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Even as India is awaiting its Prototype Fast Breeder Reactor at Kalpakkam to achieve criticality, it is undertaking research and development work on a wider scale to develop technologies for the third stage of its nuclear power programme – that is to develop Thorium-fuelled Advanced Heavy Water Reactors (AHWRs).

India has huge reserves of Thorium and the thorium-fuelled AHWRs were proposed in 1950s by Homi Bhabha to make India self-reliant in nuclear power. India has to import Uranium for its nuclear reactors. Bhabha Atomic Research Centre (BARC) – a unit of Department of Atomic Energy – has already developed a technology demonstrator of thorium fuel-based vertical pressure tube type, heavy water moderated and boiling light water cooled reactor.

“Efforts are currently on to enlarge the present Thorium related R&D work and activities to a bigger scale and towards development of technologies for the third stage of our nuclear power programme. Safety has been accorded paramount importance in all Thorium technology development studies,” Jitendra Singh, the Union Minister of State (Independent Charge) Development of North-Eastern Region (DoNER), MoS PMO, Personnel, Public Grievances & Pensions, Atomic Energy and Space told Indian Parliament in a written response.

FBR is the missing link to India’s quest for a closed nuclear fuel cycle. A closed fuel cycle means that the country is reprocessing and remaking the spent fuel from its nuclear power reactors. India has been following a three-stage nuclear electricity programme. The three stages are as follows – pressurised heavy-water reactors (PHWRs) using natural uranium as fuel; fast breeder reactors (FBRs) using plutonium and depleted uranium from the PHWRs; and reactors using the abundant thorium found in India. The home-grown prototype fast breeder reactor (PFBR) had undergone sodium commissioning in 2018 and is expected to achieve criticality in 2019. This would make India, the second country after Russia that operates a Fast Breeder Reactor.

The large scale introduction and utilization of Thorium in the programme has been contemplated after an adequate inventory of Plutonium becomes available from our Fast Breeder Reactors (FBRs), comprising the second stage of Indian nuclear power programme. This will be after a few decades of large scale deployment of FBRs.

Thorium is being termed as the long-term option and “inexhaustible” energy source for a sustainable Indian nuclear power programme. “The three stage nuclear power programme aims to multiply the domestically available fissile resource through the use of natural Uranium in Pressurised Heavy Water Reactors, followed by use of Plutonium obtained from the spent fuel of Pressurised Heavy Water Reactors in Fast Breeder Reactors. Large scale use of Thorium will subsequently follow making use of the Uranium-233 that will be bred in Reactors,” Dr. Singh added. It is not possible to build a nuclear reactor using Thorium (Thorium-232) alone. Thorium has to be converted to Uranium-233 in a reactor before it can be used as fuel.

“Development of technologies pertaining to utilisation of thorium has been a part of ongoing activities in Department of Atomic Energy. With sustained efforts over the years, India has gained experience in different areas of Thorium fuel cycle,” the minister added. In preparation for the utilisation of Thorium in Third Stage of India’s Nuclear Power Programme, efforts towards technology development and demonstration are made now so that a mature technology for Thorium utilisation is available in time.