Axial Distributions of Fission Reaction Rates in the Annular Core of the ASTRA Critical Facility with Poison Profiling Elements in the Internal Reflector

Computational modeling of experiments on measurement of axial distributions of fission reaction rates in configurations of the ASTRA critical facility simulating a HTGR with annular core is performed. Absorbing elements were installed in the internal reflector of critical assemblies to flatten the neutron flux radial distribution. Measurements of the fission reaction rates were performed both in a configuration with a flattened neutron field and in a configuration with control rods (CR) inserted in an external graphite reflector.