Calculation of critical parameters of the experimental stand «FKBN»

The experimental stand «FKBN» (physical fast-neutron boiler) is a critical assembly in which the vertical lift mechanism is used. With the help of such stands, in the second half of the 20th century, experiments were conducted on the effect of various materials in various designs on the kinetic characteristics of a system with fissile material. Mostly, such works were conducted in Los Alamos National Laboratory (USA), Oak Ridge Laboratory (USA), VNIIEF (Russia), VNIITF (Russia). On such installations, there were often accidents with the emergence of a self-sustaining chain reaction. One of these occurred on April 5, 1968 in VNIITF in Chelyabinsk-70 (now Snezhinsk). In this paper, the critical state of the stand is calculated for different distances of the reflector from the core under the conditions of the presence and absence of solid polyethylene inside the core. The configurations in which K_eff=1,000 and K_eff=1,000+β_eff are of interest are of interest. As a tool, the CSAS6 sequence of the SCALE-6.2.1 software package was used. (paper)