Group 4 2013: Thorium Reactors

Thorium Reactors

Abstract

Nuclear energy power has been proved that it is a powerful and efficiency sources while maintaining the health environment. Uranium is on resource for nuclear power. But scientists indicated that uranium is not safe and it produces nuclear waste. For this group assignment, we have chosen to focus on controversy of thorium should replace uranium.
This article will demonstrates why and how thorium can replace uranium, from safe, clean and economics perspectives. We make several lists to compare the advantage and disadvantage for U-233 and U 235. And we also list the current countries who set up projects for uranium and costs.

Background

Nuclear fission was first recognized by “Otto Hahn and Fritz Strassmann in Berlin in 1938” (Crossland 3). They bombarded uranium with neutrons and found that atoms of barium-roughly half the atomic weight of uranium were produced. In 1933, Niels Bohr established that the isotope U-235 constituting only “0.7%” of natural uranium which fissioned”. (3). Until1933, the progress of understanding fission and nuclear reactions was generally slow. With the war in Europe, American scientists and refugees, began to work secretly together to see if fission could be put to military use. America entered World War II in December 1941 and next year, the work was officially under the umbrella of the Manhattan project. Since on, bomb making is widely used, “U-235 would be needed at that time there was no way of separating the isotopes” (4). Now, uranium provides major resources for nuclear power and weapons. Natural uranium contains three isotopes. Uranium-238 (238U) is the bulk isotope comprising over “99%” of the total with uranium-235(235U) present at around “0.71%” by weight and uranium-234(234U) at “0.0053%” (Pg. 151). Among three of isotopes, only “235U is fissile and capable of sustain” a nuclear chain reaction (4). As the result, uranium is the major resources of nuclear weapons.

Uranium and Thorium

However, uranium is not a safe resource of nuclear power. Scientists found out that thorium is a better resource to replace uranium. In the U.S., “Oak Ridge National Laboratory developed a thorium-powered, molten salt nuclear reactor in the 1960s” (4) “Safe thorium reactors could have defined the nuclear power era, then in its formative years. But the Nixon administration scotched thorium in favor of weapons-friendly uranium. The Cold War was on, both the U.S. and the Soviet Union were building an atomic arsenal”. (5)Studying the thorium cycle is ongoing in several countries, because thorium can combine with another sources for future development of nuclear energy, which U-233 is the best fissile isotope for thermal neutrons. Which indicate that uranium maybe is not safe and green for the society.

Using uranium for nuclear power is not safe for the society, the reaction can release a large quantities of radioactive particles. There have been two classified as a level 7 event (the maximum classification) up to now. One is the Chernobyl disaster, which was occurred on “26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine”, which is in the central authorities of the Soviet Union. (Wikipedia). It is widely considered to have been the worst nuclear power plant accident in history, and is one of only two classified as a level 7 event on the International Nuclear Event Scale. The reason is the collapse can release a large quantities of radioactive particles. And if it comes the containment building which is store the particles, it will cause a dramatic lose and safety. The disaster involved over “500,000” workers and cost almost “18 billion” rubles (Wikipedia).

Another disaster is the Fukushima Daiichi nuclear disaster, which was happened on “11 March 2011” (Wiki). This is the second nuclear disaster since Chernobyl disaster. Even though, a tsunami caused the nuclear disaster, it has a large impact on Japan. Professo Shinzo Kimura of Dokkyo Medical University in Japan, who collectradiation contamination data, demonstrated that “with predictions that 25 times as many people in Fukushima area will develop thyroid cancer after the disaster compared to before.” (Wiki) Meanwhile, On July 22, 2013, more than two years after the incident, it was revealed that the plant is leaking radioactive water into the Pacific Ocean, something long suspected by local fishermen and independent investigators.

