Thorium Energy Viability

Jason Ting
November 12, 2015

Submitted as coursework for PH240, Stanford University, Fall 2015


Fig. 1: Early thorium-based molten salt nuclear reactor at Oak Ridge National Laboratory in the 1960s. (Source: Wikimedia Commons)

After World War II when the United State's Oak Ridge National Laboratory was developing nuclear energy, uranium was identified as a source for nuclear fuel to produce electricity, so the United States built uranium-based nuclear reactors to generate electricity. [1] During this period of nuclear energy research, it was also discovered that thorium can be used as a source for nuclear reactors. However, in 1973 the United States government shut down all thorium related nuclear research due to the success of the uranium reactor to produce energy, so the vast majority of the nuclear reactors that exists today use enriched uranium (U-235) or reprocessed plutonium (Pu-239) as their source of energy. [2] By 2008, there has been a renewed interest in a wide variety of countries and institutions in using thorium instead of uranium as nuclear fuel to generate nuclear power due to the advantages it potentially has. In particular, there is a large interest research and development of thorium from India and China due to the substantial reserves of thorium-bearing material and the limited amount of uranium in their respective countries. [3] This paper briefly goes over the background on using thorium as a source for nuclear reactors and discusses the major benefits and drawbacks of using thorium as an energy source for nuclear power.


Thorium has properties like uranium which allows it to fuel a nuclear chain reaction. But unlike uranium which splits and releases energy, thorium goes through a series of nuclear reactions when exposed to neutrons until it emerges as an isotope of uranium called U-233. This isotope will readily split and release energy next time it absorbs a neutron. The type of reactor that can handle the thorium-urnaium fuel cycle would be a class of molten salt reactors called liquid fluoride thorium reactors (Fig. 1), which is the type of reactor the Oak Ridge National Laboratory researched on. These types of reactors dissolve the fuel into a vat a liquid salt as opposed to being cast into pellets. The chain reaction of the thorium into uranium heats the salt, which convects through a heat exchanger and into a turbine, thus producing electricity.



© Jason Ting. 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] "Atomic Energy 'Secret' Put into Language That Public Can Understand," Pittsburgh Press, 29 Sep 1946.

[2] R. W. Moir and E. Teller, "Thorium-Fueled Reactor Using Molten Salt Technology," Nucl. Technol. 151, 334 (2005).

[3] B. Hakes, "Institutions Developing Thorium as Fuel," Physics 241, Stanford University, Winter 2015.

[4] F. Kreigh and D. Y. Goswami, eds. CRC Handbook of Mechanical Engineering, 2nd Ed (CRC Press, 2012) pp. 7-45

[5] "Thorium Fuel Cycle - Potential Benefits and Challenges," International Atomic Energy Agency, IAEA-TECDOC-1450, May 2005.

[6] R. K. Morse, "Cleaning Up Coal," Foreign Affairs 91, No. 4, (July/August 2012).

[7] D. Berryrieser, "Liquid Fluoride Thorium Reactors," Physics 241, Stanford University, Winter 2012.

[8] R. Martin, Superfuel: Thorium, the Green Energy Source for the Future (St. Martin's Press, 2012).

[9] J. Kang and F. von Hippel, "232 and the Proliferation-Resistance of U-233 in Spent Fuel," Science & Global Security 9, 1 (2001).