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The modern world experiences an ever-growing demand for clean energy production with reducing supplies of fossil fuels and the threat of permanent damage to the environment owing to prolonged dependence on non-renewable energy resources. There is an urgent requirement for suitable energy sources that will meet these demands economically without any further detriment to the planet. One of the key alternatives that has been developed is nuclear power.
How is Nuclear Energy Produced?
Uranium ore is mined from the surface of the Earth. This ore is largely made up of the non-radioactive isotope U-238, however it also contains small quantities of radioactive isotope U-235. Once mined, the ore is purified, enhanced to increase the quantity of U-235 and finally packaged in small ceramic pellets.
The U-235 pellets are stacked in 12-foot zirconium alloy tubes, that are resistant to corrosion, radiation and heat, to form fuel rods. These rods are then bundled together to make up a fuel assembly. The fuel assemblies are placed in storage bins at the reactor sites and at this stage the uranium is mildly radioactive. They are then placed next to each other in a reactor and the nuclear reaction is initiated with the addition of water.
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Following this, the fuel assemblies, which become highly radioactive, are removed and stored in a spent fuel pool at the reactor for several years. The spent fuel continues to generate heat with the continued decay of radioactive elements produced by the splitting of uranium atoms, even once the fission reaction has stopped. It is then moved to a dry cask storage container for on-site storage after cooling the fuel assemblies for several years.
The amount of uranium consumed during nuclear reactions is less than 4%. The rest of the uranium remains unchanged. The spent fuel material can be chemically processed to recover the remaining portion of fissionable products that can be used in fresh fuel assemblies. Finally, the spent fuel assemblies are collected from the interim storage sites and the remaining high-level nuclear waste is disposed of.
Evaluating Nuclear Power
Nuclear power is a very reliable source of energy and one power plant can generate a great deal of energy. Compared to oil and gas per kilogram, uranium can produce two to three million times more kWh. The power plants are compact and often much smaller than thermal power stations and they have low maintenance and operating costs. One of the major advantages of nuclear power is that, unlike fossil fuels, no greenhouse gases are released during the nuclear reactions.
However, there are certain limitations associated with nuclear power. Firstly, there is an uneven and fairly limited distribution of the radioactive mineral uranium across the globe. Despite the nuclear reactions not releasing greenhouse gases, nuclear waste can produce significant amounts of thermal pollution. As well as pollution, nuclear waste is highly radioactive and accidental spillages or leaks can cause ecological disasters. Costs for building nuclear power plants are high and construction takes a long time. Mining and refinement of uranium are both expensive and can cause environmental problems.
Nuclear Power and the Environment
Although nuclear power plants are regulated by federal and state laws for protecting human health and the environment, there is a great deal of variation in the environmental impact caused by nuclear power.
In terms of air emissions, nuclear power plants do not emit nitrogen oxide, sulfur dioxide or carbon dioxide during power generation. However, fossil fuels are emitted during mining and enrichment processes of uranium and transport of uranium fuel to and from the nuclear plant.
Nuclear power plants consume a vast amount of water for steam production and for cooling during operation. The water used is then released containing heavy metals and salts which can affect the quality of water and harm aquatic life. The waste from uranium mining operations can also contaminate groundwater.
The removal of nuclear waste has detrimental effects on the environment. The waste generated during operation can last for millions of years giving off radiation. Structural materials and equipment used during the plant's operation can even become radioactive and so if the plant shuts down, these too are very difficult to safely dispose of.
The topic of nuclear power is very difficult to call. Whilst it can be very advantageous over coal and oil in terms of amounts of power produced, it also has serious effects on the environment through the generation of nuclear waste. Until an effective and safe technique to dispose of nuclear waste is developed, people across the world will continue to debate over its use and many will struggle to choose a side to the argument.
Sources and Further Reading