Explained: Why India is racing to build its own Light Water Nuclear Reactor

(Representative Image)

India has opened its nuclear power sector to private participation and is exploring opportunities in exports with the Department of Atomic Energy (DAE) having identified the need to expedite the fabrication of an Indian Light Water Reactor (LWR) as a key priority, The Indian Express has learnt.

Accordingly, there is a renewed push within the DAE to accelerate work on the 900 MWe (megawatt electric) LWR, whose design phase began in 2015. Officials say the availability of a homegrown LWR, alongside India’s established fleet of pressurised heavy water reactors (PHWRs), would strengthen New Delhi’s negotiating position with foreign reactor suppliers and help secure more favourable import terms, official were quoted as saying by IE.

What are LWRs?

LWRs or Light Water Reactors, are the most common type of nuclear reactor, using ordinary water (light water) as both the coolant to remove heat and the moderator to slow down neutrons for efficient fission. The two main designs are Pressurized Heavy Water Reactors (PWRs) and Boiling Water Reactors (BWRs), which generate steam to drive turbines for electricity, forming the backbone of global nuclear power.

LWRs dominate the global nuclear reactor market and officials acknowledge that without embedding Indian firms in international supply chains linked to this technology, breaking into the export market would remain challenging. This context also underpins the Sustainable Harnessing and Advancement of Nuclear Energy for Transforming India Act, 2025, passed during the winter session of Parliament.

The legislation enables greater scope for imported LWR-based nuclear projects, similar to the projects being set up by Russian in Kudankulam.

The legal changes are seen within the establishment as necessary to tap the dominant global LWR ecosystem, even as India retains its core strengths in other reactor types, Indian Express states.

India’s civil nuclear programme has long-standing expertise in PHWRs, ranging from the older 220 MWe units to the latest 700 MWe reactors. Based on heavy water (deuterium) and natural uranium, PHWR technology is an area in which India has achieved a high degree of self-reliance. Globally, however, PHWRs have increasingly been eclipsed by LWRs, which now account for more than 85% of the world’s civilian nuclear reactor capacity.

Why are LWRs dominating the global market?

The predominance of LWRs is driven by several factors. Compared to heavy water reactors, LWRs have simpler designs and engineering requirements, as they use ordinary water as both coolant and moderator, creating overlaps with conventional thermal power plant technologies. Their widespread deployment has also led to economies of scale that lower construction costs and these reactors are generally considered more thermally efficient.

While LWRs use normal water, they require enriched uranium as fuel. In most Western countries, access to enriched uranium is not a limiting factor, which is why LWRs are widely deployed by the United States, Russia and France and form the backbone of their nuclear fleets.

On the other hand, PHWRs are valued for their fuel flexibility and ability to operate on natural uranium — a significant advantage for India, given its limited uranium reserves. In export markets dominated by LWR-based technology and supply chains, however, this feature becomes less advantageous.

Key concerns around LWR export

The import of high-cost LWRs raises two key concerns. First, imported projects should not undermine indigenous reactor development and PHWR manufacturing capabilities. Second, higher capital costs translate into higher electricity tariffs, which must be viable within Indian market conditions.

These issues have contributed to delays at the Jaitapur nuclear project in Maharashtra, where tariff concerns, along with earlier liability issues and financial difficulties faced by French nuclear major Areva, stalled progress. The liability-related obstacles have since been addressed through the recent nuclear amendments.

At the same time, policymakers and experts see value in reinforcing India’s proven PHWR capabilities alongside a renewed emphasis on fuel manufacturing, particularly in view of the country’s vast thorium reserves. Proposals to position India as a supplier of PHWRs fuelled by a combination of thorium and imported low-enriched uranium are being cited as holding significant promise, IE reported.

This approach gains relevance as nuclear power is expected to play an important role in economic growth across several emerging economies. Countries such as the UAE, Bangladesh, Saudi Arabia and Turkey have indicated plans to expand their nuclear energy programmes.

India’s long-term nuclear strategy, centred on the eventual utilisation of thorium, reflects its unique resource profile of limited uranium and abundant thorium. Incorporating thorium alongside low-enriched uranium in existing reactor designs could help overcome constraints on scaling up nuclear capacity.

From this standpoint, PHWRs are seen by some within the establishment as particularly attractive — potentially even more so than LWRs. Officials suggest that India could leverage this advantage to emerge as a major supplier of PHWRs using mixed thorium and low-enriched uranium fuel, sources were cited as saying by Indian Express.

This discussion is unfolding alongside India’s ambitions to become a competitive manufacturing hub for nuclear reactors, especially small modular reactors (SMRs) in the 30–300 MWe range, produced at scale and at lower cost.