|Fig. 1: Map showing location of India's thorium reserves amounting to a total of 1 million metric tons.  (Source: Wikimedia Commons)|
As the second most populous nation in the world, India faces serious challenges in developing reliable and sustainable fuel and electricity. Due to India's rising population and rapid industrialization, energy consumption has risen to third in the world behind China and the United States.  In the process of reducing poverty and maintaining economic growth, India may need to increase their energy demand by four times relative to current consumption levels 
To meet these demands, India imports energy heavily in the form of coal and crude oil.  Electricity outages and scheduled blackouts remain a continuous problem in India due to ineffective electricity infrastructure. In addition, the widespread use of government- subsidized kerosene as cooking fuel poses a major health and environmental threat due to the heavy CO2 emissions from kerosene relative to other fuels.  These challenges underscore the need for India to develop energy systems that are climate-friendly, dependable, and energy- independent.
Homi Bhabha, a prominent Indian nuclear physicist in the 1940s and 1950s, pushed heavily for India to develop nuclear weapons and nuclear power initiatives to address these concerns. He is known as the father of Indian nuclear programme and is credited with India's three-stage nuclear power program which has been overviewed in previous essays from this course. 
The emphasis of India's three-stage nuclear power program is to utilize the large thorium deposits that are present throughout the country (Fig. 1). India is estimated to have nearly 400 thousand tonnes of thorium reserves, close to 25% of the global total thorium reserves.  Thorium itself is not fissile, but is fertile as it can be converted to U-233 which can then undergo fission to produce energy. 
Stage 1: Use natural uranium to fuel pressurized heavy water reactors (PHWRs). The byproduct, Pu-239, of these reactors are key for Stage 2.
Stage 2: Develop fast breeder reactors (FBRs) to produce excess Pu-239 which will then be convert Th-232 to fissile U-233.
Stage 3: Build thorium-based reactors that can be refueled using India's thorium reserves, which are converted to U-233 inside the reactor.
Currently, nearly all of Indias 5 GW of nuclear power is powered by PHWRs although the low natural abundance of uranium in India represents the natural end to Stage 1 of this program.  Developing Stage 2 FBRs is the goal for the next 4-5 decades in order to produce enough fissile material to begin Stage 3. Projections suggest that achieving 50 GW of nuclear power, an order of magnitude increase compared to current levels, will result in the start of Stage 3. 
Since 1985, India has operated a Fast Breeder Test Reactor (FBTR), which has been used to gather data and operational experience to develop future breeder reactors for Stage 2. This has resulted in the 500 MW Prototype Fast Breeder Reactor (PFBR), which, after 15 years of development, which was scheduled to be commissioned by Feb. 2018 but has still not been officially opened as of the writing of this article. Delays in the start-up of the PFBR will also likely push back the start of planned commercial power generation. This reactor is only the second fast breeder reactor in the world, behind Russia's Beloyarsk Nuclear Power Plant and is expected to be the start of the full-scale launch of Stage 2. Currently plans are underway to build 5 further fast breeder reactors with a total capacity of 2.5 GW. 
However, the construction of these fast breeder reactors are long term goals which greatly delays the implementation of Stage 3 thorium reactors. In fact, technological barriers to thorium reactors are likely less of a challenge than the material deficiency of having insufficient fissile material. A global trade in plutonium is a potential method to increase fissile material stores although significant diplomatic issues would hinder this option. 
To bypass the limitation of fissile material, an Advanced Heavy-Water Reactor (AHWR) is being designed currently as a 300 MW reactor that uses thorium-based fuel. These reactors are proposed as both an intermediate step towards immediate nuclear energy goals and also an important research center for the future large-scale construction of thorium-based reactors in the later parts of this century.  The AHWR is projected to be functional around 2020 although no reports of the start of construction have appeared which suggests a longer time-frame before the AHWR becomes reality.
© David Koshy. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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