The Pros And Cons Of Using Thiorium As A Nuclear Fuel

Introduction

Could thorium, as a nuclear fuel, be an alternative to fossil fuels as a sustainable energy source?

The world’s supply of fossil fuels is rapidly decreasing and it is imperative that new, sustainable sources of energy are utilised. Furthermore, the burning of fossil fuels releases gases such as carbon dioxide, methane, nitrous oxide and sulfur dioxide into the atmosphere. An excess of these gases in the atmosphere has a negative impact on the environment and are possible contributors to climate change.

It is clear that a sustainable, efficient and environmentally friendly source of energy needs to be developed and implemented. Wind and solar energy are beginning to be more readily used, but the need for more energy is clearly evident.

This research will investigate the idea of using thorium as a nuclear fuel as opposed to uranium. To focus this research more specifically, the possibility of a thorium-powered motor car will be investigated. Vehicles consume a huge amount of fossil fuels and a new source of fuel is an urgent necessity. The research will focus on three aspects – the economics and efficiency of thorium, the safety of thorium as a nuclear fuel with regard to humans and the impact that thorium could have on the environment.

Thorium is an element that is abundant in the earth’s crust and is non-localised – it is found in North America, Australia, India, South Africa and many other countries.

During the initial experiments with nuclear energy, thorium was in fact tested as a nuclear fuel. Uranium was favoured as it is fissile, while thorium is fertile. A fissile atom automatically begins the nuclear chain reaction that releases energy. Thorium must undergo an enriching-process, breeding it into an isotope of uranium before the chain reaction begins. This requires additional energy and therefore uranium was chosen as the chief nuclear fuel.

To begin the chain-reaction, a neutron is added to thorium-232 (the most common isotope of thorium) and it becomes thorium-233. This quickly decays into protactinium-233 and this in turn decays to become uranium-233. As this isotope of uranium is fissile, the chain-reaction will begin and energy will be released

Furthermore, the bulk of this plutonium is useless in nuclear weapon production. He does, however, note that small amounts of uranium-232 can be a result of the energy production. Uranium-232 and many of its decay products are strong gamma (radiation) emitters. In addition, some thorium reactors can use nuclear waste mixed with thorium as a fuel. Furthermore, uranium-233 sometimes absorbs a neutron to become uranium-234, which can absorb another neutron to become uranium-255 and this isotope either fissions as a nuclear fuel or continues absorbing neutrons to become other isotopes, one being plutonium-239, which is fissile. Protactinium-231 is generated in the decay of thorium-232 and is a huge portion of the long-term radiation of the used fuel.

Drenkhahn adds that thorium reactors are safer in regard to nuclear explosions as they have a higher melting point, and the reactors also conduct heat more readily and therefore during the nuclear reaction the thorium can ‘shed’ the heat more easily to avoid overheating.

Drenkhahn’s thesis is a very useful source and is very relevant to my research. He discusses most of the topics to be investigated. He has since received his bachelor’s degree in nuclear science and engineering at the Massachusetts Institute of Technology. It is clear that his work is of high academic standard and based on sound research, therefore