We might think of induced nuclear fission as a fission reactionthat occurs when a neutron is captured by, say, a uranium-235 atomand that atomic nucleus undergoes fission as a result. Most all ofthe fission events within a nuclear reactor or nuclear weapon areinduced. Given this, we might then compare that fission event to aspontaneous fission event wherein the atomic nucleus of auranium-235 atom spontaneously undergoes fission without havingcaptured a neutron.