How To Start A Nuclear Chain Reaction

The Neutron was discovered in the 1930's when scientists found unknown radiation being emitted by a Polonium 210 reacting with Berylium. This would lead to the discovery of nuclear fission, the invention of the nuclear reactor, and the nuclear bomb. And while the energy from the bomb would come from fission, it would need some neutrons generated in the plutonium pit at exactly the right time to kick off the reaction near peak criticality, not too soon, and not too late. And that's what we're t