Energy sources

NUCLEAR

What is it?

Nuclear energy is generated from radioactive material, such as uranium. Uranium is a natural occurring mineral found in the ground. Australia has large reserves of uranium and supplies it to other countries to use for power. The first commercial nuclear power plant opened in 1957 in the United States.

How does it work?

Just like in a coal fired power station, uranium is used to generate heat to turn water into steam. The steam turns the turbines, which results in electricity being generated. However, uranium is not burnt like coal. Uranium atoms are split, which produces heat. It uses a controlled series of nuclear reactions to release energy for work.

Nuclear energy is produced by a controlled nuclear chain reaction. The uranium is processed into pellets which are placed in tubes inside a nuclear reactor. The pellets are hit with neutrons, which causes the uranium atoms to split (fission), releasing heat and more neutrons. This is called nuclear fission. The other neutrons produced can strike more uranium atoms, splitting more atoms so that the process continues and forms a chain reaction. Nuclear fission gives off large amounts of heat, which is used to turn water into steam.

The steam is channelled to turn the blades of the turbine, which connects to the generator. The generator converts the rotations (mechanical energy) into electricity.

When the uranium is used up, it is radioactive, and must be stored. Usually it is buried deep in the ground in special containers designed to stop any radioactivity from leaking.

Did you know? Plutonium-239, a by-product of uranium, remains radioactive for 24,110 years!

Advantages

Nuclear power is between 20 and 50 per cent more expensive to produce than coal or gas-fired power. However it does not produce any greenhouse gases, unlike coal. It can produce large amounts of electricity and it is a reliable source of energy.

Disadvantages

Uranium is not a renewable source of energy. Nuclear accidents are among the worst type of man-made disasters possible and a great deal of money has to be spent on safety in nuclear power plants to try and avoid these disasters. Also, waste from nuclear energy stays radioactive for thousands of years making it harmful to both humans and the environment. Great care has to be taken in storing this waste safely.

Use in Australia and around the world

Australia has never generated electricity from nuclear energy. The only nuclear activity in Australia is conducted at a research reactor at Lucas Heights, Sydney. It has operated safely since 1958 and is run by ANSTO - the Australian Nuclear Science and Technology Organisation.

A research reactor is different from one used to generate electricity. Instead of producing heat, it produces neutrons which are used for medicine and research. The ANSTO reactor is also much smaller than a power reactor.

A power reactor can contain more than 150 tonnes of radioactive fuel, whereas the research reactor has only about 7 kg. Because uranium is very dense, 7kg can fit into a coffee mug.

Nuclear energy provides 17% of the world's electricity. It is generated in over 400 plants in around 25 countries.