Irradiation growth of zirconium single crystals: A review

Theoretical investigation of microstructure evolution and deformation of zirconium under neutron irradiation

“…Available experimental data can be summarized as follows: (a) a loops nucleate from the very beginning of irradiation and reach a typical density of $10 22 m À3 after several dpa, and (b) c loops are of vacancy type and do not appear to nucleate prior to a dose of $3 dpa and reach an order of magnitude smaller density, $10 21 m À3 (see [24,25] for reviews and [26,27] for observations). The reasons for the incubation dose for nucleation of basal vacancy loops are unknown as yet.…”

“…2 shows the evolution of the number densities of interstitial-type prismatic loops and vacancy-type basal loops, calculated using Eqs. (24) and (25) with the parameters presented in Table 1. The total number density in this figure is the sum of densities of prismatic loops with different Burgers vectors: N a;max ¼ N a 1 ;max þ N a 2 ;max þ N a 3 ;max .…”

Neutron irradiation performance of Zircaloy-4 under research reactor operating conditions

“…Holt and Gilbert (1986) examined the hci type dislocation loop of annealed zircaloys under a high fluence with 8.6 Â 10 25 n/m 2 between 553 and 584 K. In these results, hci-loops were observed for annealed zircaloy-2 and zircaloy-4 at greater than 3.0 Â 10 25 n/m 2 , while hai-loops were only shown for specimens irradiated with fluence below 3.0 Â 10 25 n/m 2 . Further work by many authors confirmed that hai-loops nucleate from the beginning of the irradiation, while hci-loops form above a threshold dose only, indicating that the kinetics of the formation of hai and hci-type loops differ (Bacon, 1993;Carpenter et al, 1981Carpenter et al, , 1988Frank, 1988;Holt and Gilbert, 1986;Hood, 1988;Jostsons et al, 1977aJostsons et al, , 1977bNorthwood et al, 1979;Osetsky et al, 2002;Pasianot and Monti, 1999;Was, 2007;Woo, 1979;Woo, 1988Woo, , 2000Woo and Liu, 2009). …”

Dislocation-accelerated void formation under irradiation in zirconium

“…It seems that vacancies diffuse to the metal-oxide interface to relieve stress, leading to the nucleation and growth of vacancy loops. The nucleation, growth and character of c-component vacancy loops are governed to a large extent by a stress in the matrix, and the results would be accelerated or "breakaway" growth in neutron-irradiated zirconium [54]. Brager et al [12] have also shown that applied tensile stresses enhance swelling in neutron-irradiated 316 stainless steel, and that the number densities of both voids and Frankel loops are sensitive to the stress level.…”