Irradiation growth in cold-worked Zircaloy-2

Irradiation growth has been studied in 25 percent cold-worked Zircaloy-2 at temperatures of 353 and 553 K. At 353 K, a rapid increase in growth strain occurs at doses less than 1024 n/m2(neutrons per square meter) followed by a linear growth rate at higher dose. At 553 K, significantly lower strains are attained upon irradiation to 1024 n/m2, but the subsequent growth rate is higher. Thus, at a dose of about 1025 n/m2, the growth strains achieved at the two temperatures are similar. The data have been fitted to both linear and power law relationships, and comparisons are made with data reported for both annealed and cold-worked Zircaloy-2. The observed growth behavior is interpreted in terms of a growth model consisting of two temperature-dependent components; one due to the nucleation and growth of small defect clusters and loops during the early stages of irradiation, and a second due to the preferential absorption of interstitials at the existing dislocation structure. 15 refs