Neutrons

[Kylon]

When neutrons leave fissionable materials, does the energy come from the neutron becoming a electron and a proton? Or does the neutron itself break down into pure energy?

[superchump]

Well to sustain a fission reaction, a supply of neutrons must continue the reaction. The energy is mostly from the fissioning process itself and neutron release is a by-product. The neutrons hopefully continue the chain reaction.

[JaKiri]

It's because of the mass (and energy obviously) defecit between the products and the reactants.

 

The curve of nuclear binding energy per nucleon starts at 0 (obviously), quickly increases to it's peak at Iron, then gradually drops away.

 

You get energy released from a reaction which results in an increase of NBE/Nucleon, which is why fusion of light elements releases energy, and so does fission of heavy elements.

 

This would be easier to explain if someone drew me/found a copy of the curve.

 

ps. This curve also explains why the transironic (now there's a silly name, I can't remember if it's actually used or not) elements aren't created in your average star, but by supernovae.