Irradiation growth in zirconium-tin alloys at 353 and 553 K

Irradiation growth measurements have been made on annealed polycrystalline Zr-0.1% Sn and Zr-1.5% Sn alloy specimens irradiated at 353 and 553 K in the DIDO reactor up to fast neutron fluences of 11.0x1025 n/m2 and 6.6x1025 n/m2 (E > 1 MeV) respectively. Breakaway growth is observed in Zr-1.5% Sn at both temperatures above a fluence of ≅ 3x1025 n/m2 with the post-breakaway growth rates exhibiting a direct temperature dependence. Differences in high fluence growth behaviour in annealed Zr-1.5% Sn alloy and Zircaloy-2 have been tentatively associated with the influence of minor alloying elements and impurities on the evolution of the damage microstructure in Zircaloy-2. Growth strains in annealed Zr-0.1% Sn at 353 and 553 K are similar to those in iodide grade zirconium but differences in high fluence linear growth rates are now apparent. (orig.)