# How do nuclear reactors utilize chain reactions?

The typical source that is used in a nuclear reactor is ${U}^{235}$, which absorbs a neutron to become ${U}^{236}$, which is unstable, so it splits, releasing energy in the form of heat, as well as two stable nuclei, such as barium-144 and krypton-89, which release a neutron to continue the chain as it strikes another ${U}^{235}$ nucleus, causing that one to become unstable, and so on, until all the reactor''s fuel has been used up.