Since it is desirable for power reactors to operate at steady power at a temperature of ∼300°C, the main purpose of this study is to relate the dispersion and spheroidization of zirconium hydrides to operating procedures. Accordingly, we stress the hydride attack and supersaturation of hydrogen solubilities in the pre- and post-irradiated Zircaloys. Through this study we could find a way to improve the dispersed spheroidization process. The hydrogen diffusion coefficient of post-irradiated Zircaloy-4 with a neutron fluence of 1.64 × 1019 n/cm2 is 5 to 50% higher than that of the pre-irradiated Zircaloy-4. We considered there is a workable way to spheroidize hydrides with a temperature lower than the eutectoid temperature for irradiated Zircaloy, 547°C. Therefore, we propose to adapt the peritectoid reaction temperature, 255°C, to spheroidize zirconium hydrides. In the next section, we have studied the creep and corrosion behavior of annealed, hydrided, and spheroidized pre-irradiated Zircaloy-4 specimens following the proposed process. An annealed Zircaloy-4 specimen has the lowest minimum creep rate and the highest ductility and loading strain. A hydrided Zircaloy-4 specimen has the smallest loading strain and the lowest ductility. The spheroidized Zircaloy-4 specimen following the proposed process has a higher minimum creep rate than that of a hydrided one; however, the ductility of the specimen with sperhoidized hydrides is recovered to ∼90% of the annealed one at 500°C The spheroidization treatment can improve the corrosion resistance of the hydrided specimen effectively in the temperature range of 200 to 400°C with the hydrogen concentration of the specimen up to 1000 ppm, although at 500°C the effect of spheroidization treatment on the hydride is decreased. We conclude that the proposed process with pre-irradiated Zircaloy and partially complete spheroidization can still improve the mechanical properties and corrosion behavior of the Zircaloy.