Corrosion of some V- and Nb-base alloys under irradiation in water

In the work, results of the irradiation influence in first circuit water of the SM reactor on the weight alteration, phase composition of corrosion pr oducts, and rupture type of some V- and Nb-base alloys are presented. The i rradiation was carried out at 50-65 degrees C in water and at 70-95 degrees C in helium for comparison to neutron fluence of similar or equal to 5 x 1 0(21) n/cm(2) (E > 0.1 MeV). Water rate was about 13.5 m/s and dissolved ox ygen content was 550-720 ppb. As it is shown, V-alloys have undergone the s trong corrosion in water under irradiation already at such low temperature as 50-65 degrees C. The maximum corrosion rate occurs with V3.0T1 alloy (ab out 900 mu m/yr), and the minimal with the V-6.1Cr-5.3Ti-ZrC alloy (about 5 0 mu m/yr). The corrosion products are oxides: V2O5 for pure vanadium, TiO2 for V-3.0Ti alloy and TiO for V-4.4Cr-3.9Ti. The overwhelming majority of corrosion products are taken away by the water flow. These results compare with the data of the autoclave testings carried out in the Argonne National Laboratory. (C) 1999 Published by Elsevier Science B.V. All rights reserve d.