Question: what is a nuclear reaction

Michael Wharmby answered on 11 Jun 2011:

A nuclear reaction is (literally) a reaction which takes place in the nucleus (the very middle bit of an atom). There are two sorts of nuclear reaction: fission and fusion.
In fission, the nucleus splits in two and loses a tiny bit of mass. By E = mc^2 (E – energy, m -mass and c – the speed of light, 300,000,000 m/s) that tiny bit of mass gets changed into an awful lot of energy. The nuclear reaction also releases other radiation which is dangerous the people. This is what nuclear power stations currently use.
In fusion two small nuclei come together, combine and lose a little mass to make a new bigger nucleus. This again releases lots of energy, but none of the dangerous radiation is released. Currently this isn’t usable on a big scale, but it does work and the technology is improving to make it work.