Some results of studying of spatial kinetics in fast reactors

The paper presents an analysis of the solution to the spatial non-stationary equation of neutron transport the example of a fast reactor. To solve the spatial kinetics equation in three-dimensional geometry in diffusion approximation a calculated code TIME was created. In a direct problem the neutron flux density and its derivatives (for example, reactor power) are determinate at each time step. Solution of a direct problem allows to investigate a deformation of a steady neutron field form which is one of the main reasons of spatial effects occurrence in a reactor. Such deformations affect spatial distribution of delayed-neutrons that is reflected in behavior of reactivity and in related with it results of experiments. The paper also considers some questions of reducing of spatial effects through a choice of a point of reactivity input or detector location. In the inverse problem the reactor reactivity is calculated using the known dependence of reactor power on time. The paper describes some problems of solving the inverse problem taking into account spatial effects. (author)