Volume 2, Issue 6 (June 2005)
The Effect of Beta-Quenching in Final Dimension on the Irradiation Growth of Tubes and Channels
The effect of β-quenching performed in the final size of Zircaloy-4 guide tubes and Zircaloy-2 sheets during fabrication process on the products' mechanical properties, crystallographic texture, microstructure, and corrosion behavior has been investigated and presented in this paper. Moreover, the impact of this processing on the irradiation growth of pressurized water reactor Zircaloy-4 guide tubes in a test reactor and Zircaloy-2 fuel channels in boiling water reactors has been evaluated. The results indicate that the irradiation growth rates of the final dimension β-quenched (FDBQ) products are substantially lower than those fabricated by conventional (Standard) techniques. BWR channels irradiated up to a fast neutron fluence of about 9 × 1025 m−2 maintain this low growth behavior. Corrosion properties of FDBQ products have been made similar to that of the Standard material by performing an α-annealing step after the β-quenching. The annealing temperature and annealing time have been optimized in order to obtain good corrosion resistance. In-reactor data on Zircaloy-2 channels irradiated to a fuel assembly exposure of about 50 MWd/kgU indicate similar corrosion performance for the FDBQ and Standard materials. Finally, the in-reactor data on Zircaloy-2 channels show that bowing of the FDBQ and Standard channels is comparable up to a fast neutron fluence of about 7 × 1025 m−2.