Statistical investigation of the weld joint efficiencies in the repaired WWER pressure vessel

Highlights: • This is the article on weld joint efficiencies in the repaired WWER pressure vessel. • The analysis showed good agreement between the empirical and theoretical curves. • The study describes the specific case of defected nozzle after the crack repair. • Joints welded under ceramic flux showed lower durability. • Ceramic flux cannot be recommended for welding of steel 15Cr2MoVA intended for WWER. From a fatigue point of view, the second most important WWER (Water-Water Energetic Reactor) pressure vessel component (after closure studs) are the primary nozzles. These parts are included in the in-service inspection performed every 4 years when non-destructive testing techniques like ultrasonic, eddy-current and dye-penetration methods are applied. After the determination of the severity of fatigue crack, the progress of initial defects over time can be prevented by repair welding.