Marissa Hall | Shale Plays Media
“You don’t see any oil refineries in Star Trek. You don’t see any coal mines.” – Kirk Sorenson
The world eyes nuclear energy with skepticism. It is expensive to build nuclear facilities, it creates far fewer jobs in comparison to that of the oil and gas industry, and it carries immense risk. Catastrophes due to mechanical malfunction, such as the Chernobyl disaster in 1986 or the Fukushima Daiichi nuclear meltdown in 2011, understandably make people wary of dependence on such a volatile energy resource.
Even when the system appears stable and successful, many still remain concerned about nuclear energy infrastructure. France leads the world in nuclear power, deriving 75 percent of its electricity from the 58 nuclear plants in the nation. However, President Francois Hollande promised to reduce that to 50 percent by 2025 during his campaign, and the idea has gained support. Public concern grows for the continued sustainability of nuclear energy without a meltdown, even in a nation that has invested billions into the system.
There is an alternative that could make nuclear energy significantly less unnerving. Of the hundreds of nuclear reactors on the globe, most run on uranium- or plutonium-based fuel. Uranium (U) reactors utilize less than 1 percent of the energy value of their fuel, creating large amounts of radioactive waste for a miniscule ratio of energy potential.
One alternative has remained largely unexploited: thorium (Th). Named after the Norse god of thunder and lightning, this naturally-occurring and little-known element is actually about four times more common in the earth’s crust than uranium, and it has the potential to be far more efficient.
Some scientists have begun to endorse a new type of nuclear reactor: the liquid fluoride thorium reactor (LFTR). The idea was developed by former NASA researcher and energyfromthorium.com founder Kirk Sorenson in 2006. The liquid form of fission ideally maintains the benefits of using solid thorium while simultaneously solving all of the disadvantages of the nuclear energy source.
Only two countries are actively seeking to put thorium to use as a nuclear fuel on an industrial scale. India hopes to put its vast reserves of thorium to use with a program that should be operational in 2020. But the stronger program looks to be arising in China, which anticipates an LFTR up and running by 2017.
In order to for thorium to be a viable energy option, it has to undergo fission. If you’re not an expert in physics fission can be difficult to understand, so let’s break down thorium’s fuel cycle.
To start the fission process, a 232Th isotope must be forced to absorb a neutron, usually by making the two collide at a high speed. It then becomes 233Th, which decays in about 22 minutes, loses an electron, and becomes protactinium 233 (233Pa). The decay process continues until 233Pa loses another electron about 27 days later and becomes 233U. That isotope releases energy by splitting itself apart (that’s the fission), which releases more neutrons back into the system to continue the process with more thorium.
Here are four reasons thorium has the potential to be the nuclear energy of the future:
1. Thorium is highly unlikely to cause a meltdown.
Thorium has a significant number of natural fail-safes which would prevent the types of meltdowns we have seen at places like Chernobyl or Fukushima, even though it needs to be heated more than uranium-based fuels. As a molten mixture of fluoride and thorium, the salts (which serve as coolants for the thorium) will not burn or explode.
If, somehow, the LFTR does grow too hot, thorium would begin to absorb more neutrons than it would in a normal fission process, reducing the number of reaction agents and ultimately shutting down the reactor.
Because of the liquid nature of the fuel and coolant in the LFTR cores, these reactors can operate at low pressures. It is difficult to change the pressure in the reactor and it is unlikely that the volume of the core is going to change. Little pressure or expansion means a small likelihood of an explosion like the one seen in the Fukushima Daiichi nuclear accident.
2. It is difficult to create nuclear weapons out of thorium.
During the reaction process in an LFTR, it is possible not all the 233Pa will decay into 233U. What remains of the isotope will instead decay into 232U. While naturally-occurring 235U was used in the atomic bomb Little Boy that was dropped on Hiroshima in 1945, the uranium involved in thorium’s fuel cycle wouldn’t work for bomb production if 232U is present. What seems like a minor difference actually results in the creation of an entirely different chain of decay from the thorium fuel cycle, ultimately producing gamma rays that make creating a bomb impossible.
While uranium-based nuclear fuel also creates large amounts of plutonium byproduct, an LFTR would leave relatively little in comparison. Plutonium (Pu) was the element used to create Fat Man, the bomb used by the United States on Nagasaki in 1945. However, that atomic bomb used 239Pu. An LFTR would generate 238Pu, which isn’t feasible for a fission bomb.
3. Thorium is more abundant than uranium.
As previously mentioned, thorium is about four times more common in the earth’s crust than uranium. Specifically, thorium is about 9.6 parts per million (ppm), while uranium is only 2 ppm. If you’re a person who likes races, thorium is coming in 39th of all the components in the earth’s surface. Uranium is sitting solidly behind at 51st.
Unlike uranium, thorium only naturally occurs as one isotope, 232Th. Uranium has two isotopes, 238U and 235U. These two isotopes can’t be used together in a sustainable nuclear reaction. This means that unlike uranium, thorium doesn’t require the added step of isotope separation before it can become a nuclear fuel.
4. Thorium would be far more efficient as an energy source.
A less-than-1% return of energy value is wastefully miniscule for the world’s most common nuclear fuel. The thorium fuel cycle, however, has the potential to use up to 98 or 99 percent of its potential energy, which means that a lifetime supply of energy could come from a handful of thorium. That makes thorium’s potential as a nuclear fuel up 200 times greater than that of uranium.
Why hasn’t thorium been harnessed for nuclear energy already?
1. There’s little historical proof that thorium is a good investment.
The LFTR requires a molten salt reactor (MSR). Few MSRs have been built and fewer still are operational. Only one, called the Fuji MSR, is currently functional, and it is a collaboration between a Japanese company and partners in the Czech Republic. Although China is attempting to build a new LFTR program, there is an overall lack of abundant evidence that thorium is a great source of energy, despite scientific assertion. This uncertainty works against thorium and in favor of tried-and-true energy sources such as coal, oil, and gas.
To build an LFTR facility is expensive, projected around $1 billion, and nuclear programs are notorious for ending up more expensive than initially expected. Investing $1 billion in a new form of energy that isn’t already used on a massive scale seems risky. Regardless of scientific theory from individuals like Kirk Sorenson, there aren’t 50 LFTR plants to show that it’s a good financial investment. If there’s anything the oil booms have proven in the last century, it’s that drilling for oil pays off. Why invest in a new energy that might not pay off if the money could just go into the oil industry and come back tenfold instead?
2. Thorium fluoride could be highly water soluble.
Thorium isn’t capable of fission when it is mined from the earth. It only becomes so when is forced to collide with another neutron. Using a liquid fluoride thorium molten energy source appears to be the best way to promote continued fission in the thorium fuel cycle, but this chemical mixture might be highly water soluble.
Proper storage of solid radioactive waste is already a hot topic when it comes to nuclear energy, but a water soluble waste product would be even more harmful if it leaked into the biosphere. This means it would need to be contained on a more urgent scale. Some scientists have recommended turning it into an insoluble form, such as glass, but the details need to be worked out before the use of LFTRs can be pursued on a large scale.