Branching-chain reactions nuclear fission

Chain reactions are recursive reaction cycles that regenerate their intermediates. Such cycles occur in combustion, atmospheric chemistry, pyrolysis. photolysis, polymerization, nuclear fusion and fission, and catalysis. Typical steps in these systems include initiation, propagation, and termination. often accompanied by chain branching and various side reactions. Examples 2.2 to 2.5 describe simple chain reaction schemes. 

Figure 26-11 A self-propagating nuclear chain reaction. A stray neutron induces a single fission, liberating more neutrons. Each of them induces another fission, each of which is accompanied by release of two or three neutrons. The chain continues to branch in this way, very quickly resulting in an explosive rate of fission.

Nuclear reaction(s) producing noble gas isotope(s) from stable or long-lived isotope during an irradiation in a nuclear reactor, or parent isotopes with half-lives less than 10 years, typical or suspected abundance at the time of formation of the solar system. For longer-lived parent isotopes, current abundance (%) of element. For actinides, " He yields are the number of atoms produced per decay chain, fission Xe yields are branching ratio for Xe. Yields for other isotopes are given in Table 2. 

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