The contribution of dislocation loops to radiation growth and creep of Zircaloy - 2

Abstract

Annealed specimens of Zircaloy-2 have been examined using transmission electron microscopy after irradiation to various fluences up to 1 × 10 26n · m −2 ( E > 1 MeV ) at 573 K. Measurements of the size and concentration of the radiation-induced defects show that they make a negligible contribution to radiation growth. An alternative mechanism is sug-gested, based on the bias interaction between interstitials and dislocations. A specimen of cold-worked and stress-relieved Zircaloy-2, creep tested at 138 MPa in a reactor at 573 K, was also examined. It was shown that the total number of point defects in the form of clusters was the same as in an unstressed, annealed specimen. It can be concluded that the stress-induced orientation of dislocation loops makes a negligible contribution to radiation creep of Zircaloy-2 at 573 K, regardless of the magnitude of the applied stress.