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The Nuclear Fission ReactionNuclear fission is the process of splitting the nuclei of heavy elements such as Uranium 235 in order to release energy. This is a naturally occurring process that has been going on since the formation of the Earth. However, not all isotopes of Uranium are fissile (can be split), so Uranium ore must first be refined in order to extract the more potent U-235 from the inactive U-238. When an atom of Uranium 235, or U-235, is split, it breaks into two smaller elements and also releases three super fast moving neutrons. The process looks like this:
Lots of energy is also released during this process in the form of heat. Nuclear power stations use this reaction to to super-heat steam in order to drive turbines, as in a conventional power station. The difference is that no fossil fuels are burned, removing the problem of greenhouse gas emissions associated with this power supply. What is a Chain Reaction?Because three super-fast neutrons are produced to every single split U-235 atom, there is the potential for the reaction rate to increase threefold with each bunch of split U-235 atoms. That would look like this:
Clearly this has the potential to run out of control, and nuclear power reactors must be very carefully controlled in order to keep the rate of reaction at the best level for energy production. Reactors employ both fuel rods, which emit the neutrons, and control rods that absorb excess neutrons and keep the reaction rate under control. Have a look at this little animation of the reaction:
And here's what that same reaction can do if put into a weapon. Note; those ships were unoccupied and were moored within the explosion range to test the effects of the weapon on conventional vessels. Many of the ships you see were captured Japanese ships from World War 2.
Return from Nuclear Fission to Fossil Future or return to the Green Planet home page for more Solar Power Facts.
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