Structural features of hydrogenated E110opt and E635 tubes

The paper investigates the behavior of the hydride phase in hydrogenated tubes made of Russian zirconium E635 and E110opt alloys. The orientation and fraction of mesoscale hydrides in the alloy matrix have been described by analyzing optical metallographic images using the developed software. Metallographic images were used to assess the predominant orientation of hydrides in the axial section of the tube, as well as the surface density of the hydride phase with an increase in the concentration of hydrogen in tubes made of different alloys. It has been shown that increasing the hydrogen concentration to 600–700 wppm increases the number of radially oriented hydrides, which is associated with the development of compressive radial stress during the formation of tangentially oriented hydrides at the initial stage. Increasing the hydrogen concentration in E110opt alloy cladding tubes to 600–700 wppm leads to a change in the orientation of the (cid:14) -zirconium basal axes, which results in an increase in the integral textural f R f -parameter and a decrease in the f T ff - and f L f -parameters. This change is due to the development of radial compressive stress and is only possible due to the activation of twinning in the grains, the basal axes of which are deflected from the compressive stress at an angle of up to 90 degrees.