[en] The activity sources of the primary circuit of a sodium cooled fast reactor are considered. The circuit activity caused by solid and gaseous fission products is shown to be coamparble with the activity of corrosion products and sodium in the case of failure of approximately 1% of total number of fuel elements. The activity of the reactor gas system at a specific activity of ⁴¹Ar 2x10^-4 Ci/l is determined by fission products already at 10^-4-10^-3% fuel element failure. The dependence is shown of the shielding thickness around the column with protection and control system o(PCS) mechanisms n radiation of radioactive inert gases at different share of fuel elements with failed cans. Exposure doses to population outside the sanitary-protection zone would not exceed the rated value (0.17 rem per year) provided not more than 1-2% of total number of fuel elements fail