Compared to uranium, thorium is much safer. Richard Martin, the author of SuperFuel demonstrates that thorium is a naturally occurring element that is so safe you can hold it in your bare hand. The thorium nuclear fission cycle eliminates the risk of meltdown and weapons proliferation while the byproducts have a reduced half-life “on the order of 1/2 century rather than thousands of years” (Browns). If the facilities themselves were attacked is harmful, but thorium can be recycled and poses no direct for our environment. Even though, Chermoble disaster, the leak impact millions of people, but in this situation “we would not have another Chermoble” (Halper). In October of 2008 under the Bush administration the house threw out a bill called the Thorium Energy Independence and Security Act of 2008. This document could be the most important piece of legation in the history in the United States.

Safe and More Efficient

Thorium is safer and more efficient than uranium. Thorium can be used in what are called “molten salt reactors” and, because it can be used in molten form, the temperature of the reactor self-regulates but, in addition, if there were to be overheating of the reactor, a drain plug allows the nuclear reactor to be “switched off” instantly. With “solid fuel reactors”, which is what we currently have world-wide with uranium, it takes many hours for the hot fuel to cool down to safe levels. Thorium is also safer than uranium in two other ways. Firstly, the way that thorium is burned as a nuclear fuel means that the radioactive isotopes that are created along the path-way are less easily used for nuclear weapons because the thorium fuel cycle produces no plutonium. This in turn means that countries could use thorium reactors without the same risk of their developing nuclear weapons, and also that the reactors are less likely to be attacked by enemies.

Secondly, thorium is safer because there is much less waste leftover and what does remain is significantly less radioactive and less dangerous than the waste from uranium reactors. In fact, most of the radioactive products will become inert within just 30 years, as compared with hundreds of years from existing uranium reactors. In addition to all these advantages, thorium reactors would enable us to burn much of our existing nuclear waste, which is costing a vast amount to store and decommission. What is currently regarded as “waste” could actually be turned into fuel and become an asset. Because we would be able to burn much of our existing nuclear waste, thorium becomes much more energy and resource efficient than uranium.

Advantages of Thorium 233 over Uranium 235
1. Waste products can contain significantly less long-lived radioactive waste than uranium or plutonium.
2. Weapons cannot be proliferated from Thorium.
3. Thorium is more energy efficient, operating at higher temperatures.
4. There are massive supplies of Thorium worldwide.
5. Less environmental damage to the environment through mining, extraction, and processing.
6. Less damaging health effects to workers during extraction.
7. Many valuable metals can be extracted as by-products during the processing of Thorium, as well as medical applications.
8. Thorium does not require enrichment.

Disadvantages of Thorium 233 over Uranium 235

1. Thorium is non-fissile on its own; it needs a kick-start from Uranium 235, to start a chain reaction, raising the radioactivity of the waste.
2. Although thorium produces much less long lived transuranic; some long life actinides are produced.
3. Research and development of thorium has been slow and underfunded owing to the difficulty to form it into nuclear weapons.
4. It would be difficult to convert existing uranium fuelled plants to thorium use.

Norway Experimenting with Thorium Reactors

Norway is the biggest oil producer in Europe, and the 13th largest producer in the world, yet this fact does not stop it from pursing an alternative source of energy for producing electricity domestically. That is not to say that it will dump fossil fuels, the energy switch that it is hoping to make is from uranium nuclear power plants, to thorium nuclear power plants. Thor Energy will team up with the Norwegian government and Westinghouse of the US to begin a four year test which will determine whether or not thorium is a viable alternative to uranium. The test will occur at the government controlled nuclear reactor in Halden.

For decades supporters of thorium have argued that it is superior to uranium in every way, yet nearly all of the world’s nuclear reactors have been designed around uranium. Thorium reacts more efficiently than uranium, the resultant radioactive waste has a much shorter half-life, due to its very high melting point nuclear meltdowns are impossible, and no plutonium is produced in the reaction, therefore it cannot be used to create nuclear weapons.

