Abstract :
Nuclear fission is the most fundamental reaction between neutrons and atomic nuclei of nuclear fuel in a reactor. In this paper, according to the nonlinear dynamical behavior of the neutron transport system in space (or the distribution behavior of neutrons in the reactor) which reveals this essential reaction, we investigate the relation between nuclear fission and spatial chaos, neutron multiplication theory, as well as the relation between spatial periodic bifurcation, concentration rate of uranium and neutron effective gain coefficient. In addition, from the chaotic behavior of spatial nonlinear dynamical system, we obtain that the absolutely stable area of nuclear reactor is neutron effective multiplication factor 0 < k < 3/4, which is markedly different from the formerly mentioned k < 1.