[en] Tests of niobium and vanadium base alloys are carried out in sodium on the test bench during 1000 h at 400 and 600 deg C and in the BOR-60 primary circuit during 8000 h at 400-600 deg C. Alloy systems with different doping element contents (Nb-W; Nb-V; Nb-Zr-C; V-Ti; V-Cr; V-Ti-Cr; V-Zr-C) as well as multiple-component systems on the base of these alloys are investigated. Considerable difference in results of reactor and bench tests, conditioned by radiation and corrosion damage of metals and by emergence of new effects, resulting from the combined action of damageing factors is revealed. It is shown, that the reason for decreasing service properties of vanadium and niobium base alloy in sodium medium under irradiation leis in the reduction of alloy ductility down to complete embrittlement, which appears together with radiation hardening. Material dissolution in sodium under irradiation is not sufficient. Corrosion resistance of the investigated materials, estimated by corrosion rate, is satisfactory. Minimal changes of properties of niobium alloys (Nb-Zr-C and Nb-W-Zr-C) and vanadium W-Ti-Cr-type alloys are registered