Thorium Nuclear Reactors – Nuclear Energy We Should be Talking About

When many people hear “nuclear” they think of the disasters of Chernobyl and 3 Mile Island, or more recently the meltdown at Fukushima in 2011. These events coupled with the threat of nuclear weapons proliferation has led to a stagnation in research, especially in the United States. While we cannot deny the dangers of nuclear energy and material, we should also acknowledge the benefits and the possibility that further research could solve or mitigate the dangers. Thorium Nuclear Reactors have this potential, to change the way we view nuclear energy and revolutionize the world.

Thorium crystal

At this point, most people would ask, “Is this some new miracle-cure or a dream scientists have been chasing like cold-fusion?” The answer would be neither. Thorium was seen as a potential energy source in the 1960s, an experimental reactor was created and tested at the Oak Ridge National Laboratory in the 1960s using a Molten-Salt Reactor, which we will discuss more in-depth later. Even though thorium is about 3 times more abundant in the earth than uranium (the fuel used in almost all commercial reactors worldwide), further study was discontinued in the US, and most other countries. Multiple sources point to the disadvantage of thorium at that time, the nuclear process did not produce easily-weaponized nuclear material, unlike uranium and plutonium. Recently funding was denied to a project by Dr. Carlo Rubbia in 2000, a Nobel laureate and former director of CERN. Some thorium experts argue that the European Energy Commission, along with the US Department of Energy, is biased against thorium because of the large, in-place investments in mining and utilizing uranium.

While other countries, like India and China, have recently delved into the realm of thorium reactors, the state of information about thorium in the world news is dancing on the fringes. Tech magazines such as Wired or web resources such as Tech News Daily have glowing reports of thorium reactors and every once and a while a big news source such as Forbes or the Washington Post will elaborate on a new development. However, compared to the green tech such as wind, solar or even wave power, there is only a little exposure. This can be explained by market penetration, more commercialization equals more news exposure, and research funding, it is much cheaper to fund a few million dollars for a wind turbine study than a couple hundred million for an experimental reactor. Along with the stigma of nuclear energy, the entrenched forces of the current energy industry, both uranium-based and hydrocarbon-based companies, may fight any implementations of large changes.

Molten Salt Reactor from the Oak Ridge National Laboratory

While thorium is much more abundant than uranium or plutonium, using the Molten Salt Reactor design, a thorium reactor is much more efficient. Dr. Rubbia argues that 1 ton of thorium produces as much energy as 200 tons of uranium or 3,500,000 tons of coal. This is possible through thorium's inherent properties and the different reactor design, which can harnesses up to 98% of the available energy in a given volume of thorium, compared to the typical 3% of energy to volume of uranium. Some put this efficiency rate at 50%, which is still much higher than uranium. The salt is a mixture of the thorium fuel and sodium fluoride, which has an added safety feature, the mixture can exist at high temperatures but low pressures, which would prevent the pressured-caused explosions at Fukushima and Chernobyl (other fuels can be used in this design but thorium is the most efficient). Coupled with this would be a plug of solid salt in the molten chamber, cooled by an electric system. When the power goes out, the plug would melt, allowing the molten salt to passively cool in a larger chamber, which would end the nuclear conversion process. These multiple safety features could assuage the fears of many anti-nuclear activists, possibly bring the risk of a meltdown to 0. 

This high efficiency is the largest downfall of a thorium reactor, first it needs a large input of energy for the process to begin, Rubbia suggests using a large particle accelerator which alone would cost over 500 million euros. Yet this process can use weapons-grade plutonium, thus "using up" the huge stockpile of warhead-grade plutonium we have worldwide. The other side of the efficiency rate is that the chamber holding the molten salt would need to be designed to meet the high temperatures and degradation caused by the nuclear reaction. Coupled with this is the problem of converting thorium into useable uranium-233, the thorium is first converted into protactinium-233, then to uranium while some atoms turns into protactinium-234 which cannot be used in the fissile (nuclear fuel) material. This unwanted product would need to be filtered out and a efficient process is still being worked on.

Some people call thorium the “magic silver bullet.” With high energy-to-volume conversion rates, abundant to the point that thorium is a waste product when mining for rare earth minerals, and a much shorter half-life (only a few hundred years compared to the thousands of years of uranium), at minimum thorium should be further investigated as a potential alternative to conventional nuclear fuel. Perhaps with enough funding thorium could power the future?