Whilst many proclaim that molten salt reactors are the best type of reactor for thorium fuel, none currently exist or have received regulatory approval. Thor Energy will test the thorium in a heavy water reactor at Halden. The reaction may not be as efficient as possible, but for the fact that the reactor has already been officially approved the testing can begin right away rather than waiting years for a molten salt reactor to be built, checked and approved.

The United States should allocate significant resources toward developing thorium nuclear power because it is better and it is safer. Uranium is currently the actinide of choice for the industry, used sometimes with a little plutonium in 100 percent of the world’s commercial reactors, but it’s a problematic fuel. In most reactors, sustaining a chain reaction requires extremely rare uranium-235, which must be purified, or enriched from far more common U-238 (Martin, 2009). Uranium mining poses huge health risks to its workers, the majority of whom are Native Americans employed in the low paying mining positions. They are exposed to dust and radioactive radon gas, presenting a lung cancer hazard. For example, in the United States 87% of lung cancer cases are a result of smoking. Among underground uranium miners however it is estimated that 70% of lung cancer deaths in non-smoking miners and 40% of lung cancer deaths in smoking miners are due to exposure to radon progeny (Dangers of Uranium). When I say that thorium power is safer, I mean that you can hold it in your bare hand. Thorium power is the new green nuke because of how safe it is to us and the environment. Thorium’s biggest advantage is its high efficiency but it also creates challenges. The reaction is sustained for a very long time so the fuel needs special containers that are extremely durable and can stand up to corrosive salts. The combination of certain kinds of corrosion-resistant alloys and graphite could meet these requirements but such a system has yet to be developed.

However Thorium Nuclear power is cleaner, safer, and cheaper still. Uranium power is neither cleaner, safer nor cheaper and in today’s world. Uranium nuclear power is not safe for our society and can release large quantities of radioactive particles. We have seen this first hand with the disasters, Chernobyl and the Fukushima nuclear plants. Who knows what can be next if we keep using uranium rather than using thorium. The thorium nuclear fission cycle eliminates the risk of meltdown and weapons proliferation while the byproducts have a reduced half-life. With Thorium there is limited radioactive debris as a result of the reaction, and in terms of chemical stability and resistance to radioactivity thorium is a safer alternative compared to uranium (Is Thorium Cleaner?).

Although thorium can already be used, a number of technical challenges need to be resolved before this new technology can reach its full potential. For example, higher temperatures are required to produce thorium based fuels. Residual materials from thorium based nuclear power lose their radioactivity faster than residual materials from uranium based nuclear fuels.
Recently, many countries moved toward using thorium due to its safety, availability, and its efficiency, which is being examined by research and developed.
Recently, many countries moved toward using thorium due to its safety, availability, and its efficiency, which is being examined by research and developed.

Current Thorium Projects

A significant amount of countries started Thorium programs including the US, China, UK, India and many others in addition to Norway.

In 2011, China officially announced the launch of its program on thorium-fueled molten-salt nuclear reactors [1]. The Chinese program is considered to be one of the biggest nowadays. China plans to install up to 100 reactors in the next 20 years [1b], which will make China by then holds almost quarter of the world share of nuclear reactors. By that, China will go green by depending more on safe and clean nuclear reactors power rather than oil and coal generated power.

One other country that has been making a lot of efforts using this technology is India. By 2025, India is expected to have up to 62 nuclear reactors where most of them are based on thorium. The idea was initialized in the 1950s when Dr. Homi Bhabha raised the concern of India’s energy independence [2]. His project, three-stage nuclear program, included thorium reactors as the third advanced stage. Due to the availability of thorium which India has 16% of its reserves in the world, it is more favorable for India to use thorium rather than uranium [3]. The future of this project seems to be promising according to Richard Martin, a science writer and a physicist. He stated that India is the "only country in the world with a detailed, funded, government-approved plan" [4]. The goal of India from this project, as Martin assured, is to make India completely independent regarding its energy and don’t rely on the imports in the abundance of thorium.

