核分裂---- slow-moving neutrons?!

The neutrons are slow-moving so that the nuclear fission process is controllable.

If the neutrons are moving with high speeds, then they have a high content of kinetic energy, in which the rate of reaction and the amount of energy released will be uncontrollable, this will lead to an explosion (release of energy in a very short period of time (simultaneously)). This is undesirable.

We need the energy released in a controllable way. So, the neutrons used has to be slowed down.

2. The neutrons are slow so that it has a higher chance to be captured by nucleus. This is easy to understand. When the neutrons are slow-moving, then it has a longer time stay in the attraction region of the nucleus, and hence it has a higher chance to be captured. Just like a thief, if he ran slowly, then it is much easier for a police to catch him.


To slow down the neutrons, moderators are used (deutrium (heavy water)). The amount of neutrons are controlled by using control rods.