India's three-stage nuclear power programme is an Indian nuclear program focused on enabling the utilisation of India's thorium reserves in meeting the country's energy requirements through the use of nuclear power. It was planned by physicist Homi J. Bhabha in the 1950s to secure the country's long term energy independence, through the use of uranium and thorium reserves found in the monazite sands of coastal regions of South India.
Thorium is particularly attractive for India, as India has only around 1–2% of the global uranium reserves, but one of the largest shares of global thorium reserves at about 25% of the world's known thorium reserves. However, thorium is more difficult to use than uranium as a fuel because it requires breeding, and global uranium prices remain low enough that breeding is not cost effective.
India published about twice the number of papers on thorium as its nearest competitors, during each of the years from 2002 to 2006. The Indian nuclear establishment estimates that the country could produce 500 GWe for at least four centuries using just the country's economically extractable thorium reserves.
The first Prototype Fast Breeder Reactor has been repeatedly delayed – and was commissioned in March 2024 – and India continues to import thousands of tonnes of uranium from Russia, Kazakhstan, France, and Uzbekistan. The 2005 Indo–US Nuclear Deal and the NSG waiver, which ended more than three decades of international isolation of the Indian civil nuclear programme, have created many hitherto unexplored alternatives for the success of the three-stage nuclear power programme.
Origin and rationale
Homi Bhabha conceived of the three-stage nuclear programme as a way to develop nuclear energy by working around India's limited uranium resources. Thorium itself is not a fissile material, and thus cannot undergo fission to produce energy. Instead, it must be transmuted to uranium-233 in a reactor fueled by other fissile materials. The first two stages, natural uranium-fueled heavy water reactors and plutonium-fueled fast breeder reactors, are intended to generate sufficient fissile material from India's limited uranium resources, so that all its vast thorium reserves can be fully utilised in the third stage of thermal breeder reactors.
Bhabha summarised the rationale for the three-stage approach as follows:
In November 1954, Bhabha presented the three-stage plan for national development at the conference on "Development of Atomic Energy for Peaceful Purposes" which was also attended by India's first Prime Minister Jawaharlal Nehru. Four years later, the Indian government formally adopted the three-stage plan. Indian energy resource base was estimated to be capable of yielding a total electric power output of the order shown in the table below. Indian government recognised that thorium was a source that could provide power to the Indian people for the long term.
Energy resource type Amount (tonnes) Power potential (TWe-year) Coal 54 billion 11 Hydrocarbons 12 billion 6 Uranium (in PHWR) 61,000 0.3–0.42 Uranium (in FBR) 61,000 16–54 Thorium ~300,000 155–168 or 358
Fuel reserves and research capability According to a report issued by the IAEA, India has limited uranium reserves, consisting of approximately 54,636 tonnes of "reasonably assured resources", 25,245 tonnes of "estimated additional resources", 15,488 tonnes of "undiscovered conventional resources, and 17,000 tonnes of "speculative resources". According to NPCIL, these reserves are only sufficient to generate about 10 GWe for about 40 years. In July 2011, it was reported that a four-year-long mining survey done at Tummalapalle mine in Kadapa district near Hyderabad had yielded confirmed reserve figure of 49,000 tonnes with a potential that it could rise to 150,000 tonnes. This was a rise from an earlier estimate of 15,000 tonnes for that area.
Although India has only around 1–2% of the global uranium reserves, thorium reserves are bigger; around 12–33% of global reserves, according to IAEA and US Geological Survey. Several in-depth independent studies put Indian thorium reserves at 30% of the total world thorium reserves. Indian uranium production is constrained by government investment decisions rather than by any shortage of ore.
As per official estimates shared in the country's Parliament in August 2011, the country can obtain 846,477 tonnes of thorium from 963,000 tonnes of ThO2, which in turn can be obtained from 10.7 million tonnes of monazite occurring in beaches and river sands in association with other heavy metals. Indian monazite contains about 9–10% ThO2. The 846,477 tonne figure compares with the earlier estimates for India, made by IAEA and US Geological Survey of 319,000 tonnes and 290,000 to 650,000 tonnes respectively. The 800,000 tonne figure is given by other sources as well.
It was further clarified in the country's parliament on 21 March 2012 that, "Out of nearly 100 deposits of the heavy minerals, at present only 17 deposits containing about 4 million tonnes of monazite have been identified as exploitable. Mine-able reserves are ~70% of identified exploitable resources. Therefore, about 225,000 tonnes of thorium metal is available for nuclear power program."
India is a leader of thorium based research. It is also by far the most committed nation as far as the use of thorium fuel is concerned, and no other country has done as much neutron physics work on thorium. The country published about twice the number of papers on thorium as its nearest competitors during each of the years from 2002 to 2006. Bhabha Atomic Research Centre (BARC) had the highest number of publications in the thorium area, across all research institutions in the world during the period 1982–2004. During this same period, India ranks an overall second behind the United States in the research output on Thorium. According to Siegfried Hecker, a former director (1986–1997) of the Los Alamos National Laboratory in the United States, "India has the most technically ambitious and innovative nuclear energy programme in the world. The extent and functionality of its nuclear experimental facilities are matched only by those in Russia and are far ahead of what is left in the US."
