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Introduction

Nuclear power, currently limited mainly to nuclear fission, is the process of releasing huge amounts of energy by splitting an atomic nucleus. Since the first commercial nuclear power plant was built in 1954, nuclear energy has grown to provide 17% of the world's electricity.

Safety is a major concern of nuclear power. Following the 1979 Three Mile Island accident and 1986 disaster at Chernobyl, the construction of nuclear power plants began to decline. However, there is currently renewed interest in nuclear energy from national governments, the public and environmentalists due to rising oil prices, need for low emission energy sources, and improvements to safety in the design of plants.

Nuclear Fuel: Uranium-235 (U-235)

Uranium is a common element on the Earth incorporated into the planet during its formation. A certain type of uranium, Uranium-235 (U-235), is most commonly used in nuclear power production because of its unique properties. Namely, U-235 is able to undergo induced fission, occurring when a free neutron bombards a U-235 nucleus. Under induced fission, the free neutron will be absorbed by the U-235 nucleus and cause the atom to become unstable and split immediately. The action of capturing the neutron and splitting the atom takes place within a matter of picoseoncds.

Induced fission of U-235

When the atom is split, it releases 2 to 3 neutrons, and a huge of amount of energy (in the form of heat and gamma radiation). The 2 to 3 released neutrons are free to join new atoms and cause them to split, creating a chain reaction. The chain reaction will continue until all the Uranium is split.

Chain reaction

In order for nuclear fission with U-235 to work ideally in power generation, uranium must be enriched so that it contains 2% to 3% or more of U-235.

How a Nuclear Plant Works

Now that energy has been released through nuclear fission, it needs to be captured somehow. All that energy within the reactor is captured by water pipes surrounding the reactor. The water passes through the heat exchanger, which will transfer heat from the reactor water to fresh water. The fresh water will turn into steam, which will drive a turbine connected to a generator to create electricity.

Click here to see a nuclear power animation

Nuclear Power Advantages and Disadvantages
  • Very little fuel (uranium) needed
  • Fuel has a low cost
  • Water vapour is the only significant emission from nuclear power plants
  • Comparable to the cost of coal energy
  • High electricity output
  • High initial construction costs
  • High operating and maintenance costs
  • Mining and purifying uranium is not a very clean process
  • Improperly functioning nuclear plants can lead to devastating disasters (eg. meltdowns)
  • Spent fuel from nuclear power plants is toxic for centuries and there is no safe/permanent storage area for it

Summary

Nuclear energy is a economically viable and efficient power source. However, there continues to be concerns over safety and waste disposal. Ongoing international research seeks to continue to improve the safety of nuclear power. Nuclear energy remains and is becoming increasingly important throughout the world, especially in light of efforts to reduce greenhouse gas emissions.

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