The process by which neutrons released from the fission of a ²³⁵U uranium nucleus may fission other uranium nuclei, and neutrons released from these fissions may in turn fission other uranium nuclei. The chain fission reaction can occur under the condition that the resulting neutrons almost always hit the nucleus of the uranium atom. Then the number of split atoms in each successive generation multiplies and the amount of energy released increases rapidly. This is the principle of the atomic bomb. For the peaceful use of a fission chain reaction, the number of neutrons involved in the fission is usually regulated by an absorber so that only about one neutron from each fission initiates the next fission. Thus, the intensity of the reaction does not decrease or increase and the energy released can be used, for example, in a nuclear power plant reactor.