MICROSTRUCTURAL ASPECTS OF ACCELERATED DEFORMATION OF ZIRCALOY NUCLEAR-REACTOR COMPONENTS DURING SERVICE

X-ray diffraction (XRD) and transmission electron microscopy (TEM) hav e been used to characterize microstructural and microchemical changes produced by irradiation in nuclear reactor core components fabricated from Zircaloy-2 and -4. These microstructural measurements have been c orrelated with the known deformation characteristics of the various co mponents. The results show that the c-component defect structure in th e as-fabricated state, in addition to that which develops during irrad iation, is important in controlling the rate of irradiation-induced de formation.