Thorium and Nuclear Energy in India

David Davis
February 24, 2015

Submitted as coursework for PH241, Stanford University, Winter 2015


Fig. 1: Prime Minister Narendra Modi, President Barack Obama and First Lady Michelle Obama wave to the crowd at the Rajpath saluting base following the Republic Day Parade in New Delhi, India. January 26, 2015. (Source: Wikimedia Commons)

This article will focus your attention to the potential promise of nuclear energy and its inherent dangers when it comes to proliferation. In light of a recent trip to Delhi by the U.S. President Barack Obama (Fig. 1), I felt it necessary to examine India's effort to expand its nuclear energy program. This trip comes at a time when advancements in research using Th-232 as a viable replacement for U-235 in nuclear reactors are gaining momentum on the nuclear energy landscape.

What We Know ...

On January 25, 2015, President Obama visited India and unlocked billions of dollars in economic growth when he reached a compromise with Indian Prime Minister Narendra Modi. According to Reuters, the new deal resolved differences over the liability of suppliers to India in the event of a nuclear accident and U.S. demands on tracking the whereabouts of material supplied to the country. Failed compromise was the issue in the 2006 deal struck by Indian President Manmohan Singh that did not shield suppliers from liability nor did it produce the amount of business U.S. companies were expecting. Now there is an understanding of liability on behalf of companies who seek to assist India in furthering its nuclear energy ambitions. In addition, the two leaders agreed upon a 10-year framework for defense ties and deals on cooperation. Included in the framework is the "joint production of drone aircraft and equipment for Lockheed Martin Corp's C-130 military transport plane." [1]

Shortly putting aside the obvious association between nuclear energy and military ties, let us recognize India for its efforts. The move to build more reactors and embrace renewable/clean energy appears to show that the world's second largest democracy is moving toward curbing its carbon emissions. Since, "the two governments came to an understanding," the focus shifts to the number and type of reactors to be built. More importantly, how will these new reactors be fueled?

Is Thorium the Answer?

Fig. 2: Diagram extracted from Generation IV roadmap and cleaned up to remove excess grouping. [7] (Source: Wikimedia Commons)

In a 2012-13 article published by the Rand Corporation titled "Abundant Thorium as an Alternative Nuclear Fuel: Important Waste Disposal and Weapon Proliferation Advantages,", it was asserted that the abundance of thorium that can be found in the earth's crust made an ideal substitute for uranium as a nuclear fuel. "It has long been known that Th-232 is a fertile radioactive material that can produce energy in nuclear reactors for conversion to electricity. Th-232 is well suited to a variety of reactor types including molten fluoride salt designs, heavy water CANDU configurations, and helium-cooled TRISO-fueled systems." [2]

Designs for using thorium as nuclear fuel span decades and multiple different reactor types. Thus, showing its versatility and bolstering its position as the alternative to uranium. There are designs for high-temperature gas reactors (Fig. 2) using thorium, which date back to 1947. As early as 1962 in Buchanan, NY the Indian Point reactor was the earliest liquid water-cooled reactor which used thorium-232 oxide pellets and a lesser amount of uranium-235. Although there are none currently on-line, molten salt thorium reactors were researched at Oak Ridge National Laboratories in the 1960's and have recently re-emerged as development projects across the globe. Though still in the research and development phase, Carlo Rubbio's 'Accelerator Driven Subcritical Reactor (ADSR)' design or Energy Amplifier design proposes that the neutrons needed to fertilize thorium can be generated in energy amplifying reactors. [2,3] Ultimately, despite the type of reactors the Indian government chooses to build to advance its nuclear energy program, thorium has the flexibility to be incorporated into the designs as the potential fuel.

Risks and Rewards of Thorium

Fig. 3: India Nuclear power plants. [8] (Source: Wikimedia Commons)

Now that the two governments have an agreement on advancing nuclear energy in India, why is this news? What about the waste? And how are these things related to the proliferation of nuclear materials?

Taking into consideration the volatile and ongoing conflict between India and Pakistan, the instability of Afghanistan, and the Iranian pursuit for a nuclear program, an important question emerged. Why would the U.S. expose itself to international scrutiny by endorsing an expansion of an Indian nuclear energy program given the proliferation history and current concerns in that particular region? The answer may very well lay in the fact that India has the world's largest known thorium deposits. "The total known world reserves of Th in RAR category are estimated at about 1.16 million tonnes. About 31% of this (0.36 mt) is known to be available in the beach and inland placers of India. The possibility of finding primary occurrences in the alkaline and other acidic rocks is good, in India."[4] The U.S. is another country with sizeable thorium reserves.[4] Now that a deal between the U.S. and India is in place the worlds's number one potential source of thorium and the U.S.A have essentially become business partners.

