Effect of tin on the irradiation growth of polycrystalline zirconium

Abstract

Measurements of irradiation growth of polycrystalline Zr-1.5% Sn and Zr-0.1% Sn alloys at 353 K and 553 K have been made following fast neutron irradiation with fluences up to 3.1 × 10 25 n/m 2. At 353 K, growth of Zr-1.5% Sn virtually saturated at a strain of 4.5 × 10 −4 after a fluence of ~10 24 n/m 2. At this temperature, Zr-0.1% Sn continued to grów until ~ 2 × 10 25 n/m 2, when the strain levelled off at ~ 1.2×10 −3 . At 553 K, Zr-1.5% Sn initially grew about twice as fast as the 0.1% Sn alloy, but both eventually reached the same steady state rate of ~ 2.4 × 10 −29 m 2/n. Comparison of the data for the 1.5% Sn material with those for Zircaloy-2 from earlier work reveals that at 353 K, growth is suppressed by the presence of Sn atoms, which may serve as vacancy traps. However, at 553 K, minor additions and impurities in Zircaloy-2 (such as Fe, Ni, Cr and O) play an important role and cannot be neglected. The growth behaviour of Zr-0.1% Sn is similar to that of pure polycrystalline zirconium, especially at 353 K, indicating that the addition of Sn at this concentration does not strongly influence the growth of zirconium.