Effect of dissolved oxygen in steam on the corrosion behaviors of zirconium alloys

Advanced boiling water reactors (ABWRS) show optimistic application prospect in the future. However, in these reactors, influence of dissolved oxygen (DO) on the corrosion rate of zirconium fuel claddings should be seriously considered. In this work, the effect of the dissolved oxygen (DO) on the corrosion behaviors of Zr-4, N18 (Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr) and N36 (Zr-1.0Sn-1.0Nb-0.3Fe) alloys in 400℃ and 10.3 MPa steam was investigated. A recirculation loop was used to control the DO level at about 0.1×10^-6 and 1.0×10^-6, respectively. The results showed that, under the two DO level conditions, N18 had almost the same weight gain as Zr-4 after exposure for 90 d, and N36 had the highest weight gain. In the initial period of the corrosion test, the three alloys had lower weight gain under higher DO level condition. With the increase of exposure time, the weight gain under 1.0×10^-6DO level exceeded gradually the weight gain under 0.1×10^-6 level for each alloy, and the time needed for exceeding was significantly shorter for the alloy with higher Nb content.