The ore must go through many stages of refinement before it is of sufficient concentration to be used as a fuel rod.
World supplies of Uranium are dwindling, this is NOT a renewable energy source.
Nuclear Power
When Uranium 235 nuclei split up energy is released. How do we harness this energy to produce electricity?
It is not as easy as you might think to get a chain reaction started for a number of reasons.
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Uranium ore contains very little uranium and
very little of that is the useful isotope Uranium 235.
The ore must go through many stages of refinement before it is of sufficient concentration to be used as a fuel rod. World supplies of Uranium are dwindling, this is NOT a renewable energy source. |
The neutrons released by fission are unlikely to cause further fission events because they are traveling way too fast. They need to be slowed down. This is the job of a moderator, this is a material that does not absorb neutrons that the neutrons can bang into and lose kinetic energy.
Most power stations use carbon in the form of graphite as it has the required properties and is relatively cheap.
If too many neutrons escape from the fuel rod before causing fission then a chain reaction will not start. The larger the sample of uranium the more chance there is that a neutron will cause a fission, a chain reaction will not occur if the uranium is below a certain "critical mass".
So now we have achieved a chain reaction how do we control it?
Some materials, such as boron, are very good at absorbing neutrons. They are used in control rods to adjust the neutron flux. To speed up the reaction remove them, to slow it down insert them.
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The coolant carries heat energy away from the reactor. It
will go to a boiler where water is heated into steam to drive turbines
etc.
Some power stations use liquid sodium as a coolant, others use pressurised water or gas. |
The Problem with Nuclear Power
Nuclear power stations are very reliable, work 24 hours a day and produce a lot of electricity but.....
They are expensive. When you take into account the coast of building and taking down power stations (decommissioning) and dealing with the waste.
Nuclear waste must be stored safely. The waste products of this industry are VERY dangerous and some have incredibly long half lives. They are of no use to anyone, except perhaps terrorists. Where would you keep something safe for half a million years?
Accidents do happen. ( 3 Mile Island, Chernobyl) and the results can be catastrophic. One millionth of a gram of plutonium breathed in will give you lung cancer.
Many small countries are now vying for power by developing nuclear power with the sole intention of producing the materials needed to make atomic weapons.
If governments in the 1980s subsidised renewable energy resources to the extent that nuclear power was subsidised we probably wouldn't have an energy problem.
If you are getting the feeling that I am not a big fan of nuclear power you'd be right!
