Аннотация:Various versions of fuel cycle relative to WWER-440 are studied. It is shown that the five-year run of fuel assembly with fuel enrichment of 4.4% by scheme of its interreactor motion from centre to reactor core periphery is most efficient for power units with load factor exceeding the design one. Reliability of calculational fuel element modelling is confirmed by measuring activity of the primary circuit coolant and CGS fuel elements. Total specific activity of the coolant (7; 7.5; 6.8)10-5 Ci/l and iodine (17; 6.8; 6.2)10-6 Ci/l is shown for initial, middle and end stages of the fuel cycle correspondingly.