However, conventional uranium-fueled reactors are much cheaper to operate; so India imports large quantities of uranium from abroad. Also, in March 2011, large deposits of uranium were discovered in the Tummalapalle belt in the southern part of the Kadapa basin in Andhra Pradesh.
Stage I – Pressurised Heavy Water Reactor
In the first stage of the programme, natural uranium fueled pressurised heavy water reactors (PHWR) produce electricity while generating plutonium-239 as by-product. PHWRs was a natural choice for implementing the first stage because it had the most efficient reactor design in terms of uranium utilisation, and the existing Indian infrastructure in the 1960s allowed for quick adoption of the PHWR technology. India correctly calculated that it would be easier to create heavy water production facilities (required for PHWRs) than uranium enrichment facilities (required for LWRs). Natural uranium contains only 0.7% of the fissile isotope uranium-235. Most of the remaining 99.3% is uranium-238 which is not fissile but can be converted in a reactor to the fissile isotope plutonium-239. Heavy water (deuterium oxide, D2O) is used as moderator and coolant. Since the program began, India has developed a series of sequentially larger PHWR's under the IPHWR series derived from the original Canadian supplied CANDU reactors. The IPHWR series consists of three designs of 220 MWe, 540 MWe and 700 MWe capacity under the designations IPHWR-220, IPHWR-540 and IPHWR-700 respectively.
Indian uranium reserves are capable of generating a total power capacity of 420 GWe-years, but the Indian government limited the number of PHWRs fueled exclusively by indigenous uranium reserves, in an attempt to ensure that existing plants get a lifetime supply of uranium. US analysts calculate this limit as being slightly over 13 GW in capacity. Several other sources estimate that the known reserves of natural uranium in the country permit only about 10 GW of capacity to be built through indigenously fueled PHWRs. The three-stage programme explicitly incorporates this limit as the upper cut off of the first stage, beyond which PHWRs are not planned to be built.
Almost the entire existing base of Indian nuclear power (4780 MW) is composed of first stage PHWRs of the IPHWR series, with the exception of the two Boiling Water Reactor (BWR) units at Tarapur. The installed capacity of Kaiga station is now 880 MW consisting of four 220 MWe IPHWR-220 reactors, making it the third largest after Tarapur (1400 MW) (2 x BWR Mark-1, 2 x IPHWR-540) and Rawatbhata (1180 MW) (2 x CANDU, 2 x IPHWR-220). The remaining three power stations at Kakrapar, Kalpakkam and Narora all have 2 units of 220 MWe, thus contributing 440 MW each to the grid. The 2 units of 700 MWe each (IPHWR-700) that are under construction at both Kakrapar and Rawatbhata, and the one planned for Banswara would also come under the first stage of the programme, totalling a further addition of 4200 MW. These additions will bring the total power capacity from the first stage PHWRs to near the total planned capacity of 10 GW called for by the three-stage power programme.
Capital costs of PHWRs is in the range of Rs. 6 to 7 crore ($1.2 to $1.4 million) per MW, coupled with a designed plant life of 40 years. Time required for construction has improved over time and is now at about five years. Tariffs of the operating plants are in the range of Rs. 1.75 to 2.80 per unit, depending on the life of the reactor. In the year 2007–08 the average tariff was Rs. 2.28.
India is also working on the design of reactors based on the more efficient Pressurized Water Reactor technology derived from the work on the Arihant-class submarine program to develop a 900 MWe IPWR-900 reactor platform to supplement the currently deployed PHWR's of the IPHWR series.
Stage II – Fast Breeder Reactor In the second stage, fast breeder reactors (FBRs) would use a mixed oxide (MOX) fuel made from plutonium-239, recovered by reprocessing spent fuel from the first stage, and natural uranium. In FBRs, plutonium-239 undergoes fission to produce energy, while the uranium-238 present in the mixed oxide fuel transmutes to additional plutonium-239. Thus, the Stage II FBRs are designed to "breed" more fuel than they consume. Once the inventory of plutonium-239 is built up thorium can be introduced as a blanket material in the reactor and transmuted to uranium-233 for use in the third stage.
The surplus plutonium bred in each fast reactor can be used to set up more such reactors, and might thus grow the Indian civil nuclear power capacity till the point where the third stage reactors using thorium as fuel can be brought online, which is forecasted as being possible once 50 GW of nuclear power capacity has been achieved. The uranium in the first stage PHWRs that yield 29 EJ of energy in the once-through fuel cycle, can be made to yield between 65 and 128 times more energy through multiple cycles in fast breeder reactors.
The design of the country's first fast breeder, called Prototype Fast Breeder Reactor (PFBR), was done by Indira Gandhi Centre for Atomic Research (IGCAR). Bharatiya Nabhikiya Vidyut Nigam Ltd (Bhavini), a public sector company under the Department of Atomic Energy (DAE), has been given the responsibility to build the fast breeder reactors in India. The construction of this PFBR at Kalpakkam was due to be completed in 2012. It is not yet complete. The date of commission has been delayed to October 2022 from the previous date in 2019.
Doubling time Doubling time refers to the time required to extract as output, double the amount of fissile fuel, which was fed as input into the breeder reactors.