Examination of the radiation state of the graphite masonry of commercial reactors

The results of an examination of the radiation state of the graphite masonry in three commercial uranium-graphite reactors at the Mayak Industrial Association are presented. On the basis of these results, conclusions are drawn about the nuclear safety of the masonry and radiation licenses are composed. The comprehensive radiation examination made it possible to determine the level, composition, and distribution of radioactive contamination of the masonry and the level and distribution of neutron and γ radiation and to predict the variation of the radionuclide activity in the graphite as a function of the holding time. These data are required to make design decisions about further reactor decommissioning stages.