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Written by: Gordon Lanza
Written on: July 7th, 2011
Tags: chemical engineering, energy & sustainability, material science
Thumbnail by: Morton/Illumin
About the Author
Gordy Lanza was a junior at the University of Southern California and studied biomedical engineering. He enjoys cooking, philosophy, and hiking.
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Volume XIV Issue I > Thorium Reactors: Solving the Global Energy Crisis
As global demand for energy increases and access to fossil fuels decreases, we face a crisis. Nuclear power offers ecologically sound energy, but it is costly to produce and maintain. In the wake of the tragedy at the Japanese nuclear power plant Fukushima Daiichi, nuclear energy seems less safe in the eyes of the public, and, as a result, some nations are veering away from nuclear energy. Liquid fluoride thorium reactors are a next-generation nuclear energy option that offer all of the benefits of traditional uranium-based nuclear energy with several key advantages.

Nuclear Energy in the 21st Century

One of the greatest challenges we currently face is meeting the energy demand of our global community. We have relied on fossil fuels for energy in the past, but these fuels produce greenhouse gases that are destructive to the environment, and our supply of fossil fuels is rapidly depleting. Some ecologically conscientious energy sources have been developed: we now harvest the energies of the sun, wind, and ocean. But these solutions are not efficient enough to effectively meet our energy consumption, and cannot scale energy production with changing grid demands.
The grid demands less energy late at night when most people are asleep but uses more energy in the evening when people are home from work. Windmills, however, cannot produce energy without wind, and solar panels cannot produce energy during the night. They are, consequently, only circumstantial energy sources.
Currently, nuclear power is an energy solution that is carbon neutral and can produce energy to meet grid demand. However, it is expensive and difficult to deploy with absolute safety, as the world recently saw at the Fukushima Daiichi power plant in Japan following the 2011 earthquake and tsunami. Liquid Fluoride Thorium Reactors, however, offer safer nuclear technology, and promise cheap, efficient, carbon-neutral energy [1]. Thorium is a fairly sustainable source: the supply of thorium is estimated to be able to power the planet for another thousand years. The events at Fukushima illustrate the key safety advantages of a liquid fluoride thorium reactor, primarily being that it is not explosive nor can it melt down. This article looks at the technology behind LFTRs, the advantages of LFTRs over traditional nuclear reactors, and lastly what occurred at Fukushima Daiichi and why a LFTR could have prevented such a tragedy.

How a Liquid Fluoride Thorium Reactor Works

Thorium itself is not a nuclear fuel. The idea behind thorium as a fuel source originated from the fact that it can easily be turned into uranium, a fissile nuclear fuel. The process as shown in Fig. 1 starts with thorium232, a naturally occurring isotope that is so abundant that it is considered a "waste product" of mining operations. If thorium is bombarded with a single neutron, it will become uranium233 in roughly one month.
Figure​ 1: Reaction series to produce fissile uranium from thorium.
This uranium is fissile, and if it is again bombarded with a single neutron, it will split and release energy with two neutrons, which will continue on to split more atoms, further driving the fission reaction. This process is similar to current nuclear technology: both generate energy by splitting a uranium atom. The biggest difference between LFTRs and current nuclear reactors is that the fission reaction in LFTRs occurs in a molten salt solution instead of water, making the reaction more efficient while preventing a meltdown.