Nuclear fission and nuclear fusion
A power station makes electricity. Fossil fuel (coal, oil and gas) power stations and nuclear (uranium) power stations both use the same processes to make electricity. These are:
The only difference between fossil fuel and nuclear power stations is how the water is heated. Fossil fuel power stations burn their fuel while a nuclear power station uses the fission of uranium to generate heat.
Uranium is a non-renewable energy resource.
All nuclear reactors produce radioactive waste. At present the most dangerous waste is sealed in glass-like blocks which are buried deep within rocks. Careless disposal of waste in the past has led to pollution of land, rivers and the ocean.
As well as producing heat the nuclear reactor can be used to make other materials radioactive. The chain reaction inside the reactor releases neutrons. If a material is put into the reactor some of these neutrons may be absorbed by the nuclei of its atoms. This will make an atom's nucleus unstable which means it has become radioactive. These man-made radioisotopes are often then used as tracers in hospitals to diagnose and treat patients or in industry to detect leaks in pipes.
The nuclear reactor is designed to allow a controlled chain reaction to take place. Each time a uranium nucleus splits up it releases energy and three neutrons. If all the neutrons are allowed to be absorbed by other uranium nuclei the chain reaction will spiral out of control causing an explosion. To control the energy released in the reactor moveable control rods are placed between the fuel rods. These control rods are made of boron which absorbs some of the neutrons so fewer neutrons are available to split uranium nuclei. The control rods are raised to increase and lowered to decrease the number of free neutrons.