Stochastic neutron dynamics is important task in nuclear power plant design and nuclear reactor safety. In this paper, basic concepts and research methods for stochastic neutron kinetics are introduced and historical development and research status in the field are sketched out. Multiplicities of fission neutrons and photons are main sources of zero power reactor noise. Based on description equation of neutron fluctuation and its solution, stochastic theory of zero power and power reactor noise is evolved. Stochastic neutron dynamics are applied in important areas such as reactivity microscopic measurement, power reactor noise measurement and analysis, nuclear criticality excursion analysis, nuclear material detection and identification and so on. In the past half century, however, it lacks available method and tool to implement quantitative analysis of problems such as probability distribution of burst waiting time of neutron initiation in pulse reactor. In recent years, important progress is made in generalized semi-Markov process simulation method, which is applied to stochastic neutron kinetic process simulation. It reveals inherent law of neutron initiation experiments conducted in pulse reactor. At last, research topics to be solved in stochastic neutron dynamics are discussed.

A method is proposed for choosing electron cutoff energy,which is self-adaptive with cell size,background material and electron position.As residuary range of an electron defined by total stopping power is less than distance to the nearest cell boundary,the electron is killed.Compared with the CUT model used in MCNP program,efficiency and precision of self-adaptation method is higher.The most important is that cutoff energy of electron is selected automatically in program in all models,without consideration of energy of particles or dimension of model.

The influences of the second periodic-forced term on the forced Brusselator are discussed.When the frequency of the two forces are commensurable, the system, which is chaos without the second forcing, can be chaos or periodic. If the two frequency are incommensurable, the system appears one mo re new movement state other than chaos and periodic:that is an strange nonchaotic attractor.