Abstarct: Using Natural uranium, a chain reaction can be created. This was used by Enrico Fermi for first time in 1942 at the University of Chicago. With the exploitation of Bushehr nuclear power plant, Iran joined to the ranks of nuclear power producers in 1393. Then considering the importance of this issue, in this study we discuss introducing, studying and researching in sections related to nuclear technology particularly how to design the burning processes and control of these processes to the appropriate utilization in the Bushehr nuclear power plant that is the type PWR -1000. To carry out controlled fission of Uranium chains, we need to have a uniform neutron flux. After the nuclear fission process, a variety of fission fragments are produced that may affect the stability of rate neutron flux. The most important fragments of these fission fragments are Xenon and Samarium which because of their high thermal neutron absorption cross section, they change neutron flux rate resulting reactor shutdown. Given the importance of this issue, there are various methods to study the oscillation rates of production and consumption of these nucleuses. In this study, we are going to investigate this issue by determination the density of neutrons in the core of the reactor by solving the point reactor kinetic equation and by using it, coupled differential equations related to rate of production and consumption of them would be investigated. By studying the feedback, this topic will be discussed. During the reactor cycle Xenon by changing power to the highest level, and then navigating to the previous level, in approximately 65 hours after the change of power, it reaches to its highest level. When restarting the reactor, Samarium also has a maximum amount.