(Source of the complete post: Wikipedia)
According to Siegfried Hecker, former director, Los Alamos National Laboratory, U.S.,
“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.”
India’s three-stage nuclear power programme was formulated by Dr. Homi 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. The ultimate focus of the programme is on enabling the thorium reserves of India to be utilised in meeting the country’s energy requirements. Thorium is particularly attractive for India, as it 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 not economically viable because global uranium prices are much lower.
The country 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.
As of August 2014, India’s first Prototype Fast Breeder Reactor had been delayed – with first criticality expected in 2015 – and India continued to import thousands of tonnes of uranium from Russia, Kazakhstan, France, and Uzbekistan. The recent India-Australia Nuclear Deal, Indo-US Nuclear Deal, India-Canada Nuclear Deal and the NSG waiver (Nuclear Suppliers Group), 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.
Dr. 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 first be converted into the fissile isotope uranium-233 by transmutation 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.
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 in 1958, the Indian government formally adopted the three-stage plan. Indian government recognised that thorium was a source that could provide power to the Indian people for the long term.
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.
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. Analysis shows that majority of the authors involved in thorium research publications appear to be from India.
- Stage I – Pressurized Heavy Water Reactors (PHWR)
In the first stage of the programme, natural uranium fuelled pressurised heavy water reactors (PHWR) produce electricity while generating plutonium-239 as by-product.
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.
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.
- Stage II – Fast Breeder Reactors (FBR)
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. A start date in 2015 has been suggested.
In addition, the country proposes to undertake the construction of four FBRs as part of the 12th Five Year Plan spanning 2012–17, thus targeting 2500 MW from the five reactors. One of these five reactors is planned to be operated with metallic fuel instead of oxide fuel, since the design will have the flexibility to accept metallic fuel, although the reference design is for oxide fuel. Indian government has already allotted Rs.250 crore for pre-project activities for two more 500 MW units, although the location is yet to be finalised. Because of the inherent danger in fast breeder reactors, there has been some talk of building the new ones underground.
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. This metric is critical for understanding the time durations that are unavoidable while transitioning from the second stage to the third stage of Bhabha’s plan, because building up a sufficiently large fissile stock is essential to the large deployment of the third stage.
- Stage III – Thorium Based Reactors (TBR)
A Stage III reactor or an advanced nuclear power system involves a self-sustaining series of thorium-232-uranium-233 fuelled reactors. This would be a thermal breeder reactor, which in principle can be refueled – after its initial fuel charge – using only naturally occurring thorium. According to the three-stage programme, Indian nuclear energy could grow to about 10 GW through PHWRs fueled by domestic uranium, and the growth above that would have to come from FBRs till about 50GW. The third stage is to be deployed only after this capacity has been achieved.
According to replies given in Q&A in the Indian Parliament on two separate occasions, 19 August 2010 and 21 March 2012, large scale thorium deployment is only to be expected “3 – 4 decades after the commercial operation of fast breeder reactors with short doubling time”. Full exploitation of India’s domestic thorium reserves will likely not occur until after the year 2050.
As there is a long delay before direct thorium utilisation in the three-stage programme, the country is now looking at reactor designs that allow more direct use of thorium in parallel with the sequential three-stage programme. Three options under consideration are the Accelerator Driven Systems (ADS), Advanced Heavy Water Reactor (AHWR) and Compact High Temperature Reactor. Molten Salt Reactor may also be under consideration based on some recent reports.