Proponents of thorium as a nuclear fuel alternative such as Rand Corp. researcher Marvin Schaffer, claim that Thorium has important waste disposal and proliferation advantages. An article in Nature, which explains the manner in which the bi-products of using thorium in a nuclear reactor are much less likely to be used for weapons making, supports Schaffer's's claim. (See Table 1.) It states, "The discharge from such reactors contains 98.7% U-238, 0.8% fission products, 0.4% plutonium, and trace amounts of other transuranics. If thorium is used instead of natural uranium, the burn-up is much more complete." [2,5] In fact, India has been operating a low-power U-233 fueled reactor at Kalpakkam since 1996 called Research Reactor "Kamini" (Fig. 3). A significant fact because it is the only U-233 fueled reactor in the world, "though it does not in itself directly support thorium fuel R&D. The reactor is adjacent to the 40 MWt Fast Breeder Test Reactor in which ThO2 is irradiated, producing the U-233 for Kamini." [4]

However, there has been an important observation about the potential to convert the abundant wonder fuel into U-233. Ashley et al. have pointed out the proliferation risk would now shift to the abundant stockpile of thorium present before the fuel cycle process as opposed to the bi-products their resulting proliferation value: [5]

"We are concerned, however, that other processes, which might be conducted in smaller facilities, could be used to convert Th-232 into U-233 while minimizing contamination by U-232, thus posing a proliferation threat. Notably, the chemical separation of an intermediate isotope that decays into U-233 is a cause for concern." [5]

They go on to explain, "After irradiating thorium with neutrons for around one month, chemical separation of Pa-233 could yield minimal U-232 contamination, making the U-233 rich product easier to handle. If pure Pa-233 can be extracted, then it merely needs to be left to decay to produce pure U-233. The problem is that neutron irradiation of Th-232 could take place in a small facility, such as a research reactor, of which around 500 exist worldwide. The Th-232 need not be part of a nuclear-fuel assembly nor be involved in energy generation." [5] The associated proliferation risks is that "8 kilograms of uranium-233 is considered enough to construct a bomb, and uranium-233 is exactly what thorium reactors breed." [6] India has already demonstrated its ability to use U-233 for nuclear weapons applications when it detonated a very small device based on U-233 called 'Shakti V.' in 1998. [4]

Element Concentration (g/L) Salts Concentration (g/L)
Th 5 Th(NO3)4 · 5 H2O 12.29
Cs 0.04 CsNO3 0.064
Sr 0.0266 Sr(NO3)2 0.0684
Fe 2.2 Fe(NO3)3 · 9H2O 15.91
Cr 0.54 CrO 1.0384
Ni 0.24 Ni(NO3)2 · 6H2O 1.188
Na 0.37 NaF 0.68
F 0.3 ~ ~
Al 1.3 Al(NO3)3 · 9H2O 18.07
Ru 0.000141 Ru(NO3)3 · xH2O 0.000426
Ce 0.00166 Ce(NO3)3 · 6H2O 0.00512
Molarity (HNO3) 3.3 Concentrated HNO3 (16M) 208 mL
Table 1: Composition of waste likely to be produced from thoria spent fuel. [9] - This table dangles. - RBL


It is my intention that the questions raised in this article lead you down a path of considering the risks/rewards of all potential energy sources, not just nuclear energy. There is a global conversation happening about climate change and divesting from fossil fuels for our energy. Leaving out the politics and conspiracy theories for a moment, it is important to keep a keen eye the potential benefits from the latest scientific advances on old research and the connection to underlying motives that would have second and third world countries become an experimentation zone for the viability of "new" energy technology and policy.

© David Davis. 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.


[1] R. Rampton and S. Miglani, "Obama Reveals Nuclear Breakthrough on Landmark India Trip," Reuters, 25 Jan 15.

[2] M. B. Schaffer, "Abundant Thorium as an Alternative Nuclear Fuel: Important Waste Disposal and Weapon Proliferation Advantages," Energ. Policy 60, 4 (2013).

[3] P. Baxevanis, "Accelerator Driven Subcritical Reactors," PH241, Stanford University, Winter 2013.

[4] "Thorium-Based Nuclear Fuel: Current Status and Perspectives," International Atomic Energy Agency, IAEA-TECDOC-412, March 1987.

[5] S. F. Ashley et al., "Nuclear Energy: Thorium Fuel Has Risks," Nature 492, 31 (2012).

[6] A. Micks, "Thorium Reactors: An Improvement over Uranium?" PH241, Stanford University, Winter 2013.

[7] "A Technology Roadmap for Generation IV Nuclear Energy Systems," Generation IV International Forum, GIF-002-00, December 2002.

[8] R. G. Bucher, "India's Baseline Plan for Nuclear Energy Self-Sufficiency," Argonne National Laboratory, ANL/NE-09/03, January 2009.

[9] P. Sengupta, C. P. Kaushik, and G. K. Dey, "Immobilization of High Level Nuclear Wastes: The Indian Scenario," in On a Sustainable Future of Earth's Natural Resources, ed. by M. Ramkumar (Springer, 2012), p. 25.