportedly delivered on its commitments despite the impact on global supply chains. The project is, however, moving ahead and it is expected that it will enter into its full operational phase by 2035.
There is little doubt that the expertise and experience gained from this fusion project will support India in its nuclear energy research and development and allow it to responsibly develop a safe nuclear fusion energy programme in future. India’s role in this critical infrastructure development and the role of fusion in India’s future energy mix cannot be underestimated.