The United States, as a matter of fact, has been trying to have a hand in this technology. The US department of energy has been collaborating with China to design a nuclear power molten-salt that is based on thorium. The U.S. has a significant share of thorium in its land. According to the World Nuclear Association, it has approximately 8% of the thorium reserves in the world. Previous attempts did not succeed in Nixon’s Period after Oak Ridge Laboratory proposed for molten-salt thorium-based reactors but the administration favored uranium on it [5].

In 2011, Japan experienced nuclear reactors meltdowns that they are still recovering from. Japan is attempting on having a safe source of energy. Recently, people in charge noted that thorium might be a better nuclear reactor option.

The United Kingdom is also moving toward possessing nuclear reactors that are thorium-based. Multiple organizations have adopted the idea in the U.K. including the University of Huddersfeild. A group of researchers in this institution are studying generating power using thorium. Although it is not assured that the result will be handy soon, but the researchers had their effect on the government so the idea might be applicable [5b].

Types of Thorium-based Reactors

According the World Nuclear Association, there exist seven types of nuclear reactors in which thorium can be used as a nuclear fuel. The first five types are in operation, where the last two need more research and studied to be applied [3].

• Heavy Water Reactors (PHWRs)
• High-Temperature Gas-Cooled Reactors (HTRs)
• Boiling Water Reactors (BWRs)
• Pressurized Water Reactors (PWRs)
• Fast Neutron Reactors (FNRs)
• Molten Salt Reactors (MSRs)
• Accelerator Driven Reactors (ADS), or Liquid Fluoride Thorium Reactor (LFTRs)

World Reserves of Thorium

Thorium is considered to be a rare-mineral across the world. It could be found in very small amounts in rocks and soils, whereas its occurrence is natural. Only few countries across the world have reasonable amounts of it that could be a good source for long term dependability.
As estimated in 2011, Australia, United States, India, Turkey and Brazil hold almost 60% of the world reserves of thorium [3]. A table shown below shows of each country share estimated according to World Nuclear Association:
Country Quantity (Tonnes) % of total
India 846,000 16
Turkey 744,000 14
Brazil 606,000 11
Australia 521,000 10
USA 434,000 8
Egypt 380,000 7
Norway 320,000 6
Venezuela 300,000 6
Canada 172,000 3
Russia 155,000 3
South Africa 148,000 3
China 100,000 2
Other countries 659,000 13
World total 5,385,000

Conclusion

It has been debated that if thorium is safer than uranium then why it is not being used. Thorium was ignored because the government wanted to build a lot of nukes and uranium reactors allowed that to happen. The DoD did not have the budget or the manpower to research both solutions and private industry was not going to do the research so we ended up with uranium reactors for both military and civilian usage. Furthermore, Makhijani does not believe that thorium is a panacea to the waste and weapons proliferation challenges of nuclear. Arjun Makhijani, president of the Institute of Energy and Environmental Research and an ardent believer in solar power state’s that “it doesn’t solve the waste problem, either. So every nuclear reactor, no matter what type, creates fission products, which are highly radioactive materials, some short-lived, some long-lived, to make energy”. On the other hand Richard Martin, one of thorium’s most visible supporters state’s that “When we talk about the waste, one of the things that skeptics of the liquid fuel thorium reactor ignore is the fact that because the core is a liquid, you can continually process waste, even from existing conventional reactors into forms that are much smaller in terms of volume, and the radioactivity drops off much, much quicker. We’re talking about a few hundred years as opposed to tens of thousands of years”.
Although Thorium is not without problems, it is currently the best solution we have to combat our dependency on foreign fuel. “The biggest challenge when moving from uranium to thorium is the time and the investments that are required. Many countries, because of these high investment costs, cling to the uranium that is already used as a nuclear fuel. Given that thorium is regarded as a less dangerous, less expensive, more accessible and more environmentally friendly alternative to uranium, there are good reasons to keep an eye on developments”( Is Thorium Cleaner?).

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