Thorium as an Alternative Form of Nuclear Energy

Nuclear Energy has been a source of power  for many years. When it was first revealed as a source of energy, the people became excited to think of a new energy source to counter energy issues, though nuclear energy has become more infamous than nostalgic. Thoughts of nuclear power from uranium and plutonium are crowded by its usage in nuclear weapons and the incidents with plant meltdowns like the Chernobyl incident, which was caused by a faulty reactor design that led to a meltdown and major radiation leak. These incidents ended public support, causing nuclear energy to be pushed aside, and increase the usage of fossil fuels . At the end of the next century, there's a consensus that the world population may be saturated at the value between ten and fifteen billion. This means about ten kWH or seven kWH per capita on an average corresponding to the two times or three times increase in the world population, respectively (Thorium 1990). This is significant because with an impending energy crisis on the line, researches have turned back to nuclear energy as a possible solution, and extended their research into other types of nuclear energy besides uranium, specifically thorium. thorium is a metal with an atomic number of ninety. thorium and uranium are closely related in their properties, so thorium could be an alternate form of nuclear energy. thorium would be an effective energy source that can replace most of the usage of fossil fuels and other nuclear energy forms. Both scientists and energy consumers, that being the public, agree thorium based fuels would be safer than uranium based fuels in terms of meltdowns, proliferation, and cheap fast ways of waste removal, but the economist believe there would need to be more companies mining,  working with thorium, and a complete change of the infrastructure needed to produce thorium-based energy, an expensive process and not worth the benefits thorium has.

Scientists View on Thorium

Current nuclear reactors use plutonium and uranium to create the energy, through a process where the elements undergo nuclear fission, creating thermal energy. The issue with this is that plutonium can't catalyze efficient consumption of uranium in slowed neutron reactors, and fast neutron reactors have their own challenges, including an increased chance of overheating and meltdown. If plutonium is allowed to instead fission near thorium, the thorium would absorb the neutron from the plutonium and become Uranium-233. In the three-phase plan for efficiently using thorium, a uranium-fueled reactor consumes U-235 and as it fissions it generates neutrons that are absorbed in U-238 to create Pu-239. The Pu-239 is chemically extracted from the reactor and put into another reactor for the second phase. The second phase consumes the Pu-239 through fission, releasing neutrons near thorium that generate U-233. In the third phase, the U-233 is fissioned and releases neutrons near thorium, which absorbs the excess neutrons and creates enough plutonium to continue turning out energy as long as thorium is supplied (Sorensen 2016).  U-233/Th cycle is best suited from molten salt reactors, where a breeding ratio of 1.05 can be achieved (Banerjee 2016). This means thorium is nearly self sustaining. Another benefit of thorium is its waste.  Average uranium burnup is fifty GWd/t, with optimization at 135 GWd/t, which means large amounts of waste (Irwanto 2012).

Equilibrium burnups of about 10 MWd/kg of heavy element per pass are feasible in 1200 MW(e), units operating on an SSET cycle provided careful attention is given to neutron economy, and reprocessing plus fabrication losses can be kept below 1% This is important because it shows how at equilibrium, neutron economics are most efficient, and this equilibrium can be reached using thorium. (Critoph 1975). thorium already has a much shorter half life than uranium does, which means its waste lasts a shorter amount of time. Along with this, a study has shown biosorbents, especially the ginkgo leaf, which are cheap natural adsorbents, can be used as a inexpensive way to absorb radioactive thorium ions, absorbing the nuclear waste (Huang 2018). Scientists believe thorium is an effective nuclear energy source for these reasons, but there are other benefits to thorium besides the scientific examples.

Consumers View on Thorium

 The benefits of thorium are more appealing to the public than those of uranium. As the consumers of the energy, their views are an important consideration. Their major concern involve risks of proliferation and meltdown. thorium isn't a concern of proliferation, with its requirement of uranium or plutonium to kickstart the reaction (Schimmoller 2014). For meltdown concerns, thorium is fertile not fissile, which means it cannot undergo radioactive decay by itself, but it can absorb a neutron from plutonium making it become Uranium-233, which is fissile, and will start the process that generates electricity (Nelson 2012). This means the reactor create energy until there's manual interference from the scientists and/or reactor operators, so there's no threat of the reactor reaching the critical temperatures for meltdown, since someone would be present to shut it down. However, thorium reactor requirements include design changes to existing reactors, which would allow thorium-oxide and uranium-oxide fuel rods to be interchangeable. Also, a new reactor design would be important because reaction with oxygen, nitrogen, and water vapor cause thorium to degrade (Nelson 2012).

This is a costly switch to the reactors needed to consider using thorium. Another concern with the current usage of uranium is the depleting amounts of the element in the earth's crust. thorium is three to four times more prevalent, and uranium is estimated to last 100 years with the current uranium reserves and consumption rate (Schimmoller 2014). The more abundant thorium, burned in breeder reactors like large High Temperature Gas-Cooled Reactors, followed by chemical reprocessing of the spent fuel, could stretch the 100 years for uranium supply to 15,000 years (Furukawa 2013). thorium is more appealing to consumers out of their concerns of proliferation and depleting uranium amounts, because these are not threats with thorium, and with some  expensive reactor changes thorium also isn't a threat of meltdowns, which is another consumer concern.

Economist View on Thorium

Though there are many benefits of using thorium, all costs must be considered. This includes the costs needed in mining thorium and to create reactors where thorium could be used. Since there are so few miners of thorium, prices for the metal are currently much higher than uranium, although Cameco corp and unity energy corp are uranium mining companies working in areas with high thorium concentration. These companies currently don't mine the thorium, but are in a position to do so if the demand for thorium increases, which would decrease thorium price. There are also few companies working on creating thorium reactors, with the only notable one being Lightbridge corp, a company working on creating thorium reactors that use thorium-uranium oxide pelletized fuel rods in light water reactors, replacing the uranium-oxide currently used (Energy and Capital 2018). This means there's an opportunity for the thorium industry to grow, but with the current lack of companies working with thorium, economists believe the costs would outway potential benefits.

Conclusion

thorium would be an efficient source of nuclear energy with many benefits over currently used uranium. The scientist perspective is efficiency of thorium in reactors is greater than uranium, as it's largely self sustaining, that thorium is safer because it cannot have meltdown without manual interference, and because thorium waste is much less of a lasting concern. The consumer perspective is that thorium is ideal because it isn't a concern of proliferation or meltdowns, and would be an answer to the crisis of depleting fossil fuel and uranium amounts. However, the Economist view is the insufficient thorium miners, which contributes to high thorium prices, and the costs required to transfer uranium reactors to, or build new, thorium reactors are too high. Though there are comparative advantages of thorium, the costs involved with the creation of thorium reactors, and insufficient tests that thorium-uranium oxide will be a successful energy source, means the costs and risks of the infrastructure switch out needed to use thorium efficiently outway the benefits of thorium.

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