In the 1930s and 40s scientists found out that if they bombarded a uranium atom with a neutron the nucleus would split up into two parts. When this happens, energy is set free. We call this nuclear fission.

Fission was first used in atomic bombs that the Americans dropped over Japan to end the Second World War. The bombs released so much energy that they killed hundreds of thousands of people. Later on, scientists found out how this energy could be used in a peaceful way.

In the 1950s the first atomic reactors were built. They produced energy by splitting atoms.

Mushroom cloud of the atomic bomb dropped over Nagasaki in 1945
Image:By James Charles - U.S. National Archives and Records Administration,
Public Domain, Link 


First nuclear power station in Calder Hall, UK in 1957
Image:UK government agencies, OGL 3,
via Wikimedia Commons